determining distance between catamaran hulls

Discussion in 'Boat Design' started by Thai, Mar 29, 2006.

  1. Thai
    Joined: Nov 2004
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    Location: VietNam

    Thai Junior Member

    Hi everybody!
    Now I want to build a catamaran. But I don't know formula to calculate distance between two hull. Could you guide or show doccument for this issue
    HochiMinh City - Viet Nam
  2. wingsails
    Joined: Jan 2004
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    Location: Warialda Australia

    wingsails Kim Prentis

    There is no set formula that I am aware of, it depends on how stable you want it to be and how much of a problem being too wide is eg on a trailer behind a car.
    Years ago width was 1/2 of length, but now wider boat are more popular.
    That is only the start of your problems though, take advice and think things through trying to imagine how it will all come together.
  3. Hisham
    Joined: Oct 2005
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    Location: Egypt

    Hisham Marine engineer

    be care the larger span the larger bending moment
  4. Thai
    Joined: Nov 2004
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    Location: VietNam

    Thai Junior Member

    I agree with Hisham. This distance keep eye on bending moment and shear force effect vertical wave. So I want a detail formula. Could everybody help me ?, Thank
    HochiMinh City - Viet Nam

  5. JonathanCole
    Joined: May 2005
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    Location: Hawaii

    JonathanCole imagineer

    The width of a catamaran depends on many things. What kind of speeds you travel, what kind of sea and wave conditions you regularly expect, what the length is, etc.

    Catamarans create diverging waves between the hulls . These waves can interfere with and sometimes assist the forward movement of the boat. This depends on many other design issues including the symmetry or lack of it in the hull design, the fineness of the bow in pushing through the water, the angle of the bow to the waterplane, and the speed that the hull is moving.

    At some speed the waves actually can assist the movement of the boat by something called constructive interference. There is no set formula because all of the catamarn hull design characteristics effect the wave interference.

    I think the most common point of view among experienced designers is wider is better than narrower. The wider the better, until you start getting so wide that you can't find a berth for the boat.
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