I bought my 1988 Crestliner Sabre a few years ago with a 1989 Evinrude 150. The prop was a 15x17. It was my opinion that the boat was sluggish to get on plan with a full load, and I ran this prop for 2 full seasons. So I researched some prop selector tools online and they recommended a 15.25x15, based on the weight of my fishing gear and people on board (heavy load). Both props are aluminum 3 blade. It seems that heavier loaded boats require a smaller pitch prop, such as a 15 pitch instead of the 17 pitch I started with.
Now I feel that my boat gets up on plane more smoothly, and my top speed is slightly faster at 34 and some change. That's close to 2 mph faster at 5200 rpm wot. I also think the motor is burning less fuel. I'll have to check my owners manual for my motor wot rpm range, but iirc 5200 rpm is in the ballpark.
Just wanted to pass this along because I had asked the question before, on which prop to choose, and I couldn't get a straight answer.