Apollo 14 3/8 x 15 too much?? 15 x 14?

[Sorrento 25]

I'm not sure of my drive ratio and I'm guessing it may be 1.5, but an old beat up 15 pitch aluminum prop turned about 4400 when I first got this boat and before I added about 400 lbs to it. Now the new Apollo SS 15" only turns about 4100 at 36. Cruise is about 3500 at 31. What would be a good step down in pitch from this prop in SS? I thought 15 pitch was about minimum. Do I need a gear ratio change?

 

[Bondo]

Re: Apollo 14 3/8 x 15 too much?? 15 x 14?

Do I need a gear ratio change?

Ayuh,........ Sure sounds like it.........Or your motor is Way Down on Power......

 

[Sorrento 25]

Re: Apollo 14 3/8 x 15 too much?? 15 x 14?

1988
Sorrento 250DA
7.4L Merc
1.32
15.5 X 18
4600

There is the OEM info from SeaRay. I don't see how a 6000 lb. 25' boat could swing 18" of pitch at 4600 RPM with 1.32 ratio? My engine runs perfectly. How it could it be that far down on power?