Garmin 172 GPS Receiver User Manual

GPSMAP 172/172C
chartplotting receivers
owner’s manual
GPSMAP172C Cover.indd 1
10/5/2004 11:05:26 AM
© Copyright 2004 Garmin Ltd. or its subsidiaries
Garmin International, Inc.
1200 East 151st Street,
Olathe, Kansas 66062, U.S.A.
Tel. 913/397.8200 or 800/800.1020
Fax 913/397.8282
Garmin (Europe) Ltd.
Unit 5, The Quadrangle, Abbey Park Industrial
Estate, Romsey, SO51 9DL, U.K.
Tel. 44/0870.8501241
Fax 44/0870.8501251
Garmin Corporation
No. 68, Jangshu 2nd Road, Shijr, Taipei County,
Taiwan
Tel. 886/2.2642.9199
Fax 886/2.2642.9099
All rights reserved. Except as expressly provided herein, no part of this manual may be reproduced, copied, transmitted, disseminated, downloaded or stored in any storage
medium, for any purpose without the express prior written consent of Garmin. Garmin hereby grants permission to download a single copy of this manual onto a hard drive
or other electronic storage medium to be viewed and to print one copy of this manual or of any revision hereto, provided that such electronic or printed copy of this manual
must contain the complete text of this copyright notice and provided further that any unauthorized commercial distribution of this manual or any revision hereto is strictly
prohibited.
Information in this document is subject to change without notice. Garmin reserves the right to change or improve its products and to make changes in the content without
obligation to notify any person or organization of such changes or improvements. Visit the Garmin Web site (www.garmin.com) for current updates and supplemental
information concerning the use and operation of this and other Garmin products.
Garmin®, GPSMAP®, AutoLocate®, TracBack®, BlueChart®, and MapSource® are registered trademarks of Garmin Ltd. or its subsidiaries and may not be used without the
express permission of Garmin.
October 2004
GPSMAP172C Cover.indd 2
Part Number 190-00321-00 Rev. B
Printed in Taiwan
10/5/2004 11:06:30 AM
Preface
Congratulations on choosing one of the most advanced marine navigation systems available! The
Garmin GPSMAP 172/172C models utilize the proven performance of Garmin GPS and full-featured mapping to create an unsurpassed marine navigation chartplotter.
This manual covers instructions for the GPSMAP 172 and GPSMAP 172C (color). Unit operation
and specifications will be the same on both models unless otheriwse specified. For GSD 20 sonar related
operations, refer to “GSD 20 Sounder Module with Garmin Chartplotters” (190-00241-03). To get the
most out of your new navigation system, take the time to go through this owner’s manual and learn the
operating procedures for your unit. This manual is broken down into two parts for your convenience.
Part One introduces you to the GPSMAP 172/172C and provides a Getting Started tour so that you
may become more familiar with the unit. This section provides you with a basic knowledge necessary to
use the unit.
Part Two is divided into sections that provide detailed references to the advanced features and operations of the GPSMAP 172/172C. This allows you to concentrate on a specific topic quickly and look up
detailed information about the GPSMAP 172/172C.
Software License Agreement
BY USING THE GPSMAP 172/172C, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS OF THE FOLLOWING SOFTWARE LICENSE AGREEMENT. PLEASE READ THIS AGREEMENT
CAREFULLY.
Garmin grants you a limited license to use the software embedded in this device (the “Software”) in
binary executable form in the normal operation of the product. Title, ownership rights and intellectual
property rights in and to the Software remain in Garmin.
You acknowledge that the Software is the property of Garmin and is protected under the United
States of America copyright laws and international copyright treaties. You further acknowledge that the
structure, organization and code of the Software are valuable trade secrets of Garmin and that the Software
in source code form remains a valuable trade secret of Garmin. You agree not to decompile, disassemble,
modify, reverse assemble, reverse engineer or reduce to human readable form the Software or any part
thereof or create any derivative works based on the Software. You agree not to export or re-export the
Software to any country in violation of the export control laws of the United States of America.
Introduction
Preface/Registration/
Software License Agreement
Customer Service Product Registration
Help us better support you by completing our
on-line registration today!
Have the serial number of your GPSMAP 172/172C
handy and connect to our web site (www.garmin.com).
Look for the Product Registration link on the Home
page. Also, be sure to record your serial number in the
area provided on page iv of this manual.
NOTE: If you have previously registered a Garmin
product purchase, we invite you to re-register using
our NEW on-line system. Many services provided by
our new product registration system are now being
automated and re-registering your purchase ensures
you the best possible support from Garmin.
i
Introduction
FCC Compliance
FCC Compliance
The GPSMAP 172/172C complies with Part 15 of the FCC interference limits for Class B digital devices
FOR HOME OR OFFICE USE. These limits are designed to provide more reasonable protection against
harmful interference in a residential installation, and are more stringent than “outdoor” requirements.
Operation of this device is subject to the following conditions: (1) This device may not cause harmful
interference, and (2) this device must accept any interference received, including interference that may
cause undesired operation.
This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in
accordance with the instructions, may cause harmful interference to radio communications. However,
there is no guarantee that interference will not occur in a particular installation. If this equipment does
cause harmful interference to radio or television reception, which can be determined by turning the
equipment off and on, the user is encouraged to try to correct the interference by one of the following
measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and the receiver.
• Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected.
• Consult the dealer or an experienced radio/TV technician for help.
The GPS 172/172C does not contain any user-serviceable parts. Repairs should only be made by an
authorized Garmin service center. Unauthorized repairs or modifications could result in permanent
damage to the equipment, and void your warranty and your authority to operate this device under Part
15 regulations.
ii
The GPS system is operated by the United States government, which is solely responsible for its accuracy
and maintenance. The system is subject to changes which could affect the accuracy and performance of
all GPS equipment. Although the Garmin GPSMAP 172/172C is a precision electronic NAVigation AID
(NAVAID), any NAVAID can be misused or misinterpreted and, therefore, become unsafe.
Introduction
Warnings and
Precautions
The electronic chart is an aid to navigation and is designed to facilitate the use of authorized government
charts, not replace them. Only official government charts and notices to mariners contain all information
needed for safe navigation – and, as always, the user is responsible for their prudent use.
Use the GPSMAP 172/172C at your own risk. To reduce the risk of unsafe operation, carefully review
and understand all aspects of this Owner’s Manual—and thoroughly practice operation using the simulator
mode prior to actual use. When in actual use, carefully compare indications from the GPSMAP 172/172C to
all available navigation sources, including the information from other NAVAIDs, visual sightings, charts, etc.
For safety, always resolve any discrepancies before continuing navigation.
CAUTION: IT IS THE USER’S RESPONSIBILITY TO USE THIS PRODUCT PRUDENTLY. THIS
PRODUCT IS INTENDED TO BE USED ONLY AS A NAVIGATIONAL AID AND MUST NOT BE USED
FOR ANY PURPOSE REQUIRING PRECISE MEASUREMENT OF DIRECTION, DISTANCE, LOCATION, OR TOPOGRAPHY.

MAP DATA INFORMATION: One of the goals of Garmin is to provide customers with the most
complete and accurate cartography that is available to us at a reasonable cost. We use a combination of
governmental and private data sources, which we identify (as required) in product literature and copyright messages displayed to the consumer. Virtually all data sources contain inaccurate or incomplete
data to some degree. This is particularly true outside the United States, where complete and accurate
digital data is either not available or prohibitively expensive.
WARNING: This product, its packaging, and its components contain chemicals known to the State
of California to cause cancer, birth defects, or reproductive harm. This Notice is being provided in
accordance with California’s Proposition 65. If you have any questions or would like additional information, please refer to our web site at http://www.garmin.com/prop65.
iii
Introduction
Warranty and
Serial Number
Serial Number
Use this area to record the serial number (8-digit number
located on the back of the unit) in case it is lost, stolen, or
needs service. Be sure to keep your original sales receipt in a
safe place or attach a photocopy inside the manual.
Serial Number:
*
*

The Garmin GPSMAP 172/172C has no user-serviceable
parts. and is fastened shut with screws. Any attempt to
open the case to change or modify the unit in any way voids
your warranty and may result in permanent damage to the
equipment.
iv
This Garmin product is warranted to be free from defects in materials or workmanship for one year
from the date of purchase. Within this period, Garmin will at its sole option repair or replace any components that fail in normal use. Such repairs or replacement will be made at no charge to the customer for
parts or labor, provided that the customer shall be responsible for any transportation cost. This warranty
does not cover failures due to abuse, misuse, accident or unauthorized alteration or repairs.
THE WARRANTIES AND REMEDIES CONTAINED HEREIN ARE EXCLUSIVE AND IN LIEU OF ALL
OTHER WARRANTIES EXPRESS OR IMPLIED OR STATUTORY, INCLUDING ANY LIABILITY ARISING
UNDER ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, STATUTORY OR OTHERWISE. THIS WARRANTY GIVES YOU SPECIFIC LEGAL Rights, WHICH MAY VARY
FROM STATE TO STATE.
IN NO EVENT SHALL GARMIN BE LIABLE FOR ANY INCIDENTAL, SPECIAL, INDIRECT OR
CONSEQUENTIAL DAMAGES, WHETHER RESULTING FROM THE USE, MISUSE, OR INABILITY TO
USE THIS PRODUCT OR FROM DEFECTS IN THE PRODUCT. Some states do not allow the exclusion of
incidental or consequential damages, so the above limitations may not apply to you.
Garmin retains the exclusive right to repair or replace the unit or software or offer a full refund of the
purchase price at its sole discretion. SUCH REMEDY SHALL BE YOUR SOLE AND EXCLUSIVE REMEDY
FOR ANY BREACH OF WARRANTY.
Products sold through online auctions are not eligible for rebates or other special offers from Garmin.
Online auction confirmations are not accepted for warranty verification. To obtain warranty service, an
original or copy of the sales receipt from the original retailer is required. Garmin will not replace missing
components from any package purchased through an online auction.
To obtain warranty service, contact your local Garmin authorized dealer or call Garmin Product Support for shipping instructions and an RMA tracking number. The unit should be securely packed with the
tracking number clearly written on the outside of the package. The unit should then be sent, freight charges
prepaid, to any Garmin warranty service station. A copy of the original sales receipt is required as the proof
of purchase for warranty repairs.
Garmin International, Inc.
1200 E 151st Street, Olathe, Kansas 66062 U.S.A.
Tel. 913/397.8200
Fax. 913/397.8282
Garmin (Europe) Ltd.
Unit 5, The Quadrangle, Abbey Park Industrial Estate,
Romsey, SO51 9DL U.K.
Tel. 44/0870.8501241
Fax 44/0870.8501251
Designed for detailed electronic charting capability, the Garmin GPSMAP 172/172C is a powerful
navigation device that can give you the information you need:
Precision Performance
• (172) 10 level grayscale FSTN display with backlighting
• (172C) 256-color CSTN display with backlighting
• 12-channel parallel receiver tracks and uses up to 12 satellites for fast, accurate positioning
• WAAS Capable — receive signals from the additional set of WAAS (Wide Area Augmentation
System) satellites to give you better accuracy
• Differential-Ready — just add an optional Garmin beacon receiver for better than 5-meter
accuracy
• Fully gasketed, high-impact plastic alloy case, waterproof to IEC 60529-IPX-7
Advanced Navigating and Plotting
• 3000 alphanumeric waypoints with selectable icons and comments
• Built-in Worldwide basemap to 20 miles includes detailed ocean, river and lake coastlines,
cities, interstates, US state highways and local thoroughfares
• 50 reversible routes with up to 50 waypoints each
• Uploadable maps using Garmin’s MapSource PC products and BlueChart Data Cards
• Coordinates: Lat/Lon, UTM/UPS, Loran TD, over 20 grids, including Maidenhead
• TracBack route feature which allows you to quickly retrace your track log to a starting position
• Built-in simulator mode
• Built-in tide information from over 3,000 tide stations around the USA coastline, Alaska,
Hawaii, western Canada and several Caribbean Islands
Introduction
Capabilities
Superior Fishfinding Ability (when combined with the GSD 20 Sounder Module)
• Whiteline feature provides a clear image
of bottom hardness and structure
• See-Thru technology which helps separate fish returns from thermoclines and
structure
• Depth Control Gain (DCG) feature
automatically adjusts fishfinder sensitivity
according to depth
• Multiple Zoom levels with a moving view
window, plus bottom lock
• Underwater waypoint marking
• Map/Sonar split screen combines
navigation and fishfinding ability
• Fish and Depth alarms
v
Introduction
Packing List
Before installing and getting started with your unit, please check to see that your package includes
the following items. If any parts are missing, please contact your Garmin dealer immediately.
Standard Package:
• GPSMAP 172/172C Unit
• GA 29 Remote External Antenna and 30’ cable*
• Internal Antenna**
• Single-Knob Tilt & Swivel Bracket
• Power/Data Cable
• Owner’s Manual
• Quick Reference Card
• Protective Cover
* Not included with part numbers 010-00327-01 with internal antenna.
** Not included with part numbers 010-00327-00 with remote antenna.
Optional Accessories:
• US A/C, PC Adapter
• EURO A/C, PC Adapter
• UK A/C, PC Adapter
• Cigarette Lighter Adapter
• BlueChart Marine Data Cards, MapSource CDs, USB Data Card Programmer, and Data Cards
• GSD 20 Remote Sounder Module
• GBR 23 Beacon Receiver for differential corrections
vi
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
Preface/Registration . . . . . . . . . . . . . . . . . . . . . . i
Software License Agreement . . . . . . . . . . . . . . . i
FCC Compliance. . . . . . . . . . . . . . . . . . . . . . . .ii
Warnings and Precautions . . . . . . . . . . . . . . . . iii
Warranty andSerial Number . . . . . . . . . . . . . . iv
Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Packing List. . . . . . . . . . . . . . . . . . . . . . . . . . . vi
Table of Contents . . . . . . . . . . . . . . . . . . . . . . vii
“How To” Index. . . . . . . . . . . . . . . . . . . . . . . viii
Section One: Getting Started . . . . . . . . . . . . . 1-17
Keypad Usage . . . . . . . . . . . . . . . . . . . . . . . . . .1
Selecting Options . . . . . . . . . . . . . . . . . . . . . . .2
Entering Data . . . . . . . . . . . . . . . . . . . . . . . . . .3
Initializing the Receiver . . . . . . . . . . . . . . . . . . .4
Power On/Screen Backlighting . . . . . . . . . . . . .6
Simulator Mode. . . . . . . . . . . . . . . . . . . . . . . . .7
Main Pages . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Map Page. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Waypoints . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Marking Waypoints . . . . . . . . . . . . . . . . . .10
Using the NAV Key . . . . . . . . . . . . . . . . . . . . .11
Simulated Tour . . . . . . . . . . . . . . . . . . . . . . . .12
Reviewing/Creating Map Waypoints . . . . .13
Compass Navigation Page . . . . . . . . . . . . .14
Highway Page . . . . . . . . . . . . . . . . . . . . . .15
Active Route Page . . . . . . . . . . . . . . . . . . .16
Main Menu Page . . . . . . . . . . . . . . . . . . . .16
Deleting Waypointst . . . . . . . . . . . . . . . . .17
Powering Off Unit . . . . . . . . . . . . . . . . . . .17
Section Two: Reference . . . . . . . . . . . . . . . . 18-77
Map Page. . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Cursor and Zooming . . . . . . . . . . . . . . . . .19
Options . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Compass Page . . . . . . . . . . . . . . . . . . . . . . . . .27
Highway Page . . . . . . . . . . . . . . . . . . . . . . . . .28
Highway Page Options . . . . . . . . . . . . . . .29
Waypoints . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Creating . . . . . . . . . . . . . . . . . . . . . . . . . .30
Reviewing . . . . . . . . . . . . . . . . . . . . . . . . .34
Editing. . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Lists. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Going to a Destination. . . . . . . . . . . . . . . . . . .39
TracBack Navigation . . . . . . . . . . . . . . . . . . . .40
MOB: Man OverBoard. . . . . . . . . . . . . . . . . . .42
Routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Creating. . . . . . . . . . . . . . . . . . . . . . . . . . .44
Following . . . . . . . . . . . . . . . . . . . . . . . . .44
List Page . . . . . . . . . . . . . . . . . . . . . . . . . .45
Review Page. . . . . . . . . . . . . . . . . . . . . . . .46
Editing. . . . . . . . . . . . . . . . . . . . . . . . . . . .47
Active Route Page . . . . . . . . . . . . . . . . . . . . . .50
Introduction
Table of Contents
Find Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
Find Options . . . . . . . . . . . . . . . . . . . . . . .52
Main Menu Page . . . . . . . . . . . . . . . . . . . . . . .53
GPS Tab. . . . . . . . . . . . . . . . . . . . . . . . . . .54
Tide Tab . . . . . . . . . . . . . . . . . . . . . . . . . .58
Trip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
Celes Tab . . . . . . . . . . . . . . . . . . . . . . . . . .60
Track Tab. . . . . . . . . . . . . . . . . . . . . . . . . .61
DSC Tab . . . . . . . . . . . . . . . . . . . . . . . . . .63
Card Tabs . . . . . . . . . . . . . . . . . . . . . . . . .68
Temp Tab. . . . . . . . . . . . . . . . . . . . . . . . . .69
Setup Tab . . . . . . . . . . . . . . . . . . . . . . . . .69
Comm Tab. . . . . . . . . . . . . . . . . . . . . . . . .72
Alarm Tab . . . . . . . . . . . . . . . . . . . . . . . . .76
Appendix A: LORAN TD . . . . . . . . . . . . . . . . . .78
Appendix B: Time Offsets . . . . . . . . . . . . . . . .80
Appendix C: Messages . . . . . . . . . . . . . . . . . .81
Appendix D: Map Datums. . . . . . . . . . . . . . . .83
Appendix E: Navigation Terms . . . . . . . . . . . .85
Appendix F: Specifications/Unit Care . . . . . . .87
Appendix G: Installation. . . . . . . . . . . . . . . . .94
Appendix H: Index . . . . . . . . . . . . . . . . . . . . .94
vii
Introduction
“How To” Index

The list to the right is provided to help you quickly find
some of the more important procedures you may use on
your new GPSMAP 172/172C.
viii
TO DO THIS:
SEE PAGE(S):
Turn the unit on or off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Adjust screen backlighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Enter data and select options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Learn how to operate the unit’s function keys . . . . . . . . . . . . . . . . . . . . . . . . . 1
Mark your present location as a waypoint . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Go to a destination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Create and use a route . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Pan using the map arrow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Zoom in or out on the Map page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Reconfigure the Map page display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Access the Main Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Change units of measure (statute, nautical, metric) . . . . . . . . . . . . . . . . . . . 71
Change the displayed time (zone) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
View tide information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
View celestial information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Set Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Use the Find function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
View a unit message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
(ZOOM) OUT Key
The OUT key adjusts the map scale to display a larger area with less detail. (Zooms out)
Getting Started
(ZOOM) IN Key
The IN key adjusts the map scale to display a smaller area with more detail. (Zooms in)
Keypad Usage
PAGE Key
The PAGE key selects the main pages in sequence and returns display from a submenu page.
OUT
PAGE
QUIT Key
The QUIT key returns the display to the previous page and, when entering data, it restores the previous value
(cancels data entry).
ARROW KEYPAD
The ARROW KEYPAD is used to select (Highlight) menu options and enter data. It also controls cursor movement on the Map Page.
ENTER/MARK Key
The ENTER/MARK key selects a highlighted menu option. When entering data, it allows you to initiate entry, and
then to accept the selected value(s). It also marks the current location as a waypoint when pressed and held for
more than one second.
IN
QUIT
ENTER
MARK
Arrow Keypad
MENU Key
The MENU key displays a menu of available options for the current page. Press twice (or press and hold for more
than one second) to display the Main Menu.
NAV/ MOB Key
The NAV key displays the Go To and Follow navigation menu. MOB (Man OverBoard) actives the Man OverBoard
navigation feature when pressed and held for more than one second.
FIND Key
The FIND key activates the find function to search for nearby items and user waypoints.
POWER/ BACKLIGHT Key
The POWER/ BACKLIGHT key turns on/off the unit and adjusts the display illumination/contrast. Multiple
presses toggle the unit’s backlight between maximum, user-set, and minimum brightness levels.
MENU
NAV
MOB
FIND
Power Key
Always press and release a key to perform its primary function. Press, hold for more than one second, then release the
ENTER/MARK , NAV/MOB, and MENU keys to activate
their secondary function.
1
Getting Started
Selecting Options
The GPSMAP 172/172C’s advanced keypad system is designed to allow for fast, convenient selection of navigation options and data entry. The Getting Started Tour introduces you to the keypad and
provides a ‘hands-on’ lesson in using the GPSMAP 172/172C. We strongly encourage you to take the
Getting Started tour before using your unit for actual navigation. The GPSMAP 172/172C Quick Reference Guide contains helpful tips on using the unit and performing various navigation tasks.
How To Select Options and Enter Data
You can select and activate options and enter data to customize the GPSMAP 172/172C to fit your
requirements. You can use the ENTER/MARK key and ARROW KEYPAD to select options, enter
names and numbers in data fields, and activate your selections.
Options Menu with
highlighted option.
Use the ARROW
KEYPAD to highlight
the next option. Press
ENTER/MARK to
activate.
To select and activate an optional feature:
1. With any page displayed, press the MENU key to pop-up the options menu. The options menu
displays a list of optional features which are specific for that particular page. To select any feature
on the list of options requires movement of the cursor, which is called “highlighting”, selecting or
choosing an item in a list or a field (box) on a page.
2. Use the ARROW KEYPAD to move the cursor (highlight) up and down a list or up, down, and
sideways on menus.
3. Once you have moved to the desired selection, press the ENTER/MARK key to either activate the
feature or the MENU key to pop-up a sub-menu or list of yet more feature options. Repeat this
process to select an option from the list or press the QUIT key to return to the previous setting.
The QUIT key moves backwards through these steps back to the main page you started on.
To select and activate a function button:
Pop-up list of options for a highlighted field.
2
1. When moving about a page with function buttons, like the ‘New Map Waypoint’ page, you observe
functions such as ‘Show Map’, ‘Delete’ and ’OK’. To activate the function, highlight the desired
button and press the ENTER key.
Naming a waypoint or placing any sort of data that has not been predefined requires the use of
both the ARROW KEYPAD and the ENTER/MARK key.
To enter a name or number in a data field:
Getting Started
Entering Data
1. Once you have accessed a page with programmable data fields (e.g. ‘ Waypoint Edit’) you can use
the ARROW KEYPAD to move the cursor (Highlight) to fields on the page. Use the UP/DOWN
arrows to move up or down and the LEFT/RIGHT arrows to move sideways.
2. Pressing the ENTER key with the field highlighted begins the process for entering data in the form
of alphanumeric characters.
3. Use the ARROW KEYPAD UP/DOWN arrows to cycle through numbers 0 to 9, plus/minus symbols,
blank space, and the alphabet. Pressing and releasing the keypad moves you character by character
through the list. Pressing and holding the keypad moves you rapidly through the list.
4. Use the ARROW KEYPAD LEFT/RIGHT arrows to move to the next character on the line or backwards to edit characters. If there are more than two lines of data, keep pressing to the RIGHT to
drop down to the next line.
5. When data entry is completed press ENTER to accept data, then move to the next programmable
field. Not all data fields are programmable, such as the date and time. When moving about a page
with these fields, the cursor skips over them.
Every field and button on this page
can be programmed or activated.
Pressing LEFT or RIGHT
on the ARROW KEYPAD
moves the cursor along the
line or to the next line.
Data Entry Field
The waypoint can be renamed.
A depth can be entered.
A waypoint symbol can be selected
from a list of symbols.
Pressing UP or DOWN
on the ARROW KEYPAD
changes numbers and
letters.
A water temperature can be
entered.
Non-programable
data fields
A comment can be added.
Option buttons can be activated.
The coordinates can be changed.
3
Getting Started
Initializing the Receiver
Initializing the Receiver
The first time you power up your new GPSMAP 172/172C, the receiver must be given an opportunity to collect satellite data and establish its present position. To ensure proper initialization, the
GPSMAP 172/172C is shipped from the factory in AutoLocate mode, which allows the receiver to “find
itself” anywhere in the world. To speed up the initialization process, we recommend using the graphic
initialization process described on the next page, which usually provides a position fix within a few
minutes.
Before you initialize, make sure the GPSMAP 172/172C unit and antenna have been correctly
installed on your vessel according to the instructions in Appendix G. The antenna needs to be in a
location with a clear and unobstructed view of the sky to receive satellite signals.
To turn the GPSMAP 172/172C on:
1. Press and hold the POWER key until the power tone sounds and the display comes on, then release
the POWER key.
An introduction page appears, asking you to read and acknowledge important information regarding the proper use of the unit.
GPSMAP 172/172C
Warning Screen
4
To acknowledge the introduction:
1. After reading the introduction page, press the ENTER key if you agree.
To graphically initialize the GPSMAP 172/172C:
1. Press the MENU key twice for the Main Menu. Press Up or Down on the ARROW KEYPAD until
the ‘GPS’ tab is highlighted, then press the MENU key once.
Getting Started
Initializing the Receiver
2. Using the ARROW KEYPAD, highlight ‘Initialize Position’ and press ENTER to initialize the
receiver from the map. The Initialize Position Page appears, prompting you to select your approximate location with the map cursor.
3. Use the ARROW KEYPAD to move the map cursor and point to your approximate location within
200 miles. If you have difficulty identifying your position, press and release the IN key to see the
next lower map scale.
4. Once you have determined your approximate location on the map, press the ENTER key.

