Prop Masters - Specialist in Boat Propeller Repair and Maintenance

Frequently Asked Questions
Common Propeller Terms
How To Select A Propeller
Useful Links

Frequently Asked Questions

Q: How do I know if my propeller can be repaired?

A: A maximum of one third of the blade can be replaced. Contact us for further information regarding your particular situation.

Q: How much can I change the pitch on my propeller?

A: It really depends on the individual propeller. Typically, most propellers can be changed 1" up or 1" down.

Q: Can one propeller give top speed, plus lots of power?

A: No. To get the highest speed possible, this may involve sizes or pitch ratios that are unsuitable for the load carrying capabilities or working conditions. Decide what is most important and select the propeller accordingly, or change propellers with boating conditions.

Q: What is the purpose of the rubber cushion hub in an outboard propeller?

A: The "hub" in the propeller protects the lower unit parts by cushioning the shock of propeller impact. If impact is severe enough, this "hub" can slip, and may have to be replaced.

Q: What prop is best suited for MY boat?

A: Much more information is needed before an accurate propeller can be determined for your application. Call us for a FREE propeller sizing.

Serving marines, boat dealers and boat owners in Alberta, British Columbia, Manitoba and Saskatchewan

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Common Propeller Terms

  1. LEADING EDGE - The edge of the propeller nearest to the boat cuts through the water first, starting at the hub it extends to the blade tip.

  2. BLADE TIP - This is the farthest point that a propeller extends from the center of the hub to the outer radius of the blade.

  3. TRAILING EDGE - The edge of the propeller farthest away from the boat where the water leaves the blade.

  4. CUP - The cup on a propeller is designed to help lock the propeller in the water to reduce slippage and prevent cavitation. The cupped area is located on the trailing edge of the blade starting approximately 1" from the hub extending outward to the blade tip.

  5. PUSHING FACE - This is the face of the propeller blade away from the boat. More commonly called the PITCH FACE which faces the pitch block when being repaired.

  6. NEGATIVE FACE - This is the face of the propeller blade toward the boat.

  7. BLADE ROOT - The thickest area of a propeller where the blade and the hub are joined together.

  8. HUB - The center of the propeller that fits over the propeller shaft.

  9. OVER HUB EXHAUST - Exhaust gases flow over the hub and blades.

  10. THRU HUB EXHAUST - Exhaust gases flow through the hub to prevent exhaust gases from flowing over the blades of the propeller.

  11. RUBBER HUB - Inner hub bushing made of hard rubber, moulded to a splined spindle to protect the drive train when shifting.

  12. ACR/DIFFUSER RING - The flared ring used on through hub exhaust propellers. The ACR/Diffuser ring prevents the exhaust gases from backing up on the blades which produces cavitation during take-off.

  13. CAVITATION - The introduction of air on the propeller blades resulting from running a damaged propeller, or from sucking air from the surface of the water. A cavitating propeller is actually slipping and produces very little thrust.

  14. PITCH - The theoretical travel of a propeller through a mass per revolution. EX: A 19" pitch propeller moves forward approximately 19" per revolution.

  15. STRAIGHT PITCH - The pitch is constant or the same from leading edge to the trailing edge of the propeller.

  16. PROGRESSIVE PITCH - The pitch increases from the leading edge to the trailing edge. EX: Leading edge measures 17", trailing edge measures 20" pitch - this is a 3" progressive pitch.

  17. VARIABLE PITCH - The pitch increases from the leading edge to the trailing edge, and from the hub to the outer tip.

  18. RAKE - The angle of the propeller blade in correspondence with the propeller shaft.

  19. FORWARD RAKE - Blades are angled toward the boat. Commonly used for inboard propellers and small outboard propellers.

  20. AFT RAKE - Blades are angled back or away from the boat. This type of rake is used to help lift the stern of the boat on take-off, and on top end will help to lift the bow up - improving performance.

  21. PARABOLIC RAKE - The off center development of a propeller blade used to make the rake concave or convex.

  22. DIAMETER - The overall width of a propeller.

  23. RIGHT HAND ROTATION - The propeller turns clockwise on the shaft.

  24. LEFT HAND ROTATION - The propeller turns counter-clockwise on the shaft.

We work on brass propellers, aluminum propellers, stainless steel propellers, NiBrA1 propellers

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How To Select A Propeller

Best all around performance is achieved when wide-open-throttle (WOT) engine operation occurs at the top of (but within) the wide-open-throttle RPM operating range designated by the manufacturer for that specific engine. The WOT RPM operating range can be found in your owners manual. Incorrectly propping an engine can not only reduce performance, but, in fact, may damage the engine.

An engine that does not reach the rated RPM at wide-open-throttle is in an "overpropped" condition.-- This will cause an excessive load throughout the entire RPM range from idle to WOT, not just at wide open throttle. This "lugging" puts a tremendous load on the pistons, crankshaft, bearings and the entire driveline.

On the other hand, an engine that revs past the recommended WOT RPM is "underpropped" and can cause damage when operating past the WOT RPM range. This also creates less speed at cruising RPM.

This is why it is so critical to be sure your engine is propped correctly for your boat / engine combination and type of boating you want to do.

Using your existing propeller, determine the maximum RPM you are able to obtain (it is best to use a photo tach if possible). If during this test you begin to exceed the maximum rated RPM of the engine, reduce the throttle setting to a position where the maximum RPM is not exceeded. If you can exceed the recommended RPM of your motor, you need to increase the pitch of your propeller. If you can not reach your rated RPM, you need to decrease the pitch. Once your wide-open-throttle RPM falls within the recommended range of your engine manufacturer, you have the propeller that is best suited for your boat.

And remember that a properly pitched propeller will improve your fuel economy and extend the life of your engine!

We specialize in boat propeller repair and maintenance; marine sales and service

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Useful Links

Your local weather forecast
National Marine Propeller Association
Southern Alberta Walleye Tournaments
BOATsmart!® Canada
Duval Point Lodge - BC’s BEST fishing lodge
Western Canadian Walleye Trail
The APP for Fishing in Alberta
Custom Fabrication Stub Tech Enterprises

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