WildWarrior

We just installed 800s with a 5600rpm red line and new Max Marine Billet drives with 1.35 ratios which are 2'" shorter than the Stock Bravos on our Kevlar 38' Top Gun.
Last season with stock 600s, fuel , 6 people and Bravo 4/b 26 pitch props and 1.36 ratio we topped out at 83mph gps @ 5400rpms and she planed out quickly.
When I do the math for our new power with slip% etc I come up with 29 pitch props ,they seem a bit small compared to what I see other guy's running with similar power ,we are looking for the best cruising props not that last 2mph. Anyone with a similar combo, our boat is approx 9900lbs dry.

throttleup

Your calculations seem to be close. I think you may have a problem with excessive slip due to raising the drive 2".

I would try your current props to get an idea of what your slip is with the new set-up and power. Ultimately you may find that a set of 5 blade props with 27-28" of pitch will get your boat to 95 or so at 5600 rpm.

When changing power and drive height expect to spend some time setting the boat up to get the most out of it. Don't be discouraged if the boat doesn't perform the way you hoped it would the first time out.

Matt

WildWarrior

Thanks for the input Matt, it's much appreciated.
We plan on base lining our 4 /b 26s first, we also have a set of labbed 4 blade 30 pitch props to try, i'm not sure she will pull 5600rpms with the 30s but we don't have anything in between to test.
When we get close I will send you my data and then price up a pair of 5 blades for our application!
Glen

bbladesprops

With your current slip %, it will take 29P Bravo 1's to reach 95mph @ 5600 with 1.35 gr. With the 2" shorties, the 30's should make great test wheels.

shawn

Let me know if you need a pair of Hydromotive 32" P5s labbed by Throttle Up. They are too big for my engines.