This does not “calibrate” the unit in any way, but rather helps to speed up the initial
satellite acquisition. If the unit displays “Ready (2D) or (3D )” during this process, it is
not necessary to initialize the unit.
Point to your approximate location and press ENTER/MARK.
The GPS Information Page appears as the receiver begins acquiring satellites for your region and
should acquire a fix within a few minutes. When viewing the ‘GPS’ tab on the Main Menu, a signal
strength bar for each satellite in view appears on the bottom of the page, with the appropriate satellite
number under each bar. The progress of satellite acquisition is shown in three stages:
• No signal strength bars— the receiver is looking for the satellites indicated.
• Hollow signal strength bars— the receiver has found the indicated satellite(s) and is collecting
data.
• Solid signal strength bars— the receiver has collected the necessary data and the satellite(s) are
ready for use.
Once the receiver has collected information from at least three satellites, the top of the screen
displays either “Ready (2D or 3D)”, and the GPSMAP 172/172C is ready for use.
A satellite’s strength bars turns
green when it’s ready for use.
5
Getting Started
Power On/Screen Backlighting
GPSMAP 172/172C Getting Started Tour
The Garmin GPSMAP 172/172C is a powerful electronic navigation system that provides detailed
map coverage and convenient control of many advanced features right from the screen display. This
tour is designed to take you through the basic pages and functions of the system using the simulator
mode. Once you’re familiar with the main pages and functions of the unit, refer to the reference section
for instructions on performing specific tasks and functions. For GSD 20 sonar related operations, refer
to “GSD 20 Sounder Module with Garmin Chartplotters” (190-00241-03).
The Getting Started Tour assumes that the receiver has been properly installed and initialized, and
you have not changed any of the default unit settings. If you have changed any settings (position formats, units of measure, etc.), the descriptions and pictures in the tour may not match your configuration.
To turn the GPSMAP 172/172C on:
A full-screen GPS Information pop-up page is displayed
after you press the ENTER key to acknowledge the
Warning Page. The pop-up page goes away after the unit
gets a position fix or you press either ENTER or QUIT.
1. Press and hold the POWER key until the power tone sounds, then release the POWER key. The
Warning Page appears while the unit conducts a self-test.
2. Once the self-test is complete, press the ENTER/MARK key, if you agree, to acknowledge the
warning.
The GPS Information Page appears as the receiver begins acquiring satellites. From this or any
other page, you may also adjust the screen backlighting.
The GPSMAP 172/172C’s adjustable screen backlighting is controlled with the POWER key. The
backlight can cycle through minimum, user-defined, and maximum backlight levels by repeatedly
pressing the POWER key.
To adjust the backlighting and contrast:
1. Press POWER and the Light/Contrast window appears.
Use the ARROW KEYPAD to move the backlighting slider
UP for brighter or DOWN for dimmer backlighting. Press
LEF or RIGHT to adjust the display contrast.
6
2. Press POWER again and the user-defined level of backlighting activates. You may adjust this level
by pressing UP or DOWN on the ARROW KEYPAD. If you press POWER one more time, the backlighting is at the minimum setting. Press LEFT (brighter) or RIGHT (darker) to adjust the contrast.
3. Press ENTER or QUIT when done.
Each page of the GPSMAP 172/172C’s system also features an options page, which gives you access
to other functions and features that relate to the specific page you are viewing. To get a feel for how the
options pages work, let’s put the GPSMAP 172/172C into simulator mode.
Getting Started
Simulator Mode
To place the GPSMAP 172/172C in simulator mode:
1. Press the MENU key twice for the Main Menu. Press Up or Down on the ARROW KEYPAD until
the ‘GPS’ tab is highlighted, then press the MENU key once.
2. Use the UP or DOWN arrow of the ARROW KEYPAD to highlight the ‘Start Simulator’ option and
press ENTER. Choose ‘No’ to the retail demonstration and press the ENTER key.
3. Press the ENTER key to confirm the ‘Running Simulator’ message that appears at the bottom of the
display. ‘Simulating’ appears at the top of the Main pages.
While in Simulator mode, a ‘Running Simulator’ message appears after 2 minutes of inactivity. Now
you’re ready to continue the rest of the simulated tour. Keep in mind that the GPSMAP 172/172C
does not track satellites in simulator mode, and this mode should never be used for actual
navigation. All the waypoint and route planning done in simulator mode is retained in memory for
future use.
A “Running Simulator” message
appears at 2 minute intervalss.
7
Getting Started
Main Pages/
Map Page
The Map Page is one of six main pages used in the GPSMAP 172/172C’s system. The six main pages
are the Map Page, Map/Sonar Split Page*, Sonar Page* , Compass Page, Highway Page, and Active Route
Page. All pages are linked together in a simple chain, which allows you to scroll through the pages in
either direction using the PAGE and QUIT keys.
(* If equipped with GSD 20. For GSD 20 sonar related operations, refer to “GSD 20 Sounder Module
with Garmin Chartplotters” (190-00241-03))
Map Page
Map/Sonar Split Page
PAGE
Sonar Page
Compass Page
Highway Page
Active Route Page
QUIT
Map Page
8
The GPSMAP 172/172C’s Map Page combines digital chartplotting with a user-selectable display
of navigation data and a built-in worldwide database. It is also the page you use most to create and
edit waypoints and routes. Before we take off on our practice route, let’s take a brief look at its various
features and displays.
The map display shows your “boat” as a triangle marker on an electronically generated chart.
Geographic names, roads, markers and buoys that are provided by the optional BlueChart or MapSource
data are also shown. It also displays your track, routes and nearby waypoints. An on-screen cursor
lets you pan to other map areas, determine the range and bearing to a position, and perform various
waypoint and route functions.
The data window, located at the top of the page, provides a user-selectable display of various navigation data, including speed over ground, distance to the next navigation point, compass ribbon and
current position coordinates. The current map scale setting is located at the bottom right of the page.
Using the Map Cursor
Working from the Map Page is a simple process that centers around the use of the cursor. Controlled by the ARROW KEYPAD, the cursor is an important tool that can be used to pan to other map
locations, mark and edit waypoints and routes, and review position data of on-screen map items and
waypoints.
Getting Started
Map Cursor
To get a feel for using the Map Page and using the cursor, try the following exercise:
1. Use the IN/OUT keys to set the map scale to the 50 nm setting. Your boat should be near the
center of the map, at the receiver’s last known position. (If your boat isn’t where it should be, make
sure that you have initialized the receiver and acquired a position as described on pages 1-2.)
2. Use the ARROW KEYPAD to move the cursor. Notice how another data field appears, showing the
bearing and distance from your boat to the cursor, along with the latitude/longitude of the cursor.
3. Press the QUIT key to remove the cursor and re-center your boat on the map display.
As you become more familiar with the cursor, you’ll see that the map display actively scrolls or
‘pans’, letting you explore areas around the world and create waypoints and routes. Wherever you
move the cursor, you’ll always be just one QUIT keystroke away from returning the map to your present position.
Now that you’ve seen how the Map Page can be used to monitor your present location, let’s take a
minute to learn how to mark and store your present position as a “waypoint”. (Since you’re in simulator mode, the present position displayed is the last position calculated by the receiver, which should be
the spot where you’ve initialized the unit.) This also gives you an opportunity to see how the GPSMAP
172/172C’s keypad and ENTER key are used for data entry and changing the waypoint name and
symbol.
Current position
Map Scale
Distance/
Bearing
Cursor
Coordinates
Map Cursor
9
Getting Started
Marking Waypoints
To mark your present position:
1. Hold down the ENTER/MARK key until the ‘New Waypoint’ window appears then release the key.
The window shows a default three-digit waypoint name/number (001), symbol (dot), and position.
You can leave the name as the auto-assigned number, but for this exercise, lets change the name to
‘DOCK’.
2. Use the ARROW KEYPAD to highlight the waypoint name field (001) and press ENTER. You see
that just the first ‘0’ is now highlighted.
3. Press LEFT on the ARROW KEYPAD to clear the name field.
Press ENTER/MARK
after entering the name.
4. Press UP or DOWN on of the ARROW KEYPAD until the letter ‘D’ appears, and then press RIGHT
to go to the next space to the right, then UP or DOWN again until ‘O’ appears. Repeat this until
you have entered the name ‘DOCK’. If you make a mistake and select an incorrect character, simply
press LEFT on the ARROW KEYPAD to backspace the cursor and then UP or DOWN to correct the
entry. (If you accidentally press ENTER before you are done, simply press ENTER again and move
the highlight to where you left off.)
5. After you have entered all the letters, press ENTER to confirm the name.
6. To access the waypoint symbol page, highlight the waypoint symbol field which is to the left of the
waypoint’s name and press ENTER. Note: The default symbol is a dot.
7. You see a grid of available waypoint symbols to choose from. Use the ARROW KEYPAD to highlight the ‘ANCHOR’ symbol.
8. Press ENTER to confirm the ‘ANCHOR’ symbol.
You can choose from a list of useful symbols.
There are two Diver Down waypoint
symbols to select from: the International and
U.S. versions.
10
9. Highlight ‘OK’ at the bottom of the window and press ENTER again to confirm the ‘OK’ prompt
and save the waypoint.
The waypoint is now stored in memory. Note that waypoints may also be created graphically from
the map display or by manually entering position coordinates. Each of these techniques is described in
thes reference section of this manual.
Going to a Destination
GPS is all about marking positions as waypoints and navigating to them using the receiver’s steering guidance and map displays. We’ve already seen how to use the ENTER/MARK key to store our
present position, so it’s time to move on to the fun part—going to a destination.
Getting Started
Using the NAV Key
The NAV/MOB key, located on the keypad above the QUIT key, is the primary tool used to select a
destination waypoint, TracBack, or a route to navigate. The NAV key can be used in two primary ways:
• Pressing NAV once displays a list of options from which you can select ‘Go To Point’, ‘Follow
Route’, ‘Follow Track’, or ‘Stop Navigation’.
• Highlighting an on-screen waypoint or map item as a destination directly from the Map Page
and pressing NAV allows you to graphically select points to “Go To”.
For our simulated trip, you’re going to select a pre-programmed tour route using the first method.
This also shows how the MENU key is used throughout the GPSMAP 172/172C system to provide tab
style options and functions. Let’s start by changing the position to where the practice route is located.
Text entry for simulator position.
To change the GPSMAP 172/172C position in simulator mode:
1. Press the MENU key twice to display the list of Main Menu tab items.
2. Use the UP or DOWN arrow of the ARROW KEYPAD to highlight the ‘Setup’ tab, then LEFT or
RIGHT to highlight the ‘System’ submenu tab.
3. Highlight ‘Set Position’ in the simulator setup window and press ENTER.
4. From the Initialize Position page, press the MENU key. You see ‘Enter As Text’ highlighted, then
press ENTER.
5. On the Enter Position window, press ENTER then use the ARROW KEYPAD to enter N34°56.800’,
W076°24.066’ and press ENTER when done, then press QUIT to return to the Map Page.
For future practice, you may skip steps
3 and 4 and point to a location from the
Initialize Position page.
11
Getting Started
Simulated Tour
To activate the practice route stored in memory for navigation:
1. Press NAV. The option list page appears. (If you were selecting a single waypoint to navigate
to rather than a route, you could highlight the waypoint on the map, press NAV and then press
ENTER.)
2. Use the ARROW KEYPAD to highlight the ‘Follow Route’ option. Press ENTER to confirm.
3. The Select Route page appears, with the ‘GPSMAP TOUR’ route highlighted.
4. Press ENTER then highlight ‘Activate’ and press ENTER again.
To zoom in to a closer map scale:
1. Repeatedly press the IN key until the 3 nm scale displays.
You can also Invert a route to
follow it in reverse.
You may also hold the IN or OUT keys down to quickly scroll through the map scales. The Map
Page should now display five waypoints chained together in a simple route, with your boat at the first
route waypoint.
A data field at the top of the page now displays the speed, distance to the second route waypoint,
and a compass ribbon which shows you which way to go. To get started, let’s enter a speed for our
vessel, which we can do from the Main Menu Page.
To enter a boat speed:
1. Press the MENU key twice to display the Main Menu Page.
2. Use the ARROW KEYPAD to highlight the ‘Setup’ tab, then press RIGHT then DOWN until the field
below the word ‘Speed’ is highlighted on the ‘System’ submenu tab and press ENTER.
3. Use the ARROW KEYPAD to enter a speed of 40 knots.
The Set Position, Track Control, Track
and Speed fields only show while in
simulator mode.
12
4. Press ENTER to finish, and PAGE until you return to the Map Page.
Once a speed has been entered, you’ll notice that the map automatically begins to move slowly,
keeping your boat centered on the display. The direction of movement, also called ‘track’, is controlled
by the simulator.
You’ll now have a clearer picture of the route you are navigating. Keep in mind that whenever you
do exceed the usable range of the built-in database or the optional MapSource or BlueChart data in use,
the range field displays ‘OVERZOOM’ to indicate that you should exercise extreme caution using the
map data. Press the IN key to zoom into the 2 nm scale. Now that you’ve zoomed in a little closer to
your route, you can pan ahead of your vessel with the cursor to review map items and create on-screen
waypoints. Try moving the cursor to highlight the ‘TOUR3’ waypoint— just use the ARROW KEYPAD
to move the cursor as close as possible to the waypoint. (To move the cursor in small increments, try a
series of short key presses.)
Once the cursor is over the TOUR3 waypoint, you’ll notice that the waypoint symbol and name
becomes highlighted. The data field at the top of the map displays the waypoint name, the range and
bearing from your present position, and the coordinates for the waypoint.
To review the waypoint page for a selected waypoint:
1. With the waypoint highlighted, press the ENTER key.
2. To return to the Map Page, press ENTER again or press QUIT.
Getting Started
Reviewing/Creating
Map Waypoints
The waypoint ‘highlights’
when the cursor is moved
over it.
The cursor can also be used to create new waypoints right from the map display.
To create a new waypoint using the cursor:
1. Use the ARROW KEYPAD to move the cursor as close as possible to the following position:
N35º 02.914; W 076º 26.152’ (Use the data window to verify the cursor position.)
2. Press and release the ENTER key to capture the cursor position. Do not hold the button down, as
doing so marks your present position, not the map position.
3. Use the ARROW KEYPAD to highlight the waypoint symbol field to the left of the waypoint name/
number.
4. Press ENTER to access the symbol page.
5. Use the ARROW KEYPAD to select the ‘Shipwreck’ symbol and press ENTER to confirm.
6. Highlight ‘OK’ at the bottom and press ENTER again to finish.
Waypoint numbering starts with
001 and continually counts up,
even if the waypoint name has
been deleted.
13
Getting Started
Compass Navigation Page
Data
Fields
Compass
Ring
Current
Destination
Pointer
Arrow
Compass Page
Now that we’re navigating to an actual destination, let’s move on to the GPSMAP 172/172C navigation pages by pressing the PAGE key three times. (When using the GPSMAP 172/172C in simulator
mode, the optional GSD 20 Map/Sonar Page and Sonar Page are displayed (see page 8)
The Compass Page provides graphic steering guidance to a destination waypoint, with an emphasis
on the bearing to your destination and current direction of travel. The middle of the page features a
rotating ‘compass ring’ that shows your course over ground (track) while you’re moving, and a bearing
pointer that indicates the direction of the destination (bearing) relative to the course over ground.
The compass ring and pointer arrow work independently to show—at a glance—the direction of your
movement and the direction to your destination. For instance, if the arrow points up, you are going
directly to the waypoint. If the arrow points any direction other than up, turn toward the arrow until it
points up—then continue in that direction. Because the compass rings uses GPS technology, you must
be moving in order for the track to display properly.
The current speed, distance to the next waypoint, turn angle and and time to the next waypoint
display at the top of the screen. When you are not navigating to a waypoint, the compass shows your
direction of travel as you move, but the arrow does not appear.
The Compass Page allows for precision navigation to one degree of steerage. The default page displays one row of medium numbers fields. You may customize the Compass Page to display the size and
number of fields along with the type data you wish to see. (See pages 25-26) for changing the types of
data.)
Let’s move on to the Highway Page by pressing the PAGE key.
14
Getting Started
Highway Page
The GPSMAP 172/172C’s Highway Page also provides graphic steering guidance to a destination
waypoint, placing greater emphasis on the straight-line desired course and the distance and direction
you are off course. As you head toward your destination, the middle of the screen provides visual guidance to your waypoint on a moving graphic “highway.” Your present position is at the bottom center of
the highway display. The line down the middle of the highway represents your desired course.
As you navigate toward a waypoint, the highway actually moves—indicating the direction you’re
off course. To stay on course, simply steer toward the center of the highway or “keep it on the road”.
The default data fields at the top of the page indicate ‘Speed’ and ‘Distance To Next’ point, along with
‘To Course’ which shows the bearing to get you back on course and ‘Time To Next’ point. Use the Highway Page as your primary navigation page (in lieu of the Compass Page) when your main concern is
following a defined course.
Highway Page
Data
Fields
Present
Position
Current
Destination
Zoom
Scale
Desired
Course
Highway Page
Whenever the GPSMAP 172/172C is in simulator mode, you can also adjust your speed and course
from the Highway Page using the ARROW KEYPAD. As you head toward each waypoint in the tour
route, try adjusting your boat speed and course to get a feel for how the Highway Page works.
To adjust the simulated boat speed/heading from the Highway Page:
1. Press the UP arrow of the ARROW KEYPAD to increase the speed in 10 knot/kph/mph increments.
Press the DOWN arrow to decrease the speed in the same increments. Press the LEFT and RIGHT
arrows of the ARROW KEYPAD to steer the boat.
Notice that as you get off course, the highway moves to give you graphic guidance to get back on
course. You can zoom in or out on the Highway display for a smaller or larger view. Five available settings range from 1X to 16X, with a default setting of 8X. The current scale appears in the bottom right
of the display.
To zoom in or out on the highway display:
Steer towards the center of the highway to get back
on course.
1. Press either the IN or OUT key to increase or decrease the zoom scale.
15
Getting Started
Active Route Page/
Main Menu Page
The main pages’ data fields may also be configured to display several different information categories (see pages 25-26 for the complete list). On the Highway Page, let’s change the ‘TIME TO NEXT’
field to ‘TIME OF DAY’.
To change a data field:
1. Press the MENU key to display the Highway Page options.
2. With ‘Change Numbers’ highlighted, press ENTER.
3. Use the ARROW KEYPAD to highlight ‘TIME TO NEXT’, then press ENTER.
4. On the alphabetical list of options, press UP or DOWN on the ARROW KEYPAD to highlight a selection. Press LEFT or RIGHT to jump through the list a page at a time. The scroll bar on the right side of
the window indicates the current position on the entire list of options. Select ‘TIME OF DAY’ and press
ENTER.
You may choose from several
different types of data
Current
waypoint
5. Press QUIT when finished.
Press PAGE to see the last page appearing in the main sequence, which is the Active Route Page.
Whenever you have activated a route or Follow Track, this page shows each waypoint name along with
useful data for each point. As you navigate the route, the information automatically updates to indicate
the next point along the route. For more detailed information on the Active Route Page, see page 50.
As you’ve seen, the primary pages provide map and navigation information. The tour’s last page is the
Main Menu page, which allows access to the GPSMAP 172/172C’s waypoint, route and planning functions, as well as various operational and navigation setup features, and celestial and tide data.
The Main Menu is available from any page, and is accessed through the MENU key.
To access the main menu page:
1. Press the MENU key twice (or hold down the MENU key for two seconds.).
Active Route Page
16
The Main Menu page lists 16 menu ‘tabs’ that are divided into categories by function. You can view
a particular menu by simply highlighting the desired tab, which shows any secondary submenu tabs
and options for that tab.
To get a basic feel for how the Main Menu page works, let’s delete the two waypoints you created
during the simulated tour. This ensures that you have a clean slate once you start navigating in your home
waters.
Getting Started
Deleting Waypoints/
Powering Off Unit
To select the Points (Waypoint) submenu tab:
1. Use the ARROW KEYPAD to highlight the ‘Points’ menu tab. You see a list of stored waypoints
appear to the right of the Main Menu list.
2. Press to the right one time on the ARROW KEYPAD and you see the ‘User’ submenu tab highlighted.
3. Press down on the ARROW KEYPAD until waypoint 001 with the shipwreck symbol is highlighted.
4. You may delete the waypoint by either pressing MENU, then highlighting ‘Delete Waypoint’ or press
ENTER and then highlight ‘Delete’ from the Waypoint Edit page.
Submenu
Tabs
5. Press ENTER to delete the waypoint, then ENTER again to confirm. Repeat the above steps to delete
the ‘Dock’ waypoint also.
Congratulations! You’ve now gone through the basic operation of the Garmin GPSMAP 172/172C.
Your new digital chartplotter is a powerful tool with many advanced features not covered in the Getting
Started tour. For detailed instructions on using these features or performing a specific task, please refer to
the Quick Reference Guide or the appropriate reference section of this manual. If equipped with GSD 20,
refer to the “GSD 20 Sounder Module with Garmin Chartplotters” (190-00241-03) for sonar operations.
The unit is still in Simulator mode for practice, but automatically returns to it’s ‘Normal’ operation mode
when you shut it off and turn it back on.
Main
Menu
Tabs
Main Menu
To turn the GPSMAP 172/172C off:
1. Press and hold the POWER key for about two seconds, until the screen is blank.
2. When the screen is blank, release the POWER key.
The next section of the manual describes the pages and functions of the GPSMAP 172/172C in detail.
If you are unable to locate a specific option or function, please refer to the Index.
17
Map Page
Reference
Map Page
Data Fields
Land
User
Waypoint
Map
Item
Boat Icon
Water
Navaids
Geographic Name
Map Page shown using optional
MapSource data.
Map Scale
The GPSMAP 172/172C’s Map Page provides a comprehensive display of electronic cartography,
plotting and navigational data. When using the unit with the optional BlueChart data or MapSource
software, the map display shows your boat on a digital chart, complete with geographic names, map
items, navaids and a host of other chart features. It also plots your track and displays any routes and
waypoints you create. An on-screen cursor lets you pan and scroll to other map areas, determine the
distance and bearing to a position, and perform various route and waypoint functions.
When the cursor is active, an additional data window appears below the data fields to indicate the
position, range and bearing to the cursor or a selected waypoint or map item. The map scale displays at
the bottom right of the page.
The (ZOOM) IN and (ZOOM) OUT keys, combined with the ARROW KEYPAD, let you select
zoom ranges and move the cursor. Two basic map operating modes, position mode and cursor mode,
determine what cartography is shown on the map display. Position mode pans the cartography to keep
the present position marker within the display area, while cursor mode pans the cartography to keep
the cursor within the display area.
The GPSMAP system always powers up in the position mode, with your vessel centered on the
map display.
• When sufficient map coverage is not available to keep the boat centered, the boat icon moves
toward the edge of the display.
When the ARROW KEYPAD is pressed, the GPSMAP 172/172C enters cursor mode. In cursor
mode:
• The cursor can be moved over the map display using the ARROW KEYPAD.
• Whenever the cursor reaches the edge of the display, the map scrolls forward under the cursor.
Keep in mind that the boat icon moves with the map scrolling and may go off the display screen
(you may not be able to see your present position).
• When the cursor is stationary, a fixed coordinate position appears in the position field. Note
that the distance and bearing changes as the boat’s position changes.
18
• Whenever you zoom in cursor mode, the cursor is centered on screen.
• To return to position mode, press the QUIT key.

