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Frequently Asked Questions and Answers

Q: How do I know if my prop is sized correctly?
Q: How do I determine the diameter of my propeller?
Q: What is pitch?
Q: How do I determine the pitch of my propeller?
Q: What is slip?
Q: If I increase the pitch of my propeller, will I go faster?
Q: Can I go faster if I decrease diameter and increase pitch?
Q: What is cup?
Q: What is the difference in performance between 3-blade and 4-blade propellers?
Q: What is Nibral?
Q: What is the difference between stainless steel and nibral propellers?
Q: Aren’t stainless props more likely to damage my shaft if I hit something?
Q: I ski at a 3000’ lake. Do I need a modified propeller for this elevation?
Q: How do I remove an inboard propeller?
Q: How do I install an inboard propeller?
Q: What is the correct propeller for my boat?
Q: My boat vibrates, what could it be?
Q: What kind of drive shaft should I use?
Q: How do I measure my drive shaft?
Q: How do I align my engine?

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)