How to determine NACA section?

Discussion in 'Hydrodynamics and Aerodynamics' started by massandspace, Jan 16, 2018.

  1. massandspace
    Joined: Sep 2017
    Posts: 34
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    Location: Salt Chuck

    massandspace Junior Member

    How does one determine the proper NACA section for a daggerboard or rudder??

    Building a catamaran and would “love to know”!
     
  2. Dolfiman
    Joined: Aug 2017
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    Location: France

    Dolfiman Senior Member

    I think the most current profiles are Naca 00xx, 63-0xx or 65-0xx , with thickness ratio xx around 12% (9 to 15).
     
  3. Joakim
    Joined: Apr 2004
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    Location: Finland

    Joakim Senior Member

    Daggerboard should be asymmetric for best performance, if it is kept down on one side only.
     

  4. tspeer
    Joined: Feb 2002
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    If the boundary layer is fully turbulent, there is very little difference in minimum profile drag between different section shapes. The profile drag depends almost entirely on thickness - thinner is faster.

    It's far more important to size the planform properly. A longer daggerboard will have significantly less drag due to lift. Cutting the chord will reduce the drag more than changing the section shape, but you still need to have enough area for the boat to tack and sail well in light winds.
     
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