what speeds am i doing?

[dzalj1]

hi guys,
i would just like to know if anyone can work this out for me please. i have a johnrude superstrangler v4, its spinning a 26 merc v6 chopper, on a 2:1 gearbox, bobs lowwater pick up nose cone, (the nose cone point is 1 inch below the pad), i am doing 7500rpm, on a light weight kevlar bullet 1750 race boat.

thank you.

[hsbob]

86 by calculaction.

[pyro]

I would doubt that he's getting 6% slip on that hull with that prop. 10-15% slip is a more common range for a chopper. Big difference between 6% and 15% slip. Like 78 MPH vs 86 MPH. Could be anywhere in between, but probably closer to 80-83.

[hsbob]

i used 9%. that what i get with my worked tempest24. yes 6% is too good.

[Jimboat]

9% slip = 85.6mph with 2:1 ratio, 7500rpm and 26" cupped chopper.
12% slip = 82.8mph

[pyro]

Tempests have a lot of progressive pitching and cup, they run taller than stamped.

[dzalj1]

holy crap guys i cant believe i'm doing that speeds. jesus i'm probably guessing roughly then 79-80 mph is more appropriate but still thats fast to get out of a cross flow v4. now i can tell all the merc guys here that i can keep up with them now and not stay be hind lol, thank for the input guys.

[pyro]

Take a GPS with you, find out what speed and slip percentage you're actually running, it can be helpful to know that in terms of setup.