Greg B said:
I know you did a lot more research on this than I have, what are you using for weight - I used 7000 lbs and the Suzuki gear ratio is 2.08:1. I think I either have more slip that that or I'm doing something wrong. I bought a Suzuki 16x18.5 and I'll see how that does.
Not sure what you mean by using weight.
The prop calc uses RPM, gear ratio and pitch to calculate theoretical speed. That is simply based on each revolution of the prop moving the boat forward a distance equal to the pitch in inches.
The actual speed is then used to calculate the slip.
If you used the prop calc that I provided a link to, did you forget to convert your speed of 31.5kts to MPH? That would be 36.27 in this case.
Using 5500RPM, 19" pitch, 2.08 gear ratio, and 31.5kts, gave 24% slip.
The 7000# is probably pretty close for our weight, with fuel, water, batteries and engines, but with none of our gear onboard.
Brian