When the cursor reaches the edge of the map, the unit may pause as it loads new map
data.
Reference
Map Page: Cursor
Using the Cursor
The cursor allows you to pan away from your present position and scroll to other map areas
around the world (even outside of your current detail coverage). As you pan past the edge of the current map display, the screen actively scrolls forward to provide continuous map coverage. You see an
hourglass symbol by the pointer while the unit is busy drawing new map detail.
To move the cursor:
1. Press the ARROW KEYPAD to move the cursor in an up, down, left or right direction.
Move the cursor over an item
on the map to highlight it.
As you move the cursor, the distance and bearing from your present position to the cursor is
displayed in the data window, along with the cursor’s position coordinates. Keep in mind that when the
cursor is stationary, the distance and bearing from your present position changes as your boat moves.
The cursor may also be used to ‘snap’ to on-screen waypoints and map items, allowing you to review a
selected position directly from the map display.
Additional information
tabs.
To select an on-screen waypoint or map item with the cursor:
1. Use the ARROW KEYPAD to move the cursor to the desired waypoint or map item (if there are
several waypoints grouped closely together, zoom in closer for a better view).
2. When a waypoint or map item is selected, it becomes highlighted on screen, with the name
and position displayed. Press ENTER to show details of the map item. When using BlueChart or
MapSource data, additional information tabs appears. Use the ARROW KEYPAD to highlight the
individual tabs to display the information and additional options.
Pressing ENTER/MARK
while highlighting a map
item brings up additional
details and options.
Option buttons
19
Reference
Map Page: Cursor
and Zooming
To eliminate the cursor and re-center your position on-screen:
1. Press the QUIT key.
The cursor may also be used to create new waypoints directly from the map.
To create a waypoint with the cursor:
1. Use the ARROW KEYPAD to move the cursor to the desired map position.
2. Press the ENTER/MARK key and the ‘New Map Waypoint’ window appears. If the cursor is on
a map item, you get a new window with details about the item when ENTER/MARK is pressed.
Press ENTER again on the highlighted ‘Create Wpt’ option.
3. Press ENTER to confirm the new waypoint using the default three-digit name and symbol.
Selecting Map Scales
The map display has 28 available range scales from 20 ft. to 800 mi. (5 m to 1200 km). The map
scale is controlled by the IN and OUT keys, with the current scale displayed at the bottom right of the
data window.
Creating New Map Waypoint
To select a map scale:
1. Press the OUT key to zoom out and the IN key to zoom in.

Using Built-In Basemap
Using BlueChart/MapSource Data
Overzoom, no additional data
20
The scale value represents the distance from one end of the scale bar to the other.
The GPSMAP 172/172C’s system has a built-in worldwide database to 20 mi, with more detailed
coverage available through the use of the optional BlueChart or MapSource data. The GPSMAP
172/172C displays cartography as long as there is chart information available for the range you’ve
selected. Map coverage conforms to the following conditions:
• When the selected zoom range is covered by either the internal database, BlueChart, or
MapSource data, cartography is displayed.
• When the selected zoom range is covered by both the internal database and BlueChart/
MapSource data, cartography is displayed using the data with the best resolution.
• When the selected zoom range exceeds the resolution of the data in use, overzoom cartography is
displayed and an ‘overzoom’ warning appears below the scale field.
Map Page Options
Many features of the GPSMAP 172/172C are menu driven. Each of the main pages have an options
menu, allowing you to custom tailor the corresponding page to your preferences and/or select special
features that specifically relate to that page. The data window, located at the top of the main pages
provides a user-selectable layout of various types of useful data. Each data field may be configured to
display any one of several data options. The data window layout may also be changed to display additional data fields and change the actual size of the data displayed.
Reference
Map Page: Options
The GPSMAP 172/172C’s Map Page provides access to functions and features relating to the Map
Page and the layout options.
To display the Map Page options:
1. Press MENU.
To select a menu option:
1. Use the ARROW KEYPAD to highlight the desired option and press ENTER.
The available options are Full Screen Map/Show Data, Measure Distance, Set Up Map, Set Up Page
Layout, Change Numbers, and Turn Declutter On/Off. Following are details on using each of these
options.
• Full Screen Map/Show Data — toggles between a Map Page without or with data fields on the
map display. The unit defaults back to ‘Show Data” the next time it is powered on.
Map Page Options
To maximize the map/show data fields:
1. Highlight the ‘Full Screen Map’ option and press ENTER. The Map Page is now maximized with no
data fields.
2. To show the data fields again, press MENU, highlight ‘Show Data’ and press ENTER.
21
• Measure Distance— allows you to measure the bearing and distance between any two points
on the map display.
Reference
Map Page: Options
Cursor
Coordinates
Distance and
Bearing
Map Cursor
Full screen map shown
To measure the Bearing/distance between two points:
1. Highlight the ‘Measure Distance’ option and press ENTER. An on-screen pointer appears on the
map display at your present position with ‘ENT REF’ below it.
2. Move the cursor to the desired reference point (the point that you want to measure from) and
press ENTER.
3. Move the cursor to the point that you want to measure to. The bearing and distance from the reference point and cursor coordinates is displayed in the data window at the top of the display. Press
the QUIT key to finish.
• Set Up Map— allows you to configure the map display to your preferences, including map
detail, map orientation, automatic zoom, and various map items and points. The map set up option
uses a ‘file tab’ feature, making it easier to organize the various settings for ease of use. The following
table lists the file tabs and the settings available under each tab:
General
Detail, Orientation, AutoZoom, Color Mode
Source
Basemap, Data Card Maps
Waypoints
Waypoints, Active Route
Points
Spot Soundings, Tide Stations, Services
Navaids
Symbol Set, Symbol, Size, Text Size, Light Sectors
Nav Line
Heading Line, Bearing Line, Course Line
Track
Saved Tracks, Track Log
Other
Accuracy Circle, Lat/Lon Grid, Map Outlines
To change a map setup feature:
Main Menu—
Map Configuration Tab
22
1. From the Map Page menu, highlight ‘Set Up Map’ and press ENTER.
2. Move LEFT or RIGHT on the ARROW KEYPAD to highlight the desired tab, then UP or DOWN on
the ARROW KEYPAD to move the highlight to the setting you want to change and press ENTER.
3. Move UP or DOWN on the ARROW KEYPAD to highlight to the desired setting and press
ENTER. To exit, press QUIT.
General Tab
Detail— Most, More, Normal, Less, Least: controls how much map detail displays. Those
features which have a specified scale or turned “Off” are unaffected by this setting.
Orientation— North Up— fixes the top of the map display to a north heading; Track Up
Below— fixes the top of the map display to the current track heading and centers your position
on the lower portion of the screen. Set to ‘Off; for constant Track Up.The numeric value is the
range the unit switches to North Up when zooming out. Course Up— fixes the map so the
direction of navigation is always “up” and turns the navigation leg line vertical on the screen.
AutoZoom — On/Off: when “On” the map automatically adjusts the map scale to a lower scale
as you approach you destination point.
Color Mode — (172C) For Sun, For Dark (172) Water Mode, Land Mode
Source Tab
Basemap— On/Off: turns the built in base map on or off.
Data Card Maps— On/Off: turns all optional BlueChart/MapSource data loaded on the data
card on or off. The ‘Data Card Maps’ option box shows a list of the optional BlueChart/
MapSource data loaded on the data card. Each area is described by name and may be deselected if you do not wish to display the data on the Map Page.
Reference
Map Page Options
General Tab
Source Tab
To display the Map Information Page:
1. Highlight the ‘Data Card Maps’ option box and press ENTER.
2. Use the ARROW KEYPAD to scroll through the list of maps.
3. To select/deselect a map family, highlight the check box to the left of the name and press ENTER
to select/deselect the map. The map is selected and is displayed on the Map Page when an “”
appears in the box adjacent to that map. You may also press MENU and choose to ‘Show All’ or
‘Show None’ and press ENTER.
4. To display detailed information/notes for each area or to turn individual maps in the family on/off,
highlight the family name and press ENTER. To view the notes for that area, choose ‘Show Notes’.
To scroll through the notes, you may either highlight the notes, press ENTER and use the ARROW
KEYPAD to scroll UP, DOWN, LEFT and RIGHT or press MENU and choose the desired scroll option.
‘Data Card
Maps’ Map
Information
Page
23
Reference
Map Page Options
Waypoints
Tab
Points Tab
Navaids Tab
Nav Line Tab
Track Tab
24
Waypoints Tab— Waypoints/Active Route
Text— None, Small, Medium, and Large: controls the screen size of the name.
Zoom— Auto, Off, 20 ft.-800 mi.: sets the maximum scale at which the feature should appear on
the screen. Some types of data only shows up to certain zoom scales.
Points Tab— Spot Soundings/Tide Stations/Services
Text— None (except Spot Snd.), Small, Medium, and Large: controls the screen size of the name.
Zoom— Auto, Off, 20 ft.-800 mi.: sets the maximum scale at which the feature should appear on
the screen. Some types of data only shows up to certain zoom scales.
Navaids Tab—
Symbol Set— Auto, GARMIN, NOAA, International: controls the desired navaid symbol set.
Auto - BlueChart maps are drawn using symbols similar to the NOAA/NIMA standard. NonBlueChart maps are drawn using traditional Garmin symbols.
GARMIN - All maps are drawn using traditional Garmin symbols.
NOAA - All maps are drawn using a symbol set similar to NOAA/NIMA.
International - All maps are drawn using a symbol set similar to the IALA symbol set.
Symbol/Text Size— Small, Medium, and Large: controls the screen size of the symbol/name.
Light Sectors— Off, Auto, On: controls the drawing light sectors on the map. Color units indicate
the actual color of each sector using the color of the light.
Off— No light sectors are ever drawn.
Auto— Light sectors appear when you point to them with the map cursor.
On— Light sectors are drawn for all lights that have them.
Nav Line Tab—
Heading Line— On/Off: draws an extension from the end of the boat icon in the direction of travel.
Bearing Line— On/Off: toggles the black/white line which points to the current navigation point.
Course Line— Auto, Off, 20 ft.-800 mi.: sets the maximum zoom scale at which the desired course
line should appear on the screen.
Track Tab— Saved Tracks/Track Log
Zoom— Auto, Off, 20 ft.-800 mi.: sets the maximum scale at which the feature should appear on
the screen. Some types of data only display up to certain zoom scales.
Other Tab—
Accuracy Circle— On/Off: toggles the circle “On” and “Off”. The circle represents the approximate
accuracy of the unit based on EPE, DOP, and basemap quality. Your position is within the circle.
Lat/Lon Grid— Text— None, Small, Medium, and Large: controls the screen size of the name.
Zoom— Auto, Off, 20 ft.-800 mi.: sets the maximum scale at which the feature should appear.
Map Outlines— On/Off: toggles the coverage boxes for BlueChart/MapSource data “On” and “Off”.
From the map setup page, you can access the following menu options by pressing MENU:
• Defaults— restores settings back to factory settings for the tab highlighted.
• All Map Defaults— restores settings back to factory settings for all tabs.
Reference
Map Page Options
Other Tab
• Set Up Page Layout — the layout of the data fields may be changed to show more fields (with a smaller
number size) or less fields (with a larger number size).You may also choose to show a Compass Tape on the
Map Page only.
To set up the page layout:
1. Press the MENU key to display the Page options.
2. Highlight ‘Set Up Page Layout’ and press ENTER.
3. The current setting displays, press ENTER to change. Use the ARROW KEYPAD to highlight the desired
setting, then press ENTER.
4. Press QUIT when finished.
• Change Numbers — allows you to specify the type of data displayed in each data field used on
the map display. This option is available from any of the main pages. See pages 25-26 for instructions on
changing data field numbers.
The following data options are available for data fields on the main pages:
• BEARING – Compass direction from your position to destination
• COMPASS – Compass ribbon
• COURSE – Desired Track
• DEPTH* – Depth below transducer
• DIST TO DESTINATION – Distance to final waypoint
• DIST TO NEXT – Distance to next waypoint
Highlight the field you
wish to change
25
Reference
Map Page Options
Choose the type of data
you wish to display.
Map Setup
Menu Options
• ELEVATION – Elevation above/below MSL (Mean Sea Level)
• ETA AT DESTINATION – Estimated Time of Arrival to final waypoint
• ETA AT NEXT – Estimated Time of Arrival to next waypoint
• GPS ACCURACY – Shows estimated GPS accuracy
• HIGHWAY – Smaller version of the Highway Page
• MAXIMUM SPEED – Fastest speed the unit has traveled
• MOVE AVERAGE SPEED – Average moving speed
• MOVE TRIP TIME – Time unit has been moving for a trip
• OFF COURSE – Distance from desired track
• POINTER – Arrow points to your destination
• POSITION – Current position coordinates
• SONAR* – Compressed view of sonar data
• SPEED – Speed over ground
• TIME OF DAY – Current time
• TIME TO DESTINATION – Time to final waypoint
• TIME TO NEXT – Time to next waypoint
• TO COURSE – Bearing to desired track
• TOTAL AVERAGE SPEED – Total average speed
• TOTAL TRIP TIME – Total travel time of trip, stopped and moving
• TRACK – Current compass direction of travel
• TRIP ODOMETER – Trip Odometer
• TURN – Directional amount of turn needed to match bearing
• VELOCITY MADE GOOD – Velocity Made Good to destination
• VOLTAGE – Current voltage reading being received by unit
• WATER SPEED* – Speed through the water
• WATER TEMP. LOG* – Timeline graph of the transducer’s temperature reading.
• WATER TEMPERATURE * – Water temperature
*If receiving proper sonar data from other device, such as a GSD 20 Sounder Module or NMEA device.
NOTE: COMPASS, HIGHWAY, POSITION, SONAR, and WATER TEMP. LOG are only available on Large and Huge
sized data fields.
• Turn Declutter On/Off — toggles between showing spot soundings and map outlines for easier
viewing.
26
Compass Page
The GPSMAP 172/172C features two different navigation pages: Compass and Highway. Whenever
a NAV goto, Follow Track (TracBack), or Follow Route have been activated, the GPSMAP 172/172C’s
Compass Page guides you to your destination with digital readouts and a graphic compass display, which
includes a bearing pointer. Use this page (instead of the Highway Page) when your desired path may be
varied in direction. The middle of the page features a rotating ‘compass ring’ that shows your course over
ground (track) while you’re moving. Your present course over ground is indicated at the top of the compass
ring. A bearing pointer arrow, in the middle of the compass ring, and a bearing ‘bug’ indicator on the
outside of the compass ring, indicate the direction of the destination (bearing) relative to the course over
ground. The compass ring and pointer arrow work independently to show—at a glance—the direction of
your movement and the direction to your destination. For instance, if the arrow points up, you are going
directly to the waypoint. If the arrow points any direction other than up, turn toward the arrow until it
points up, then continue in that direction.

The bearing pointer, bearing bug and/or compass ring may point in various directions
when you are stationary or at very low speeds. Once you start moving, the pointer is
correct.
The GPSMAP 172/172C’s Compass Page features a menu page that provides access to layout and
data field options. The data window, located at the top of the page, provides a user-selectable layout of
various types of useful data. Each data field may be configured to display several data options.
Reference
Compass Page
Data Fields
Bearing
‘Bug’
Bearing
Pointer
Destination
Compass
Ring
To display the Compass Page options:
1. Press MENU.
To select a menu option:
1. Use the ARROW KEYPAD to highlight the desired option and press ENTER. For detailed instructions on changing the data fields and layout of the Compass Page, see pages 25-26.
For detailed instructions on changing the data fields and layout of the Compass Page, see pages 25-26.
27
Reference
Highway Page
Whenever a Go To, TracBack or route has been activated, the GPSMAP 172/172C’s Highway Page
provides digital and graphic steering guidance to the destination with the Navigation Page. The top half
of the Highway Page features user-selectable data fields that display useful navigation data. The bottom
section of the screen provides visual guidance to the waypoint on a graphic highway display. The line
down the center of the highway represents your desired track line.
As you head toward your destination, the highway perspective moves to indicate your progress to
the waypoint and which direction you should steer to stay on course. If you are navigating a route, the
Highway Page shows each route waypoint in sequence connected by a red “road” with a yellow line
down the middle, which is your desired track line. Nearby waypoints not in the active route can also
be displayed. The highway perspective scale may also be zoomed in or out to display a larger or smaller
view of the highway. Five settings are available from 1X to 16X, with a default setting of 8X.
Data Fields
Current Nav Point
To change the highway perspective scale:
Route Waypoints
1. Press the IN or OUT key to select the desired setting.
Desired Track Line
Current Position
Zoom Scale
Highway Page
Highway Page
The GPSMAP 172/172C’s Highway options page allows you to define the data fields and select
which waypoints and track are displayed on screen. The data window, located at the top of the page,
provides a user-selectable layout of various types of useful data. Each data field may be configured to
display several data options. The data window layout may also be changed to display additional data
fields and change the actual size of the data displayed.
The GPSMAP 172/172C’s Highway Page features a menu options page that provides access to functions and features relating to the Highway Page and the layout options.
To display the Highway Page options:
1. Press MENU.
28
To select a menu option:
1. Using the ARROW KEYPAD, highlight the desired option and press ENTER.
The following options are available from the Highway Page menu:
• Set Up Highway— allows you to select what waypoints and tracks are shown on the Highway
display. Use the ARROW KEYPAD and ENTER key to select/deselect the desired options. Four
options are available:
• Active Route Waypoints— all active route waypoints
• User Waypoints— only nearby waypoints
• Track Log— current active track log
• Saved Tracks— any saved track logs
• Set Up Page Layout— allows you to change the layout of the data fields to show more fields
(with a smaller number size) or less fields (with a larger number size). See page 25.
• Change Numbers— allows you to specify the type of data displayed in each data field used on
the map display. For detailed instructions on changing the data fields and layout of the Highway page,
see pages 25-26.
Reference
Highway Page Options
Check or uncheck
the options you wish
to show/hide on the
Highway Page.
Preview Window
Selecting the ‘Setup Highway’
option takes you to the Hiway
tab of the Main Menu.
Active Route Page
Whenever you have activated a route in the GPSMAP 172/172C system, the Active Route page
shows each waypoint of the active route, along with various, user-selectable types of data. For additional details on the Active Route Page, see page 50.
Active Route Page
29
Reference
Creating Waypoints
Creating and Using Waypoints
The Garmin GPSMAP 172/172C stores up to 3000 alphanumeric waypoints with a user-defined
icon, comments, depth, and water temperature available for each waypoint. Waypoints can be created
using three basic methods:
• ENTER/MARK key– used primarily for marking your present position, the ENTER/MARK key
also provides options that allow you to select a map position or map item from the map display.
• Graphically– allows you to define a new waypoint position from the map display using the
ARROW KEYPAD.
• Text Entry– allows you to enter a new waypoint’s coordinates manually (from a chart, etc.).
Marking Your Present Position
Highlight ‘OK’ and press ENTER to
use the default name and symbol.
The Garmin GPSMAP 172/172C’s ENTER/MARK key lets you quickly capture your present position (or cursor or map item position) in order to create a new waypoint. You must have a valid position
(2D or 3D) fix to mark your present position. This can be determined by looking at the GPS tab on the
Main Menu.
To mark your present position:
1. Press and hold the ENTER/MARK key until the ‘New Waypoint’ window appears, then release it.
You see a default three-digit name and symbol for the new waypoint.
2. To accept the waypoint with the default name and symbol, press ENTER to confirm the highlighted
‘OK’ prompt.
3. To enter a different name, highlight the name field and press ENTER, then use the ARROW
KEYPAD to enter the new letters/numbers and press ENTER when done. You may use up to 10
alphanumeric characters for the name.
Highlight a field and press ENTER
to enter a new symbol, name, comment or depth.
30
4. To enter a different symbol, highlight the symbol field to the left of the name and press ENTER,
then use the ARROW KEYPAD to highlight the new symbol and press ENTER.
5. To enter optional comments, depth, or water temp, highlight the appropriate field and press
ENTER, then use the ARROW KEYPAD to enter a value and press ENTER.
6. To manually enter a set of coordinates, highlight the coordinates and press ENTER, then use the
ARROW KEYPAD to enter the new coordinates and press ENTER when done.
7. When done, use the ARROW KEYPAD to highlight the ‘OK’ prompt and press ENTER to save the
waypoint into memory.
Reference
Creating Waypoints
Creating Waypoints Graphically
Waypoints may also be quickly created with the Map Page cursor, which allows you to ‘point and
shoot’ at any map position or map feature to create a new waypoint. When you move the cursor over
a map item, you see a highlighted description of that item. The GPSMAP 172/172C uses the map item
text shown on the cartography as the default name and symbol for the new waypoint.
To create a new waypoint on an open map location:
1. Use the ARROW KEYPAD to move the cursor to the desired map position.
2. Press and quickly release the ENTER/MARK key to capture the cursor position (press and hold
ENTER/MARK to mark your present location, not the map cursor’s position).
3. The ‘New Map Waypoint’ page appears. To accept the waypoint with the default name and symbol,
press ENTER.
To change the name, symbol, position, or add a comment, depth, or water temp, highlight the
appropriate field and press ENTER. Make your changes and press ENTER when done. After entering and confirming your changes, highlight ‘OK’ and press ENTER.
Creating a waypoint on
an open map location.
To create a new waypoint from a map feature:
1. Use the ARROW KEYPAD to move the cursor and highlight the desired map feature.
2. Press ENTER/MARK to capture the cursor position. An Information page for that map feature
appears. Use the ARROW KEYPAD to highlight ‘Create Wpt’ and press ENTER.
3. The ‘New Waypoint’ page appears. To accept the waypoint with the default name and symbol
(based on the map feature), highlight ‘OK’ and press ENTER.
To change the name, symbol, position, or enter comments, depth, or water temp, highlight the
appropriate field and press ENTER. Make your changes and press ENTER. After entering and
confirming your changes, use the ARROW KEYPAD to highlight ‘OK’ and press ENTER.
Using a map item to create
a new waypoint.
31
Reference
Creating Waypoints
Additional Options For Creating Waypoints
Waypoints may also be created by manually entering position coordinates through the Points tab
of the Main Menu. This method can be useful for creating a waypoint at a specific latitude/longitude
position from a chart.
To create a new waypoint by entering location coordinates:
1. Press MENU twice to display the Main Menu. Highlight the ‘Points’ tab and press MENU.
2. Highlight ‘Create Waypoint’ and press ENTER. The ‘New Waypoint’ page appears, with the next
available waypoint number and the receiver’s last know position as the default name and position.
3. Use the ARROW KEYPAD to highlight the position field and press ENTER. Use the ARROW
KEYPAD to enter the desired position coordinates and press ENTER when finished.
4. To change the name, symbol, or enter comments, depth, or water temp, highlight the appropriate
field and press ENTER. Make your changes and press ENTER when finished.
Highlight the position field and use the
ARROW KEYPAD to enter the desired
position coordinates.
5. Use the ARROW KEYPAD to highlight ‘OK’ and press ENTER to save the waypoint.
A waypoint may also be created by “projecting” the distance and bearing from a specific location to
a new location. Start by accessing the ‘New Waypoint’ page or the ‘New Map Waypoint’ page.
To create a new waypoint by projecting its location:
1. To project the waypoint from your current location, be sure the field to the right of the word ‘From’
reads ‘Current Position’ (if not, highlight the field and press ENTER, highlight ‘Current Position’ and
press ENTER).
2. To select a map location from which to project a waypoint, highlight the field next to ‘From’ and
press ENTER. The ‘Find’ screen appears. Highlight ‘Other Position’ and press ENTER. Use the zoom
IN key and ARROW KEYPAD to highlight the desired position on the map and press ENTER.
Select a point from which to
project a new waypoint.
32
3. To select another location from which to project a waypoint, highlight the field next to ‘From’ and
press ENTER. The ‘Find’ screen appears. Highlight the desired type of location (waypoints, cities,
etc.) and press ENTER. Use the submenus to narrow down your search (for more information see
‘Find’ on pages 51-52). Highlight the desired location and press ENTER. With ‘OK’ highlighted,
press ENTER again.
Reference
Creating Waypoints
4. Highlight the distance and/or bearing fields below ‘From Current Position’ and press ENTER. Use
the ARROW KEYPAD to enter the projected distance and/or bearing from your current position for
the new waypoint and press ENTER.
5. Make any other desired changes to the new waypoint data (name, symbol, etc.), then highlight ‘OK’
and press ENTER to save the waypoint.
Waypoint Options Menu
Waypoint Menu Options
Two additional options are available by pressing MENU on the New Waypoint and New Map
Waypoint Pages: Append To Route and Move Waypoint. (these menu options also appear on the
Waypoint Edit and Waypoint Review pages).
• Append to Route— Adds the new waypoint to the end of a route.
• Move Waypoint— Allows you to move the waypoint to a new location on the map display.
To append a new waypoint to a route:
1. Select ‘Append To Route’ from the options menu.
2. The ‘Select Route’ screen appears. Highlight the desired route or select ‘New Route’ and press
ENTER.
3. With ‘OK’ highlighted, press ENTER to save the waypoint.
To move a waypoint:
1. Select ‘Move Waypoint’ from the options menu.
2. The selected waypoint is centered and highlighted on a map display. Use the ARROW KEYPAD to
move the waypoint to the new position and press ENTER. Press QUIT to exit.
Use the ARROW KEYPAD to move the
waypoint to a new position on the map.
33
Reference
Reviewing/Editing Waypoints
Reviewing and Editing Waypoints
Once you have created and stored a waypoint, it may be modified, reviewed, renamed, moved, or
deleted at any time through the Waypoint Review and Waypoint Edit pages.
To access the Waypoint Review page:
1. Use the ARROW KEYPAD to highlight the desired waypoint on the Map Page.
2. Press ENTER to display the Waypoint Review page. If the waypoint is located on a map feature, or
on a MapSource or BlueChart feature, the Waypoint Review page includes additional information
tabs about the other features at that location.
To access the Waypoint Edit page:
1. Press MENU twice to view the Main Menu. Use the ARROW KEYPAD to highlight the ‘Points’ tab,
then highlight the desired waypoint from the ‘User’ or ‘Proximity’ lists.
Waypoint Review Page— Highlight ‘OK’ and
press ENTER to exit/save changes.
2. Press ENTER to display the Waypoint Edit page. If the waypoint is located on a map feature, or
on a MapSource or BlueChart feature, the Waypoint Edit page does NOT display the details of the
other map features.
From the Waypoint Review and Edit pages, you may change the name, symbol, comment, position
coordinates, depth, or water temp for the selected waypoint. Once the changes have been made, highlight ‘OK’ (Waypoint Review Page) or ‘Next’ (Waypoint Edit Page) and press ENTER to save them.
To change the waypoint name:
1. Highlight the waypoint name field and press ENTER.
2. Use the ARROW KEYPAD to enter a new name and press ENTER when done.
To change the waypoint symbol:
Changing a Waypoint symbol.
34
1. Highlight the waypoint symbol field to the left of the waypoint name and press ENTER.
2. Use the ARROW KEYPAD to select the desired symbol and press ENTER when done.
Reference
To change the comment/position coordinates/depth/water temperature:
1. Highlight the desired field and press ENTER.
Editing Waypoints
2. Use the ARROW KEYPAD to edit/enter the data. To drop to the next line, press to the right on the
ARROW KEYPAD. Press ENTER when done.
On the Waypoint Review and Waypoint Edit pages, you may also delete the selected waypoint,
view the waypoint on the map, and move the waypoint on the map.
To delete a waypoint:
1. On the Waypoint Review/Waypoint Edit page, use the ARROW KEYPAD to highlight ‘Delete’ and
press ENTER.
2. With ‘OK’ highlighted, press ENTER again to confirm the deletion.
To view and move a waypoint on the map:
1. From the Waypoint Review/Waypoint Edit page, highlight ‘Show Map’ and press ENTER. The
waypoint is highlighted on a map screen with an information window that shows the waypoint
name, position and distance and bearing from your current position.
2. To move the waypoint, press ENTER. A ‘MOVE’ label now appears under the cursor arrow. It may
be necessary to use the IN and OUT keys to zoom the map.
3. Use the ARROW KEYPAD to move the waypoint to a new position. As you move the cursor around
the map display, the information window at the top changes to show the distance, bearing, and
position of the map cursor (in relation to the waypoint’s original position), and a description of
where the cursor is on the map. If you wish to stop the move process, press QUIT.
Symbol
Name
Comment
Depth
Water
Temperature
Coordinates
Waypoint Edit Page
4. With the pointer at the desired position, press ENTER. To return to the Waypoint Edit/Waypoint
Review page, press QUIT.
On the ‘Show Map’ map display, an additional option is available by pressing MENU:
• Point to on Map Page— returns to the highlighted waypoint on the main Map Page (exits the
Waypoint Review/Waypoint Edit Page).
35
Reference
Waypoint Lists
Submenu Tabs
Waypoint Lists
The GPSMAP 172/172C’s Main Menu Page features two waypoint submenu tabs, ‘User’ and ‘Proximity’, that let you manage a large number of waypoints quickly and efficiently. The submenu tabs also
provide a continuously updated proximity waypoint alarm function that can be used to define an alarm
circle around submerged hazards, shallow waters, etc.
To access the waypoint submenus of the Main Menu:
1. Press MENU twice, highlight the ‘Points’ tab using the ARROW KEYPAD, then highlight the
desired submenu tab.
User Waypoint List
Main Menu—Points Tab
The ‘User’ submenu of the Points tab displays a master list of all waypoints currently stored in
memory. From the User list, you may review, edit, rename or delete individual waypoints, or delete all
user waypoints. The total number of stored and available waypoints is displayed at the bottom of the
User page, with the stored waypoints arranged in numerical/alphabetical order.
To scroll through and review the waypoint list:
1. With the ARROW KEYPAD, highlight the ‘Points’ tab on the main menu, then highlight ‘User’.
2. Use the ARROW KEYPAD to scroll through the list in the desired direction.
3. Press ENTER to review the highlighted waypoint on the ‘Waypoint Edit’ page (see page 34 for
detailed information on reviewing and editing waypoints).
4. With ‘Next’ highlighted, press ENTER to return to the list. The field highlight automatically moves
to the next waypoint in the list.
Options Menu
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The following options are available by pressing MENU while highlighting the Points tab, the User
submenu or one of the User waypoint names:
• Create Waypoint— allows you to create a waypoint. (See page 30)
• Delete Waypoint— deletes selected waypoint from list and any route in which it was used.
• Delete By Symbol— deletes waypoints that use the same symbol.
• Delete All— deletes all waypoints from the unit.

