Garmin 400C Fish Finder User Manual

Fishfinder 400C
owner’s manual
© 2006, 2007 Garmin Ltd. or its subsidiaries
Garmin International, Inc.
1200 East 151st Street,
Olathe, Kansas 66062, USA
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, UK
Tel.+44 (0) 870.8501241 (outside the UK)
0808 2380000 (within the UK)
Fax+44 (0) 870.8501251
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 ( for current updates and
supplemental information concerning the use and operation of this and other Garmin products.
Garmin®, CANetTM, See-Thru®, and UltrascrollTM are registered trademarks or trademarks of Garmin Ltd. or its subsidiaries and may not be used without the
express permission of Garmin.
January 2007
Part Number 190-00757-00 Rev. B
Printed in Taiwan
The Fishfinder 400C is a full-featured, color sonar that offers a choice
of display styles, a dual beam or dual frequency option, and more.
Fishfinder 400C Tips and Shortcuts
• Press HOME from any screen to return to the Home screen.
• Press MENU from any of the main screens to access
advanced settings.
• Press and release the POWER key to adjust the display
Quick Links
Installing the Fishfinder 400C: page 1
Mounting the Fishfinder 400C: page 2
Installing the Transducer: page 4
Basic Operation: page 15
Customizing the Fishfinder 400C: page 21
Changing the System Settings: page 23
Customizing the Transducer Settings: page 23
Advanced Settings: page 25
Alarms and Messages: page 28
Fishfinder 400C Owner’s Manual
Table of Contents
Fishfinder 400C Tips and Shortcuts........................................ i
Quick Links................................................................................ i
Product Registration............................................................... iii
Caring for the Fishfinder 400C............................................... iii
Warnings.................................................................................. iv
Important Information............................................................. iv
Installing the Fishfinder 400C.............................................1
Step 1: Select a Location for the Fishfinder.......................... 1
Step 2: Mount the Fishfinder................................................... 2
Step 3: Install the Transducer................................................. 4
Step 4: Install the Wiring Harness........................................ 10
Step 5: Test the Installation................................................... 13
Basic Operation..................................................................15
Turning the Fishfinder 400C On or Off................................. 15
Adjusting the Backlight Setting............................................ 15
Using Simulator Mode........................................................... 15
Using the Fishfinder 400C Keypad....................................... 15
Understanding the Home Screen.......................................... 16
Understanding the Full Screen............................................. 17
Understanding the Split Zoom Screen................................. 17
Understanding the Flasher Screen....................................... 18
Understanding the Split Freq Screen................................... 18
Understanding the Numbers Screen.................................... 19
Understanding the Temp Log Screen................................... 19
Understanding the Configure Screen................................... 20
Customizing the Fishfinder 400C......................................21
Setting Alarms........................................................................ 21
Changing the Display Settings............................................. 21
Changing the Sonar Settings................................................ 22
Changing the System Settings............................................. 23
Configuring Transducer Settings......................................... 23
Customizing Units of Measure.............................................. 24
Advanced Settings.............................................................25
Resetting the Odometer......................................................... 26
Setting the Temp Log Duration and Scale........................... 26
Specifications......................................................................... 27
Optional Accessories............................................................. 27
Alarms and Messages............................................................ 28
Limited Warranty.................................................................... 29
Declaration of Conformity (DoC).......................................... 30
Software License Agreement................................................ 30
Fishfinder 400C Owner’s Manual
Product Registration
Caring for the Fishfinder 400C
Use this area to record the serial number (8-digit number located on
the back of the Fishfinder 400C) in case your Fishfinder 400C needs
service. Keep the original sales receipt, or a photocopy, in a safe
Cleaning the Case
Help us better support you by completing our online registration
today! Connect to our Web site at
Serial Number: ___ ___ ___ ___ ___ ___ ___ __
Contact Garmin
Contact Garmin if you have any questions while using your
Fishfinder 400C. In the USA contact Garmin Product Support
by phone: (913) 397-8200 or (800) 800-1020, Monday–Friday,
8 AM–5 PM Central Time; or go to, and
click Product Support.
In Europe, contact Garmin (Europe) Ltd. at +44 (0) 870.8501241
(outside the UK) or 0808 2380000 (within the UK).
Tell Us What You Think
Tell us how you like this manual! Fill out the Product
Documentation Survey. Go to, and
click Product Documentation Survey.
Fishfinder 400C Owner’s Manual
The case is constructed of high-quality materials and does not
require user maintenance, except cleaning.
Clean the unit’s outer casing (except for the screen) using a cloth
dampened with a mild detergent solution and then wipe dry. Avoid
chemical cleaners and solvents that may damage plastic components.
Cleaning the Screen
The unit’s lens is coated with a special anti-reflective coating that
is sensitive to skin oils, waxes and abrasive cleaners. Cleaners
containing ammonia, alcohol, abrasives, or anti-grease detergents
will harm the anti-reflective coating. It is important to clean the lens
using an eyeglass lens cleaner (that is specified as safe for antireflective coatings) and a clean, lint-free cloth.
Water Immersion
The unit 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 wipe and air dry the unit before reuse.
Failure to avoid the following potentially hazardous situations could result in an accident or collision resulting in death or serious injury.
When navigating, carefully compare information displayed on the unit to all available navigation sources, including information from visual
sightings, and maps. For safety, always resolve any discrepancies or questions before continuing navigation.
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 provided in accordance with California’s Proposition 65. See for more information.
Hg - lamp(s) inside this product may contain mercury and must be recycled or disposed of according to
local, state, or federal laws.
Important Information
The California Waste Recycling Act of 2003 requires the recycling of certain electronics. For more information on the applicability to this product, see
Fishfinder 400C Owner’s Manual
Installing the Fishfinder 400C
Installing the Fishfinder 400C
To successfully operate your Fishfinder 400C, you must properly
install the fishfinder and all of its related parts. Compare the contents
of this package with the packing list on the box. If any pieces are
missing, contact your Garmin dealer immediately. Before you begin
the installation:
• Read and follow the instructions to install the unit.
