Fibregalss Upper and Lower Hull Separation

Discussion in 'Fiberglass and Composite Boat Building' started by EricM, Nov 18, 2009.

  1. EricM
    Joined: Nov 2009
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    EricM New Member

    I recently purchased a 1998 Haines Signature 493F and I am concerned about what appears to be separation between the upper and lower mouldings to the left and right of the transom above the rear steps. on one side the gap is about 1/4 inch running for about one inch thinning down to a noticeable 'crack' between the moulds which extends for another 4 or 5 inches. I am guessing this is from standing on the steps as they have some play which suggests that the may have flexed the hull. Does this require expert appraisal or will packing with selastic to stop potential leaks be sufficient.
  2. marshmat
    Joined: Apr 2005
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    marshmat Senior Member


    The gaps you're talking about.... it sounds like they're at the joint between the hull and the deck?

    Standard practice in fibreglass boat production is to mould the hull as one piece, and the deck/cockpit/etc. as a second piece. The joint between the two is a very common failure point. Not because there's anything wrong with the concept, but because so many builders just don't do a proper job of the joint.

    I have seen some hull-to-deck joints held together with little more than tap screws and sealant. More appropriate methods include through-bolting every few inches, or epoxy/glass laminate over the joint, or Plexus adhesive.

    Can you post some photos of how the defective joint looks on your boat, from the outside of course, but also from the inside (looking up into the joint from under the coamings/gunwales)? Once we know how your boat is put together, it will be easier to figure out what might be needed to fix it.
  3. Fanie
    Joined: Oct 2007
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    Fanie Fanie

    Post pictures please.
  4. EricM
    Joined: Nov 2009
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    EricM New Member

    Thanks for response will take some pictures tonight. It certainly looks like it has been packed with sealant before though I am guessing there is a gap which is leeting some water in, so I am hoping it isnt serious and just needs re-sealing..... I live in hope
  5. Herman
    Joined: Oct 2004
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    Herman Senior Member

    Do not worry to much. Usually it is a relatively easy fix, opening the crack with whatever tool available, and rejoining with some structural stuff.

    Once we can see photos, it is easier to give advise.

  6. EricM
    Joined: Nov 2009
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    EricM New Member

    Thankyou for your response, I apologise for delay in returning . I have removed the external trim and now see that the upper and lower shells have what appears to be a rubber spacer between them. The gap is where the spacer ends an inch or so before the transom, so this appears to be intentional and just needs to be filled with a marine silastic. The crack which continues around the rear steps may be caused by the movement in the hull allowed by the rubber seal when people have stood on the rear steps. I have removed both steps as they had movement and cleaned in order to re-silastic back to the hull and re-tighten and seal the mountng screws.

    Thanks for advise
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