Re: yamaha 90
A lighter boat.
Welcome to iboats.
Stainless props typically go faster than aluminum props of the same pitch. Sometimes you can go up an inch in pitch for even better results. Right now to give any more precise opinions, we need to know how many RPMs the motor does at full throttle.
You might have a look where the antiventilation plate above the prop is related to the bottom of the hull. For average operation it should be even with the bottom of the boat. For more bite in rough waters, down an inch is better. For speed on calmer water, up an inch is better. With a stainless, you might get two inches up. By raising the motor on the transom, you drag less gearcase through the water and gain speed. But the prop has to be able to handle it and not suck air.