• Gather the appropriate fasteners and tools.
• Verify that all cables can reach the unit mounting location and
the transducer.
• Wear safety goggles and a dust mask when drilling, cutting, or
If you experience difficulty installing the unit, contact Garmin
Product Support or contact a professional installer.
To install and use your fishfinder:
Select a location for the fishfinder.
Mount the fishfinder.
Install the transducer.
Install the wiring harness.
Test the installation.
Fishfinder 400C Owner’s Manual
Step 1: Select a Location for the Fishfinder
Consider the following when you select an installation location:
• Provides optimal viewing as you operate your vessel.
• Allows easy access to the unit’s keypad.
• Is strong enough to support the weight of the fishfinder and
protect it from excessive vibration or shock.
• Allows room for the routing and connection of the power/data
and transducer cables. There should be at least a 3-inch (8 cm)
clearance behind the case.
DO NOT mount the unit in an area that is exposed to extreme
temperature conditions.
NOTE: The temperature range for the Fishfinder 400C is 5°F
to 131°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
Installing the Fishfinder 400C
Step 2: Mount the Fishfinder
You can mount your fishfinder in one of two ways:
• Surface Mount—mount the fishfinder onto a bracket
(included) that attaches to the console or overhead.
• Flush Mount—use the optional flush mount kit to mount
the fishfinder into a flat panel. See the “Appendix” for more
Surface Mounting the Fishfinder
The Fishfinder 400C’s compact, waterproof case is suitable for
mounting in exposed locations or at the nav station. The Fishfinder
400C comes with a tilt/swivel mounting bracket that can be used for
console or overhead mounting.
Mounting the Bracket Assembly
Tools (not included)—drill, screwdriver (Phillips or standard), and
one of the following:
• Three #8 (4 mm) pan-head machine bolts with matching nuts
and washers and a 5/32" (5 mm) drill bit.
• Three #8 pan-head self-tapping screws and a 1/16" drill bit for
drilling starter holes.
Use a pan-head machine bolt or self-tapping screw to secure the
swivel base. If you use a screw with a countersunk head, you risk
damaging the mounting bracket.
Fishfinder 400C Owner’s Manual
Installing the Fishfinder 400C
To mount the bracket assembly:
1. Using the swivel base as a template, mark the location of the
three holes that secure the bracket to the mounting surface.
2. Drill the mounting holes.
• If you secure the base with machine bolts, drill three
5/32" (5 mm) holes at the locations you marked.
• If you secure the base with self-tapping screws, drill
starter holes at the locations you marked. Do not make
the starter holes deeper than half the screw length.
3. Secure the swivel base with three bolts or screws. DO NOT
4. Place the swivel mount bracket over the swivel base and
secure it with the short knob.
Fishfinder 400C Owner’s Manual
Installing the Fishfinder 400C on the Mounting Bracket
To install the unit on the mounting bracket:
1. Align the slot on the back of the fishfinder with the long
mounting knob, and slide the fishfinder into place. If
necessary, adjust the long knob to spread the bracket arms
apart. (Turn counter-clockwise to widen the bracket arms and
clockwise to tighten.)
2. Adjust the fishfinder angle, and tighten the long mounting
knob until snug.
3. Rotate the swivel mount bracket by twisting it left or right.
The bracket clicks as you turn it. Select a good viewing
angle, and then tighten all knobs.
4. Connect the power/data and transducer cables to the back
of the fishfinder, making sure the locking rings are fully
tightened on both connectors.
Installing the Fishfinder 400C
Step 3: Install the Transducer
Proper transducer installation is key to getting the best performance
from your fishfinder. If the transducer lead is too short, extension
cables are available from your Garmin dealer. Coil and secure any
excess cable.
CAUTION: DO NOT cut the transducer lead or any part of
the transducer cable, because cutting the transducer cable voids
your warranty. The cable cannot be spliced and connected to any
existing (Garmin or non-Garmin) transducer cables.
The following pages contain tips and basic installation instructions
for some popular transducers. Detailed installation instructions are
provided in the transducer kits. Some transducers might have to be
installed by a professional marine installer.
Assembling the Transducer
To �������������������������
assemble the transducer:
1. Insert the rubber washer and plastic spacer into the
transducer at the same time. DO NOT lubricate the rubber
2. Route the cable toward the back of the transducer. Slide the
transducer into the transducer mount.
3. Place a 5 mm flat washer on the 10-32 x 1.75" screw, and
insert the screw through the transducer mount, spacer, and
rubber washer.
4. Place the remaining 5 mm flat washer on the exposed end.
Install the 10-32 lock nut finger tight. You can tighten the
transducer further after installation on the boat.
Cable tie slot
Back of the transducer
Fishfinder 400C Owner’s Manual
Installing the Fishfinder 400C
Mounting the Transducer on a Trolling Motor
(Dual Beam Transducers Only)
To mount the transducer on a trolling motor:
1. Slide the large cable tie through the slot on the transducer
mount with the ridges of the band facing up until equal
lengths extend on both sides of the mount.
note: For cold water, or heavy timber or debris areas, a metal
4-5" worm gear clamp is recommended.
2. Position the mount gasket on the curved top of the
transducer mount.
3. Place the transducer assembly against the motor body of the
trolling motor, with the front of the transducer pointed away
from the trolling motor propeller.
4. Wrap the two ends of the cable tie around the motor body.
Place the pointed end of the cable tie through the fastener
hole on the opposite end and pull it through until it is snug but
not tight. (The cable tie clicks when you pull it.)
5. Position the transducer so that it is parallel with the bottom
when in use, and make sure the gasket is aligned properly.
