Q: How do
I know if my prop is sized correctly?
A: Your prop is sized correctly if the engine rpm of
the boat is redlined at wide open throttle. If the engine rpms
are below redline, decrease the pitch of the prop. If the engine
rpms are above redline, increase the pitch of the prop. (Back
To Top) Q:
How do I determine the diameter of my propeller?
A: Double the distance between the center of the hub
and the tip of one of the blades. (Back To
Top)
Q: What is pitch?
A: Pitch is the amount of ‘twist’ in the
blades of the propeller. It is defined as the theoretical
distance the propeller will travel forward in one revolution.
Thus, in theory, a 13” pitch propeller will move the
boat forward 13” with each revolution. In actuality,
the boat will move forward less than 13” due to slip.
(Back To Top)
Q: How do I determine
the pitch of my propeller?
A: The pitch is usually stamped on the hub of the propeller.
(Back To Top)
Q: What is slip?
A: Slip is the difference between theoretical and actual
speed expressed as a percentage. A 14” pitch propeller
that moves the boat forward 7” per revolution has 50%
slip. Slip can be used to compare the efficiency of propellers
with the same pitch and diameter. (Back To
Top)
Q: If I increase
the pitch of my propeller, will I go faster?
A: In most cases, no. Increasing the pitch will only
help if your engine rpms currently exceed the redline at wide
open throttle. Otherwise, unless horsepower is increased,
the additional pitch will decrease engine rpm and the boat
will probably go slower. This is also harder on the engine.
(Back To Top)
Q: Can I go faster
if I decrease diameter and increase pitch?
A: Pitch cannot be substituted for diameter without
a loss in efficiency and performance. (Back
To Top)
Q: What is cup?
A: Cup is a small curl placed on the trailing edge
of the propeller blades. Cup reduces cavitation and slip,
typically producing an average increase of 3 mph over uncupped
propellers. (Back To Top)
Q: What is the difference
in performance between 3-blade and 4-blade propellers?
A: 4-blade propellers have superior acceleration, improved
handling, and better throttle response than 3-blade propellers.
4-blade propellers also have less vibration than 3-blade propellers.
This makes 4-blade propellers an excellent choice for 3-event
skiing. 3-blade propellers produce higher top speeds. This
makes a 3-blade more suitable for barefoot skiing. Also 3-blade
propellers are less expensive than 4-blade propellers. (Back
To Top)
Q: What is Nibral?
A: Nibral is an alloy of nickel, bronze, and aluminum.
It is stronger than bronze, but not as strong as stainless
steel. Most propellers for tournament inboards are made of
nibral. (Back To Top)
Q: What is the difference
between stainless steel and nibral propellers?
A: Stainless steel is stronger, more durable, and more
expensive than nibral. Stainless steel props typically have
a higher top end than nibral propellers. (Back
To Top)
Q: Aren’t stainless
props more likely to damage my shaft if I hit something?
A: A major propeller strike will bend the shaft no
matter what material the propeller is made of. A minor strike
is more likely to damage a nibral propeller, while leaving
a stainless prop and the underwater gear undamaged. (Back
To Top)
Q: I ski at a 3000’
lake. Do I need a modified propeller for this elevation?
A: At 3000’ your engine will experience an approximate
10% loss in power. The loss in power is even greater above
3000’. Therefore, a modified propeller is necessary at
elevations of 3000’ and above. Additionally, if your
boat is used at sea level and at elevations of 3000’
or higher you will need two differently sized propellers to
run properly at both locations. (Back To Top)
Q: How do I remove
an inboard propeller?
A: Inboard propellers are removed with a prop puller.
Position and tighten the prop puller until the propeller comes
loose. For propellers that are particularly stubborn, try
tapping the puller bolt in line with the drive shaft with
a soft faced hammer. It is also a good idea to only back off
the prop nut two turns until the propeller has been broken
free from the shaft taper. Finish removing the nut. (Back
To Top)
Q: How do I install
an inboard propeller?
