RazorsEdge

How does prop diameter affect the performance of a prop? What would going to a small diameter prop change? (Mach Stern driver 25" to a Merc High five 25") I have a 1995 24' Superboat, 454mag 350HP.

Here are my thoughts, am I on the write track, or way off base?
Less force on the drive.
Increased whole shot.
Increased cruising speed.
Decreased top speed.
Better rough water performance.
Slip numbers when running should be about the same.
Should run about the same RPM.
Less slip in turns.
May bolwout, correct with a nose cone...

Please let me know.

Will my only downside be less top speed?

Pat McPherson

Hey Razor,
A Merc High Five is an outboard prop; it's not likely to work on your I/O.
I'm sure one of the prop gurus will chime in about the diameter question, but I believe a smaller dia is fast for the most part. What is most important though is the correct prop design for you hull.
The slip numbers are vary low with Merc Mirage plus 3 blade and Bravo one 4 blade props running on a 24' Super.
The 3 blade is a click or two faster on top but the 4 blade is better overall.
I have found a modified for added bow lift B1 to be a great prop.
I did test a Hydro P5-X last week and that is an awesome 5 blade but big $$.
I will be trying a Merc Maximus 5 blade in a week or two and I'll let you know how it runs.
Dave M. and I have both recommended to you to try a 26p Bravo 1. I think you will be pleasantly surprised how well it will run for you right out of the box.
Happy Boating!

Rebel_Heart

Pat - will be interested in your thoughts about the Maximus vs. the P5-X. Wondering what would work better with high x-dim?