Pull the cable tie end until tight. Trim off the excess if
necessary. Tighten the 10-32 locking nut until it touches the
mounting bracket, and then tighten 1/4 turn more. (Do not
Fishfinder 400C Owner’s Manual
6. Route the 30-foot (9 m) transducer cable using the supplied
cable ties to secure the cable to the motor shaft. You can fill
the forward-facing portion (except the cable tie pocket) of the
transducer mount with sealant to avoid accumulating debris.
Cable tie
Front of the transducer
Installing the Fishfinder 400C
Mounting the Transducer on a Transom
Fishfinder 400C Owner’s Manual
Installing the Fishfinder 400C
When selecting a transom mount location, consider the following for
optimal performance:
• For your sonar to operate properly, the transducer must be
located in calm water. DO NOT mount the transducer behind
strakes, rivet lines, struts, fittings, water intake, discharge
ports, eroding paint, or anything that creates turbulence.
• Mount the transducer as close to the center of the boat as
• DO NOT cut the transducer lead. (This voids your warranty.)
• DO NOT mount the transducer in locations where it might be
jarred when launching, hauling, trailering, or storing.
• DO NOT mount the transducer in the path of the prop on
single-drive boats. The transducer can cause cavitation that
can degrade the boat’s performance and damage the prop. On
twin-drive boats, mount the transducer between the drives, if
NOTE: DO NOT mount the transducer behind strakes, struts,
fittings, water intake or discharge ports, or anything that creates
air bubbles or causes the water to become turbulent. The
transducer must be in clean (non-turbulent) water for optimal
Fishfinder 400C Owner’s Manual
Tool List (not included)—drill, 3/8" wrench or socket, 5/32" and
1/8" drill bits, masking tape, #2 Phillips screwdriver, and marine
To mount the transducer on a transom:
1. Position the transducer mount at the selected transom
location. Make sure the transducer is parallel with the water
line. Mark the center locations of each hole on the transducer
2. Using a 5/32" bit, drill the pilot holes approximately 1"
(25 mm) deep at the marked locations. To avoid drilling the
holes too deep, wrap a piece of tape around the bit at 1" from
the point of the bit.
3. Apply marine sealant to the 5 x 30 mm screws. Attach the
transducer assembly to the transom using the 5 x 30 mm
screws. Adjust the transducer assembly to extend beyond
the bottom of the transom approximately 1/8" (3 mm) on
fiberglass hulls or 3/8" (10 mm) on aluminum hulls. Adjust the
transducer assembly to be aligned parallel with the water.
4. Tighten the 10-32 locking nut until it touches the mounting
bracket, and then tighten 1/4 turn more. (Do not overtighten.)
5. Place the first cable clamp on the transducer cable
approximately one third of the distance between the
transducer and the top of the transom.
Installing the Fishfinder 400C
6. Mark the location. Using a 1/8" bit, drill a pilot hole
approximately 3/8" (10 mm) deep.
7. Attach the cable clamp using a 4 x 12 mm screw. Coat the
screw with marine sealant before installation. Repeat steps 5
and 6 using the other cable clamp.
8. Route the transducer cable, as needed, to the fishfinder. DO
NOT CUT THE CABLE. Avoid routing the cable with electrical
wires or other sources of electrical interference.
Drill pilot holes here.
Bottom of
To avoid drilling a hole to mount a thru-hull transducer, a
transducer can be secured with epoxy inside a boat (shoot-thruhull installation). This type of installation can provide better
noise reduction and allow you to use a higher Gain setting. For
a transducer to be mounted inside the hull (shoot-thru, not thruhull), the boat must be fiberglass, with no core. Contact your boat
manufacturer if you are unsure. Professional installation might be
Some transducers are specifically designed to be mounted inside a
fiberglass hull. The standard plastic transom mount transducer can
also be mounted using this method. If using a temperature sensing
transducer, the temperature shown reflects the hull temperature.
Align with the transom
bottom. The transducer
should extend 1/8"
below fiberglass hulls
or 3/8" below aluminum
Shoot-Thru-Hull Installation
the transo
Keep it parallel with the water line.
Fishfinder 400C Owner’s Manual
Installing the Fishfinder 400C
Selecting a Location for a Shoot-Thru-Hull Installation
When installing a transducer, the installation location must be the
• Solid fiberglass, without any air bubbles, laminates, fillers, or
dead air space.
• In an area of clean (non-turbulent) water at all speeds.
• The location must not be over any strakes or behind any
obstruction on the hull that would create turbulence.
NOTE: Many modern hulls have a dedicated pocket for
shoot-thru-hull transducer installation. If you are unsure if your
hull is equipped with a pre-located pocket, contact your hull
To test the location:
1. Fabricate a test device from a section of PVC pipe or a can,
as shown in the following illustration.
2. Temporarily seal the test device to the hull with caulking or
RTV sealer, and fill with water or light mineral oil.
3. Place the transducer in the water, pointed directly at
the bottom and weight it down. Set the unit for optimum
performance. If the sonar performance is significantly
degraded, another location must be tested.
Fishfinder 400C Owner’s Manual
PVC pipe
or a can
Strip caulk or
RTV sealer
Weight the transducer
to hold it in place.
Fill a pipe or can with
water or a light mineral oil.
Hull surface
Testing the Location
To permanently install the transducer:
1. Lightly sand the surface of the hull and face of the transducer
with 400 grit wet or dry sandpaper.
2. Build a dam using strip caulk about 1/4" (6 mm) tall. Pour
about 1/8" (3 mm) of two-part, slow-cure epoxy into the dam.
3. Place the transducer in the epoxy, turning the transducer to
work out any air bubbles.
4. Weight the transducer in place, and allow it to cure for
24 hours.
