CHOOSING THE CORRECT PROPELLER

March 31, 2015 Boat Operation, Vessel Performance 129

Selecting the correct propeller for your vessel is one of the most important factors for your boats performance. There are many styles, shapes, number of blades, and types of marine propellers available to the power boater.
Selecting the correct pitch and diameter for your engine/vessel combination is step one.
The propeller should let the engine spin up to maximum RPM under the average load at WOT.
All propellers have “slip” the loss of efficiency when turning through water, when compared to the theoretical movement through a solid. Stainless Steel propellers have less “slip” than propellers made out of aluminum, due to the aluminum material’s flex.
The better designed Stainless steel propellers (usually more expensive) have less power robbing SLIP than others.
Obviously, the propeller with the lowest SLIP, will be more efficient, and usually produce higher vessel speeds at a given RPM.
The diameter should be as large as possible, while fitting the housing properly, and clearing the anode.
Having a good propeller shop add “cup” to the blade edges, will help to improve the propellers grip through the water.
Blade numbers depend on the desired results.
Three blade propellers are good for most applications, while four blade propellers usually provide more stern lift.
Five or more blade propellers are usually configured for either torque, or used in surface piercing designs.
As to material, most outboards & stern-drives use either aluminum or stainless.
Stainless Steel Propellers offer more performance and options than aluminum.
Stainless propellers flex less under load, and can be manufactured into high rake designs.
Correct venting of your propeller can greatly improve hole-shot, while still maintaining top speed characteristics.
A good propeller shop can vent your propeller for you, if it was not manufactured with vents.
In S/W Florida BURRIS PROPELLER SERVICE does a GREAT job with Outboard MARINE PROPELLERS.
If your propeller has damage to the outside blade area, this can negatively affect it’s performance, and increase fuel consumption.