planning hull running surface

Discussion in 'Powerboats' started by gtflash, Sep 22, 2013.

  1. gtflash
    Joined: Jun 2006
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    gtflash Senior Member

    How much wetted area does a planning boat hull run on when at speed?

    Bit of an open ended question, but i have spent ages looking at youtube videos, of racing boats and im still undecided. Id guess at less than 1/3
     
  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    1/3 of what, the below chine area ? The below static waterline area ? Depends on a number of things, principally the speed, weight of boat, hull shape, trim angle etc. Why do you want to quantify this ?
     
  3. Olav
    Joined: Dec 2003
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    Olav arch. nav.

    gtflash,

    you might want to get familiar with Savitsky's 1964 method for estimating the running attitude (trim, rise) and resistance of a prismatic planing hull. There are also several approaches to include non-prismatic (warped) hulls as well.

    A member of this forum (Dingo) did a superb job and made an Excel spreadsheet which you can download here.
     

  4. gtflash
    Joined: Jun 2006
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    gtflash Senior Member

    Thanks Olav, I will research more on that.

    Mr efficiency, I was thinking high speed craft, +70mph. I kind of decided in my head that at lesser speeds, hull sizes and weight would create different resolutions, however over a certain speed all hulls would be balancing on an equally small surface as a % of running surface. Yet watching videos it didnt appear i was right
     
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