Once a waypoint is deleted from the list, it cannot be recovered from the unit. It is
advisable to backup important waypoints to a computer using an optional PC cable
and interface software, save them to a data card, or write them down by hand.
To delete an individual waypoint from the ‘User’ list:
Reference
Waypoint Lists
1. Use the ARROW KEYPAD to highlight the waypoint to be deleted.
2. Press MENU, highlight ‘Delete Waypoint’ and press ENTER.
OR, press ENTER, highlight ‘Delete’ and press ENTER.
3. Press the ENTER key to confirm the deletion warning.
Name
Field
To delete waypoints by symbol:
1. From the ‘User’ tab, highlight the waypoint to be deleted and press MENU, then select ‘Delete By
Symbol’ and press ENTER.
2. Use the ARROW KEYPAD to highlight the symbol of the waypoint(s) to be deleted and press
ENTER.
3. Press ENTER to confirm. Choose ‘Cancel’ or press QUIT to stop the deletion.
To delete all user waypoints:
1. Press the MENU key to select the options window.
2. Use the ARROW KEYPAD to highlight ‘Delete All’ and then press ENTER.
3. Highlight the ‘OK’ prompt and press ENTER to confirm.
Proximity Waypoint List
The ‘Proximity’ submenu of the Points tab lets you define an alarm circle around a stored waypoint
position, and can be used to help you avoid reefs, rocks, or restricted waters. Up to ten waypoints may
be listed, with a maximum alarm radius of 99.99 nautical or statute miles or kilometers. If a proximity
alarm circle overlaps with an existing alarm circle, the message ‘Proximity Overlaps Another Proximity
Waypoint’ appears. Since the unit only alerts for one of the overlap points, use caution when navigating in these areas. If you enter an alarm circle overlap, you are only alerted to the closest proximity
waypoint.
Waypoint
List
You can also search for a waypoint by name:
1. Highlight the name field and press ENTER.
2. Use the ARROW KEYPAD to select the first letter of
the name.
3. Move to the RIGHT and enter the second letter if you do
not see it on the list below.
4. Repeat this until the name appears. Press ENTER when
you see the name.
5. Highlight the name on the list and press ENTER again
to review the waypoint. When done, highlight ‘OK’ and
press ENTER.
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Reference
To add a proximity waypoint:
1. Use the ARROW KEYPAD to highlight an empty space on the Proximity list and press ENTER. The
‘Find’ screen appears. Highlight ‘Waypoints’ and press ENTER.
Waypoint Lists
2. Use the ARROW KEYPAD to highlight the desired waypoint from the ‘By Name’ or ‘Nearest’ tab
lists. The Waypoint Review page appears for the selected waypoint.
3. With ‘OK’ highlighted, press ENTER to confirm. The distance field is now highlighted.
4. Press ENTER to begin entry of the proximity radius.
5. Use the ARROW KEYPAD to enter a distance value (to 99.99 units) and press ENTER.
To turn proximity alarms on or off:
1. Use the ARROW KEYPAD to highlight the field below “Proximity Alarm” and press ENTER.
2. Select the desired ‘ON’ or ‘OFF’ setting and press ENTER.
Proximity Waypoints List
The following options are available from the ‘Proximity’ submenu of the ‘Points’ tab:
• Delete Alarm— removes selected waypoint from proximity list.
• Delete All— removes all waypoints from proximity list.
To display the waypoint menu options:
1. Using the ARROW KEYPAD, highlight the ‘Proximity’ tab and press MENU.
Proximity
Waypoint
Proximity
Circle
To clear one or all proximity waypoint(s) from the list:
1. Use the ARROW KEYPAD to highlight the proximity waypoint to clear and press MENU.
2. To clear a single alarm, highlight the ‘Delete Alarm’ option and press ENTER.
3. To clear all proximity waypoints, select the ‘Delete All’ option and press ENTER.
A dashed circle appears showing
the alert boundary for the
proximity waypoints.
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4. Use the ARROW KEYPAD to highlight the ‘OK’ prompt and press ENTER to confirm.
Going to a Destination
Using the NAV key, the GPSMAP 172/172C provides three ways to navigate to a destination: Go
To Point, Follow Route, and Follow Track (TracBack). Once you are actively navigating, you see a
straight line that always runs from your current location to the destination on the Map Page. The easiest
method for selecting a destination is the ‘Go To’ function, which lets you select a destination point,
then quickly sets a direct course from your present position. If you highlight a point on a list or the
map and press NAV, ‘Go To <point name>’ appears in addition to ‘Go To Point’. The ‘Go To’ function
can be accessed from any list of points or graphically from the map display.
Reference
Going to a Destination
To activate a ‘Go To’ from a point list:
1. Press the NAV key.
2. Use the ARROW KEYPAD to highlight ‘Go To Point’ and press ENTER.
3. From the ‘Find’ menu, highlight ‘Waypoints’ and press ENTER. (You may also choose to go to other
points, such as Cities, Tide Stations, etc. from this list.)
4. Select a waypoint from the ‘By Name’ or ‘Nearest’ list, then press ENTER. To display the Waypoint
Review page for the selected waypoint.
Choose a waypoint from either
the ‘User’ or ‘Nearest’ tab list.
5. With the ‘Go To’ button highlighted, press ENTER to begin navigation.
To stop navigation:
1. Press the NAV key. Use the ARROW KEYPAD to highlight ‘Stop Navigation’ and press ENTER.
Selecting a ‘Go To’ Graphically
A graphical ‘Go To’ may be used to select one of three items from the map display: an existing
waypoint, an on-screen map item (roads, rivers, cities, navaids, etc.), or a new map point (non-map
item). If you select a map item as the ‘Go To’ destination, the GPSMAP 172/172C automatically uses
the name of the map item, but the point is not stored in the waypoint list (see page 13 for creating
waypoints using map items). If you select a new map point (non-map item) as the ‘Go To’ destination,
the GPSMAP 172/172C automatically creates or moves a waypoint named ‘MAP’ at the cursor position.
The waypoint or map item name
automatically appears when highlighted and NAV is pressed.
39
Reference
Going to a Destination/
TracBack Navigation
To activate an existing waypoint or map item as a ‘Go To’ from the map display:
1. Use the ARROW KEYPAD to highlight the waypoint or map item on the screen and press NAV.
2. With ‘Go To <waypoint name>’, press ENTER.
To activate a new map point (non-map item) as a ‘Go To’ from the map display:
1. Use the ARROW KEYPAD to move the arrow cursor to the desired position and press NAV.
2. With ‘Go To MAP Point’ highlighted, press ENTER.
To stop navigation:
1. Press the NAV key. Use the ARROW KEYPAD to highlight ‘Stop Navigation’ and press ENTER.
TracBack Navigation (Follow Track)
‘Go To MAP Point’ allows you to
navigate to a spot on the map that is
not a waypoint or map item.
The TracBack function allows you to retrace your path using the track log automatically stored in
the receiver’s memory, which eliminates the need to store waypoints along the way. TracBack routes are
created by reducing your track log into a route of up to 50 turns and activating an inverted route along
those points. Once activated, a TracBack route leads you back to the oldest stored track log point, so it’s
a good idea to clear the existing track log before you start your current trip.
To clear the track log and define a starting point for a TracBack route:
1. Press MENU twice to display the Main Menu page.
2. Using the ARROW KEYPAD, highlight the ‘Track’ tab, then highlight the ‘Active’ tab to the right.
3. Use the ARROW KEYPAD to highlight ‘Erase’ and press ENTER.
4. Highlight ‘OK’ and press ENTER.
Highlight ‘Save’ and press ENTER
to save an active track log.
40
You must first save the track log before you can use the ‘Follow Track’ feature. The Save feature
allows you to store up to 15 track logs from certain times and dates.
To save a track log:
1. From the Main Menu, use the ARROW KEYPAD to highlight the ‘Track’ tab, then highlight the
‘Active’ tab to the right.
2. Use the ARROW KEYPAD to select ‘Save’ and press ENTER.
3. On the ‘Save Back Through’ window, highlight the desired time, date, or ‘Entire Log’ and press
ENTER.
4. Next, the track begins saving and then display the ‘Saved Track’ window when done. The default
name, distance, and number of points (700 maximum) are displayed.
Reference
TracBack Navigation
To change the name of the saved track, highlight the name field and press ENTER, make your
changes and press ENTER again.
Default Track name
To choose a color/style that is used to display the saved track line, highlight the field and press
ENTER, choose a Color and press ENTER again.
Total Distance
To display the track on the Map and Highway pages, highlight the check box to the left of ‘Show on
Map and Highway’ and press ENTER.
Change color or
style of track line
To view the track on the map, highlight ‘Review on Map’ and press ENTER. Press QUIT to exit the
Track Map window.
Check this box to
display track
5. Highlight ‘OK’ and press ENTER to save the track.
To activate a TracBack using the NAV key:
Total number of points
1. Press the NAV key, then highlight the ‘Follow Track’ option and press ENTER.
2. Highlight the track you wish to follow and press ENTER.
3. Choose either ‘Original’, which navigates you from the start to the end of your trip, or ‘Reverse’,
which navigates you from the end to the start of your trip and press ENTER.
Once a TracBack has been activated, the GPSMAP 172/172C takes the track log currently stored
in memory and divides it into segments called ‘legs’. Up to 50 temporary ‘turns’ (BEGIN, TURN 1,
TURN 2, TURN 3,...., TURN X, END) are created to mark the most significant features of the track log
in order to duplicate your exact path as closely as possible. To get the most out of the TracBack feature,
remember the following tips:
• Always clear the track log at the point that you want to go back to (dock, etc.).
• The ‘Record Mode’ option on the track log setup page must be set to ‘Fill’ or ‘Wrap’.
• There must be at least two track log points stored in memory to create a TracBack route.
You must first save a track before using the ‘Follow
Track’ option. If there are no saved tracks, the message
“There are no saved Tracks to follow” appears after you
select ‘Follow Track.’
41
Reference
• If the track log interval is set to the ‘Time’ option, the route may not follow your exact path
(keep the interval set to ‘resolution’ for best performance).
TracBack Navigation/
MOB: Man OverBoard
• If the receiver is turned off or satellite coverage is lost during your trip, the TracBack draws a
straight line between any point where coverage was lost and where it resumed.
• If your track log’s changes in distance and direction are too complex, 50 waypoints may not
mark your path accurately. The receiver then assigns the 50 waypoints to the most significant
points of your track, and simplifies segments with fewer changes in direction.
To stop TracBack navigation:
1. Press the NAV key, highlight ‘Stop Navigation’ and press ENTER.
For more information on setting up the Track options and saved tracks, see pages 61.
MOB Key
The MOB function allows you to
quickly activate a course back to
a location.
The GPSMAP 172/172C’s Man OverBoard function (MOB) lets you simultaneously mark and set a
course to a position for quick response to emergency situations.
To activate the MOB function:
1. Press and hold the MOB key for two seconds.
2. Press ENTER to confirm and begin navigating to the MOB position.
Once a MOB has been activated, a ‘MOB’ waypoint with an international MOB symbol is created
and the unit is set on an active navigation to that point. Use any of the Navigation Pages to guide you
back to the MOB point. The MOB waypoint is stored in the waypoint list and may be deleted like any
other waypoint (see page 17).
To stop navigation to the MOB position:
Highlight ‘Stop Navigation’ and
press ENTER to stop navigating.
42
1. Press the NAV key, highlight ‘Stop Navigation’ and press ENTER.
Routes
The last way to navigate to a destination is to create a user-defined route. The Garmin GPSMAP
172/172C system lets you create and store up to 50 reversible routes (numbered 1-50), with up to 50
waypoints each. Routes can be created and modified in two ways. The first way is to ‘Edit on Map’ from
the Route Edit map page, allowing you to see each route graphically on-screen as you create, review, or
modify the route. The second way is to ‘Edit as Text’ from the Route Review page, allowing you to see
a list of the waypoints as you create, review, or modify the route. All of the GPSMAP 172/172C’s route
functions are accessed through the Main Menu page or the NAV key.
Reference
Creating Routes
To create a route graphically from the Route Edit map page:
1. Press the MENU key twice to display the Main Menu page. Use the ARROW KEYPAD to highlight
the ‘Route’ tab.
2. Press the MENU key to display the route options page. Select ‘New Route’ and press ENTER.
Or, highlight the first available blank slot in the Route List and press ENTER.
3. To add an existing waypoint or map item to the route, use the ARROW KEYPAD to highlight
the desired waypoint or map item on screen and press ENTER. Map items do not appear in the
waypoint list. To create a waypoint from a map item, see page 13.
Main Menu—Route Tab and
Route Options Menu
4. To add a new waypoint to the route, use the map cursor to select the desired map position and
press ENTER. Press ENTER again to confirm the new waypoint. You may also change the name,
symbol and other properties of the new waypoint (see pages 34).
As you add each new waypoint to the route, the data window at the top of the map display shows
the waypoint/map item name, bearing and distance from your location, and coordinates of the
cursor. The bottom of the display shows you the number of available and used points. A route line
appears on the map to indicate each completed leg, and a dotted line appears to indicate the
distance and bearing to the arrow cursor from the last route waypoint.
5. Repeat steps 3 and 4 until you have finished defining all route waypoints.
6. When finished press QUIT twice to return to the Route List page; or press MENU, highlight ‘Edit as
Text’ and press ENTER to return to the Route Review page.
You see ‘ADD’ below the
cursor as you add points.
43
Reference
Creating a Route/
Following a Route
To create a route using text from the Route Review page:
1. Press the MENU key twice to display the Main Menu page. Use the ARROW KEYPAD to highlight
the ‘Route’ tab.
2. Press the MENU key to display the route options page. Select the ‘New Route’ option and press
ENTER.
Or, highlight the first available blank route slot and press ENTER.
3. Press MENU, select ‘Edit as text’ and press ENTER.
4. Use the ARROW KEYPAD to highlight the first field under the word “Waypoint” and press
ENTER.
5. From the Find menu, highlight ‘Waypoints’ and press ENTER. (You may also choose from other
points, such as Cities, Tide Stations, etc. from this list.) Select a waypoint from either the “By Name”
or “Nearest” list and press ENTER. (See page 37 for searching for waypoints by name.)
Choose the type of point you
want to add to the route.
6. On the Point Review or Waypoint Review page, ‘OK’ is automatically highlighted. Choose ‘Show
Map’ and press ENTER to view the point on the map, then press QUIT to return to the Waypoint/
Point Review page. With ‘OK’ highlighted, press ENTER to add the point to the route.
7. Repeat steps 4-6 until the desired route points have been entered. Press QUIT to return to the
Route List page.
Following a Route
Once a route has been created, it can be activated and used for navigation with the NAV key. A
route may be followed in the same sequence as it was originally created, or inverted and followed from
the end point back to the beginning point.
To activate and follow a route:
44
Choose a waypoint from either
the ‘By Name’ or ‘Nearest’
tab list.
1. From any page, press the NAV key, then using the ARROW KEYPAD, highlight ‘Follow Route’ and
press ENTER. (If you highlight a route from the Route List or Route Review page and press NAV,
the window automatically displays, ‘Follow <the route name>’.)
2. Highlight the route you wish to navigate and press ENTER.
3. Choose ‘Activate’ or ‘Invert and Activate’ and press ENTER. (‘Activate’ uses the route as is, ‘Invert
and Activate’ reverses the route then activate it.)
Reference
Route List Page
To deactivate (stop navigation) of a route:
1. Press the NAV key, highlight ‘Stop Navigation’ and press ENTER.
Route List Page
The GPSMAP 172/172C Route List page (‘Route’ tab of the Main Menu) displays all the routes
currently stored in memory, along with a descriptive name for each route. By pressing MENU while on
the Route List page, the following menu options appear: ‘New Route’ (page 44), ‘Copy Route’, ‘Delete
Route’, or ‘Delete All’.
To select and follow a route:
1. On the Route List page, use the ARROW KEYPAD to highlight the desired route and press NAV.
2. With ‘Follow <route name>’ highlighted, press ENTER. Highlight ‘Activate’ or ‘Invert and
activate’ and press ENTER.
If you highlight a route name from
the Route List and press NAV, the
name automatically appears.
To deactivate (stop following) the route:
1. Press the NAV key, highlight ‘Stop Navigation’ and press ENTER.
To copy or delete a route:
1. From the Route List, using the ARROW KEYPAD, highlight the route you want to copy or delete
and press MENU.
2. Choose either ‘Copy Route’ or ‘Delete Route’ and press ENTER and with ‘OK’ highlighted, press
ENTER again to confirm a deletion. Copy uses the same route name with an additional number,
starting at 1, at the end of the route name.
To delete all routes:
1. From the Route List, press MENU.
2. Highlight ‘Delete All’ and press ENTER. With ‘OK’ highlighted, press ENTER again to confirm.
Route List Options Menu
45
Reference
Route Review Page
Route Review Page
Once you have created a route, the Route Review page allows you to edit a selected route.
To access the Route Review page:
1. Press MENU twice and highlight the ‘Route’ tab.
Route Name
Data Fields
2. Highlight the name of the route you wish to review and press ENTER.
The Route Review page also allows you to enter a 15-character name for any listed route. By
default the name includes the first and last waypoints in the route.
To enter a custom route name:
Route Points
1. From the Route Review page, highlight the name field and press ENTER to begin editing.
2. Use the ARROW KEYPAD to enter the desired name and press ENTER when finished.
Data Totals
Once you are on the Route Review page, you may review the route points (waypoints or map
items) one at a time from the list.
To review individual route points:
1. Highlight the desired point and press ENTER.
2. On the Point Review window, you may choose ‘Next’ (highlight the next point on the route list),
‘Show Map’ (show the point on a map window), or ‘Delete’ (permanently delete the waypoint from
the unit) and press ENTER. If the route point is a user waypoint, you may edit any of the waypoint
properties on the Waypoint Review page (see pages 34 for details).
Once you are back on the Route Point List, the next point in the route is automatically highlighted.
This allows you to review each point on the route by repeatedly pressing ENTER.
Route Review
Options Menu
46
Route Review Options Menu
By pressing MENU on the Route Review page, the following options are available: Edit on Map,
Add Before, Remove, and Trip Planning.
• Edit on Map — review and modify the route displayed for each point (waypoint or map item)
on a map page. You may also use the cursor to insert a new route point on a route leg, review the
waypoint or map item.
To edit a route on the map:
Reference
Editing Routes
1. From the Route Review page, press MENU, highlight ‘Edit on Map’ and press ENTER.
To review a route point:
1. Highlight the point and press ENTER. The Review page appears. Highlight ‘Next’ and press ENTER
to return to the map with the next route point highlighted.
To edit a route point:
1. Use the ARROW KEYPAD to highlight the desired route waypoint and press MENU.
A pop-up menu of editing choices appears, with the following options: Edit as Text (return to the
Route Review page), Remove, Move (user waypoints only), and Add.
To remove a route waypoint:
Highlight a route point and
press ENTER to review it.
1. Highlight the ‘Remove’ option and press ENTER.
To move a route waypoint:
1. Highlight the ‘Move’ option and press ENTER.
2. Move the cursor to the new map position and press ENTER.
To add points to the beginning or end of the route:
1. With the map cursor, select the first route waypoint (to add waypoints to the beginning of the
route) or last (to add waypoints to the end of the route) and press MENU.
2. Highlight the ‘Add’ option and press ENTER.
3. Move the cursor to the new point or position and press ENTER.
4. If you are not adding an existing waypoint, press ENTER to confirm the new waypoint.
5. Repeat steps 3 and 4 to add additional waypoints or press QUIT to finish.
Choose ‘Next’ to center the map on the next
point in the route. You can step through the
points by repeatedly pressing ENTER.
47
Reference
Editing Routes
The GPSMAP 172/172C’s route edit mode also allows you to insert a new route point in any route
leg using the map cursor.
To insert a new point between two existing route waypoints:
1. Use the ARROW KEYPAD to select the leg in which you want to insert the new waypoint (the
route line highlights and changes to a dotted line when the leg is selected) and press ENTER.
2. Move the cursor to the new map position, existing waypoint, or map item (You see ’ADD’ below the
arrow and the route lines moves with the arrow) and press ENTER.
3. If you are not inserting an existing point, press ENTER to confirm the new waypoint.
4. Press QUIT to return to the Route Review page.
• Add Before — Insert a waypoint into the route points list.
Highlight the route leg on which
you wish to insert a waypoint and
press ENTER.
To insert a point into the route:
1. From either the Route Review or Active Route pages, use the ARROW KEYPAD to highlight the
point you wish to insert the new point before and press MENU.
2. Highlight ‘Add Before’ and press ENTER.
3. From the ‘Find’ menu, highlight ‘Waypoints’ and press ENTER. (You may also choose from other
points, such as Cities, Tide Stations, etc. from this list.) Select the point you want and press ENTER
twice. (See page 37 for searching for waypoints by name.)
• Remove — Remove a point (waypoint or map item) from a route. This option is available from
both the Route Review and Active Route Pages.
To remove a point from a route:
Drag the route leg to an existing
waypoint, map item, or an open spot
on the map (shown) to create a new
route point.
48
1. From either the Route Review or Active Route pages, use the ARROW KEYPAD to highlight the
point to remove and press MENU.
2. Highlight ‘Remove’ and press ENTER.
• Trip Planning — The Route Review and Active Route pages also display trip-planning information
for each leg or the entire route. Available information includes Course, ETA, Fuel (to point), Leg
Distance, Leg Fuel, Leg Time, Sunrise and Sunset (at point location) and Time To (point).
Reference
Editing Routes
To use the trip planning feature:
1. Highlight the desired route from the Route List and press ENTER to display the Route Review page.
2. One of nine available planning figures appears to the right of each route waypoint and its distance.
Use the LEFT/RIGHT keys on the ARROW KEYPAD to select the desired item.
3. To enter planning information (from the Route Review Page only), press MENU and select ‘Trip
Planning’ from the options list. Enter the figures for Speed, Fuel Flow, Departure Time, and
Departure Date.
4. Press QUIT to return to the Route Review Page.

