The correct propeller size allows the motor to achieve maximum RPM within the manufacturer's maximum rated RPM range at wide open throttle. If you are below the rated RPM range you need to purchase a propeller with less pitch. If you are over the maximum range you need to purchase a propeller with more pitch. One inch of pitch equals approximately 200 RPM on outboard and sterndrive applications. Inboard applications depend on reduction gear ratios and operating conditions.
Is your current propeller the correct size?
The following test run is required and is the most accurate way to correctly prop your boat. Run the boat at wide open throttle with the normal weight load and provide us with the following information: