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stopping a flat bottom from porpoising...

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Old 04-28-2011 | 09:02 PM
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Default stopping a flat bottom from porpoising...

Have a 99' Top Gun with blower motors, 5's on boxes that run level with the bottom of the hull. Cant seem to stop it from porpoising. Once i trim up in the sweet spot and hit a wave it will start, drop the drives down and it goes away, but i can feel the boat drag and slow down, If its completely calm im fine.....What seems to be the fix for this problem? Ive tried spinning the props in and out out helps a bit...
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Old 04-28-2011 | 09:25 PM
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On my 1997 Gun we lowered our X dimension a few inch's with the addition of drive spacers & we went from 87 to 94mph and also stopped running like Flipper.

Night and day difference on our hull.
Good luck!
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Old 04-28-2011 | 09:59 PM
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I still have new spacers, if you can use them.

Gary
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Old 04-28-2011 | 10:32 PM
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Originally Posted by bigfarmer
Have a 99' Top Gun with blower motors, 5's on boxes that run level with the bottom of the hull. Cant seem to stop it from porpoising. Once i trim up in the sweet spot and hit a wave it will start, drop the drives down and it goes away, but i can feel the boat drag and slow down, If its completely calm im fine.....What seems to be the fix for this problem? Ive tried spinning the props in and out out helps a bit...
Thats why you need a constant 3' to make the hull happy...
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Old 05-01-2011 | 03:54 PM
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Originally Posted by WildWarrior
On my 1997 Gun we lowered our X dimension a few inch's with the addition of drive spacers & we went from 87 to 94mph and also stopped running like Flipper.

Night and day difference on our hull.
Good luck!
Agreed, your X-Dimension is a little too high, the spacers should make a big difference. You may see an improvement with 1" spacers but 2" should be right on the mark. What length trim tabs do you have? If you don't already have them, 380's will help the combo as well.
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Old 05-01-2011 | 08:42 PM
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Not mine thats for sure!
-Mike
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Old 05-01-2011 | 08:57 PM
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Originally Posted by bigfarmer
Have a 99' Top Gun with blower motors, 5's on boxes that run level with the bottom of the hull. Cant seem to stop it from porpoising. Once i trim up in the sweet spot and hit a wave it will start, drop the drives down and it goes away, but i can feel the boat drag and slow down, If its completely calm im fine.....What seems to be the fix for this problem? Ive tried spinning the props in and out out helps a bit...
If you are in your "sweet spot" I would use tab input rather than drive input to settle her down and then when it settles out you can ease up on the tab input. A little bit of tab goes along way and you aren't scrubbing as much speed either. I agree with everyone with respect to your X being a little high as well.
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Old 05-02-2011 | 08:09 AM
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what speed is it starting at?
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Old 05-02-2011 | 08:58 AM
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id call bblades and tell them what you dont like about the way the boat acts, send them your props, and try it after they do their thing. my boat chine walked and everybody told me do this and do that. i sent my props out and had them labbed, now it runs like its on rails. just a thought.....
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Old 05-02-2011 | 09:05 AM
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props have helped the porpoise in my boat, more blades
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