NOTE: Fuel flow rates on your unit are measured in “units per hour”. System setting
changes for units of measure (statute, nautical or metric) do not affect the fuel flow
measure. You should enter fuel flow rates based upon available information for your
vehicle (operator’s manual, performance specifications, etc.) and make note of the
desired units of measure (gallons, liters, etc.).
Press LEFT or RIGHT on the
ARROW KEYPAD to change
the data field.
Trip Planning Data Fields
49
Reference
Active Route Page
Active Route Page
Whenever you have activated a route in the GPSMAP 172/172C, the Active Route page shows each
point (waypoint or map item) of the active route, with the point name, distance and choice of Course,
ETA, Fuel to point, Leg Distance, Leg Fuel, Leg Time, Sunrise and Sunset at point location, or Time
To point for each point from your present position. The current destination point, the ‘active’ point, is
marked with an arrow icon. As you navigate a route, the point list automatically updates to indicate the
next ‘active’ point first. The Active Route and Route Review pages share many of the same features and
options.
Active Route Page Options
Active Route Page
The following options are available by pressing MENU on the Active Route page:
• Edit on Map — see pages 47 for instructions.
• Add Before — see page 48 for instructions.
• Remove — see page 48 for instructions.
• Invert — reverses the direction of the route.
To invert an active route:
1. From the Active Route page, press MENU.
2. Using the ARROW KEYPAD, highlight ‘Invert’ and press ENTER to reverse the route.
• Re-evaluate — recalculates and reactivates the current route data. Selects the route leg closest to your current position as the active leg (the active leg defines the current ‘from’ and ‘to’
waypoints).
Active Route Page Menu Options
To re-evaluate an active route:
1. From the Active Route page, press MENU.
2. Using the ARROW KEYPAD, highlight ‘Re-evaluate’ and press ENTER to recalculate.
50
Find Key
The FIND key allows you to search the unit for user waypoints, map items, and any optional
BlueChart or MapSource information loaded on a data card. Press the FIND key to search for items
from your current location by default. You may also search from other locations. When you press
FIND, a list of available items to search for appears. The default items are Waypoints, Cities, Tide Stations, and Transportation. Additional items, such as Anchorages, Businesses, Exits, Navaids, Restricted
Areas, Wrecks, Obstructions, etc., are displayed depending on the optional BlueChart or MapSource
data card inserted into the unit. If you pan around on the Map Page and press FIND, the unit centers
its search from the point where the cursor is located. When using BlueChart or MapSource data, your
position or the map pointer must be within the map outline area to search for information from that
area.
To find a waypoint or other item from your current location:
1. From any page, press FIND.
2. Using the ARROW KEYPAD, highlight the desired category from the list and press ENTER.
Reference
Find Key
Find Items List From the Current Location
3. For Waypoints and Cities, you may search using ‘By Name’ or ’Nearest’. Use the ARROW KEYPAD
to highlight the desired tab. For ‘By Name’, you may use the top field to spell out the name or scroll
down through the list.
To find a waypoint or item from another location:
1. Once the search results list is displayed for a particular item, press MENU.
2. Highlight ‘Nearest to Other’ and press ENTER. If you are actively following a route, you may also
choose ‘Nearest to Next’ or ‘Nearest to Destination’.
3. Select a reference point on the map and press ENTER. The search results list changes to list items
nearest to the new map position.
To find a waypoint or item from another location on the map:
1. From the Map Page, use the ARROW KEYPAD to pan to the desired location and press FIND.
2. Using the ARROW KEYPAD, highlight the desired category from the list and press ENTER.
You may also start a ‘Find’ from
items found on the Find List or
from another location on the map.
51
Reference
To view details about an item:
1. With the desired item highlighted in the search results list, press ENTER.
Find Options
Additional Information
Tabs
Distance, Bearing,
Coordinates of item
Additional Option
Buttons
Additional Information Window
2. An Information page appears with details about the item organized in a tabbed format. Depending
on the type of item, additional options are available for viewing the item on the map, viewing notes
on a MapSource or BlueChart map, viewing a tide chart, viewing a list of maps on your data card,
and viewing the next item in the search results list.
The Find option supports a “find from” feature, which allows you to center your search around an
item that you have just found. For example, you search for “Restricted Areas” and the search shows an
“Anchoring Prohibited” search result. If you press FIND again, you see “From Anchoring Prohibited” as
the new search from point. You may also use the Find feature to center your search from any waypoint,
route list entry, map item or tide station. Highlight the item you want to Find ‘from’, and press the
FIND key.
Find Options
Using the Find options, you may search from various map data and utilize variety of nearest
criteria for all items, except waypoints. Available Find options are:
• Nearest To Boat— centers search from your boat’s current location
• Nearest To Other— allows you to choose another map location from which to search.
• Nearest To Next— centers search from the next point of your active route.
• Nearest To Destination— centers search from the last point of your active route.
To find an item using the find options:
1 From any page, press FIND.
Find Menu Options
2. Using the ARROW KEYPAD, highlight the desired category from the list and press ENTER.
3 From the search results list, press MENU, then highlight the desired option and press ENTER.
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Main Menu Page
Reference
The GPSMAP 172/172C’s Main Menu Page provides access to various waypoint, system, navigation
and interface management, and setup menus in an easy to use “tab” format. The Main Menu page is
available from any page in the GPSMAP 172/172C’s system, and is accessed through the MENU key.
See pages 2-3 for additional instructions changing settings and entering data.
Main Menu Tabs
To access the Main Menu Page:
1. Press MENU twice. The 16 Menu tabs are divided into categories by function.
Submenu Tabs
To select a Menu tab from the Main Menu page:
1. Move the ARROW KEYPAD UP or DOWN to highlight the tab you want to view. The information
for the highlighted tab automatically appears to the right. If you want to highlight any of the submenu tab items, press to the RIGHT on the ARROW KEYPAD, then move UP or DOWN to select
individual items.
Main
Menu
Tabs
2. Press either MENU for additional submenu options or press ENTER/MARK to make changes to the
highlighted item. Press LEFT on the ARROW KEYPAD to get back to the Menu tab list. Press QUIT
to return to the Main Menu page.
The Main Menu tabs are:
•
•
•
•
•
•
•
•
•
•
•
GPS – shows satellite status, accuracy, initialize position.
Tide – shows 24 hour tide chart with levels and times.
Trip – provides trip speeds, odometers, averages, and trip timers.
Celes – shows sun/moon time cycles and positions.
Points – allows you to create, edit or delete waypoints. See pages 30.
Route – allows you to create, edit, activate or delete routes. See pages 43.
Track – lets you record a track, define how it is recorded and displayed.
DSC— allows you to control the Digital Selective Calling (DSC) interface.
Card – interface control for saving waypoints, routes and tracks to a data card.
Map – sets up Map Page features, zooms, and text size. See pages 21.
Hiway – sets up Highway Page features. See pages 29.
(continued)
Main Menu Page
* See the “GSD 20 Sounder Module with Garmin
Chartplotters” (190-00241-03) for operational
instructions.
53
Reference
• Temp* – sets up and shows the water temperature log. (if equipped with GSD 20 or NMEA
compatible device)
• Sonar* – sets up Sonar Page features, speeds and calibrations. (if equipped with GSD 20)
• Setup – defines System, Units, and Time settings.
• Comm – interface settings for use with a PC or second device.
• Alarm – sets up alarms for anchor drag, arrival, off course, and clock.
Main Menu:
GPS Tab
Receiver
Status
Differential
Status
Accuracy
Sky View
Signal
Strength
Bars
Main Menu— GPS Tab
90°
Center dot - 90°
above the horizon
Inner ring- 45°
above the horizon
Outer ring the horizon
45°
54
GPS Tab— provides a visual reference of satellite acquisition, receiver status, and accuracy. The status
information gives you an idea of what the receiver is doing at any given moment. The sky view and
signal strength bars give you an indication of what satellites are visible to the receiver and whether or
not they are being tracked. The signal strength is shown on a bar graph for each satellite, with the satellite number below. As the receiver locks onto satellites, a signal strength bar appears for each satellite in
view. The progress of satellite acquisition is shown in three stages:
• No signal strength bars— the receiver is looking for the satellites indicated.
• Light/White signal strength bars— the receiver has found the satellite(s) and is collecting data.
• Dark/Green signal strength bars— the receiver has collected the necessary data and the
satellite(s) are ready for use.
As soon as the GPSMAP 172/172C has collected the necessary data from the best satellites in view
to calculate a fix, the status field indicates a 2D or 3D status. The unit then updates the position, date
and time.
You can use the sky view to help determine if any satellites are being blocked, and whether you
have a current position fix (indicated by a ‘2D’,‘2D Differential’,‘3D’, or ‘3D Differential’ in the status
field). The sky view shows a bird’s-eye view of the position of each satellite relative to the receiver’s
last known position. The outer circle represents the horizon (north up), the inner circle 45º above the
horizon, and the center point a position directly overhead. You can also set the sky view to a ‘Track Up’
configuration, causing the top of the sky view to align along your current track heading.
WAAS Capability
The GPSMAP 172/172C is capable of receiving WAAS (Wide Area Augmentation System) satellite
signals. WAAS is an FAA (Federal Aviation Administration) funded project to improve the overall accuracy and integrity of the GPS signal for aviation use, but land/sea based users may also benefit from this
system. At this time, the system is still in the development stage and is not fully operational. There are
currently two WAAS satellites that can be received in the U.S.A., one over the Atlantic Ocean and one
over the Pacific Ocean, in a geo-stationary orbit over the equator. Effective use of the WAAS satellite
signal may be limited by your geographic location in relation to those satellites, now in developmental
service. WAAS satellite signal reception requires an absolute clear view of the sky and works best when
there are no nearby obstructions such as buildings, mountains, etc. WAAS satellites are numbered 33
or higher when viewing the sky view on your GPSMAP 172/172C. Initial reception of the WAAS signal
may take up to 15-20 minutes, then 1-2 minutes afterwards. When WAAS differential correction has
been received for GPS satellites (numbers 32 or below), a ‘D’ appears in the signal bar of the sky view
and ‘2D or 3D Differential’ appears in the receiver status. To learn more about the WAAS system, its
satellite positions and current state of development, visit the FAA web site (http://gps.faa.gov). Since
WAAS requires CPU resources of the GPSMAP 172/172C to search for and track the satellites, you may
disable the WAAS feature to improve unit performance if WAAS reception is not available in your area.
Reference
Main Menu:
GPS Tab
Highlight ‘WAAS Off’ and press ENTER
to disable the WAAS capabilities.
To disable/enable WAAS capability:
1. From the GPS tab, press MENU, then use the ARROW KEYPAD to highlight ‘WAAS Off’ or ‘WAAS
On’ and press ENTER.
Receiver Status and Accuracy
Receiver status is indicated at the top field of the page, with the current Accuracy and Dilution Of
Precision (DOP) to the right of the sky view. Accuracy uses DOP and other factors to calculate horizontal position accuracy in feet or meters.
55
Reference
Main Menu:
GPS Tab
When the GPSMAP 172/172C is using a differential correction signal (either WAAS or DGPS),
a “D” is displayed at the bottom of the signal
strength indicator bars for the satellites that are
corrected.
56
The status field shows one of the following conditions:
• Looking For Satellites – the receiver is looking for any satellites.
• AutoLocate – the receiver is looking for any satellite whose almanac has been collected. This
process can take up to five minutes.
• Acquiring Satellites – the receiver is looking for and collecting data from satellites visible at its
last known or initialized position, but has not collected enough data to calculate a fix.
• 2D – at least three satellites with good geometry have been acquired and a 2 dimensional
position fix (latitude and longitude) is being calculated. ‘2D Differential’ appears when you are
receiving DGPS corrections in 2D mode and a ‘D’ shows on the strength bar of satellites being
corrected.
• 3D – at least four satellites with good geometry have been acquired and your position is now
being calculated in latitude, longitude and elevation. ‘3D Differential’ appears when you are
receiving DGPS corrections in 3D mode and a ‘D’ shows on the strength bar of satellites being
corrected.
• Poor GPS Coverage – the receiver is no longer tracking enough satellites for a 2D or 3D fix.
• Receiver Not Usable – the receiver is unusable, possibly due to interference or abnormal satellite conditions. Turn the unit off and back on to reset.
• Simulating – the receiver is in simulator mode.
The Differential Receiver status shows one of the following:
• Off – No optional beacon receiver attached or enabled in the Comm menu or WAAS Off
• Searching For WAAS – WAAS is enabled and receiver is searching for WAAS signal
• Using WAAS – WAAS capability enabled and unit receiving WAAS corrections
• No Beacon Signal – DGPS receiver attached, but not transmitting RTCM data to GPS
• Tuning Beacon – Receiver is tuning manual DGPS frequency
• Receiving Beacon – Unit is receiving DGPS corrections
• Scanning Beacon – DGPS receiver is scanning for available frequency
• Using DGPS – Indicates a Differential signal is being received (only displays when the Serial
Data Format is set to “Other DGPS” on the Comm Tab of the Main Menu)
The Differential SNR (Signal to Noise Ratio) indicates, on a scale to 0-30db with 30db being the
best, the strength of the DGPS signal being received. The SNR depends upon the mounting of your
DGPS receiver and the distance from the DGPS transmitting station.
The GPS Info tab features an options menu that provides access to functions and features relating
to the GPS Info display.
The following options are available by pressing MENU on the GPS Info Tab of the Main Menu:
• Start/Stop Simulator— toggles the unit simulator on or off. Retail Demo mode restores factory
settings to the unit if left unattended for over two minutes. This mode should only be used for
display purposes. User waypoints are NOT deleted.
• WAAS On/WAAS Off— toggles the WAAS capability of the receiver on or off.
• Track Up/North Up— allows you to select between a north up or track up sky view display for
the GPS Info display only.
• AutoLocate— allows the receiver to locate your position automatically. This process can take up
to five minutes.
• Initialize Position— allows you to initialize the receiver graphically on the Map Page to initially
help the receiver acquire more quickly. See page 4 for instructions on initialization.
• Set 2D Elevation— allows you to manually enter the elevation when in 2D or Simulator mode
only. Any elevation entered is automatically calculated when the GPS is in 3D mode.
Reference
Main Menu:
GPS Tab Options
GPS Tab Options Menu
To select a menu option:
1. Using the ARROW KEYPAD, highlight the desired option and press ENTER.