Installing the Fishfinder 400C
Step 4: Install the Wiring Harness
The Fishfinder 400C comes with a wiring harness that connects
the fishfinder to power and the transducer with one easy-to-remove
connection and provides interface capabilities for connecting
external devices.
The color code in the diagram (see ��page 11) indicates the appropriate
harness connections. The replacement fuse is a AGC/ 3AG - 3 Amp
fuse. If it is necessary to extend the power wires, use 22 AWG wire.
DO NOT cut the transducer cable, because this voids your warranty.
If your boat has an electrical system, you might be able to wire the
fishfinder directly to an unused holder on your current fuse block. If
you are using the boat’s fuse block, remove the in-line fuse holder
supplied with the fishfinder. You can also wire the fishfinder directly
to the battery.
Note: During a typical installation, use only the Red and Black
wires. The other wires do not have to be connected for normal
operation of the Fishfinder 400C unit. For information on connecting
to a NMEA or CANet compatible device, see page 12.
To 10-38 Volt boat supply
Boat ground
Caution: The Fishfinder 400C maximum input voltage is 35
Volts DC. Do not exceed this voltage, because this can damage
the Fishfinder 400C and void the warranty.
1. Use a test light or voltmeter to determine the polarity of the
voltage source.
2. Connect the Red (+ or positive) wire to the positive voltage
terminal. (If you use the boat’s fuse block, route the positive
connection through the fuse, as shown on the diagram.)
3. Connect the Black (- or ground) wire to the negative voltage
4. Install or check the 3-Amp fuse (on the boat’s fuse block or in
the in-line holder).
5. Align the notches on the cable plug and on the back of the
fishfinder. Insert the cable into the connector, and turn the
lock ring counter-clockwise until it stops.
To install the wiring harness:
To Fishfinder 400C
Fuse block
Fishfinder 400C Owner’s Manual
Installing the Fishfinder 400C
PIN 8 - Black (Ground)
PIN 13 - Red (DC Positive)
PIN 7 - Yellow (Alarm)
PIN 12 - White (CANet H)
PIN 16 - Green (CANet L)
PIN 18 - Blue (NMEA Out)
DC Power
Fishfinder 400C Pin Assignment
Fishfinder 400C Wiring Harness
Fishfinder 400C Owner’s Manual11
Installing the Fishfinder 400C
Connecting to a NMEA device
You can connect the Fishfinder 400C to another piece of NMEA
compatible electronic equipment, such as a Garmin GPS (Global
Positioning System) device. If equipped with a capable transducer,
the Fishfinder 400C can send depth, temperature, and speed
information. Refer to the wiring diagrams on page 11 for connecting
the Fishfinder 400C to NMEA compatible devices.
To install the wiring harness to a GPS or other NMEA
1. Follow the voltage source installation steps (see page 10).
For Garmin units, the ground (Black) wires serve as NMEA
ground and must be attached together or on the same
terminal. Refer to the wiring diagram of your GPS unit for
wire identification.
2. Connect the Blue (NMEA Out) wire from the Fishfinder 400C
to the NMEA In wire on the GPS/NMEA unit’s wiring harness.
3. Turn on the Fishfinder 400C NMEA Output setting (page 23).
For Garmin GPS units, set the communications interface to
Interfacing with NMEA
The Fishfinder 400C allows for NMEA 0183, Version 3.01 output
with a compatible GPS or navigation device. You must set NMEA
Output On to send data (page 23).
sent in NMEA 0183, Version 3.01 output from the Fishfinder 400C.
You can purchase complete information about National Marine
Electronics Association (NMEA) format and sentences from:
Seven Riggs Avenue
Severna Park, MD 21146 USA
Installing the Fishfinder 400C to a Garmin CANet
The Fishfinder 400C is a CANet-compatible sonar device.
Using the CANet (if applicable) optimizes the performance of
CANet-compatible units, allowing sonar information from the
Fishfinder 400C to be shared with up to two CANet compatible
Garmin GPS units. A standard NMEA connection only allows
depth, temperature, and speed information to be sent to a single GPS
device, whereas a CANet connection provides full sonar readings,
including Ultrascroll™, so you can view and control the same
information on your compatible GPS unit(s) as you can on your
Fishfinder 400C.
Note: To use the Garmin CANet with your Fishfinder 400C,
you must obtain a CANet Kit. Contact your Garmin dealer, or
Fishfinder 400C Owner’s Manual
Installing the Fishfinder 400C
Step 5: Test the Installation
To turn on your Fishfinder 400C for the first time, press and hold the POWER key until the unit beeps and turns on. Use the ROCKER
and the SELECT key and follow the screens to configure your Fishfinder 400C.
Note: Although it is possible to perform some checks with the boat trailered, the boat should be in the water to properly test the installation.
To configure your Fishfinder 400C for the first time:
Select a language.
Select a transducer
Select units of
Select a color
The Home screen appears after you select your configuration options. After 15 seconds of inactivity, the fishfinder automatically switches to
Full Screen.
Note: If the transducer is not detected, a “Transducer Disconnected, Sonar Turned Off” message appears.
Fishfinder 400C Owner’s Manual13
Installing the Fishfinder 400C
Because water is necessary to carry the sounder’s sonar signal, the
transducer must be in the water to work properly. You cannot get a
depth or distance reading when out of the water.
When you place your boat in the water check for leaks around
any screw holes that were added below the water line. DO NOT
leave your boat in the water for an extended period of time without
checking for leaks.
To test the transom mount transducer installation:
1. Begin testing the installation at a slow speed. If the sonar
appears to be working properly, gradually increase the
boat’s speed while observing the sonar’s operation. If the
sonar signal is suddenly lost or the bottom return is severely
degraded, note the speed at which this occurs.
2. Return the boat to the speed at which the signal was lost. Make
moderate turns in both directions, and see if the signal improves.
