One question often asked about props is, “How do I know if I have the correct pitch?” Luckily, that answer is pretty simple. At wide open throttle (WOT), with a normal load in your boat, your motor should be in the top 30% of its full throttle range. For the vast majority of Yamaha outboard motors, the full throttle range is 5000-6000 rpm. That makes the target range during WOT 5700-6000 rpm. If you are within that range, then you have the correct pitch.
If the motor is not within that range, changing to another propeller with a different pitch can get the rpm within the target range. A good tip to remember is 1 inch of pitch is equal to approximately 150 rpm ± 50 rpm. Increasing the pitch of the propeller will decrease the motor’s rpm; while decreasing the pitch will increase the motor’s rpm.
The correct propeller will allow your engine to reach the upper portion of the WOT range specified by the manufacturer with a normal-to-heavy load (without exceeding it).
Pitch is the distance measured in inches that a particular propeller would theoretically travel in one full revolution, as if traveling through a solid. A lower pitch will have greater acceleration and better thrust, but a lower top speed; while a higher pitch propeller will provide less acceleration, but a greater potential for higher top speeds.