NOTE: If a DGPS receiver is attached to the unit and Garmin DGPS, RTCM In/NMEA
Out, or Other DGPS is enable on Port 2, WAAS is automatically disabled (WAAS Off). It
is not possible for the GPSMAP 172/172C to receive WAAS and DGPS corrections at the
same time.
57
Reference
Main Menu:
Tide Tab
Station Name
Date
Tide Tab— shows a graphical chart which displays tide station information in a 24 hour span
starting at midnight. You can choose from different dates and over 3000 tide stations around the USA
coastline, Alaska, Hawaii, western Canada and several of the Caribbean islands.
The top of the page displays the tide station being referenced, and the date. The bottom of the
chart shows a 24-hour block of local time for your position. Daylight (light bar or yellow on 172C) and
nighttime (dark bar or blue on 172C) show across the time scale, with the time progressing from left to
right. (Local time scales and sunrise/sunset info may not be available for a few stations). The solid, light
vertical lines are in 4-hour increments, and the light, dotted vertical lines are in 1-hour increments. A
solid, vertical line (with the current time box at the top) will indicate the time of day when using current date and will intersect the tide graph to show their relation.
Tide Chart
Event Times
Main Menu—Tide Tab
Max. Level
High Tide Curve
Current Tide Height Bar
Min. Level
Current Time Box
Low Tide Curve
Day
Night
You can select from a list of
nearest stations.
58
The tide curve shows as a shaded area, with higher tides being taller (blue on 172C) and lower
tides shorter (red on 172C). The solid, horizontal line (with the current tide box on the left) indicates
the current tide height. The figure to the left of the line will show the current tide level. The Mean
Lower Low Water (MLLW) appears as a solid, horizontal line near the bottom of the chart (This line
will only appear if the tide ranges to the zero value or below). The numbers on the top and bottom of
the left side indicate the maximum/minimum levels, respectively. The four data fields below the chart,
indicate event times and levels at which the tide changes starting in the upper left field, going downward, then to the upper right and down again. When comparing with other tide tables, be sure the
depth unit value is the same for both sources.
To select the nearest tide station from your current location:
1. From the “Tide” tab, highlight the ‘At’ field and press ENTER/MARK.
2. Highlight the desired station on the list and press ENTER/MARK twice.
If you are not within this range, you will see a message “None Found”. Use the ‘Nearest To Other’
Find option and select a location closer to a tide station.
Reference
Main Menu:
Tide Tab
To select a tide station from the map:
1. Press FIND, select ‘Tide Stations’ and press ENTER/MARK.
2. Press MENU after the search results appear.
3. Highlight ‘Nearest To Other’ and press ENTER/MARK.
4. Select a position on the map and press ENTER/MARK.
5. A list is displayed showing up to nine of the nearest tide stations. Highlight the desired station
and press ENTER/MARK. Select the ‘Show Chart’ button and press ENTER/MARK. If the “None
Found” message appears, repeat steps 1-4 until you find a station.
You may also change the date to see tide charts for other days.
To change the date for the tide chart:
Tide Station List Menu Options
Press MENU on the Tide Station list to access additional
search options. The ‘Nearest to Next’ and ‘Nearest to Destination’ options are enabled when you are actively going to a
destination (following a Go To or a Route, for example). You
must select a location within 100 nm. of a tide station.
1. Using the ARROW KEYPAD, highlight the “On” field and press ENTER/MARK.
2. Enter the desired date and press ENTER/MARK.
To use the current date:
1. Press MENU, then highlight ‘Use Today’s Date’ and press ENTER/MARK.
You may move the time bar on the tide chart in 5 minute increments to show tide heights at various times on the chart.
To see tide heights at various times on the chart:
1. Move the highlight to the chart.
2. Press LEFT or RIGHT on the ARROW KEYPAD to change the time. Press QUIT when done.
You may move the cursor to see tide heights at different times. Tide data shows in a black box when
in cursor mode.
59
Reference
Trip Tab— displays data for Trip Odometer, Moving Average speed, Total Average speed, Maximum
Speed, Stopped Time, Moving Time, Total Time, and Odometer. You may reset the data by choosing
from ‘Reset Trip’, ‘Reset Odometer’, ‘Reset Max Speed’, or ‘Reset All’ and pressing ENTER.
Celes (Celestial) Tab— displays celestial data for sun and moon rise/set, moon phase, and approximate skyview location of the sun and moon. The moon phase displays the current visible portion of the
moon as a light color. You may display this data for your current position, a position from the map, or
a Find item location. Also, you may select a different date and time, or use the current data.
Main Menu: Trip/
Celes (Celestial) Tab
To choose another position:
1. From the Celestial tab, highlight the ‘At’ field and press ENTER.
2. The Find menu appears. Make a selection and press ENTER until the information for that location
is displayed on the Celestial tab. See page 51 for more information on using the Find feature. List
highlight any category, except Other Location, and press ENTER. If you wish to reference a Find
item, select from the Find list, and press ENTER.
Main Menu— Trip Tab
Date/Time
Position
To change the time or date:
Sun/Moon
Event Times
Skyview
Window
Moon
Phase
Sun
Position
1. Use the ARROW KEYPAD to highlight the date or time field and press ENTER.
2. Enter a new date or time and press ENTER.
3. To return to the current date and time, press MENU, use the ARROW KEYPAD to highlight ‘Use
Current Date and Time’ and press ENTER.
To change the skyview orientation:
1. From the Celestial tab, press MENU, then use the ARROW KEYPAD to highlight ‘North Up’ or
‘Track Up’ and press ENTER.
Overhead (90°)
45°
20°
Horizon (0°)
Main Menu— Celestial Tab
60
The location the unit is using appears in the Date/Time/Position field. The timetables displayed is
based upon your current time zone. You may change your time zone to view times from another zone.
Keep in mind this changes the time settings for the entire unit.(see page 61).
Points Tab— contains the ‘User’ and ‘Proximity’ waypoint lists. See page 30.
Route Tab— contains a list of available routes. See pages 43.
Track Tab— lets you specify whether or not to record a track log (an electronic ‘breadcrumb trail’
recording of your path), define how it is recorded, or save track log data for future use. The Track Tab
also provides an indicator of the memory used for the active track log and options to clear the track
memory or start a TracBack route. See page 40 for TracBack information. The Track submenu is divided
in two tabs: ‘Active’ tab and the ‘Saved’ tab.
Active Submenu Tab— is for the active log (the log currently being recorded). It displays track
memory used and current settings. For the ‘Active’ tab, the following settings are available:
• Record Mode— lets you select one of three track recording options:
Off— No track log is recorded. Note that selecting the ‘Off’ setting prevents you from using
the TracBack feature.
Fill— a track log is recorded until the track memory is full.
Wrap— A track log is continuously recorded, wrapping through the available memory
(replacing the oldest track data with new data).
• Color (172C) — lets you choose a color that is used to display the active track log.
• Style (172) — choose from 17 different track styles used to display the active track log.
• Interval— defines the frequency at which the track plot is recorded. Three interval settings are
available:
Distance— records track based on a user-defined distance between points.
Time— records track plot based on a user-defined time interval.
Resolution— records track plot based upon a user-defined variance from your course over
ground. The resolution option is the default setting and is recommended for the most
efficient use of memory and TracBack performance. The distance value (entered in the value
field) is the maximum error allowed from the true course before recording a track point.
• Value— defines the distance or time used to record the track log.
• Save— allows you to save the current active track log.
• Erase— allows you to clear the active track log currently stored in memory.
Reference
Main Menu: Track Tab
Main Menu— Active Track
Tab (172/172C)
Main Menu— Saved Track
Tab
61
Reference
Main Menu: Track Tab
Saved Submenu Tab— manages a list of any saved track logs, allows TracBack activation, map display
of saved logs. The active log stores up to approximately 10,000 track log points, based upon the criteria
specified in the Track settings. Up to 15 track logs may be saved in memory, with up to 700 track log
points in each saved log.
On the ‘Saved’ tab, the following options are available by highlighting a track and pressing MENU:
• Review On Map – displays the saved track log on a Track Map page.
• Delete Track – deletes highlighted saved track log from memory.
• Delete All – deletes all saved track logs from memory.
To review and edit a track:
Reviewing a saved track
(172 C shown)
1. On the ‘Saved’ Track tab of the Main Menu, highlight the desired track and press ENTER. The Saved
Track window appears.
2. You may rename the track, choose to show the track on the Map and Highway pages, delete the
track, or view the track on a map window.
3. To exit, press QUIT or highlight ‘Next’ and press ENTER.
You may also activate a TracBack from any of the saved tracks on this tab.
To activate a TracBack from the ‘Saved’ tab list:
1. Using the ARROW KEYPAD, highlight the track you wish to use for a TracBack and press NAV.
2. The ‘Follow <track name>’ automatically appears highlighted. Press ENTER.
3. Choose either ‘Original’, which navigates you from the end to the start of your trip, or ‘Reverse’,
which navigates you from the start to the end of your trip and press ENTER.
The track name automatically appears when
highlighted on the ‘Saved’ list and NAV is pressed.
62
DSC Tab— allows to control and set up DSC (Digital Selective Calling) features on the unit.
What is Digital selective calling (DSC)?
Digital Selective Calling (DSC) uses marine VHF radio and Global Positioning System (GPS) technologies to transmit and receive location information. DSC is used by mariners to assist them in two
major areas: Distress Calls and Position Reporting.
An emergency DSC Distress Call allows a vessel in trouble to transmit a substantial amount of information in a single transmission or “call,” without the need for voice communication. When any nearby
rescuer receives the DSC signal, an alarm sounds and they immediately receive the position of the caller.
The rescuer may then choose to navigate (Go To) the caller’s position to assist or forward the call on
to the Coast Guard. When the Coast Guard receives the call, they can immediately access the caller’s
information (such as who they are and the type of vessel) in their database while they are in transit to
the caller’s position.
A non-emergency DSC Position Report allows mariners to exchange and display the positions of
one another. Once a DSC position is received, the mariner may choose to create a waypoint or to show
the received position on an electronic map.
Any time a vessel receives a DSC call, they can store that location and quickly navigate to that
position using a Go To. This makes DSC a time-saver, especially in an emergency situation. In order to
use DSC, users must first register their VHF radio with the FCC and receive a Maritime Mobile Service
Identity (MMSI) number.
Reference
Main Menu: DSC Tab
DSC Tab
What is A Maritime mobile service identity (MMSI)?
Maritime Mobile Service Identity (MMSI) basically allows a VHF radio to act like a phone. In order
to make a “call” on a phone, you first need a phone number to dial. The 9-digit MMSI number acts
like a phone number when used in a Position Report and as a unique identifier to the Coast Guard
when used in an emergency Distress Call. In order to obtain a Maritime Mobile Service Identity (MMSI)
number, users must register their VHF radio with the FCC (Form 605). Garmin does not supply this
number!
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Reference
Main Menu: DSC Tab
HOW ARE MMSI ASSIGNMENTS OBTAINED?
Non-commercial users (e.g. recreational users who remain in domestic waters and only carry VHF,
EPIRB (Emergency Position Indicating Radio Beacons), and Radar) are not required to have a FCC ship
station license. The FCC and Coast Guard have authorized some second and third party vendors to assign MMSI numbers. This service is limited to registering recreational vessels only.
To receive information on how to obtain a recreational MMSI number please contact:
http://www.uscg.mil/rescue21/links/mmsi.htm or http://wireless.fcc.gov/marine/.
U.S Non-Federal User: Commercial users, or those who travel outside the U.S. or Canada, must
apply for a ship station license, or an amendment to a ship station license. To find out if you require a
Ship Station license contact: http://wireless.fcc.gov/marine/fctsht14.html. If your vessel requires licensing
by the FCC you will obtain a MMSI during the application/licensing process when you file FCC Forms
159 and 605.
U.S. Federal User: Federal users can obtain MMSI assignments from their agency radio spectrum
management office. These procedures are currently under review by the NTIA (National Telecommunications and Information Administration).
Outside the U.S.: Users can obtain an MMSI assignment from their telecommunications authority
or ship registry, often by obtaining or amending their ship station license.
In Canada: Industry Canada is responsible for assigning MMSI numbers to commercial and recreational vessels. Information is available at the following web site: http://apollo.ic.gc.ca/english/mmsi.html.
For more information on MMSI’s visit: http://www.navcen.uscg.gov/marcomms/gmdss/mmsi.htm.
HOW CAN GARMIN HELP YOU WITH DSC?
To receive Distress Calls or Position Reports, you must have a DSC-equipped chartplotter as well as a
VHF radio with DSC support. During normal, non-emergency Position Report communication, Channel
70 (156.525 MHz) has been set aside as the VHF/DSC digital call channel. For a Distress Call, a mariner
presses the MayDay button on their VHF radio. The call transmits on an emergency channel with the
64
MMSI number attached to the call (if you have DSC support). Any DSC-equipped mariner (on sea or
land) within range can receive the call.
When the Garmin GPSMAP 172/172C is connected to a VHF with DSC support, the GPS unit
displays a Call List, Log, and a Directory available to store incoming information received from another
user’s DSC capable VHF/GPS combination. Basic wiring is required for the Garmin unit and VHF radio
to send and receive NMEA data from each other (pg. 92).
Reference
Main Menu: DSC Tab
DSC Distress Call
With a Garmin DSC capable chartplotter/sounder properly connected to a VHF radio with DSC
output, you may receive any DSC Distress Call within range. A window pops up and a message displays when a Distress Call is received. To notify you a Distress Call has been received, an alarm sounds
(if enabled). The alarm only sounds on a Distress Call, and it does not sound on a Position Report.
Distress Calls are broadcasted to all DSC users in radio range.
Options available from this screen are:
• Show on Map: If you immediately want to see the caller’s position they select ‘Show on Map’.
• Create Waypoint: If you want to create a waypoint of that position, highlight ‘Create Waypoint’
and press ENTER/MARK.
You also have the ability to input a caller’s name, if it is known. (The caller’s name replaces the
MMSI number as a reference once it is entered.)
Distress Call Message
DSC Position Report
The Position Report operates similarly to the Distress Call. Remember this type of contact is like a
phone call, but no emergency alarms are set off and the call is specific to the receiver. Position Reports
are not broadcasted to all DSC users.
Position Report Message
65
Reference
Main Menu: DSC Tab
DSC Call List
The DSC Call List displays the current calls received. The GPS can manage up to 50 calls. When
‘calls’ are received, they are updated constantly to give the most current information, even if the unit is
left unattended. Any entry from the Call List can be selected to show an Entry Review.
DSC Log
When DSC calls are received, they are automatically stored in the Log, with the latest call at the top.
The unit may store up to 100 logs. Once 100 logs are received, the oldest log file is removed when a
new call is received. The Log displays information of call Type, Date/Time, Position, and MMSI/Name.
Pressing MENU from this page allows you to ‘Sort By Time’, ‘Sort By Name’, ‘Sort By (Call) Type’,
‘Delete’ (only after highlighting a particular call), and ‘Delete All’.
To Review a Call:
DSC Entry Review
1. From the DSC tab of the Main Menu and the Log or Call List tab highlighted, press DOWN Arrow
Keypad until the call you want to review is highlighted.
2. Press ENTER to select the call.
DSC Entry Review
The DSC Entry Review operates similarly to the Distress Page and Position Report Page. This page
has the additional option to ‘Delete’ the displayed call. From the DSC Entry Review, you can ‘Delete’ the
entry, ‘Show on map’, or ‘Create Waypoint’.and create a name for the entry.
DSC Log
66
DSC Directory
The DSC Directory acts much like a phone book. A user can save up to 50 contacts. The directory
lists by Name and MMSI number. Pressing MENU from this page allows you to create a ‘New Item’,
‘Delete Item’, or ‘Delete All’.
There are two ways to add a new entry into the directory.
To add a new Directory entry:
1. Press Menu, then highlight ‘New Item’ and press ENTER.
Reference
Main Menu: DSC Tab
2. Or, with the Directory Tab highlighted press the Arrow Keypad DOWN, highlight an empty field and
press ENTER to access the New Directory Item window.
The New Directory Item window allows you to input information of a known contact.
To add the MMSI number, Name, or Comment:
1. Press UP/DOWN on the Arrow Keypad to highlight the MMSI, Name, or Comment field.
2. Press ENTER to highlight the first digit on that field.
3. Press UP/DOWN on the Arrow Keypad to enter the numbers/letters.
4. Press LEFT/RIGHT on the Arrow Keypad to move to the next position.
5. Press ENTER to accept the entry.
Adding a Directory Entry
6. Press UP/DOWN on the Arrow Keypad, highlight the ‘Delete’ button and press ENTER to delete
the entry, or highlight the ‘OK’ button and press ENTER to accept the entry.
After creating a New Directory Item entry, the name created is attached to that particular MMSI
number. If you return to the Log, the new name is displayed under the corresponding MMSI number.
Another way to input a name is from the Entry Review page or the DSC Distress Call or DSC Position Report pages. The Name field is only available in the GPS. Names cannot be sent like the MMSI
numbers to other DSC users.
DSC Setup
Garmin chartplotters have the ability to turn DSC ‘On’ or ‘Off’. This option is beneficial for users
who have more than one GPS chartplotter. If you want only DSC to display on a particular chartplotter,
turn DSC off on the remaining Garmin chartplotters that support DSC.
DSC Setup
“Simulate..” options only appear while in
Simulator mode..
67
Reference
Main Menu: DSC/Card Tabs
A user also has the ability to simulate a Distress Call or a Position Report on this page. This is helpful for practice before connecting to the real system. The Distress Call simulator also helps to check if
alarms are working properly.
To run a simulation:
1. Place the chartplotter into simulation (see pg. 7).
2. From the Main Menu, select the DSC tab, then highlight the Setup tab.
3. Highlight which simulation you wish to run and press ENTER.
Using the NAV Key
The receiver of a Distress Call or Position Report can quickly navigate to the caller using the NAV
button. Once the call is logged, press the NAV button and select to Go To the MMSI number or the
Name of the caller.
Card Tab— interface control for saving waypoints, routes and tracks to a data card.When data is saved
to a data card, it may be exchanged with other compatible units and Garmin’s MapSource PC program.
To transfer data to/from a data card:
Card Tab
1. Insert the data card. If there is already user data on the card, highlight ‘User Card’ and press
ENTER. From the ‘Card’ tab, select the checkbox next to each type of item you want to transfer. You
may also press MENU and choose to ‘Select All’ or ‘Clear All’.
2. Highlight ‘Save To Card’ and press ENTER to save the selected items to the data card.
3. If transferring data from the card to the unit, highlight ‘Merge From Card’ and press ENTER to
combine the selected items with those of your GPS. highlight ‘Replace From Card’ and press ENTER
to overwrite all selected items on your GPS.
4. A ‘Transfer Complete’ message appears once the data has been transferred. Press ENTER.
Map Tab— contains setup options for the Map Page. See page 21.
Hiway Tab— contains setup options for the Highway Page. See page 29.
68
Temp (Temperature) Tab— displays the water temperature log (if equipped with a temperature
transducer/sensor). The chart reads from right to left, so that the most recent temperature measured is
displayed on the far right side of the chart. The dotted lines within the chart indicate intervals in the
temperature scale and the duration of time.
The following settings are available:
Reference
Main Menu: Temp Tab/
Setup Tab
• Temperature Scale – sets the temperature range (in degrees) for displaying the log. Select ‘Auto’
to have the unit automatically determine the best range, or select a span of 2, 4, 6, 8 or 10
degrees.
• Time Duration – sets how fast or slow the temperature log scrolls; the shorter the time duration,
the faster the temperature log scroll. Select a duration from 1 minute to 2.5 hours.
Sonar Tab— contains setup options for the Sonar Page. See pages 53.
Setup Tab— consists of three submenu tabs; System, Units, and Time.
System Submenu Tab— controls system settings for beeper, speed filter, languages, system mode,
simulator controls, restores factory settings, and displays software version.
The following settings and options are available:
• Beeper – controls audible beep. Select from ‘Off’, ‘Alarms Only’ (sounds for alarms/messages),
or ‘Key and Alarm’ (sounds for key presses and alarms/messages).
• Speed Filter – averages speed-readings. Choose from ‘Off’, ‘Auto’ (automatically controls filtering), or ‘On’ (allows you to enter a value from 1 to 255 seconds).
• Language – select from various languages for the unit’s on-screen display.
• System Mode – select from ‘Normal’ (Normal Navigation) or ‘Simulator’ (For practice ONLY),
Set Position* – allows to set your location while in simulator mode. See page 11, starting
with step 2, for additional instructions.
Time
Duration
Temperature
Scale
Main Menu—Temp Tab
Main Menu—System Tab
(Normal Mode)
69
Reference
Main Menu: System Tab/
Units Tab
Track Control* – ‘Auto Track’ steers to the current navigation point. ‘User Track’ allows you to
enter a heading in the ‘Track’ field.
Track* – lets you enter a heading.
Speed* – lets you enter a speed.
Transducer* – lets you simulate using a Depth Only, Temp Only, or Temp/Speed transducer.
* These fields only appear when the unit is in Simulator Mode.
• System Information – displays the unit’s software, basemap version, and electronic serial number.
Press MENU for the following options:
• Defaults – restores settings on System page to default values.
• All Unit Defaults – restores all settings to Garmin’s original setup values for the entire unit.
Units SubmenuTab— defines settings for Position Format, Map Datum, Heading, Distance, Speed,
Elevation, Depth, and Temperature.
Main Menu—System Tab
(Simulator Mode)
Main Menu—Units Tab
70
The following settings are available:
• Position Format – is used to change the coordinate system in which a given position reading is
displayed. You should only change the position format if you are using a map or chart that specifies a different position format or wish to use a format you are familiar with. The default format is
latitude and longitude in degrees, minutes, and thousandths of a minute (hddd°mm.mmm’). The
following additional formats are available:
• hddd.ddddd° – latitude/longitude in decimal degrees only
• hddd°mm’ss.s” – latitude/longitude in degrees, minutes, seconds
• UTM/UPS – Universal Transverse Mercator / Universal Polar Stereographic grids
• British Grid
• Dutch Grid
• Finnish KKJ27
• German Grid
• India Zones
• Irish Grid
• Loran TD
• Maidenhead
• MGRS
• New Zealand
• Qatar Grid
• RT90
• Swedish Grid
• Swiss Grid
• Taiwan Grid
• User Grid
• W Malayan RSO
For additional information on Loran TD setup, see page 78.
• Map Datum – allows you to manually select the datum reference used to determine a given position.
The default setting is ‘WGS 84’. The unit automatically chooses the best datum depending upon
your chosen position format. Datums are used to describe geographic positions for surveying,
mapping, and navigation and are not actual maps built in the unit. Although over 100 datums are
available (as listed on pages 83-84), you should only change the datum if you are using a map or
chart that specifies a different datum.

WARNING: Selecting the wrong map datum can result in substantial position errors.
• Heading – lets you select the reference used in calculating heading information. You can select from
‘Auto Mag Var’, ‘True’, ‘Grid’ and ‘User Mag Var’. ‘Auto Mag Var’ provides magnetic north heading
references which are automatically determined from your current position. ‘True’ provides headings
based upon a true north reference. ‘Grid’ provides headings based on a grid north reference (and
is used in conjunction with the grid position formats described on page 70). ‘User Mag Var’ allows
you to specify the magnetic variation at your current position and provides magnetic north heading
references based upon the variation you enter.
To enter a user defined magnetic variation:
1. With the Heading field set to ‘User Mag Var’, highlight the heading reference field (immediately to
the right) and press ENTER.
2. Use the ARROW KEYPAD to enter the magnetic variation at your current position and press
ENTER.
• Distance, Speed and Elevation – lets you select the desired units of measure for distance, speed and
elevation readouts in ‘Nautical’ (nm, kt, ft), ‘Nautical’ (nm, kt, m), ‘Statute’ (mi, mh, ft) or ‘Metric’
(km, kh, m) terms.
• Depth – lets you select the desired units of measure for depth in Feet (ft), Fathoms (fa) or Meters (m).
• Temperature – lets you select the desired units of measure for temperature in Fahrenheit (°F) or
Celsius (°C).
Reference
Main Menu: Units Tab

The Units tab settings affect how navigation information is
displayed on the GPSMAP 172/172C. When in doubt, seek
assistance.
If you are using a map or chart in conjunction with your
GPS, make sure the settings under the ‘Units’ tab of the
GPSMAP 172/172C match that of the map or chart. This
information should be displayed somewhere on the map or
chart. If the information is not present, contact the map or
chart maker to determine what position format, datum,
heading and units of measure are being used for the map
or chart.