3. If the signal strength improves while turning, adjust the
transducer so that it extends another 1/8" below the transom
of the boat. It might take several adjustments to eliminate the
4. If the signal does not improve, you might have to move the
transducer to a different location.
NOTE: When adjusting the depth of the transducer, make the
adjustments in small increments. Placing the transducer too
deep can adversely affect the boat’s performance and put the
transducer at greater risk of striking underwater objects.
Fishfinder 400C Owner’s Manual
Basic Operation
Basic Operation
Using the Fishfinder 400C Keypad
Turning the Fishfinder 400C On or Off
Range (-/+)
Press and hold the POWER key until the unit beeps and the
Home screen appears.
Note: When you turn on the Fishfinder 400C for the first time,
you have to select a language, transducer type, units of measure,
and color scheme.
Adjusting the Backlight Setting
1. Press and release the POWER key.
2. Press left on the ROCKER to decrease the brightness; press
right to increase.
Using Simulator Mode
If a transducer is not connected, no data is shown on the screens. By
turning on Simulator Mode, the Fishfinder 400C acts as though a
transducer is connected. Use Simulator Mode to practice and learn
how to use your Fishfinder 400C.
Caution: When in Simulator Mode, the depth, temperature,
and speed information are simulated. They do not represent the
actual depth, water temperature, or vessel speed.
POWER/BACKLIGHT—Press and hold to turn the unit on or off;
press and release to adjust the backlight and day/night modes.
RANGE (-/+)—Press to adjust the range of the sonar.
ROCKER—Press up, down, left, or right to move through menus,
highlight fields, and enter data.
SELECT—Press to select highlighted items and confirm onscreen messages.
HOME—Press to return to the Home screen.
MENU—Press to access additional settings and configuration
options; Press to return to the previous screen when indicated.
Fishfinder 400C Owner’s Manual15
Basic Operation
Understanding the Home Screen
When you turn on your Fishfinder 400C, the Home screen appears.
Press up or down on the ROCKER, and then press SELECT to
choose an option.
note: Options on this screen vary based on the type of
transducer installed.
Full Screen
Opens a full-screen graph of the transducer’s sonar readings
(page 17).
Flasher (Dual Beam transducer only)
Opens a round flasher to indicate the transducer’s sonar
readings as an alternative to the linear graph (page 18).
Split Freq (Dual Frequency transducer only)
Opens a split-screen that uses the full capability of the dual
frequency transducer. A 50kHz frequency graph appears on the
left; a 200kHz frequency graph appears on the right (page 18).
Split Zoom
Opens a split-screen with the normal graph on the right zoomed
to your preferred level on the left (page 17).
Opens a set of data fields to show information numerically
(page 19).
Temp Log
Home Screen
(Dual Beam)
Home Screen
(Dual Frequency)
Shows a customizable graph of the water temperature when
using a compatible transducer or sensor (page 19).
Configure unit settings (page 20).
Fishfinder 400C Owner’s Manual
Basic Operation
Understanding the Full Screen
Understanding the Split Zoom Screen
On the Home screen, highlight Full Screen, and press SELECT.
On the Home screen, highlight Split Zoom Screen, and press
The Full Screen is the main screen for both dual beam and dual
frequency transducers.
Use the Split Zoom screen to view the full sonar data from the graph
as well as a zoomed in portion on the same screen.
Depth, temperature,
and speed
depth scale
Transducer mode
Fishfinder 400C Owner’s Manual17
Basic Operation
Understanding the Flasher Screen
The Flasher screen (dual beam transducer only) provides an almost
instantaneous return of what is below your boat. The depth scale is
organized as a ring that starts at the top, or 12:00, and progresses
clockwise. Sonar information flashes on the ring when it is received
at the depth indicated on the inside ring. Like the regular graph, The
colors indicate different strengths of the sonar return.
Understanding the Split Freq Screen
Use the Split Freq screen (dual frequency transducer only) to view
both the 50kHz and 200kHz frequencies on the same screen.
On the Home screen, highlight Split Freq, and press SELECT.
Depth, temperature and speed
On the Home screen, highlight Flasher, and press SELECT.
Flasher ring
Fishfinder 400C Owner’s Manual
Basic Operation
Understanding the Numbers Screen
Understanding the Temp Log Screen
On the Home screen, highlight Numbers, and press SELECT.
On the Home screen, highlight Temp Log, and press SELECT.
The Numbers screen shows data fields populated by important
numeric information instead of a graph. The data fields you see are
determined by the capabilities of your transducer.
If you are using a temperature-capable transducer, the Temp Log
screen keeps a graphic log of temperature readings over time. The
current temperature and depth are shown in the top left corner.
All transducers show depth. If you are using a temperature-capable
transducer, the Water Temp field appears. If you are using a speedcapable transducer, the Water Speed and Odometer fields appear.
The temperature appears along the right side and the time
elapsed appears along the bottom. The graph scrolls to the left as
information is received.
Fishfinder 400C Owner’s Manual19
Basic Operation
Understanding the Configure Screen
The Configure screen contains the main configuration options for the
Fishfinder 400C. From this screen, you can define and adjust settings
universal to all Fishfinder 400C screens.
On the Home screen, highlight Configure, and press SELECT.
Alarms—set alarms to alert you of various events. See page 21.
Display—customize display settings including backlight and Day/
Night mode. See page 21.
Sonar—customize sonar settings. See page 22.
System—set various system options. See page 23.
Transducer—set transducer options. See page 23.
Units—customize the units of measure shown on Fishfinder 400C
screens. See page 24.
For more information on the Configure screen, see the “Customizing
the Fishfinder 400C” section beginning on page 21.
Fishfinder 400C Owner’s Manual
Customizing the Fishfinder 400C
Customizing the Fishfinder 400C
Setting Alarms
You can set the Fishfinder 400C to sound an audible alarm when
certain conditions are met. By default, all alarms are turned off.