A: Seat the propeller on the drive shaft without a
prop key. Mark the location of the propeller on the drive
shaft with a felt-tip pen. Remove the propeller, install the
prop key, and reseat the propeller on the drive shaft. The
propeller should reseat at the mark. If it does not, check
the drive shaft for burrs, reposition the prop key, and try
again. (Back To Top)
Q: How many ducks
are on this page?
A: You didn't think we would make you try to count
this many did you? That would just be mean. There are 32,000
on this page. You probably would have missed a few since some
are hiding behind images. (There are 800 rows with 40 in each
row.)(Back To Top)
Typical
Propeller Applications
4 Blade Propellers (Back
To Top)
Brendella
1993 & earlier with 1:1 13 x 13 x 1 LH
1993 & later with 1:1 13 x 13 x 1 1/8 LH
Correct Craft
with 1:1 13 x 13 x 1 RH
with 1.23:1 13 x 16 x 1 RH
with 1.46:1 14 x 18 1 1/8 RH
M.B. Sports
with 1:1 13 x 13 x 1 1/8 LH
Malibu
1992 & earlier with 1:1 13 x 13 x 1 LH
1993 & later with 1:1 13 x 13 x 1 1/8 LH
with 320 hp & 1:1 13 x 14 x 1 1/8 LH
with 1.46:1 14 x 18 x 1 1/8 LH
Mastercraft
with 1:1 13 x 13 x 1 LH
with 1.5:1 14 x 18 x 1 1/8 LH
with 454 13 x 14 x 1 LH
Moomba
with 1:1 13 x 13 x 1 LH
Sanger
1996 & earlier 13 x 13 x 1 LH
1997 & later 13 x 13 x 1 1/8 LH
Supra
with 1:1 13 x 13 x 1 LH
3-Blade Propellers
Brendella
1993 & earlier with 1:1 13 x 13 x 1 LH
1993 & later with 1:1 13 x 13 x 1 1/8 LH
Correct Craft
with 1:1 13 x 13 x 1 RH
with 1.23:1 14 x 16 x 1 RH
with 1.46:1 14 x 18 1 1/8 RH
M.B. Sports
with 1:1 13 x 13 x 1 1/8 LH
Malibu
1992 & earlier with 1:1 13 x 13 x 1 LH
1993 & later with 1:1 13 x 13 x 1 1/8 LH
with 1.46:1 14 x 18 x 1 1/8 LH
Mastercraft
with 1:1 13 x 13 x 1 LH
with 1.5:1 14 x 18 x 1 1/8 LH
with 454 14 x 14 x 1 LH
Moomba
with 1:1 13 x 13 x 1 LH
Sanger
1996 & earlier 13 x 13 x 1 LH
1997 & later 13 x 13 x 1 1/8 LH
Supra
with 1:1 13 x 13 x 1 LH (Back To Top)
Vibration
Sources
From time to time inboard boats develop a problem
with vibration. Drive train vibration, if significant, is
very debilitating to the drive train components and should
be eliminated as soon as possible.
There are many causes of vibration in the drive
train. These include a propeller that is unbalanced or improperly
seated, a bent drive shaft, strut, or rudder, worn strut bearings,
engine misalignment, loose engine mounts, or a combination
of the above. Usually, vibration can be considerably reduced
or eliminated by following a systematic checklist to pinpoint
the source(s) of the vibration. This checklist may be similar
to the following:
1. Check drive train for signs of obvious damage.
2. Check that the propeller is seated properly on the shaft
taper.
3. Check for loose engine mounts.
4. Check engine alignment.
5. Try a different propeller.
6. Remove drive shaft and have it checked for straightness
and taper runout.
7. Install new strut bearings.
8. Consider replacing the strut.
9. Seek professional help.(Back To Top)
Shaft Information
There are many decisions to be made when ordering
a replacement drive shaft. The following information may help
you make the right choices for your boat. There are two basic
designs, single-taper drive shafts and double-taper drive
shafts. A.R.E. Manufacturing, Inc. has also developed the
patented System drive shaft, which is the most advanced and
innovative double-taper drive shaft available.