WARNING: If ‘User Mag Var’ is selected, you must
periodically update the magnetic variation as your position
changes. Using this setting, the unit does not automatically calculate and update the magnetic variation at your
present position. Failure to update this setting may result in
substantial differences between the information displayed
on your unit and external references, such as a magnetic
compass.
71
Reference
Time Submenu Tab— displays the current time and date, allows you to adjust the 12 or 24-hour
time format, enter a time zone, and adjust for daylight savings to show correct local time.
Main Menu: Time/
Comm Tab
The following options are available:
• Time Format – 12 hour, 24-hour (military) or UTC time (also called Greenwich Time).
• Time Zone – choose your time zone to show correct local time or choose ‘Other’ and enter a
UTC Offset. The UTC offset is how many hours you are ahead or behind the time line. See the
table on page 80 for time offsets.
• Daylight Savings – choose from ‘Auto’, ‘On’, or ‘Off’ to adjust for daylight savings.
Comm (Communications) Tab— lets you control the input/output format used when connecting
your GPSMAP 172/172C to external NMEA devices, a DGPS beacon receiver, a personal computer,
another Garmin GPSMAP 172/172C, etc. If a DGPS receiver is used, WAAS capability is automatically
turned to ‘Off’. The unit supports two input/output ports. See page 92 for more information on wiring
and NMEA information. Individual Port settings are:
Main Menu—Time Tab
Main Menu—
Comm Tab
Data Transfer Progress
72
Port 1:
• Garmin Data Transfer – the proprietary format used to upload/download MapSource data,
exchange waypoint, route, track, almanac, and proximity data with a PC or another Garmin
GPSMAP 172/172C. When you select ‘Garmin Data Transfer’, there are 11 Transfer Modes
to choose from: Host, Request Almanac, Request Proximity, Request Routes, Request Tracks,
Request Waypoints, Send Almanac, Send Proximity, Send Routes, Send Tracks and Send
Waypoints.
• NMEA In/NMEA Out – supports the input/output of standard NMEA 0183 data, DSC, and
sonar NMEA input support for the DPT, MTW and VHW sentences.
• None – provides no interfacing capabilities.
Port 2:
• Garmin DGPS – used to connect the GPSMAP 172/172C with a Garmin DGPS beacon receiver.
• Other DGPS – allows DGPS input using a standard RTCM format, without any output capabilities.
• NMEA In/NMEA Out – supports the input/output of standard NMEA 0183 data, DSC, and sonar
NMEA input support for the DPT, MTW and VHW sentences. You may also adjust the NMEA
output.
• RTCM In/NMEA Out – allows Differential GPS (DGPS) input using a standard RTCM format and
also provides NMEA 0183 output.
• None – provides no interfacing capabilities.
Reference
Main Menu: Comm Tab
To select an input/output format:
1. Select the desired Port tab, then highlight the ‘Serial Data Format’ field and press ENTER.
2. Use the ARROW KEYPAD elect the desired setting and press ENTER.
To select a transfer mode:
1. Use the ARROW KEYPAD to select ‘Garmin Data Transfer’ in the ‘Serial Data Format’ field.
2. Highlight the ‘Transfer Mode’ field and press ENTER.
When transferring data between two Garmin units,
be sure to always set one to ‘Host’ and use the other
unit to either Send or Request the desired data.
3. Use the ARROW KEYPAD to select the desired setting and press ENTER.
You may also adjust the NMEA output to enable/disable certain sentences and adjust the number
of Lat/Lon output precision digits. You must have one of the ports set to NMEA In/NMEA Out to use
this option. Settings affects both Port 1 and Port 2 NMEA outputs.
To restore the Serial Data Format settings to the default ‘Garmin Data Transfer’:
1. From the Comm tab, press MENU, highlight ‘Defaults’ and press ENTER.
73
Reference
Main Menu: Comm Tab
If ‘Garmin DGPS’ or ‘RTCM In/NMEA Out’ format is selected, additional fields are provided to
control a Garmin differential beacon receiver directly from your GPSMAP 172/172C. You may have the
unit automatically scan for the DGPS beacon signal or you can enter the beacon frequency and bit rate
on the unit and the information is used to tune the beacon receiver.
To have the unit automatically scan for a frequency:
1. With the unit set to ‘Garmin DGPS’ or ‘RTCM In/NMEA Out’, use the ARROW KEYPAD to highlight the “Beacon” field and press ENTER.
Status Field
2. Highlight ‘Scan’ and press ENTER. The numbers in the ‘Frequency’ field changes as the unit scans
from 284 kHz to 325 kHz, 200 bit rate, then 100, at 6-second intervals.
To restart the scan:
1. Press MENU, highlight ‘Restart Scan’ and press ENTER.The “Status” field shows one of the
SNR and Distance shows data
when signal is received.
•
•
•
•
following:
Tuning – unit is attempting to tune to the specified frequency and bit rate.
Scanning – unit is automatically scanning through the frequencies and bit rates.
Receiving – unit is receiving DGPS signal and ready for operation.
Check Wiring – unit is not making connection with DGPS receiver.
When the unit is receiving a DGPS signal, the “SNR” (Signal to Noise Ratio) and “Distance” fields
shows data. The SNR range is 0dB to 30dB, with 30 being the best. The Distance may or may not show
data, depending upon the signal being broadcast from the DGPS site.
You may also manually enter a
frequency and bit rate.
74
The DGPS beacon transmitters are operated by the U.S. Coast Guard (or similar government
agency in other countries), which is responsible for their accuracy and maintenance. For DGPS transmitter problems or to find the most updated list of frequencies and coverage areas, contact your local
USCG, or see their web site at http://www.navcen.uscg.mil/.
NMEA Interface
If you are going to interface the GPSMAP 172/172C with another piece of equipment (such as a
radio or autopilot), the unit needs to be set to output NMEA data. More information on wiring and
NMEA data may be found on page 92.
Reference
Main Menu: Comm Tab
To activate the NMEA data:
1. On either port of the Comm Tab, highlight the ‘Serial Data Format’ field and press ENTER.
2. Select ‘NMEA In/NMEA Out’ and press ENTER.
Advanced NMEA Output Setup
The GPSMAP 172/172C NMEA data transmission can be customized to change the precision of the
Lat/Lon minutes, set up the waypoint IDs, and keep the output rate at two seconds. If the unit is set up
to output all of the available NMEA sentences, the output rate may exceed two seconds. The ‘Advanced
NMEA Output Setup’ page allows you to turn on/off the GPS status (GSA. GSV), Waypoint/Route
(WPL, RTE), and the Garmin Proprietary sentences. See page 92 for more information on wiring and
NMEA data.
Lat/Lon Minutes Precision allows you to adjust the number of digits to the right of the decimal
point for transmission of NMEA Output, either 2, 3 or 4 digits. The Waypoint ID setting lets you
choose to output the waypoint identifiers as names or numbers.
Activating NMEA data
To set up the Advanced NMEA page:
1. Highlight ‘NMEA In/NMEA Out’ in the Serial Data Format field, and press MENU. Select ‘NMEA
Setup’ and press ENTER.
2. To change the settings, place the highlight over the desired field and press ENTER. Make a
selection and press ENTER again to accept the selection.
75
Reference
Main Menu: Comm Tab/
Alarm Tab
GPSMAP 172/172C NMEA Sentence Output (NMEA version 3.01 compliant)
Always transmitted: GPRMC, GPGGA, GPGLL, GPBWC, GPVTG, GPXTE, GPRMB, GPBOD
Switchable sentences: GPGSA, GPGSV, GPWPL, GPRTE
Garmin proprietary: PGRME, PGRMZ, PGRMM
Alarm Tab— contains setting for the unit’s alarms. The Alarm tab is divided into three submenus:
System alarms, Nav alarms, and Sonar alarms.
System Submenu Tab
Advanced NMEA
Setup Page
Clock – provides an alarm for the system clock. Enter a time in the time field and turn the
alarm on and off from the control field menu. Remember to enter alarm times in the same time
format (UTC or local) you’re using for your system. The unit must be on for the clock alarm to
work.
Battery – sets an alarm to sound when the battery is reaching a critical state of discharge.
DGPS – sets an alarm to sound when the unit loses a differential fix.
Accuracy – sets an alarm to sound when the GPS position accuracy falls outside the user-set
value.
Nav Submenu Tab
Main Menu—Alarm Tab
(System Submenu)
76
Anchor Drag – sets an alarm to sound when you’ve exceeded a specified drift distance. Enter a
value in the distance field and use the control field to turn the alarm on and off.
Arrival – sets an alarm to sound when you’re a specified distance or time away from a destination waypoint. Enter a distance radius or time for sounding the alarm and use the control field
to set the alarm to ‘Off’, ‘Dist’ (Distance), or ‘Time’.
Off Course – sets an alarm to sound when you’re off a desired course by a specified distance.
Enter a distance in the distance field and use the control field to turn the off course alarm on
and off.
Sonar Submenu Tab*
Shallow Water/Deep Water – set alarms to sound when you enter an area of specified depth
that is too shallow and/or too deep. You must be receiving sonar data for this function to work.
Water Temperature – sets an alarm to sound when the transducer reports a temperature either
above, below, inside or outside the specified values.
Fish – sets an alarm to sound when the unit detects a fish of the specified size symbol(s).
Reference
Main Menu: Alarm Tab
To set an alarm:
1. Use the ARROW KEYPAD to highlight desired submenu tab of the Alarm Tab.
2. Highlight the field below the alarm name you wish activate and press ENTER.
3. Change the mode to the desired setting and press ENTER.
4. Highlight the next field to the right and press ENTER, then enter the desired settings and press
ENTER to finish.
5. If you want the alarm to display and beep until acknowledged, highlight the ‘Persist’ box and press
ENTER to place a check mark in the box.
Main Menu—Alarm Tab
(Nav Submenu)
*You must be receiving NMEA Sonar data or using a Garmin GSD 20 Sonar Module for the Sonar
alarms to function. Fish Alarm will only function while using a Garmin GSD 20 Sonar Module.
Main Menu—Alarm Tab
(Sonar Submenu)
77
Appendix A
Loran TD
Loran TD System
LORAN-C is a radio navigation aid operated and maintained in the United States by the United
States Coast Guard. The name LORAN is an acronym for “LOng RAnge Navigation”. The LORAN
system covers the entire United States and the U.S. Coastal Confluence Zone. From the perspective of
a mariner, the system is used for ocean and coastal navigation. It can be used as a supplemental system
for harbor and harbor approach navigation, and it is used for inland navigation by recreational vehicles.
LORAN TD Feature
On the Units Tab of the Main Menu, press
MENU, then highlight ‘Loran TD On’ and
press ENTER to select Loran TD.
The LORAN TD (Time Delay) feature eases the transition from using LORAN to using GPS. The
GPSMAP unit automatically converts GPS coordinates to LORAN TDs for those who have a collection of LORAN fixes for favorite fishing spots and other waypoints recorded as TDs. You can display
your position as a TD or enter waypoints as TDs. The accuracy to be expected from this conversion is
approximately thirty meters. When the unit is placed in the LORAN TD format mode, it simulates the
operation of a LORAN receiver. Position coordinates may be displayed as TDs, and all navigation functions may be used as if the unit was actually receiving LORAN signals.
Using the LORAN TD Format
Or, highlight the Position Format field,
highlight ‘Loran TD’ and press ENTER to
select Loran TD.
78
When creating new waypoints using LORAN TD coordinates, you must set the correct LORAN
chain number and secondary stations in the Setup TD field before storing the waypoint. You must have
the correct chain number as well as the secondary station identifiers to use this option correctly. These
values varies per coordinate set or geographical location. Failure to enter correct information could
result in inaccuracies for the desired destination. After the waypoint is stored in unit memory, it always
references the LORAN chain number and secondary stations currently selected in the Setup TD field.
If you enter a different LORAN chain number, change the secondary stations or offsets in the Setup TD
field, the active waypoint information reflects those changes. Since the GPSMAP unit does not rely on
the LORAN signal for navigation, it can reference a different GRI chain and/or secondary stations and
still navigate to the location stored in memory.
The LORAN Position Format field is located under the Units tab in the Main Menu. The ‘LORAN
TD Setup’ window contains the fields to select the Loran GRI-Chain Number, Primary and Secondary
Stations, and TD Offsets.
Appendix A
Loran TD Setup
To setup Loran TD from the Main Menu:
1. Using the ARROW KEYPAD, highlight the ‘Setup tab, then press RIGHT to highlight the ‘Units’
submenu tab. Highlight the “Position Format” field and press ENTER. You may also press MENU
from the “Units” tab to display the ‘Loran TD On’ option. (If you use ‘Loran TD On’, skip to step 3.)
2. Highlight ‘Loran TD’, press ENTER, then highlight ‘Setup’ and press ENTER.
3. To change the settings of any of the five fields, highlight the field, press ENTER, select/enter the
desired setting and press ENTER.
4. When done, press the QUIT key to return to the Main Menu.
If the active GRI Chain, secondary stations or offsets have been changed since the waypoint was
created, the waypoint now references the active GRI-chain and secondary stations and adjust the TD
coordinates accordingly. Remember that the GPS is not relying on the LORAN signal for navigation
and actually converts the TD coordinate to a useful LAT/LON coordinate (in the background) before
storing the waypoint to memory or using it for navigation. Because of this the unit can navigate to a TD
coordinate anywhere in the world.
Loran TD Setup Window
For more information on Loran TDs, you may download Garmin’s “Loran TD Position Format
Handbook” from the Garmin web site.
79
Appendix B
Time Offsets

A simple way to determine your local time offset is how
many hours you are behind or ahead of UTC (also called
‘Greenwich’ or ‘zulu’ time).
Example: EST (Eastern Standard Time) is 5 hours behind
UTC, so your offset would be -5. Adding one hour for daylight savings would make EDT (Eastern Daylight Time)
- 4. Subtract an hour for each time zone as you travel west.
Offsets for Continental U.S. would be:
EST
-5
EDT
CST
-6
CDT
MST
-7
MDT
PST
-8
PDT
80
-4
-5
-6
-7
The chart below gives an approximate UTC (Universal Time Coordinate) time offset for the various
longitudinal zones. Check with local charts for more detailed information. If you are in daylight savings
time, add one hour to the offset.
Longitudinal Zone
Offset
Longitudinal Zone
Offset
W180.0º to W172.5º
-12
E007.5º to E022.5º
+1
W172.5º to W157.5º
-11
E022.5º to E037.5º
+2
W157.5º to W142.5º
-10
E037.5º to E052.5º
+3
W142.5º to W127.5º
-9
E052.5º to E067.5º
+4
W127.5º to W112.5º
-8
E067.5º to E082.5º
+5
W112.5º to W097.5º
-7
E082.5º to E097.5º
+6
W097.5º to W082.5º
-6
E097.5º to E112.5º
+7
W082.5º to W067.5º
-5
E112.5º to E127.5º
+8
W067.5º to W052.5º
-4
E127.5º to E142.5º
+9
W052.5º to W037.5º
-3
E142.5º to E157.5º
+10
W037.5º to W022.5º
-2
E157.5º to E172.5º
+11
W022.5º to W007.5º
-1
E172.5º to E180.0º
+12
W007.5º to E007.5º
0
The GPSMAP 172/172C uses an on-screen pop-up message system
to alert you to unit operating characteristics. Press the ENTER key to
acknowledge and return to the page you were viewing.
Alarm Clock— The alarm clock has sounded.
Alarm Voltage Set Too High— Voltage range must be between 10.0 and
35.0 volts for the GPSMAP 172/172C.
Alarm Voltage Set Too Low — Voltage range must be between 10.0 and
35.0 volts for the GPSMAP 172/172C.
Anchor Drag Alarm— You have drifted out of the specified distance
range.
Antenna Input Shorted To Ground— Check antenna wiring/connections
or antenna replacement.
Approaching Waypoint— You are a specified alarm distance from a
destination waypoint.
Arrival At Waypoint— You have arrived at the destination waypoint.
Basemap Failed Unit Needs Repair— Internal problem with the unit.
Contact your dealer or Garmin Customer Service (pg. iv) to have the unit
serviced.
Battery Alarm— Specified amount of input voltage has been detected.
Battery Voltage High Please Check Connection— Input DC voltage is
too high for unit.
Battery Voltage Low Please Check Connection— Input DC voltage is
too low for unit.
Boat is Not Moving Fast Enough to Calibrate— Speed wheel is not
turning. Check for debris or boat speed is too slow.
Appendix C
Messages
Database Error— Internal problem with the unit. Contact your dealer or
Garmin Customer Service (pg. iv) to have the unit serviced.
Deep Water Alarm— Specified deep water alarm depth has been detected
below transducer.
Lost Satellite Reception— The unit has lost satellite signals. Check
antenna connections or try moving to a location with a clear view of the sky.
Memory (RAM) Failed Unit Needs Repair— Internal problem with the
unit. Contact your dealer or Garmin Customer Service (pg. iv) to have the
unit serviced.
Memory (ROM) Failed Unit Needs Repair— Internal problem with the
unit. Contact your dealer or Garmin Customer Service (pg. iv) to have the
unit serviced.
No DGPS Position— No differential correction data is available or not
enough data is available to compute a DGPS position.
No Tide Stations For That Area— There are no tide stations within 100
miles of the specified point. Try another area.
Off Course Alarm— You have exceeded the specified off-course distance.
Processor Failed Unit Needs Repair— Internal problem with the unit.
Contact your dealer or Garmin Customer Service (pg. iv) to have the unit
serviced.
81
Appendix C
Messages
Proximity Alarm List is Full— You have used all ten proximity
waypoints.
Proximity Alarm Waypoint— You have entered the alarm radius for the
proximity waypoint indicated.
Proximity Overlaps Another Proximity Waypoint—The alarm radius
specified overlaps the area specified for another proximity waypoint. Adjust
the distance.
Route Already Exists: <route name>— You have entered a route name
that already exists in memory. Modify the route name or delete the previous
route name.
Route Does Not Exist: <route name>— Route has been renamed or
removed from memory and cannot be used.
Route Is Full— You have attempted to add more than 50 points to a route.
Reduce the number of points or create a second route.
Route Memory Is Full Can’t Create Route— Maximum amount of 50
routes is already in the unit’s memory and no additional routes can be
added until existing ones are removed.
Route Truncated— An uploaded route from another device has more than
50 points. Reduce the number of points.
Running Simulator— The unit is in simulator (practice) mode.
82
Shallow Water Alarm— Specified shallow water alarm depth has been
detected below transducer.
Sonar Failed Unit Needs Repair— Internal problem with the unit.
Contact your dealer or Garmin Customer Service (page. iv) to have the unit
serviced.
Track Already Exists: <track name>— You have entered a saved track
name that already exists in memory. Modify the track name or delete the
previous track name.
Track Memory Is Full Can’t Create Track— Track log memory is full.
No additional track log data can be stored without deleting old data to
create memory space.
Track Truncated— A complete uploaded track does not fit into memory.
The oldest track log points were deleted to make space for the most recent
data.
Transducer Disconnected Sonar Turned Off— No transducer attached
or bad cable/transducer.
Transfer Complete— The unit has finished uploading/downloading information to the connected device.
Water Speed Sensor is Not Working— Speed sensor is not detected.
Check connections.
Waypoint Already Exists: <waypoint name>— You have entered a
waypoint name that already exists in memory. Modify the waypoint name or
delete the previous waypoint name.
Waypoint Memory Is Full Can’t Create Waypoint— You have used all
3000 waypoints available. Delete unwanted waypoints to make space for
new entries.
Adindan Adindan- Ethiopia, Mali, Senegal, Sudan
Chua Astro
Chua Astro- Paraguay
Afgooye Afgooye- Somalia
Croatia
Croatia
AIN EL ABD ‘70
Corrego Alegr
Corrego Alegre- Brazil
AIN EL ANBD 1970- Bahrain Island, Saudi
Arabia
Djakarta Djakarta (Batavia)- Sumatra Island
(Indonesia)
Anna 1 Ast ‘65
Anna 1 Astro ‘65- Cocos I.
ARC 1950
ARC 1950- Botswana, Lesotho, Malawi,
Swaziland, Zaire, Zambia, Zimbabwe
Dos 1968
Dos 1968- Gizo Island
(New Georgia Islands)
ARC 1960
Kenya, Tanzania
Dutch
Dutch
Ascnsn Isld ‘58
Ascension Island ‘58- Ascension Island
Easter Isld 67
Easter Island 1967
Astro B4 Sorol
Sorol Atoll- Tern Island
European 1950
Astro Bcn “E”
Astro Beacon “E”- Iwo Jima
Astro Dos 71/4
Astro Dos 71/4- St. Helena
European 1950- Austria, Belgium, Denmark,
Finland, France, Germany, Gibraltar, Greece,
Italy, Luxembourg, Netherlands, Norway,
Portugal, Spain, Sweden, Switzerland
Astr Stn ‘52
Astronomic Stn ‘52- Marcus Island
European 1979
Aus Geod ‘66
Australian Geod ‘66- Australia, Tasmania
Island
European 1979- Austria, Finland,
Netherlands, Norway, Spain, Sweden,
Switzerland
Aus Geod ‘84
Australian Geod ‘84- Australia, Tasmania
Island
Finland Hayfrd
Finland Hayford- Finland
Gandajika Base
Gandajika Base- Republic of Maldives
Austria
Austria
GDA
Geocentric Datum of Australia
Bellevue (IGN)
Efate and Erromango Islands
Geod Datm ‘49
Geodetic Datum ‘49-New Zealand
Bermuda 1957
Bermuda 1957- Bermuda Islands
Guam 1963
Guam 1963- Guam Island
Bogata Observ
Bogata Obsrvatry- Colombia
Gux 1 Astro
Guadalcanal Island
Campo Inchspe
Campo Inchauspe- Argentina
Hjorsey 1955
Hjorsey 1955- Iceland
Canton Ast ‘66
Canton Astro 1966- Phoenix Islands
Hong Kong ‘63
Hong Kong
Cape
Cape- South Africa
Hu-Tzu-Shan
Taiwan
Cape Canavrl
Cape Canaveral- Florida, Bahama Islands
Indian Bngldsh
Indian- Bangladesh, India, Nepal
Carthage Carthage- Tunisia
Indian Thailand
Indian- Thailand, Vietnam
CH-1903
CH 1903- Switzerland
Indonesia 74
Indonesia 1974-Indonesia
Chatham 1971
Chatham 1971- Chatham Island
(New Zealand)
Ireland 1965
Ireland 1965- Ireland
ISTS 073 Astro
ISTS 073 ASTRO ‘69- Diego Garcia
Appendix D
Map Datums

