Why are my maximum Engine RPMs important in choosing a propeller?

The maximum RPMs, or WOT RPMs (Wide Open Throttle), is an important benchmark, most often used to determine the best size propeller for a particular boat and application. If you think of your max RPM range as the target, your actual RPMs as the arrow, and your propeller as the load, then simply put, the load can be adjusted to put the arrow inside the target.

Furthermore, by choosing a propeller with the correct combination of diameter, pitch and cup, the max RPMs should be in the proper range to provide optimum performance for the boat and engine at all levels of operation. Fitting your boat with the wrong propeller can translate into a variety of problems (i.e., insufficient acceleration/speed/hold, over or under-revving, red-lining, poor fuel economy, etc.).

Engine RPMs are affected by a variety of factors (i.e., the amount of weight added to the boat, elevation above sea level, air/water temperature, engine condition/performance, propeller size or condition, the condition or attitude of the hull, etc.).

For typical applications the average user should have his or her max RPMs in the target range for their engine under normal load conditions. Two common applications that call for special propeller sizing are dedicated wakeboarding or wakesurfing applications that add considerable weight to increase the wake size and high elevation applications, in which the standard, stock propeller can be too much load for the engine. If you have any questions about the correct size prop for your boat, please contact us.