Single-taper shafts are tapered only on the
propeller end. They are press fit into the coupling and secured
with set screws. Since the diameter of shafting can vary by
up to .004”, single-taper shafts and couplings should
be replaced as a factory matched set. This will prevent an
improper fit, which may vibrate loose and cause major damage
to the boat. Double-taper shafts are tapered and threaded
on both ends of the shaft. The coupling is machined with a
mating taper. The tapers are seated by tightening a retaining
nut onto the shaft, which produces a secure, vibration-free
joint. Double-taper shafts, when properly machined and installed,
run truer and are much less likely to work loose from the
coupling. Also, double-taper shafts and couplings with the
same taper can be sold seperately without the fit problems
of the single-taper design.
Another consideration of drive shaft design
is serviceability. Typically, single-taper shafts are more
difficult to service than double-taper shafts. A.R.E. System
shafts are the easiest to service. Single-taper shafts are
pounded out with a slide hammer or cut in two at the coupling.
The slide hammer method is time-consuming, laborious, and
detrimental to transmission bearings and seals. Cutting the
shaft is relatively quick and easy, but is not an option when
the shaft is to be reused. With double-taper shafts, the coupling
is unbolted from the transmission flange and the retaining
nut is removed. A spacer is put on the end of the shaft and
the coupling is rebolted to the transmission flange until
the shaft breaks free from the coupling. This method works
well, but is time-consuming and could bend the transmission
flange and cause alignment problems. To solve these service
problems, A.R.E. Manufacturing, Inc. designed the System drive
shaft. The System has a threaded coupling to accept a Separator
jacking plug. After the coupling has been unbolted from the
transmission flange and the retaining nut removed, the Separator
is threaded into the retaining nut cavity and pushes the shaft
out of the coupling. Not only is this method quick and convenient,
but it eliminates the possibility of damage to other drive
train components. The System also uses a self-locking set
screw to prevent the retaining nut from working loose. This
is more accessible and much easier to service than the safety-wired
set screws, cotter pins, and tab washers that other manufacturers
use. Finally, it is very easy to convert boats with single-taper
drive shafts to A.R.E. System drive shafts. Merely specify
System shafts when a shaft needs replacing. In many cases
there is little or no difference in cost to obtain the increased
serviceability of A.R.E. System drive shafts. (Back
To Top)
Drive Shaft
Measuring
A.R.E. Manufacturing, Inc. has extensive records
on drive shaft lengths for many boats. Often, we can supply
the correct shaft length with only the year, make and model
of the boat. However, boat manufacturers sometimes change
shaft lengths during the model year. This, along with other
factors, can make determining shaft length from year, make,
and model of the boat less than 100% reliable. To ensure you
will receive the correct shaft length, please supply us with
either dimension A or dimension B.
The diameter of the shaft, if unknown, is easily
determined by measuring with calipers or a tape measure. (Back
To Top)
Engine Alignment
For inboard boats, engine alignment is very
important. The flanges of the coupling and the transmission
on a properly aligned engine are within .003” of parallel.
Improper alignment causes vibration, and greatly increases
wear on the engine, transmission, strut bearings and the stuffing
box. Significant engine misalignment can also break the drive
shaft. To keep your boat running shipshape, and to prevent
damage, check engine alignment any time there is noticeable
vibration and whenever the coupling is unbolted from the transmission.
Ideally, the engine should be aligned with the
boat in the water, but for most boats satisfactory results
can be obtained while it is on the trailer. Before checking
engine alignment, remove any burrs or dings that may prevent
the flanges from mating properly. Then use two feeler gages
sized .003” apart, for example, .020”, and .023”
to check engine alignment. Place the .020” feeler gage
between the transmission flange and the coupling flange at
position A and take up any excess gap. Determine if the .023”
feeler gage will or will not go between the flanges at positions
B, C, and D. Repeat this procedure using the .020” feeler
gage at positions B, C, and D. If the .023” feeler gage
will not go between the flanges at any of the locations, the
engine is aligned properly. Otherwise the engine is out of
alignment and should be realigned before the boat is returned
to service.(Back To Top)
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