bad idea???? (10 ft 3point hydroplane)

Discussion in 'Boat Design' started by racing fan, Feb 12, 2011.

  1. racing fan
    Joined: Nov 2010
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    racing fan Senior Member

    i got a 10 ft 3point hydroplane I am working on right now i want to do something stupid i want to stuff a 2stroke 440 cc snowmobile motor in it could this effect the handling much and would this be deadly
     
  2. wheels
    Joined: Jun 2010
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    Location: Folsom, Ca

    wheels Junior Member

    any motor you choose will affect the performance of your craft. Weight distribution, power/torque curve, prop design, drive ratio, etc. But weirder things have been done. You should have plenty of horsepower to push it fast enough to get your adrenaline rush if you put the effort into it and complete it.

    what kind of drive are you thinking of? prop? surface piercing? jet?
     
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  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    3 pointers are very sensitive to trim and weight. I'd be very surprised if you could find the room in a 10' 3 point for what you envision, let alone figure out how to keep it from not wanting to end over end, once it gets up to speed. You see, with these types of modifications you have only one shot at getting it right, because if you don't it's going to bury a bow, roll, flip or other wise come to a stop in a violent fashion, which usually means the engine is hydro locked at 7,000 RPM (usually not good) and the boat is at least in a few big pieces, if not splinters.

    So, if you have a fair bit of experience fooling around with little 3 pointers, go for it, because you know what's going to happen right? If not, hang an outboard on it's butt and have fun.
     
  4. racing fan
    Joined: Nov 2010
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    racing fan Senior Member

    i have a bit of experience i was thinking a 440 be the back hugging the transom and that would be close to having a motor hang of the back as i could get
    i was thinking a small v-drive with inboard style drive and a mid size 3 blade prop and i would play around with the pitch the cockpit is 1ft 6in wide and 5.0 ft long and 14in deep (floor to top) or maybe a small jet but its a hydro its hard to use a jet i would have 40odd hp to play with and 6500-7250rpm on my 440cc motor about 42ci what do you guys think
    (i have crashed outboard and inboards before f-350, 850 ,and a couple class c, and one semi bad 1L-mod crash)
    note i have never been this stuiped before i just want to make a lake racer now for fun (spare hull) i am no boat designer i am great with CAD systems but otherwise no
    what do you guys think
    boat designers welcome to help
     
  5. messabout
    Joined: Jan 2006
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    messabout Senior Member

    Do yourself a big favor. Forget the inboard notion. Put a decent outboard on it and go fast. Put an inboard in it and you have about 486 expensive, time consuming, and frustrating problems to solve.
     
  6. racing fan
    Joined: Nov 2010
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    racing fan Senior Member

    i got a outboard race motor (yamato 302) for it but i want to step it up and do something no one else has
     
  7. racing fan
    Joined: Nov 2010
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    racing fan Senior Member

    look what i found some one with a close idea to mine what do you guys say
     

    Attached Files:

  8. cor
    Joined: May 2008
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    cor Senior Member

    I had a very similar project that I started years ago. Unfortunately it was never completed. My drive train plan looked like a V drive, with the motor sitting over the shaft with the PTO on the front. The engine was going to be connected to the shaft with a belt drive.

    I actually machined the pulleys to fit the shaft, fabricated a stuffing box, built a rudder, etc. I just never got around to completing the hull!

    I think it's a fun project.

    C.O.
     
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  9. racing fan
    Joined: Nov 2010
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    racing fan Senior Member

    well that's a cool project i want to do something like that but no jet so a little help please
     
  10. Jimboat
    Joined: Feb 2002
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    Jimboat Senior Member

    your 440 w/V-drive will move the CG foreward, so you will have to ensure that the hull design is modified to account for change in dynamic CG, particularly if your hull was originally designed as an outboard.
     

  11. racing fan
    Joined: Nov 2010
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    racing fan Senior Member

    well if you check the balance point on the boat its exactly 2 in. behind the sponsins i checked so if i put the motor and the v-drive total it would weigh as much or slightly more than a out board race motor on it but if i made it hug the transom it should not change the cg much and on a outboard you half to move to trim the boat so i would move back to fix the problem of to much weight forward
     
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