Prop diameter?

[scott8058]

I am currently running a 14.25 x 21p on a 20ft bayliner with a 350, w the wife and 3 kids at wot i can turn 5000 rpms which is to high so i want to try a 23p but wondering what diameter to try. The current is aluminum 3 blade (as will be the new, my Christmas gift to myself) and runs in the low 50's w plenty of hole shot, fast i know, but i just want a prop that i can run wot and not worry about blowing the engine. Normal load is family, gas, and cooler, we do a little tubing but not much as kids are younger, but we like to go fast and accelerate quickly. Any thoughts?

 

[tpenfield]

Re: Prop diameter?

23P x 14.25" +/- 0.25" D will put you at about 4500 rpm WOT.

If you can get a 14.25" D, get it. Second best would be 14.0" . . . a 14.5" might be just a bit too much. If you stay within the same prop brand/model, it should be right on.

 

[jestor68]

Re: Prop diameter?

I'm not sure what you are trying to accomplish, except pull the rpm down a little(?).

Your max rpm should be 4600 or 4800, depending on the model and year.

There are two easy ways to do that without hurting the hole shot.

First would be a simply control the rpm with the throttle lever.

Second; if you really want to change props and stick with aluminum; is to put a Solas Amita 15 3/10 X 21 pitch on there. That will actually improve the hole shot and serve to load the motor a little more at WOT, reducing the rpm by about 100-200 rpm, while maintaining about the same top speed.

A 23 pitch(while getting a couple mph more top speed) will most likely drop your rpm by about 400 at WOT, hurt the hole shot , and hurt your ability to carry an additional load(which you will eventually want to do).

For more speed(and rpm reduction) while maintaining a decent hole shot, you might also consider a Solas HR Titan 3 SS 14.25 X 22 pitch. That ought to drop rpm by about 300 and get more speed.