Propeller Pitch Basics

Several propeller options are available to you, if you want to change your performance for better top end speed or to increase load carrying performance. The prop pitch setting you use will determine the way your boat accelerates and speeds. A boat that is set with the correct prop pitch will operate at a maximum of its open throttle RPM range. An example is a 12-foot boat with a 100 HP motor with a recommended wide open RPM range of 4400 to 5000. The appropriate prop pitch may allow an RPM of 4500 for this boat; however, a correctly pitched prop could run at 5300 and provide an increased overall speed. Some boat yards will assist you in the determination of the proper propeller pitch for your particular boat application, and may even allow you to test different prop combinations before purchase.

Finding the Pitch

Determine the correct prop pitch for your boat via manual testing and calculations by: a) determining the maximum wide open throttle RPM range in the owner's manual that came with your boat motor. Please note that the RPM range assumes your boat is carrying the driver and not a heavy load, b)Testing your current prop pitch configuration by taking the boat for a ride at least a quarter mile, not over revving the engine, at wide open throttle conditions. *When testing out your prop picks, remember that the "2 inch to 400 RPM" rule is only a generalization and that different props by different manufacturers may vary from this. Be conservative and do not over rev your engine.

Track your RPM

Record the RPM that your boat truly maxes out at under wide open throttle conditions, c) subtracting your current max RPM from the manufacturer's rated RPM and then subtracting 200 RPM from that number. The number that you have now arrived at is the number of RPM you need to raise to maximize your boat's wide open throttle RPM range. For every 2 inches of prop pitch, RPM will raise around 400. For example, a 21-inch prop to a 19-inch prop should raise RPM by 400 and improve acceleration of the boat, Don’t forget to test drive your efficient, faster and newer boat prop pitch at wide open throttle! Bon Voyage!