Volume 2 Edition 4

Volume 2 Edition 4
Yamaha’s
“The latest news about Yamaha propellers”
VOL. 2 | EDITION 4 | SEPTEMBER 2012
Three parts to
proper performance
Don’t forget about the propeller when
it comes to overall boat performance
(remember… without it, you go
nowhere). It’s one of the three major
performance components of a boat
package.
Boat
Know the effects
We all know a few basic propeller
buzz words. But do you know
what they actually mean, or what
manipulating them does for boat
performance? The impact can be
huge. Let’s take a deeper look into
a few of the more common ones.
pitch
Engine
Propeller
The propeller is perhaps the hardest
working single piece of equipment on
your boat, but it’s many times taken for
granted, and often overlooked when
diagnosing a performance issue. For
your boat to perform effectively, the
prop you use must be the right one
for the job and it must be kept in good
condition (see Prop Shop, Volume 2,
Edition 1).
What’s news?
Three parts to
proper performance
Know the effects
Testing propellers
Over and out?
Reconditioned propellers
definition: pitch is the distance (in inches)
a particular prop would theoretically travel
in one full revolution, as if traveling through
a solid.
effect: a lower pitch will have quicker
acceleration and “pushing power” but a lower
top speed, while a higher pitch prop provides a potential for higher top speed
but with slower acceleration. The correct propeller will allow your engine to
reach the upper portion of the wide-open throttle (WOT) range specified by
the manufacturer with a normal-to-heavy load, without exceeding it. Each inch
of pitch is equal to approximately 150 +/- 50 rpm, so adjusting the pitch adjusts
the WOT rpm.
slip
definition: slip is the amount of “wasted”
energy a particular prop generates,
meaning that the actual distance traveled
in one full propeller revolution is less than
its pitch measurement. It is normally
expressed as a “percentage of inefficiency.”
As an example, a 23" pitch with nearly 9% slip means the prop actually
moves the boat about 21".
effect: a certain amount of slip is engineered into each line of propellers to
create different performance characteristics. Slip can be beneficial, such as
helping two stroke outboards quickly hit their power band at hole shot. Other
props and boats perform best when slip is minimized.
(continued on next page)
Yamaha’s
Know the effects
| continued
diameter
definition: diameter is the total width of the “circle” at the blade tips as the
propeller spins.
effect: a larger diameter pushes more water and reaches deeper into the water,
so they’re typically used on large, heavy boats or ones with high enginemounting heights.
A smaller diameter is usually used on lighter-weight boats, where the prop
operates lower in the water or when a gain in engine RPM is desired.
Proper diameter is determined by the propeller’s design and intended application.
rake
definition: rake is the angle of the blades in relation to the propeller’s barrel, or
center, and is expressed in degrees.
effect: a high-rake propeller is best-suited for high engine-mount applications
by helping reduce ventilation and increasing bow lift. Too much rake, however,
strains the engine; decreases hole shot, and generally results in poor performance.
A propeller with a low rake angle will cause less strain on the engine, resulting in
potentially better hole shot and higher WOT operating RPM.
cup
definition: cup is the small curved lip on the blade tip and/or trailing edge.
effect: used in proper amounts, cup helps reduce ventilation and propeller slip,
allowing for higher mounting heights and greater bow lift. Too much cup, however,
will cause excessive steering torque and bow lift and limit the engine’s ability to
develop and maintain proper RPM.
blade surface area
definition: blade surface area refers to the total surface of the blades.
effect: the more blade surface area a prop has the more water it pushes, for
better “hole shot” and increased planing efficiency. Having too much blade surface
area for the application can create significantly more drag, however, potentially
restricting engine RPM and causing negative boat-handling issues.
Yamaha’s
Testing propellers
OK – so you’ve followed the procedure we’ve outlined on our
website on how to pick a prop and you’ve narrowed the field down
to two or three likely candidates. You also know that on-water
testing is the way to truly decide which propeller is best, but how
will you accurately compare them?
When it comes to evaluating propellers, it’s important for each
prop under consideration to be tested using the same criteria.
To help you in this effort, Yamaha offers a simple test form which
guides you through the proper testing procedure.
Known simply as the Propeller Performance Evaluation form, it requests and records test information
and results, so that the data from each test can be accurately compared afterward.
This, in conjunction with your personal assessment of how the propeller ‘feels’ when on the water,
will clearly demonstrate the winner.
PROPELLER PERFORMANCE EVALUATION
CUSTOMER INFORMATION
DEALER INFORMATION
NAME
DEALER COMPANY
ADDRESS
DEALER NAME
CITY
STATE
ZIP
ADDRESS
PHONE
CITY
E-MAIL
PHONE
STATE
ZIP
E-MAIL
TEST INFORMATION
DATE
Test details
prop information
boat information
test conditions/variables
PROP TESTED
DIAMETER
CRAFT
PITCH
CONSIDERATIONS
CONDITIONS
BOAT BRAND:
# OF PERSONS ABOARD:
TEST LOCATION:
BOAT MODEL:
ESTIMATED WEIGHT
AIR TEMP:
BOAT LENGTH/BEAM:
PERSONS:
BOAT WEIGHT (PUBLISHED):
ENGINE MOUNTING HOLE: 1 2 3 4
CURRENT SPEED:
# OF ENG.: 1 2 3 4
% FULL OF FUEL:
WATER CONDITIONS: (CIRCLE ONE)
SLICK
RIPPLED
MODERATE CHOP
ROUGH/WHITE CAPPED
ENG. BRAND:
ENG. MODEL/HP:
CARRIED GEAR:
# OF BATTERIES: 1 2 3 4
MAX HP:
T-TOP: Y / N
FUEL CAP:
WIND SPEED:
GROUP #:
GENERATOR: Y / N
A/C: Y / N
WAVE HEIGHT:
TEST RESULTS
UPWIND/AGAINST CURRENT
RPM
Test results
upwind/up current
downwind/down current
WOT data*
minimum planing data
ventilation record
*WOT refers to testing at wide-open
throttle with the engine(s) trimmed
out for maximum speed.