The ‘User’ datum is based on a WGS-84 Local datum and is
an advanced feature for unlisted or custom datums. To learn
more, check your local library or on the world wide web for
educational materials on datums and coordinate systems.
83
Appendix D
NAD27 Central
Map Datums
NAD27 CONUS
North Am. 1927- Mean Value (CONUS)
NAD27 Cuba
North American 1927- Cuba
NAD27 Grnland
North American 1927- Greenland
(Hayes Peninsula)
Johnston Island
Johnston Island Kandawala
Kandawala- Sri Lanka
Kerguelen Islnd
Kerguelen Island
Kertau 1948
West Malaysia, Singapore
L. C. 5 Astro
Cayman Brac Island
Liberia 1964
Liberia 1964- Liberia
NAD27 Mexico
N. American 1927- Mexico
NAD27 San Sal
North American 1927- San Salvador Island
NAD83 North American 1983- Alaska, Canada,
Central America, CONUS, Mexico
Luzon Mindanao
Luzon- Mindanao Island
Nhrwn Masirah
Nahrwn- Masirah Island (Oman)
Luzon Philippine
Luzon- Philippines
(excluding Mindanao Isl.)
Nhrwn Saudi A
Nahrwn- Saudi Arabia
Mahe 1971
Mahe 1971- Mahe Island
Marco Astro
Marco Astro- Salvage Isl.
Nhrwn United A
Nahrwn- United Arab Emirates
Naparima BWI
Naparima BWI- Trinidad and Tobago
Obsrvtorio ‘66
Observatorio 1966- Corvo and Flores Islands
(Azores)
Merchich- Morocco
Old Egyptian
Old Egyptian- Egypt
Midway Ast ‘61
Midway Astro ‘61- Midway
Old Hawaiian
Old Hawaiian- Mean Value
Minna
Minna- Nigeria
Oman
Oman- Oman
NAD27 Alaska
North American 1927- Alaska
Ord Srvy GB
NAD27 Bahamas
North American 1927- Bahamas
(excluding San Salvador Island)
Old Survey Grt Britn- England, Isle of Man,
Scotland, Shetland Isl., Wales
Pico De Las Nv
Canary Islands
Massawa Massawa- Eritrea (Ethiopia)
Merchich
84
North American 1927-Central America
(Belize, Costa Rica, El Salvador, Guatemala,
Honduras, Nicaragua)
NAD27 Canada
North American 1927- Canada and
Newfoundland
NAD27 Canal Zone
North Am. 1927- Canal Zone
NAD27 Caribbn
North American 1927- Caribbean
(Barbados, Caicos Islands, Cuba, Dom.
Rep., Grd. Cayman, Jamaica, Leeward
and Turks Islands)
Potsdam Potsdam-Germany
Ptcairn Ast ‘67
Pitcairn Astro ‘67- Pitcairn
Prov S Am ‘56
Prov So Amricn ‘56- Bolivia, Chile,Colombia,
Ecuador, Guyana, Peru, Venezuela
Prov S Chln ‘63
So Chilean ‘63- S. Chile
Puerto Rico
Puerto Rico & Virgin Isl.
Qatar
Qatar National- Qatar
Qornoq Qornoq- South Greenland
Reunion Reunion- Mascarene Island
Rome 1940
Rome 1940- Sardinia Isl.
RT 90
Sweden
Santo (Dos)
Santo (Dos)- Espirito Santo
Sao Braz Sao Braz- Sao Miguel, Santa Maria
Islands
Sapper Hill ‘43
Sapper Hill 1943- East Falkland
Island
Schwarzeck
Schwarzeck- Namibia
Sth Amrcn ‘69
S. American ‘69- Argentina, Bolivia,
Brazil, Chile, Colombia, Ecuador,
Guyana, Paraguay, Peru, Venezuela,
Trin/Tobago
South Asia
South Asia- Singapore
SE Base Southeast Base- Porto Santo and
Madiera Islands
SW Base Southwest Base- Faial, Graciosa,
Pico, Sao Jorge and Terceira Islands
Taiwan
Modified Taiwan
Timbalai 1948
Timbalai 1948- Brunei and E.
Malaysia (Sarawak and Sabah)
Tokyo
Tokyo- Japan, Korea, Okinawa
Tristan Ast ‘68
Tristan Astro 1968- Tristan da Cunha
User
User-defined custom datum
Viti Levu 1916
Viti Levu 1916- Viti Levu/Fiji
Islands
Wake-Eniwetok
Wake-Eniwetok- Marshall
WGS 72 World Geodetic System 72
WGS 84 World Geodetic System 84
Zanderij Zanderij- Surinam
Avg Speed— The average of all second-by-second speed readings since last reset.
Bearing (BRG)— The compass direction from your present position to a destination waypoint.
Course— The desired course between the active ‘from’ and ‘to’ waypoints.
Distance (Dist)— The ‘great circle’ distance from present position to a destination waypoint.
Distance to Destination— The ‘great circle’ distance from present position to a GOTO destination, or
the final waypoint in a route.
Distance to Next— The ‘great circle’ distance from present position to a GOTO destination, or the
next waypoint in a route.
Elevation— Height above mean sea level (MSL).
ETA— Estimate Time of Arrival. The estimated time you will reach your destination waypoint, based
on current speed and track.
ETA at Destination— The estimated time you will reach a GOTO destination, or the final waypoint
in a route.
ETA at Next— The estimated time you will reach a GOTO destination, or the next waypoint in a
route.
Fuel— The fuel required to travel from present position to the indicated route waypoint.
Leg Dist— The distance between two route waypoints.
Leg Fuel— The fuel required to travel from a route waypoint to the next waypoint (in sequence) in the
route.
Leg Time— The time required to travel from a route waypoint to the next waypoint (in sequence) in
the route.
Max Speed— The maximum second-by-second speed recorded since last reset.
Moving Average Speed— Average speed while the unit is moving.
Moving Trip Timer— Total time the unit has been moving.
Appendix E
Navigation Terms
85
Appendix E
Navigation Terms
BRG
TRK
F
OF
S
UR
CO
SP
EE
D
E
DES
IR
TRA ED
CK
'FROM'
WAYPOINT
86
DIS
NORTH
NORTH
TAN
CE
TO
DES
TINA
TIO
N
DESTINATION
WAYPOINT
Odometer— A running tally of distance travelled, based upon the distance between second-by-second
position readings.
Off Course— The distance you are off a desired course in either direction, left or right. Also referred
to as ‘cross-track error’ or ‘course error’.
Speed— The current velocity at which you are travelling, relative to a ground position. Also referred to
as ‘ground speed’.
Time To— The estimated time required to reach a GOTO destination, or the next waypoint in a route.
Also referred to as ‘estimated time en route’.
Time to Destination— The estimated time required to reach a GOTO destination, or the final
waypoint in a route.
Time to Next— The estimated time required to reach a GOTO destination, or the next waypoint in a
route.
To Course— The recommended direction to steer in order to reduce course error or stay on course.
Provides the most efficient heading to get back to the desired course and proceed along your route.
Track— The direction of movement relative to a ground position. Also referred to as ‘ground track’.
Trip Odometer— A running tally of distance travelled since last reset. Also see ‘Odometer’.
Total Average Speed— Average speed of unit for both moving and stopped speeds since last timer
reset.
Total Trip Timer— Total time the unit has been in operation since last reset of the trip timers.
Turn— The angle difference between the bearing to your destination and your current track. ‘L’ indicates you should turn left, ‘R’ indicates you should turn right. The degrees indicate the angle you are off
course.
VMG— Velocity Made Good. The speed you are closing in on a destination along a desired course.
Also referred to as the ‘vector velocity’ to your destination.
Physical Specifications
Size:
4.9" H x 6.3" W x 3.7" D (122.5mm x 157.5mm x 92.5mm)
Weight:
1.0 lb 1oz.(.481Kg)
Display: (172C) 3.2” W x 3.2” H (81.28mm) CSTN (Color Super Twist Nematic) with
adjustable CCFL (Cold Cathode Fluorescent Lamp) backlighting; (320x320 pixels)
(172) . 3.2” W x 3.2” H (81.6 mm) 10 level grayscale FSTN (Film Super Twist Nematic)
with adjustable CCFL (cold cathode) backlighting; (320x320 pixels)
Case:
Fully gasketed, high-impact plastic alloy, waterproof to IEC 60529-IPX-7
Temp. Range: 5°F to 158°F (-15°C to 55°C)
Performance
Receiver:
Differential-ready 12 parallel channel WAAS capable receiver
Acquisition Times:
Warm:
Approx. 15 seconds
Cold:
Approx. 45 seconds
AutoLocate: Approx. 2 minutes
Update Rate:
1/second, continuous
GPS Accuracy: Position*: <15 meters (49 feet), 95% typical*
Velocity: 0.05 meters/sec steady state
DGPS (USCG) Accuracy:
Position: 3-5 meters (10-16 feet) with optional Garmin DGPS receiver, 95% typical*
Velocity: 0.05 meters/sec steady state
DGPS (WAAS) Accuracy:
Position: <3 meters (10 feet), 95% typical*
Velocity: 0.05 meters/sec steady state
Dynamics:
6g's
* Subject to accuracy degradation to 100m 2DRMS under the U.S. DOD-imposed Selective Availability Program.
Power
Source:
10-35 vDC
Usage:
6 watts max. at 13.8 vDC
Fuse: AGC/3AG - 2.0 Amp
Appendix F
Specifications/
Unit Care
UNIT CARE
Cleaning - The unit’s case is constructed of high quality
material and does not require user maintenance other
than cleaning. Clean the unit housing using a cloth lightly
dampened with a mild detergent solution and then wipe
dry. Avoid chemical cleaners and solvents that may damage
plastic components. Do not apply cleaner to electrical
contacts on the back of the unit.
The 172C has an anti-reflective coating on the lens that can
be damaged by ammonia based cleaners. When cleaning
the lens use a soft lint free cloth. Don’t apply the cleaner
directly to the lens, apply a small amount of cleaner to the
cloth and then wipe the lens.
Storage - Do not store the unit where exposure to temperature extremes may occur (see left), as permanent damage
may result. User information, such as waypoints, routes,
etc. is retained in the unit’s memory, without the need for
external power. It is always a good practice to back up
important user data by manually recording it or downloading it to a PC (see pg. 72).
Water Immersion -The GPSMAP 172/172C is
waterproof to IEC Standard 60529 IPX7. It can withstand
immersion in 1 meter of water for 30 minutes. Prolonged
submersion can cause damage to the unit. After submersion,
be certain to remove the data card and dry the compartments before reuse.
To resolve problems that cannot be remedied using this
guide, contact Garmin Customer Support in the U.S.A. at
800-800-1020 or Garmin Europe at 44/0870.8501241
87
Appendix G
Antenna Installation
Installing the GPSMAP 172/172C
The GPSMAP 172/172C must be properly installed according to the following instructions to get
the best possible performance. If you have the GPSMAP 172/172C with the built-in internal antenna,
you may skip this section and proceed to the next page. For units purchased with the remote GA 29
antenna, follow the instructions below. To complete the installation, you’ll need the appropriate fasteners and a 1” x 14-thread marine antenna mount available at most marine dealers. When in doubt,
seek professional assistance.
Mounting the GPS Antenna
Suggested locations for mounting the GA 29 antenna.
The antenna should be mounted in a location that has a clear, unobstructed view of the sky in all
directions to ensure the best reception. Avoid mounting the antenna where it is shaded by the boat’s
superstructure, a radome antenna, or mast. Sailboat users should avoid mounting the antenna high
on the mast to prevent inaccurate speed readings caused by excessive heeling. Most marine VHF and
LORAN antennas should not seriously degrade the GPS antenna’s reception. Never paint the antenna or
clean it with harsh solvents.
The Garmin antenna screws directly onto any standard 1” x 14-thread antenna mount. If you
need to raise the antenna to avoid shading, try using a 1” x 14-thread extension mast available at most
marine dealers.
To install the GPS antenna:
It is possible to route the coaxial cable either through, or
outside the antenna mount. It is possible to remove the
BNC connector on the coaxial cable and the coaxial cable
shortened to ease installation, however, doing so voids the
antenna warranty. If the BNC connector is removed it must
be replaced with a new solder-on or crimp BNC connector.
88
1. Screw the antenna directly onto the 1” x 14-thread mount.
2. Route the cable to the mounting location of the display unit. Use the appropriate tie-wraps, fasteners and sealant to secure the cable along the route and through any bulkhead or deck.
3. Once the GPSMAP 172/172C unit has been installed, connect the cable to the antenna connector on the back of the display unit. Make sure that you turn the antenna cable connector 1/4 turn
clockwise to lock the cable into place.
Mounting the GPSMAP 172/172C Unit
The GPSMAP 172/172C’s compact, waterproof case is suitable for mounting in exposed locations
or at the nav station. The unit comes with a single-knob tilt & swivel bracket that can be used for surface
or overhead mounting. When choosing a location for the display unit, make sure you consider the
following conditions:
Appendix G
Unit Installation
• There should be at least a 3” (7 cm) clearance behind the case to allow connection of the
antenna (external antenna only), power/data cables.
• The mounting surface should be heavy enough to support the unit and protect it from excessive
vibration and shock.
• For GPSMAP 172/172C unit’s with the built-in internal antenna, it should be mounted in a location
that has the clearest, most unobstructed view of the sky in all directions to ensure the best reception.
Avoid mounting the unit where it is blocked by the boat’s superstructure, a radar arch, or mast.

The temperature range for the GPSMAP 172/172C is 5°F to 158°F (-15°C to 55°C).
Extended exposure to temperatures exceeding this range (in storage or operating
conditions) may cause failure of the LCD screen. This type of failure and related consequences are NOT covered by the manufacturer’s limited warranty.
To swivel mount the GPSMAP 172/172C display:
Tools (not included) — Drill, Screwdriver (Phillips or Standard), three #8 (4mm) pan head machine
bolts with matching nuts and washers and a 5/32” (5mm) drill bit, OR three #8 pan head self-tapping screws and an appropriately-sized drill bit for drilling starter holes. Always wear safety goggles,
ear protection, and a dust mask when drilling, cutting or sanding.
1. Using the swivel base as a template, mark the location of the three holes that are used to secure
the bracket to the mounting surface.
2. If securing the base with machine bolts, drill three 5/32” (5mm) holes at the locations you marked.
OR, if securing the base with self-tapping screws, drill starter holes at the locations you marked.
Starter holes should generally be no deeper than half the screw length.
3. Secure the swivel base with three bolts or screws. DO NOT OVERTIGHTEN.
4. Place the rest of the mount over the swivel base and secure with the short knob.
Secure the base and attach the mount
OK
The swivel base is designed to be secured using a pan
head screw or machine bolt. If you use a screw with a
countersunk head, you risk damaging the Mounting
Base.
89
Appendix G
Unit Installation
Installing the Unit on the Mounting Bracket
1. Align the slot on the back of the unit with the long mounting knob and slide in place. It may be
necessary to adjust the long mounting knob to spread the bracket arms apart. (Turn counter-clockwise to widen the bracket arms, clockwise to tighten.)
2. Adjust the unit angle and tighten the long mounting knob until snug.
3. To tilt the unit, loosen the long mounting knob on the right side of the bracket assembly.
4. To rotate the entire bracket, twist it left or right. The bracket clicks as you turn it.
5. Tighten all knobs once the desired viewing angle is obtained.
Slide the unit onto the bracket
90
Adjust for optimal viewing
Flush Mounting the GPSMAP 172/172C External Antenna Unit
The GPSMAP 172/172C External Antenna only can be flush mounted on a flat panel. When flush
mounting the GPSMAP 172/172C, be sure to choose an appropriately sized location for the unit. Check
that all cables reach the unit mounting location before beginning installation. Use the Flush Mount
Template provided in the box to determine a location. Always wear safety goggles, ear protection, and a
dust mask when drilling, cutting or sanding.
Appendix G
Unit Installation
To flush mount the GPSMAP 172/172C (External Antenna ONLY):
Included Mounting Hardware — 4 - 3mm Studs, 4 - Flat Washers, 8 - 3mm Hex Nuts.
Tools (not included) — Center Punch, Drill, 1/8” (3mm) Drill Bit, 3/8” (6mm) Drill Bit, Jig Saw, 1/16”
(2mm) Allen Wrench, 9/35” (7mm) Wrench.
1. Trim the Flush Mount Template and tape in the desired location.
2. Using a Center Punch, indent the center of each Mounting Hole location.
Hex Nuts
Washer
3. Using a 1/8” (3mm) drill bit, drill the four Mounting Holes.
4. Using a 3/8” (6mm) drill bit, drill a hole for a location to begin cutting the mounting surface.
5. Using the Jig Saw, cut the mounting surface along the inside of the dashed line indicated on the
template. Be very careful when cutting this hole, there is only a small amount of clearance between the unit and the Mounting Holes. It may be prudent to cut slightly inside the
indicated line and then sand or file the panel as needed to obtain the best fit.
Studs
6. Install the four Mounting Studs into the unit by screwing the shorter section into the back of the
unit. Use a 1/16” (2mm) Allen Wrench to tighten the Mounting Studs until the stops contact the
case. Be careful not to overtighten as this may damage the Mounting Stud. The studs have a reusable thread-locking patch pre-applied from the factory.
7. Place the unit in position inside the cutout area of the mounting surface.
8. Place washers over the Mounting Studs, then thread on one Hex Nut per Mounting Stud. Tighten
all four Hex Nuts until the unit is snug against the mounting surface. Install and tighten the second
Hex Nut on all four Mounting Studs to lock the first Hex Nut in place.
91
Appendix G
Wiring and
Interfacing
You can download a copy of Garmin's
proprietary communication protocol from the
Help and Support section of our web site at
www.garmin.com.
Documentation concerning NMEA
&RTCM formats and sentences
are available for purchase from:
Connecting the Power/Data
The power/data cable connects the GPSMAP 172/172C to a DC system and provides interface
capabilities for connecting external devices. The color code in the diagram below indicates the appropriate harness connections. Replacement fuse is a AGC/3AG 2.0 Amp fuse. For wiring the GPSMAP to
a GSD 20 Sonar Module, refer to the “GSD 20 Installation Guide” (190-00255-00).
(red) 10-35 vDC
Note: During a typical
installation, only the Red
and Black wires are used.
The other wires do not
have to be connected for
normal operation of the
unit. Replacement fuse:
AGC/3AG - 2.0 Amp
To Unit
Pin 11 - Yellow (Alarm)
National Marine Electronics
Association (NMEA)
Seven Riggs Avenue
Severna Park, MD 21146
U.S.A.
410-975-9425
410-975-9450 FAX
www.nmea.org
Radio Technical Commission For
Maritime Services (RTCM)
1800 Diagonal Road, Suite 600
Alexandria, VA 22314-2480
U.S.A.
703-684-4481 (Info Only)
703-836-4229 FAX
www.rtcm.org
92
(black) Ground (Power and Data)
(blue) NMEA OUT (Com 1 TX)
(brown) NMEA IN (Com 1 RX)
(white) RTCM/NMEA IN (Com 2 RX)
NMEA
Device with
Sonar Output
(yellow) Alarm Low
Pin 15 - Red (DC Positive)
TXD +
Pin 13 - White (RX COM 2)
Pin 16 - Brown (RX COM 1)
(Cable End View)
Autopilot/
NMEA Device
(green) NMEA OUT (Com 2 TX)
Pin 18 - Black (Ground)
Interfacing
RXD +
RXD -
Pin 14 - Green (TX COM 2)
Pin 17 - Blue (TX COM 1)
DC �
Power Source
Alarm Relay
100ma max
coil current
TX+
RX+
GSD 20,
Beacon
Receiver or
DSC VHF
The following formats are supported for connection of external devices: Garmin proprietary GSD
20 Sonar Module and Differential GPS, NMEA 0183 version 3.01, RTCM SC-104 input (version 2.0).
The following are the sentences for NMEA 0183, version 3.01 and later output:
Approved sentences— GPBWC, GPRMC, GPGGA, GPGSA, GPGSV, GPGLL, GPBOD, GPRMB, GPRTE,
GPVTG, GPWPL and GPXTE. Proprietary sentences— PGRME, PGRMM, PGRMZ, and PSLIB.
The GPSMAP 172/172C also includes NMEA input with support for the WPL sentence, DSC, and
sonar NMEA input with support for the DPT (Depth), MTW (Water Temp) and VHW (Water Speed &
Heading) sentences. If connecting to COM2 for sonar NMEA input, the unit interface must be set to
NMEA In/NMEA Out (see page 72). If connecting to COM1, the unit must be set to NMEA In/NMEA
Out.
Installing and Removing Data Cards
The GPSMAP 172/172C uses optional Garmin marine BlueChart and MapSource data cards to
display digital charts and maps on-screen. Data cards are installed in the card slot located at the bottom
right of the unit. Data cards may be installed or removed at any time, whether the unit is on or off.
To install a data card:
Appendix G
Installing and Removing
Data Cards
1. Open the card door by pressing together on the two handles at the bottom of the door and lifting it
up and open.
2. Insert the card into the slot, with the label facing top and the handle towards you.
3. Firmly push the card into the unit. It in not necessary to force the card and about 1/2” is still
exposed when it is properly inserted. If the unit is on, a confirmation tone sounds and a
message displays on the screen noting the card details when the card has been properly installed
and accepted.
4. Close the cover.
If you insert a data card and get a ‘card format not recognized’ message, try removing the card and
reinserting it. If the card is still not recognized, contact the Garmin or your Garmin dealer for assistance. Data cards are not waterproof, should not be exposed to moisture or excessive static charges, and
should be stored in the case supplied with the card.
To remove a data card:
1. Open the card door by pressing together on the two handles at the bottom of the door and lifting it
up and open.
2. Grasp the card handle and pull out firmly.
3. If the unit is on, a confirmation tone sounds when the data card has been removed.
The first time you insert a
data card, the unit takes
a few seconds to read the
card.
Once the data card has been
read, a summary screen
appears. Press ENTER/
MARK to acknowledge.
93
Appendix H
A
Index
Accuracy 55
Accuracy Alarm 76
Accuracy Circle 25
Active Route Page 16, 29, 50
Active Route Page Options 50
Active Track Log 61
Alarm Tab 76, 77
Anchor Drag Alarm 76
Append to Route 33
Arrival Alarm 76
ARROW KEYPAD 1
AutoLocate 57
AutoZoom 23
B
Backlight 1, 6
Basemap 23
Battery Alarm 76
Bearing Line 24
Bearing Pointer 27
Beeper 69
BlueChart 23, 24, 93
94
C
Capabilities v
Card Tab 68
Celes Tab 60
Change Numbers 16, 25, 29
Cleaning 87
Clock Alarm 76
Color Mode 23
Communications Tab 72-76
Compass Page 14, 27
Compass Page Options 27
Compass Ring 14, 27
Contrast 1, 6
Copying Routes 45
Course Line 24
Course Up 23
Creating Map Waypoints 13
Creating Routes 43, 44
Creating Waypoints 30-33
Cursor 9, 13, 18-20
Customer Service i
D
Data Cards 93
Data Card Maps 23
Data Fields 16, 25
Data Transfer 72, 73
Datums 71
Daylight Savings 72, 80
Declutter 26
Deep Water Alarm 77
Defaults 25
Deleting Routes 45
Deleting Tracks 62
Deleting Waypoints 35-37
Depth Units 71
Detail, Map 23
DGPS 73, 74, 92
DGPS Alarm 76
Distance Units 71
DSC (Digital Selective Calling) 63
DSC Call List 66
DSC Directory 66, 67
DSC Distress Call 64, 65
DSC Entry Review 66
DSC Log 66
DSC Position Report 64, 65
DSC Setup 67
DSC Simulation 68
DSC Tab 63-68
E
Editing Routes 46-49
Editing Waypoints 34, 35
Elevation Units 71
Entering Data 3
ENTER Key 1
Erasing Tracks 61
F
I
FCC Compliance ii
Find 51, 52
FIND Key 1, 51
Find Options 52
Fish Alarm 77
Follow Routes 11, 44, 45
Follow Track 11, 40
Full Screen Map 21
Initialize Position 57
Initializing 4, 5
Installation 88-92
Interfacing 92
Invert Route 50
IN Key 1, 18, 20
G
Keypad Usage 1, 2
General Tab 23
Going to a Destination 11, 39, 40
Go To 39
Go To Point 11, 39
GPS Information Page 5, 6
GPS Status 5, 6
GPS Tab 5, 54-57
GPS Tab Options 57
Grids 70
H
Heading 71
Heading Line 24
Highway Page 15, 28
Highway Page options 28
Highway Scale 28
How To Index viii
K
L
Language 69
Lat/Lon Grid 25
Light Sectors 24
Loran TD 70, 78, 79
Loran TD Setup 79
M
Magnetic North 71
Main Menu 16, 17
Main Menu Page 53
Main Menu Tabs 53, 54
Main Pages 8
Map, Set Up 22
MapSource 23, 93
Map Cursor 9
Appendix H
Index
Map Datums 71, 83, 84
Map Information Page 23
Map Item 11
Map Outlines 25
Map Page 8, 9, 18
Map Page Options 21
Map Scales 12, 20
Marking Waypoints 10
MARK Key 1, 30, 31
Mark Position 30
Measure Distance 22
MENU Key 1, 17
Merge From Card 68
Messages 81, 82
MGRS 70
MMSI Number 63, 64, 67
MOB 42
MOB Key 1, 42
Moon Phase 60
Moon Rise/Set 60
Moving Waypoints 33, 35
N
Navaids Tab 24
95
Appendix H
Index
Navigation Terms 85, 86
NAV Key 1, 39-42, 68
Nav Line Tab 24
Nearest To Boat 52
Nearest To Destination 52
Nearest To Next 52
Nearest To Other 52
NMEA 72, 73, 75, 76, 92
NMEA Interface 75
NMEA Output Setup 75
North Reference 71
North Up 23
Numbers, Changing 25
O
Off Course Alarm 76
Orientation, Map 23
Other Tab 25
OUT Key 1, 18, 20
Overzoom 20
P
Packing List vi
96
Q
Routes 43
Routes, Copying 45
Routes, Creating 43, 44
Routes, Deleting 45
Routes, Editing 46-49
Routes, Following 44, 45
Routes, Inverting 50
Routes, Reviewing 44, 46
Routes, TracBack 40
Routes, Trip Planning 49
Route List Page 45
Route Review Options 46
Route Review Page 46
QUIT Key 1
S
R
Saved Tracks 24, 62
Saving Tracks 61
Scale, Highway 28
Scale, Map 20
Selecting Options 2
Serial Number iv
Serial Number, Electronic 70
Service iv
Setup Tab 69
Set 2D Elevation 57
Set Up Highway 29
Set Up Map 22
Set Up Page Layout 25, 29
Shallow Water Alarm 77
PAGE Key 1
Page Layout 25, 29
Points Tab 24
Position Format 70
Power 4, 6
POWER Key 1, 17
Precautions iii
Projecting Waypoints 32
Proximity Alarms 38
Proximity Waypoints 38
Proximity Waypoint List 37
Re-evaluate Route 50
Receiver Status 55, 56
Registration i
Replace From Card 68
Reset All 60
Reset Max Speed 60
Reset Odometer 60
Reset Trip 60
Retail Demonstration 7
Reviewing Routes 46
Reviewing Tracks 62
Reviewing Waypoints 34
Show Data 21
Signal Strength Bars 54
Simulated Tour 12
Simulator 57, 69
Simulator Mode 7, 11, 15
Simulator Set Position 69
Simulator Speed 70
Simulator Track 70
Simulator Track Control 70
Simulator Transducer 70
Skyview Orientation 60
Software License i
Software Version 70
Source Tab 23
Specifications 87
Speed Filter 69
Speed Units 71
Stop Navigation 11
Storage 87
Sun Rise/Set 60
Symbol Set 24
System Information 70
System Mode 69
System Tab 70
Temperature Units 71
Tides 58, 59
Tide Tab 58, 59
Time Format 72
Time Offsets 80
Time Zone 72
TracBack 40- 42, 62
Tracks, Deleting 62
Tracks, Erasing 61
Tracks, Reviewing 62
Tracks, Saved 62
Tracks, Saving 61
Track Color 61
Track Interval 61
Track Logs 24, 40, 41, 61
Track Record Mode 61
Track Tab 24, 40, 41, 61, 62
Track Up Below 23
Track Value 61
Transfer Mode 73
Trip Data 60
Trip Planning 49
Trip Tab 60
Turn Declutter On/Off 26
T
U
Table of Contents vii
Temperature Scale 69
Temperature Tab 69
Temperature Time Duration 69
Units 70, 71
Unit Care 87
User Datum 83
User Waypoint List 36
Appendix H
W
Index
WAAS 55, 57
Warnings iii
Warranty iv
Water Immersion 87
Water Temperature Alarm 77
Waypoints, Creating 10, 13, 20, 30-33
Waypoints, Deleting 17, 35, 37
Waypoints, Editing 34, 35
Waypoints, Moving 33, 35
Waypoints, Projecting 32
Waypoints, Proximity 37, 38
Waypoints, Reviewing 13, 34
Waypoints Tab 24
Waypoint List 36
Waypoint Menu Options 33
Waypoint Symbols 10, 34
Wiring 92
Z
Zoom 15, 18, 20
97
GPSMAP172C Cover.indd 3
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For the latest free software updates (excluding map data) throughout the life of your
Garmin products, visit the Garmin Web site at www.garmin.com.
© Copyright 2004 Garmin Ltd. or its subsidiaries
Garmin International, Inc.
1200 East 151st Street, Olathe, Kansas 66062, U.S.A.
Garmin (Europe) Ltd.
Unit 5, The Quadrangle, Abbey Park Industrial Estate, Romsey, SO51 9DL, U.K.
Garmin Corporation
No. 68, Jangshu 2nd Road, Shijr, Taipei County, Taiwan
www.garmin.com
Part Number 190-00321-00 Rev. B
GPSMAP172C Cover.indd 4
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