Changing the Display Settings
You can switch between Day and Night modes and brighten or
darken the backlight.
To change the display settings, on the Configure screen, highlight
Display, and press SELECT.
To set an alarm, on the Configure screen, highlight Alarms, and
press SELECT.
Shallow Water/Deep Water—set an alarm to sound when the depth
is less than or greater than the specified value.
Fish—set an alarm to sound when the unit detects a suspended
target of the specified symbols.
Press left or right
on the ROCKER
to switch between
Day and Night
Press left or right
on the ROCKER
to adjust the
Water Temp—set an alarm to sound when the transducer reports
a temperature that is 2° F (1.1° C) above or below the specified
Battery—set an alarm to sound when the battery reaches a userdetermined low voltage.
Drift—set an alarm to sound when the depth changes by the value
Fishfinder 400C Owner’s Manual21
Customizing the Fishfinder 400C
Changing the Sonar Settings
To change the sonar settings, on the Configure screen, highlight
Sonar, and press SELECT.
Color Scheme—choose white or blue. This affects the background
on all sonar screens, but does not change the Numbers or Temp Log
Fish Symbols—set how the Fishfinder 400C interprets suspended
The Fishfinder 400C does not interpret the sonar return
data. (default)
Suspended targets appear as symbols. Background sonar
information appears, making the distinction between fish
and structure easier.
Suspended targets appear as symbols with background
information shown. The target depth of each symbol is also
Suspended targets appear as symbols. No background
information appears.
Suspended targets appear as symbols with no background
information shown. The target depth of each symbol is
Scroll Speed—adjust the rate at which the sonar scrolls from
right to left (Ultrascroll, Fast, Medium, or Slow). If you have
a speed-capable transducer, select Auto to have the scroll speed
automatically adjust to your vessel’s water speed.
Surface Noise—show or hide the sonar returns near the surface of
the water. Hide surface noise to help reduce clutter.
Whiteline—highlights the strongest signal from the bottom to help
identify its hardness or softness.
• Off—(default) Whiteline is disabled.
• High—the most sensitive setting. Almost all stronger returns
are highlighted in white.
• Medium—many stronger returns are highlighted in white.
• Low—the least sensitive setting. Only the strongest returns
are highlighted in white.
Numbers—show or hide battery voltage, water temperature, or
water speed (if your transducer is capable).
Note: To show water temperature or water speed, change the
setting to Auto. If the connected transducer is capable, the data
is shown.
Fishfinder 400C Owner’s Manual
Customizing the Fishfinder 400C
Changing the System Settings
Configuring Transducer Settings
Beeper—set when the unit makes audible sounds. The three settings
are Off, Alarms Only (default), and On (keys and alarms).
Type—select the transducer type (Dual Frequency or Dual Beam).
To change the system settings, on the Configure screen, highlight
System, and press SELECT.
Simulator—turn on the Simulator to have the Fishfinder 400C act as
though a transducer is connected.
NMEA Output— connect the Fishfinder 400C to NMEA compatible
electronic equipment (such as a Garmin GPS device) and send
information. To do so, you must change this setting to On. For more
information on connecting to a NMEA device, see page 12.
Language—select the on-screen language.
System Information—view the current operating software version
and your unit’s unique internal unit ID.
Factory Settings—reset the Fishfinder 400C to the factory settings.
You are prompted to confirm your choice to restore all factory
settings. Choose Yes. Otherwise, choose No to retain your current
To change the transducer settings, on the Configure screen, highlight
Transducer, and press SELECT.
Keel Offset­—offset the surface reading for the depth of a keel so
you can measure depth from the bottom of your keel instead of from
the transducer’s location. Enter a positive number to offset for a keel.
You can enter a negative number to compensate for a large vessel
that may draw several feet of water.
Transducer at Surface
Enter (+) positive
number to show depth
from the bottom of keel.
Transducer at Bottom
of Keel
Enter (-) negative number to
show depth from the surface.
Fishfinder 400C Owner’s Manual23
Customizing the Fishfinder 400C
To adjust the Keel Offset:
1. Highlight Keel Offset, and press SELECT.
2. Use the ROCKER to set the value of the keel offset.
3. Press SELECT to accept the number.
Note: Press MENU to cancel your changes and return to the
Transducer menu.
Calibrate Water Speed—to use a speed sensing transducer, use
this menu to calibrate the speed sensor. If you are not using a speed
sensing transducer, this menu does not appear.
To calibrate the speed sensor:
1. Highlight Calibrate Water Speed, and press SELECT.
2. Bring the boat to cruising speed. Note your top speed, and
then stop the boat.
3. Highlight OK, and press SELECT.
Customizing Units of Measure
To change the units of measure, on the Configure screen, highlight
Units, and press SELECT.
Depth—select Feet (ft), Meters (m), or Fathoms (fa).
Water Temp­—select Fahrenheit (°F) or Celsius (°C) (with a
compatible transducer).
Water Speed—select Miles/Hour (mh), Kilometers/Hour (kh), or Knots
(kt) (with a compatible transducer).
Distance—select Statute (mi), Metric (km), or Nautical (nm) (with a
compatible transducer).
Note: If the boat is not moving fast enough or the speed sensor
is not registering a speed, a “Speed Too Low” message appears.
Highlight OK, press SELECT, and safely increase boat speed. If
you get the message again, stop the boat and make sure the speed
sensor wheel is not stuck. If the wheel turns freely, check the
cable connections. If you continue to get the message, contact
Garmin Product Support.
Fishfinder 400C Owner’s Manual
Advanced Settings
Advanced Settings
Press MENU on any screen to access advanced options.
Highlight Manual Gain, and press SELECT to manually adjust
the Gain. To see more detail, increase the Gain. If there is too much
detail, or the screen is cluttered, decrease the Gain.