MPH
AVERAGE
GPH
MPH
DOWNWIND/WITH CURRENT
GPH
RPM
3500
3500
4000
4000
4500
4500
5000
GPH
5000
5500
5500
WOT _______ rpm
WOT _______ rpm
ACCELERATION TESTS
WIDE OPEN
THROTTLE DATA
(CHOOSE TWO) Seconds to Plane / 0-20 mph / 0-30 mph
RUN #
MPH
UPWIND/AGAINST CURRENT
RUN #
MINIMUM PLANING
DATA
DOWNWIND/WITH CURRENT
RPM
RPM
1
/
2
/
3
/
4
/
5
/
6
/
AVERAGE
/
AVERAGE
/
MPH
MPH
GPH
GPH
EVALUATOR COMMENTS
VENTILATION
Possible Responses: (CIRLE ONE) None Light Moderate Severe
TRIM IN
______________________________________________
TRIM OUT
______________________________________________
ACCELERATION
N L M S
CRUISE
N L M S
ACCELERATION
N L M S
CRUISE
N L M S
______________________________________________
WIDE OPEN
N L M S
TURNS
N L M S
WIDE OPEN
N L M S
TURNS
N L M S
______________________________________________
YAMAHA DEALER USE
PROPELLER SLIP %:
COMMENTS:
PROPELLER RECOMMENDATIONS:
NEXT ACTION:
© 2012 Yamaha Motor Corporation, U.S.A. All rights reserved.
MOUNTING CENTERS (MEASURED):_______________"
TOE SETTING ____________"
IN
OUT
Yamaha’s
Over and out?
If your boating season is winding
down, and/or you’re about ready
to lay up your boat for a while, now
is the ideal time to evaluate your
propeller and make any necessary
changes or upgrades.
Perform a thorough evaluation of
your prop’s condition. If there’s any
damage, such as nicks, cuts, or bent
blades, have the propeller evaluated
for possible repair. If necessary,
replace it.
Also, take the time to evaluate the
engine’s lower unit and its seals for
any damage. If found, now’s the time
to get it repaired or replaced.
Not comfortable with doing these
inspections yourself? Perhaps you
need a new Yamaha propeller for
next season, or your current one
repaired? What about a spare prop?
Your Yamaha Marine dealer can help.
Locate one convenient to you at
yamahaoutboards.com, or on
our Yamaha mobile app.
You’ll also find more helpful
information here:
http:// yamahaoutboards.
com/care-and-maintenance/
maintenance-matters.
The time to think about your prop
is now, not when you’re ready to go
boating next spring!
Reconditioned propellers
When a propeller is worn out or
damaged, particularly an expensive
one, having it reconditioned by a
reputable propeller repair shop
may represent a cost effective
option. Obviously, the amount
of work required to do that
(and the cost) is in direct relation
to the amount of the damage.
In some cases, though, despite the level of skill of the repair shop or the
technician, the level of performance obtained from a re-conditioned prop
may not be what it once was. This can either be immediately apparent, or
it may develop over time.
But don’t despair, there’s a silver lining here.
A smart boater always carries a spare propeller. If you have a
reconditioned prop that doesn’t quite measure up performance-wise,
carry it as a spare. It’s the get-home capability you’ll wish you had if,
and when, you need it and don’t have it. Then, see your Yamaha Marine
dealer for a new Yamaha prop that’s just right for your particular situation.
With a new prop installed and a fully-reconditioned spare on board,
you’ll have both peak propeller performance and peace of mind.
That’s smart boating.
If you’d like more information about which Yamaha propeller is right
for your needs, contact your local authorized Yamaha Marine Dealer at
yamaha-motor.com/outboard/dealers/dealerhome/home.aspx
For short videos on Yamaha propellers;
including proper installation, maintenance,
and more; scan this symbol using
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Also, please join us on Facebook at facebook.com/yamahaoutboards
We’ll be happy to help you get pointed in the right direction.
Turbo® propellers are manufactured by Precision Propeller Industries, Inc., a wholly-owned subsidiary of Yamaha.
This document contains many of Yamaha’s valuable trademarks. It may also contain trademarks belonging to other
companies. Any references to other companies or their products are for identification purposes only, and are not
intended to be an endorsement.
Due to Yamaha’s ongoing commitment to product improvement,
we reserve the right to change without notice, equipment,
materials, or specifications.
© 2012 Yamaha Motor Corporation, U.S.A. All rights reserved.
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