cody_white83

86 chris cat
900sc's (true 900hp)moved 2' forward, SSM IV drives with boxes 4 blades 33 x 17.5 turning in
the boat is running 109mph @ 5000rpm
terrible porpus over 95mph so bad its coming out of the water with any positive trim (have only run the boat 1' chop mixed with some boat wakes).
is it the water conditions, prop direction, do i need more power to drive through it whats the cause and problem?

jeff32

you need wings!!!!

cody_white83

its about an inch or two about the bottom of the boat.
someone else also told me to try to switch the drives (turn the props out) what will that do?

Ghostrider

Make the props turn the other way!

bobkatz

You need to get a good measurement on the drives, "an inch or two" is like a mile when playing with x dimensions.

A friend has a pair 750's in his and its at 117mph, so with 900's it should be way over that.

Any idea of your slip numbers?

wannabe

Cody, I think you are getting too much bow lift. The people that can help you are George Linder and T2X in this site. X dimension is crtical on these boats as is prop selection. You have all the power you need, where are you located?

Wannabe

Ran-Dom 32

From my experience I think you need MORE bow lift... when I went from stock lowers (bravo's) that were 2'+ lower then the hull to a -2 lower - my porpoise range went from 70-80 zone to 90+ leading me to believe I have lost some ability to carry the bow resulting in a porpoise that take more air & faster speeds to disappear, I turn mine props outward, not sure if this helps? I plan going with a prop that has been worked a bit to help carry the bow high - then I will know for sure

greencard

iTrader: (2)

Cody, we need more info. X dimension, prop diameter,engine placement etc. My 85 chris is worst on flat water with extra weight in the front. I believe you need More bow lift. There are 3 linder hulls rigged with Speedys near me, including mine. I would be glad to share info etc. The props turn in on all three, in lifts the nose...the higher the x the more necessary they spin in. Good luck, These boat are have an awesome ride in the rough for their size and they can be very efficient once set up correctly.

cody_white83

i will measure the drives
the motors are further forwardi will post a picture.
when the props turn in does it lift the bow or transom?

cody_white83

props are mercury 4 blade 33 X 17.5