L shaped centerboards

Discussion in 'Multihulls' started by guzzis3, Oct 24, 2021.

  1. guzzis3
    Joined: Nov 2009
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    guzzis3 Senior Member

    A couple of weeks ago I mentioned L shaped centerboards. Naturally I was told they had been tried, but I would like to know how successful they were.

    Multihull Structure Thoughts https://www.boatdesign.net/threads/multihull-structure-thoughts.62361/page-139

    Post 2082

    I've also read in the past of kick back dagger boards, shaped so if they hit bottom the board shape promotes kicking back rather than breaking and the case is shaped to accommodate this.

    Does anyone have any case studies on these ideas ? Actual practical experience ?

    Failing that would anyone care to discuss the details of such a design ?

    It would be a nice change from arguing about build materials/techniques etc...
     
  2. redreuben
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    redreuben redreuben

    From memory the cases pointed the board forward so it kicked backwards and upwards into the case. Pointing forward is also a technique to minimise cavitation.
    It is also great at collecting weed, rope and plastic.
     
  3. upchurchmr
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    upchurchmr Senior Member

    There was a Multihull designer who made daggerboard cases with "crash box" sections to do this.
    I am humiliated to not be able to think of his name.
     
  4. guzzis3
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    guzzis3 Senior Member

    Thank you for the replies.

    I remember the crash boxes but like you I've forgotten who did them. Mr Woods mentions doing the experiment but as I recall while it prevented a leak the board got wedged and couldn't be lifted until the boat was grounded and some serious stuff done.

    If I ever get this boat built I think I will try the double centerboard thing and see how it goes. It would be nice though to have and actual account from someone who has actual experience.

    There were a few boats in the "old days" that had quarter circle centerboards. I think the Hartley Sparkle trimaran had one.
     
  5. Gary Baigent
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    Gary Baigent Senior Member

    frogstern.jpg
     

    Attached Files:

  6. upchurchmr
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    upchurchmr Senior Member

    Look at the Tornado Catamaran.
    A centerboard that worked well, retracted for beaching, and could be set up to retract when it hit something.

    Just a part of world class performance.
     
  7. cavalier mk2
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    cavalier mk2 Senior Member

    Come on guys, crushboxes came from Dick Newick and they do the job pretty good.
     

  8. upchurchmr
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    upchurchmr Senior Member

    Thanks for fixing my poor memory.
    Newick it is.
     
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