When repairing a daggerboard....

Discussion in 'Multihulls' started by paxfish, Dec 3, 2015.

  1. paxfish
    Joined: Dec 2014
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    Location: Southern Maryland

    paxfish Junior Member

    I have a dagger that cracked at the hull exit. After grinding through the crack, which runs the width of the board, I find that the central I beam is intact.

    I am grinding a big "diamond" that runs the width of the board and has points upper and lower by about 8 inches above and below the crack.

    The glass is about 6 layers thick in the center, tapering to maybe two layers at the width of the board.

    If I were fixing a hole in a hull, I would scarf it much wider, lay in a large piece of cloth and then progressively smaller pieces of cloth until I had the right thickness.

    For a dagger, does that same method apply? Or should I start with smaller pieces, and build up progressively larger so that the outer layer is contiguous up and down and the fibers are straight?

    BTW - I am using a 50/25/25 Triaxial with the big uni oriented top to bottom.

    Also, as interest, this crack occurred in compression rather than tension.


    thanks,

    [​IMG]

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  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Yep, you got it right a big one first, then progressively smaller ones to bulk it up. This will make fairing in in easier and you'll minimize fiber cutting, between the layers. Triax is a bitcch, I'd use biax, just to make wetout and conformation easier. Maybe the first layer triax, but biax after, just to make it an easier hand laminate.
     
  3. redreuben
    Joined: Jan 2009
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    redreuben redreuben

    Sorry, I'm going to partially disagree, use biax out to the edges for sure, but fill the bulk at max chord with uni. I would also finish with full length not little bits, fill it up fair it off, then finish with a full cover, s-glass double bias last layer would be ideal. :)
     
  4. abourgault
    Joined: Jul 2014
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    abourgault Junior Member

    On what boat is it used?
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Agreed, the ideal laminate would be appropriately arranged uni, but most aren't willing to go to this extent.
     
  6. paxfish
    Joined: Dec 2014
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    Location: Southern Maryland

    paxfish Junior Member

    Thanks Guys. I don't intend to peel a whole layer off of this thing! I DO intend to build a new board over the next season.

    Meantime - I intend to do an elongated diamond, centered over max chord, and will roll in all your thoughts on Uni, DB and Triax.

    Abougault - 8.5M/28 foot Tennant Cat as below:

    [​IMG]
     

  7. paxfish
    Joined: Dec 2014
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    Location: Southern Maryland

    paxfish Junior Member

    From the bottom up, 17ounce uni, 23 ounce Triax, 8 more layers of 17 ounce uni. Not shown is two TOP layers of Uni large enough to cover the full repair.

    Using a 36" straightedge, I was able to fair it out pretty good before curing.

    Once it cures, there might be room for another layer of DB or something.

    Can't wait to test it out!

    [​IMG]
     
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