Prop advice to get to right rpm range

[mfaile]

I have a 25' Godfrey Marine Sanpan Pontoon. It has a Yamaha 4 stroke 115. Prop now is a 13.5" diameter by 15 pitch. Running at WOT RPM's are 4900 and speed is 25 MPH verified by satellite. Recommended rpm range is 5 - 6,000. Should I drop down to a 13 pitch or lower to increase rpm's and if I do what will it do to speed?

Thanks.

 

[steelespike]

Re: Prop advice to get to right rpm range

Welcome,
Rule of thumb "ABOUT" 200 rpm per inch of change.
Your motor will work better closer to the 6,000 rpm figure.
4900 is really lugging the motor.Could create premature repair problems.
A Solas Amita 4 blade 10" or 11" pitch should work well.usually larger diameters for a pontoon.
Can't tell you the speed difference but the rpm increase will help maintain speed and the 4 blade will have less slip.

 

[NHGuy]

Re: Prop advice to get to right rpm range

The other benefit you will get from the lower pitch prop is a better holeshot. Absolutely true on the 4 blade as well. I'd say do the 11"

 

[mfaile]

Re: Prop advice to get to right rpm range

Thanks Guys. Been looking on every website with every manufacturer and can't find a 14" - 11" pitch in a 4 blade. Any help is appreciated. Solas doesn't make that prop for my engine.