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Thread: PORPOISEING MOTHER

  1. #1
    donsanborn
    OK START LAUGHING.... WE HAVE A PAIR OF PONTOON BOATS, ONE 20FT RUN 60. 150 MERC...ONE 24FT RUNS 65 WITH 285HP JOHNSON V6 3L , BUT THE 24 STARTS TO SKIP ABOUT 58 AND JUMPS AT 65 LIKE A JERSEY SPEED SKIFF FUN BUT VIOLENT.....DOES ANYBODY HAVE A SUGGESTIONS. SET BACK,PROP WHAT EVER...THE HULLS ARE MISTY HARBORS, THAT ARE TWO 30" WIDE SQUARE PONTOONS AND CONCAVEED IN THE MIDDLE TO TRAP AIR...THEY JUST GLIDE THRU THE WATER...... SILLYSANFORD

  2. #2
    Infomaniac
    Take the BBQ grill off the front !! Seriously, move some weight to the rear. It bounces because it cannot carry the nose with the HP you have now. Either that or more HP

  3. #3
    PE857
    You're right, I did start laughing. Is your grandma scared to ride on that 65 mph pontoon? Whats your hurry?
    No offense.

  4. #4
    donsanborn
    THANKS FOR THE REPLY MANIAC....WE HAVE TRIED TWO BIG GUYS IN BACK ALONG WITH TWO 105LBS CHICKS STILL GET THE BOUNCE IT MAKES THE CHICKS HAPPY WE WANT 70MPH... OUR PLAN IS FOR TWO THREE HUNDREDS IF WE CAN FOR SEE IT WORKING. KEEP YOUR BRAIN WORKING ITS MUCH APPREATE SILLY

  5. #5
    donsanborn
    P[E857 WERE LAUGHIN ALL THE TIME TOO,BUT WE HAVE HAD MORE FUN WITH THIS THAN OUR STV OR OUR FIFTY METEOR WITH TRIP 650S, THE LAUGHING BOAT, SHOWS 71 ON THE SPEEDO AND WHEN YOU DO A LITTLE WOPPIN ON SOME BODY THEY ALL PULL UP AND LAUGH WITH YOU AND SAY WHAT THE HELL YOU GOT IN THAT UGLY PONTOON BOAT AND WE DO TELL THEM THAT ITS GRAMA;S THANKS FOR THE REPLY, BUT WE NEED AN LITTLE HELP TO GET TO 70 RADAR.... WITH OUT THE BIG SKIPPIN SILLY SANFORD

  6. #6
    PE857
    Don,
    Glad you have a good sense of humor about it. I didn't mean anything to upset anybody, just the thought of a 70 mph pontoon made me grin. Years ago a friend of mine put a 175 hp Mariner on a 16' alum pontoon boat, and when you would get up so fast it would start to lift one side clear out of the water. What a thrill that was, and he was just crazy enough to hold it.
    Anyway good luck on your speed quest, be careful.
    PE 857
    PS: I've always been a clamp on lover, used to have several 100 mph plus outboards, just can't let my drag boat buddies know i still like them.

  7. #7
    Tinkerboater
    Basicly that thing is just a big tunnel boat. Sounds to me like you are loosing your air entrapment. When the bow rises you loose the air packed under the boat. Try to get more stern lift by installing some tabs to block off the air exiting the back of the boat between the engine and the pontoons this will give you more lift in the back. You might want to put something like a skid fin on that thing to keep it going straight if you get it loose like I think you will.

  8. #8
    Infomaniac
    Tinkerboater: I was thinking something similar. I believe the prop is ahead of the back of the pontoons. Not enough leverage to carry the nose. I think that hull relys on hydrodynamics to get on top of the water. The prop needs to be behind the back of the pontoons or more HP.

  9. #9
    Tinkerboater
    INFO I don't think they need more setback of the engine. I can't belive you could get enought lift to raise the bow. I think that basicly what is happening is that the boat is packing air under it and it starts to lift- when the bow rises the air escapes between the water and the pontunes. This kills the lift and the front end drops. What they need to do is increase the traping effect so that when the bow rises they will still have enough to keep the bow up. Blocking off the air escaping around the engine will cause the whole boat to lift not just the bow.

  10. #10
    donsanborn
    WELL GUYS, THANKS FOR ALL THE RESPONSE.....ONE OF THE ???? WAS ABOUT THE MOTOR POS. AND ITS SET BEHIND THE PONTOONS LIKE ON A TRANSOM...WE HAVE THOUGHT ABOUT PUTTING A CENTER POD LIKE A STV OR A 8-10 SET BACK??????IF IT WASN;T 20 DEGREES I;DD THAKE A VIDO AND SEND IT TO YOU...PLEASE DON;T STOP LAUGHIN AND THINKING ABOUT THE OLD GIRL .......SILLY SANFORD

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