what pitch 4 blade prop

[89mercruiser]

Hey all my family has an 89 3.0 alpha 1 gen 1. My dad is thinking of getting a new prop. Current prop is 14.5x17p. With that one we turn about 4500 and tops out at rougly 42mph. My dad wants to go with a 4 blade for a little more hole shot and hopefully a little more top end. Our mechanic said go with a 16p but I've looked and don't see any only 15 and 17, Would going to a 15p 4 blade be the right direction? Just trying to help the old man out.

 

[Mike Zee]

Re: what pitch 4 blade prop

They always tell you to go down a size in pitch when switching to a 4 blade. The 4 blade will help your 3.0 out. You will loose a bit of top end, but 42 mph is really good for your boat. I switched to a 4 blade for pulling tubes, wont go back to a 3. Maybe a 13 x 17 would work. I think mine is a 13 x 19 (1986 3.0 140 hp, alpha one). I love the way it planes out. Before the bow was up in the air so high, you could almost roll out the back. My speed is 35 mph, dont matter what the load in the boat is.

 

[89mercruiser]

Re: what pitch 4 blade prop

I don't mind losing top end as the 3.0 i never run it WOT all the time I cruise right around 3500rpm and the current prop with 3 people and gear i got around 27-28mph according to depthfinder and speedo in boat showed 25.