Re: Yamaha Outboard Props
The first number (13.25) is the diameter of the prop. 17 (Pitch) is the theoretical distance the prop would move the boat in one revolution. In this case 17 inches. To go faster one needs a prop with more pitch. BUT -- the motor only has so much power so increasing pitch may actually slow you down because the motor can't reach its maximum recommended wide open throttle RPM. Conversely -- going less pitch gives you great hole shot, but can cause the engine to over rev on the high end. Read the first post on this forum to learn what's required and why for determining prop selection.
