A 14 1/4" x 21P OMC stainless steel propeller with a 15 spline OMC Evinrude Johnson hub can fit OMC, Johnson, and Evinrude 150 HP and up boats with a 4.75" gearbox. However, not every boat requires the same propeller, even if they are similar in length and weight. When choosing a propeller, you can consider things like:

• Engine RPM

• The correct propeller should allow your engine to run within the designed RPM range at wide open throttle (WOT). This spec is usually included in your owner's manual, or you can ask your mechanic or dealer. For example, an outboard motor might need 5000–5500 RPM, while a sterndrive might need 4200–5000 RPM.

• Boat use

• The pitch of your propeller can depend on how you use your boat. For example, a 21-pitch prop might be better for speeding up, while a 19-pitch prop might be better for a powerful holeshot