Beam—when using a Dual Beam transducer, select a wide or
narrow beam.
Frequency—when using a Dual Frequency transducer, select how
the frequencies appear on screen. By default, the frequency is set
to 200kHz. You can specify that the unit uses only the 200kHz
frequency, the 50kHz frequency, or Dual Frequency.
Note: If you choose Dual, the Split Freq screen appears.
Zoom—zoom in to a section of the Full Screen. The zoom is off, or
set to No Zoom by default. Four options are available:
Dual Frequency
Dual Beam
Range—By default, the range is set to Auto. The range of the depth
scale on the right side of the screen adjusts automatically as the
depth readings increase or decrease. Highlight Manual Range and
press SELECT to manually adjust the scope of the depth scale.
• 2x Zoom—twice the magnification.
• 4x Zoom—four times the magnification.
• Bottom Lock—locks the zoom window to the bottom. The
default zoom span is 10 ft, and can be adjusted.
• Split Zoom—opens the Split Zoom screen.
Gain—controls the sensitivity of the Fishfinder 400C’s sonar
receiver. By default, the Gain is set to Auto, which automatically
sets the sonar sensitivity.
Fishfinder 400C Owner’s Manual25
Advanced Settings
Zoom Depth (While Zoomed)—available only when you are using
a 2x or a 4x Zoom. By default, the Zoom Depth is set to Auto and
automatically adjusts with the depth. You can adjust this setting to
zoom in at a specific depth.
Span (While Zoomed with Bottom Lock)—While using Bottom
Lock, this option replaces the Range option. Adjust this setting just
as you would the Range setting to expand or contract the zoomed
distance from the bottom.
Depth Line—turn on the depth line to quickly reference a specific
depth on the Full Screen, Split Zoom screen, or Split Freq screen.
While viewing a screen showing the Depth Line, press up or down
on the ROCKER to move the line.
A-Scope (Dual Frequency Transducer)—vertical flasher that appears
along the right side of the screen. The A-Scope indicates structure
and bottom returns much like the Flasher screen (page 18). The
horizontal width of a signal in the A-Scope indicates the strength of
the signal.
Resetting the Odometer
If you are using a speed sensing transducer, an odometer is available
on the Numbers screen and the Flasher screen that tracks the
distance you travel.
To reset the odometer:
1. Press MENU.
2. Highlight Reset Odometer, and press SELECT.
3. Highlight Yes, and press SELECT.
Setting the Temp Log Duration and Scale
On Temp Log screen, press MENU to view advanced options.
Duration—set the scope of time along the bottom of the graph.
Scale—set the temperature span along the right side of the graph.
Fishfinder 400C Owner’s Manual
Optional Accessories
You can purchase the following optional accessories on the Garmin
Web site (
Physical Specifications
Flush Mount Kit—mounts your fishfinder flush on the bulkhead or
cabin wall.
Weight: 1.20 lbs (.544 kg)
CANet™ Connection Kit—allows you to connect your Fishfinder
400C to CANet-capable Garmin chartplotters, so you can read sonar
displays on chartplotters located elsewhere in the boat.
Size: 5" H x 5.7" W x 3" D (12.7 cm x 14.5 cm x 7.62 cm)
Display: 4.0" diagonal (10.19 cm), 3.21" H x 2.41" W (8.16 cm x 6.12 cm),
QVGA display with adjustable brightness, 320 x 240 pixels,
capable of 4,096 colors.
Case: Fully gasketed, high-impact plastic alloy, waterproof to IEC 529 IPX7
Temp. Range: 5ºF to 131ºF (-15ºC to 55º C)
Power Source: 10-35 VDC
Usage: 21 Watts max at 12 VDC
Fuse: AGC/3AG - 3.0 Amp
Power: Dual Frequency, 500 Watts (RMS), 4,000 Watts (peak to peak);
Dual Beam, 400 Watts (RMS), 3,200 Watts (peak to peak)
Frequency: 50/200 kHz (dual frequency), 80/200 kHz (dual beam)
Depth: 1,500 ft (dual frequency), 900 ft (dual beam)
(Depth capacity is dependent on water salinity, bottom type, and other water
Fishfinder 400C Owner’s Manual27
Alarms and Messages
The Fishfinder 400C uses an on-screen message system to alert you
to unit operating characteristics. When a message appears, press
SELECT to acknowledge the message and return to the screen you
were viewing.
Battery Alarm—battery voltage has fallen below the value entered
in the Battery Alarm setup.
Battery Voltage Is Too High—too much input voltage; the unit
shuts off in 10 seconds. Decrease the input voltage to 35 Volts or
Boat Is Not Moving Fast Enough to Calibrate—the boat is not
moving fast enough for the speed wheel to provide a valid speed.
Can’t Read Voltages That High, Limited to Top of Range—the
voltage value in the Battery Alarm setup is higher than the unit can
Can’t Read Voltages That Low, Limited to Bottom of
Range—the voltage value in the Battery Alarm setup is lower than
the voltage where the unit automatically turns off.
Deep Water Alarm—the Deep Water Alarm depth has been
Drift Alarm—the depth has changed by the amount of the Drift
Alarm value.
Fish Alarm—an icon appears and a beep sounds (if enabled) when a
fish is detected. This alarm does not show a message banner.
Shallow Water Alarm—the Shallow Water Alarm depth has been
Simulating Operation—the unit is in Simulator Mode.
Sonar Failed, Unit Needs Repair—there is an internal problem
with the fishfinder. Contact your dealer or Garmin Product Support
to have the unit serviced.
Transducer Disconnected, Sonar Turned Off—there is not a
transducer attached, bad cable/transducer, or the transducer cable
was disconnected. If the transducer cable is removed while the unit
is on, reconnect and cycle power.
