Well, here's where I am as far as prop selection goes and I've run into this with most all my power plants over the years... On GPS, my boat runs 73 MPH Period!
If I run a 32 pitch, I run 73 @ 4500 RPM. If I run a 30 pitch, I run 73 @ 5200-5300 rpm. If I run a 28... Well, you know the rest....
The application is a 1989 Arriva 24" open bow boat V bottom with a Bravo 1, 1.5:1 ratio. at what I guess is about 3500-4500 pds. The props are all bravo one 4 blades. The engine is a blown 498 w/ 10 pds boost, good heads and large cam. So, anyway is this what I should expect? It seems to be the same for all the plants I've run over the years. The first was 50 MPHw/a 330 HP 454. The second, 57 MPH the third 63 MPH and now 73 MPH@ approx 900 HP. All with the same results regardless of any prop changes.
Here's my question. Is this what you guys see too? Am I missing something? I guess I should run the 32 pitch as it delivers the same top end @ 4500 RPM rather than spinning 5500 or 6000 for the same top speed. The boat planes instantly no matter what prop. What to do? What to do??