Performance Propellers

FAQ

PerfectPitch
Frequently Asked Questions

Question: How does Flex Pitch work?

Answer: In forward, our blades are slightly overpitched, so that in calm waters you get hull speed at lower RPM. If you overpitch a metal prop for low RPMs in calms, your motor will bog down and blow black smoke when you're trying to bust through a chop. PerfectPitch blades actually pitch down in forward at full throttle, allowing you to get up to speed faster and handle any sea condition.

Flex Pitch works differently in reverse. Most marine transmissions have a higher reduction in reverse than in forward. This means the prop spins slower in reverse, and it also means that the optimum pitch in reverse should be higher. Consider the Atomic 4 Direct Drive: Best pitch is 12x6 in forward, 12x11 in reverse. Our blades actually pitch up 1-2 inches in reverse! You'll spend less time walking and have a lot more control.

Question: What about breakage?

Answer: PerfectPitch props break in a different way than bronze props do. If you hit something solid with a bronze prop, the prop will go off pitch and balance, immobilizing your boat until the prop is repaired or replaced. If the damage to your bronze prop is not too severe, for about one half of the cost of a new prop, you can have a prop shop fix it.

If you hit something solid with a PerfectPitch prop, it will usually lose some or all of only one blade. Our props are so light you can still motor home at reduced speed without further damaging the drive train with heavy vibrations. You should replace the prop at some point, but Performance Propellers will sell you a replacement for half price if it breaks; meanwhile, you can make do until it is convenient to replace the prop. Also, our props make it easy for a diver to replace, so you don't have to wait around for a haul-out. Or, you can replace the prop yourself with our prop puller; SCUBA gear isn't necessary.

You should also keep in mind that props are the least expensive and easiest component of your drive train to replace. It's financially better to break off a blade on a plastic prop than to bend a bronze blade and bend or twist something much more expensive in the drive train.

Question: Can I go hull speed at 2000 RPM?

Answer: You can by buying an overpitched prop, but if you do, you'll give up speed in a chop, and thrust to get off an accidental grounding.
A PerfectPitch prop will give you low (approximately 2200) RPM in calm conditions and full power for rough seas. And it's guaranteed to not make your motor smoke.

Question: What about Barnacles?

Answer: Barnacles grow on plastic just like they grow on your fiberglass hull. We have a special paint which is a much harder finish than bottom paint, doesn't use poisons, and lasts for about a year even with extensive motoring. We sell it in kits, with everything you need to do the job.

Traditional bottom paints don't work very well on any kind of prop. They are made to ablate (i.e., slough off) at 5 - 10 knots, revealing new poison. Prop blades spin much faster than 10 knots, so by the time you've motored for awhile, most of the poison is gone, and the barnacles can grow.

Question: How do I know if I have "perfect pitch"?

Answer: There's a simple test. On a fairly calm day, go out in the harbor, and open the throttle all the way. Your tachometer should go to within 200 RPM of the maximum rated RPM. If your tachometer exceeds the maximum rated RPM, you don't have enough pitch; if it can't get up to the maximum rated RPM, you've got too much pitch.

Question: Are 3 bladed props better than two?

Answer: Two blades are better than 3 because they interfere less with each other. The more blades you have, the less efficient the prop. (One blade is more efficient than two, but no one has licked the balance problem.)

If you can't fit a large enough 2 bladed prop, a 3 will perform better and be less noisy. However, a larger 2 bladed prop will outperform a 3. The rub is that sailboats often don't have enough space for a larger 2 bladed prop.

That's where the Extendo excels. For boats with props in open water on a strut, the Extendo will let you swing a 2 to 3" larger prop for better motoring with less drag than a smaller overloaded 3.

Any prop can give you hull speed in calm waters. When seas are rough, smaller overloaded props tend to stall, resulting in half hull speed.

Question: What about Prop Walk?

Answer: Prop walk is determined by the downward angle of your prop shaft and the amount of tip to hull clearance. The more the shaft is angled and the less clearance you have, the more walk you experience, regardless of the prop.

While we can't eliminate walk, our props will minimize the time your boat spends walking. More thrust means your vessel will answer to the rudder sooner, so you can counter the walk.


Performance Propellers


44 James Street                                     Phone 607-749-3165

Homer, NY 13077                             Fax 607-749-4604

Email performance.props@verizon.net