Water Speed Sensor Is Not Working—the speed sensor is not
detected. Check the connections.
Entering (Leaving) target water temperature—the target water
temperature is 2° F (1.1° C) above or below the temperature
specified by the Water Temperature Alarm. These messages appear
when you enter or leave that zone.
Fishfinder 400C Owner’s Manual
Limited Warranty
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.
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
To obtain warranty service, contact your local Garmin authorized dealer or
call Garmin Product Support for shipping instructions and an RMA tracking
number. Securely pack the unit and a copy of the original sales receipt, which
is required as the proof of purchase for warranty repairs. Write the tracking
number clearly on the outside of the package. Send the unit, freight charges
prepaid, to any Garmin warranty service station.
Online Auction Purchases: 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.
International Purchases: A separate warranty is provided by international
distributors for units purchased outside the United States. This warranty is
provided by the local in-country distributor and this distributor provides
local service for your unit. Distributor warranties are only valid in the area of
intended distribution. Units purchased in the United States or Canada must
be returned to the Garmin service center in the United Kingdom, the United
States, Canada, or Taiwan for service.
Garmin International, Inc.
Garmin (Europe) Ltd.
1200 East 151st Street, Unit 5, The Quadrangle,
Olathe, Kansas 66062, USA
Abbey Park Industrial Estate,
Tel. (913) 397-8200 or
Romsey, SO51 9DL, UK
(800) 800-1020
Tel. +44 (0) 870.8501241 (outside the UK)
Fax (913) 397-8282
0808.2380000 (within the UK)
Fax +44 (0) 870.8501251
Garmin Corporation
No. 68, Jangshu 2nd Road,
Shijr, Taipei County, Taiwan
Tel. 886/2.2642.9199
Fax 886/2.2642.9099
Fishfinder 400C Owner’s Manual29
Declaration of Conformity (DoC)
Software License Agreement
To view the full Declaration of Conformity, see the Garmin
Web site for your Garmin product:
fishfinder400c/. Click Manuals, and then select the Declaration of
Conformity link.
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.
Hereby, Garmin, declares that this Fishfinder 400C is in compliance
with the essential requirements and other relevant provisions of
Directive 1999/5/EC.
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.
Fishfinder 400C Owner’s Manual
A-scope 26
accessories 27
advanced settings 25
alarms 21, 28
battery 21
deep water 21
drift 21
fish 21
shallow water 21
water temp 21
arches 22
the case iii
the screen iii
clutter. See surface noise
configure screen 20
contact garmin iii
sonar settings 22
system settings 23
transducer settings 23
units of measure 24
adjusting 15
basic operation 15
beam 25
bottom lock 25
bracket assembly 2
Declaration of Conformity 30
depth 24
line 26
range 25
span 26
zoom 26
display settings
changing 21
distance 24
duration 26
calibrate the speed sensor 24
CANet 12, 27
caring for the fishfinder iii
factory settings
restoring 23
fish symbols 22
flasher 18, 26
flush mount 2, 27
frequency 25
full screen 17
fuse 10, 27
gain 25
GPS, wiring to a 12
HOME key 15
Home screen 16
important information iv
input voltage 10
installing 1
selecting a location 1
testing 13
the fishfinder on the mounting
bracket 3
the mount 2
the transducer 4
on a transom 6
on a trolling motor 5
shoot-thru-hull 8
the wiring harness 10
to a Garmin CANet 12
interfacing with NMEA 12
keel offset 23
adjusting 24
using 15
changing 23
LCD screen 1
limited warranty 29
location for shoot-thru-hull installation 9
location for the fishfinder 1
MENU key 15
messages 28
bracket 3
bracket assembly 2
transducer on a transom 7
transducer on a trolling motor 5
NMEA device
connecting to 12
noise. See surface noise
Fishfinder 400C Owner’s Manual31
numbers 22
numbers screen 19
resetting 26
optional accessories 27
physical specifications 27
power/data and transducer cables 1, 3
product registration iii
quick links i
range 25
RANGE keys 15
registration. See product registration
reset odometer 26
ROCKER key 15
scale 26
scroll speed 22
selecting a location for shoot-thru-hull
installation 8
SELECT key 15
setting alarms. See alarms
advanced 25–26
display 21
sonar 22
system 23
transducer 23
shoot-thru-hull installation 8
simulator mode 23
using 15
software license agreement 30
specifications 27
sonar settings
changing 22
specifications 27
speed sensor 24
split frequency screen 18
split zoom screen 17
surface mounting the fishfinder 2
surface noise 22
suspended targets 22
swivel base 3
swivel mount bracket 3
system information
viewing 23
temperature range for the fishfinder 1
temp log screen 19
test the installation 13
tips and shortcuts i
transducer 8
assembling 4
cables 1
dual beam 5, 18, 23
dual frequency 18, 23, 25
installing 4–7
settings 23
transom 7
transom, mounting on a 6
transom mount installation 14
trolling motor, mounting on a 5
water speed 24
calibrate 24
water temperature 24, 28
whiteline 22
wiring harness
installing 10–12
zoom 25
2x 25
4x 25
depth 26
split 17, 25
Ultrascroll 12
voltage 10
warnings iv
warranty. See limited warranty
waterproof. See water immersion
water immersion iii
Fishfinder 400C Owner’s Manual
For the latest free software updates (excluding map data) throughout the life of your
Garmin products, visit the Garmin Web site at
© 2006, 2007 Garmin Ltd. or its subsidiaries
Garmin International, Inc.
1200 East 151st Street, Olathe, Kansas 66062, USA
Garmin (Europe) Ltd.
Unit 5, The Quadrangle, Abbey Park Industrial Estate, Romsey, SO51 9DL, UK
Garmin Corporation
No. 68, Jangshu 2nd Road, Shijr, Taipei County, Taiwan
Part Number 190-00757-00 Rev. B