prop size

[dknight]

Can anyone point me in the right direction? I have a 1989 bayliner bowrider
19ft with 125hp force. The prop on the boat is a 13x19 and i can only get 4000rpms and takes a while to plane. Would a 13.5x17 help raise my rpm and get more mph? The boat should operate between 4500 and 5500.

 

[john from md]

Re: prop size

I think the rule of thumb is 200 rpm per inch. Even 400 rpm would not bring you to where you have to be. Have you checked your compression and done a good decarb on the engine?

John

 

[dknight]

Re: prop size

Going to decarb tomorrow. Finally have a day off to do it. Thanks for the suggestion.