Repairing Cold Molded Boats

Discussion in 'Boatbuilding' started by farjoe, Jun 4, 2007.

  1. farjoe
    Joined: Oct 2003
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    farjoe Senior Member

    How does one repair a holed wooden hull, constructed of 2 layers 4mm plywood double diagonal?

    regards
     
  2. Ike
    Joined: Apr 2006
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    Ike Senior Member

    By cutting out the layers and replacing them. It's hard to describe without a picture or diagram, but the aouter layer needs to overlap the inner layer.
     
  3. farjoe
    Joined: Oct 2003
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    farjoe Senior Member

    Could you please amplify?

    let us say you have a hole which is 3 in in diameter and the planking are 6 in wide by 8ft length.
    do you try to remove hole strips? if so how?
     
  4. Ike
    Joined: Apr 2006
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    Ike Senior Member

    Heck no. I would probably remove 6 inches of the inner strip and 12 inches of the outer and replace each.
     

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

    Don't think of it as planking. It's no longer individual planks but a homogenous structure of wood and plastic. If you have a painted finish then it's easy. Grind down through the outer layer to the surface of the inner layer and move the opening (in the outer planks) to at least five times the diameter of the hole (15" in your case). It will likely over lap another plank or two, don't worry, the seams on the inside will remain intact.

    Then cut away the broken pieces of wood, on the inner planking, making a neat hole, that can have a patch placed inside, with a tight fit. Make, fit and glue (use epoxy) your patch, using a backing block to keep it flush with the inside of the boat. It will only have edge glue holding it in place, but don't worry.

    Next, neaten up the outer layer edges, so a patch can fit tightly inside. Make sure you have good contact. If the hull is particularly shapely there, you may have to put some pre-bend into the patch. Do plenty of dry runs to insure the patch fits nice and with full contact. Then using some thickened epoxy glue it into place. Fair the area and repaint.

    The repair can also be made using traditional 'glassing skills. Just make a cloth reinforced patch, fair it pretty and paint. This would be the simplest way.

    If the hull is brightly finished, then the repaired area should begin and end at the planking seams. This doesn't mean you have to grind out an 8' plank, but you do want to use the edges to make it look like a butt joint or scarf is in the actual planking. The same techniques apply, but you have to work much neater, following the actual plank seams.
     
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