[Question] info on porpoising
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info on porpoising

  1. #1
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    Default info on porpoising

    i have a blown 19 foot daytona with a semi-V. if i trim the place diverter up to shoot a rooster, it porpoises violently. it has a droop snoot on a dominator pump. it also porpoised before the droop snoot. i tried a ride plate on it, but it did not make a difference. with the place diverter trimmed down, it is stable as it can be, but trimmed up you cant stay in the throttle. any ideas would help.

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    Quote Originally Posted by blown496daytona View Post
    i have a blown 19 foot daytona with a semi-V. if i trim the place diverter up to shoot a rooster, it porpoises violently. it has a droop snoot on a dominator pump. it also porpoised before the droop snoot. i tried a ride plate on it, but it did not make a difference. with the place diverter trimmed down, it is stable as it can be, but trimmed up you cant stay in the throttle. any ideas would help.
    If I were you I would keep going on the ride plate idea. You just have to keep tweaking it until you find the sweet spot.
    Quote Originally Posted by cordog009 View Post
    Nitrous is like a really hot chick with an STD...you know you wanna hit it, you're just afraid of the consequences

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    Hows the bottom of the boat look as well ? have u put a straight edge to her?
    (GN7)Just a simple waste of perfectly good sour mash. If you need a fuel, use something that will poison you, not something that makes you buzzed.

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    The boat is porpousing because you are trying to pick the nose up higher than the balance & power of the boat can hold it. So what happens is it lifts up in the air and then falls down and on and on. There are endless reasons for this but here are a few... Nozzel angle to high, try raising it up off the water a little at a time and see if you find a happy spot. If a ride plate is set to high or to low the boat will not be able to find the sweet spot where it is happy. Fine tunning nozzel angle & plate adjustment is necessary and sometimes very time consuming. Hook in the bottom, weight placement, shoe height, ride plate angle, leverage point and angle of nozzel etc all have effects on this... Probably not the answer you wanted to hear...

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    Senior Member HotRodJosh's Avatar
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    My boat does the same thing......have been told many different things could be contributing to it.
    But the one most common is that ya need more power (bone-stock 455)....if the water is glass and I slowly bring the nozzle up under full power, it will not porpoise, but once I cross some waves or ripples it begins...

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    Default Someone say Oldsmobile ? ? ?

    mine did it real bad first season I had it. I started dropping the plate down til it quit,but noticed a loss in mph (4-5) and a miserable ride in chop. Next season little better built motor same pump/plate setup and it was back to bouncing ... raised the plate up to where it was before and lost the bounce and gained my mph back plus a couple along with a better ride. Jet boats are just wierd huh .... that or I lost some weight ..... nah ,,,,
    It may be OLD ,it may be Slow ... but at least it's MOBILE !!!

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    Quote Originally Posted by hellnback View Post
    mine did it real bad first season I had it. I started dropping the plate down til it quit,but noticed a loss in mph (4-5) and a miserable ride in chop. Next season little better built motor same pump/plate setup and it was back to bouncing ... raised the plate up to where it was before and lost the bounce and gained my mph back plus a couple along with a better ride. Jet boats are just wierd huh .... that or I lost some weight ..... nah ,,,,
    Thats it you lost weight. Horse power can overcome most all things even the driver. Such kinky angles when you are trying to throw that roost. The intake is somewhat flat faced + any loader, water is trying to make a V angle to roost, Bottom is plowing water, and U want what!!!!

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    Senior Member motomattox's Avatar
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    Quote Originally Posted by [email protected] View Post
    Thats it you lost weight. Horse power can overcome most all things even the driver. Such kinky angles when you are trying to throw that roost. The intake is somewhat flat faced + any loader, water is trying to make a V angle to roost, Bottom is plowing water, and U want what!!!!
    x2
    I'd be more concerned with porpoising if the diverter were level. when you want to go fast, leave the diverter level. when you want to roost, raise it up. Not both.
    "Keep talking...it aint often I get to hear a genius speak"

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