Fixing a leaking keel line in GRP skiff

Discussion in 'Fiberglass and Composite Boat Building' started by liki, Jan 1, 2014.

  1. liki
    Joined: Nov 2008
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    Location: Finland

    liki Senior Member

    I have an old GRP outboard skiff from the era of bomb-proof GRP construction. It is of 1 1/2 shell construction and has a sealed off bottom and has a plastic keel strip fixed with screws through the bottom.

    Eventually the screws have rusted and the strip has taken enough beating to develop a leak into the sealed bottom compartment through the screw holes. I am planning to remove the strip, sand old gelcoat away and recoat the whole outside with epoxy and paint, plugging the holes and repairing other damage in the process.

    The hull has a pronounced deep fore foot that I would prefer to protect somehow because of the use that skiff has to bear. However I do not want to install anything with screws through the bottom, so I would prefer something that bends readily to take the curve and adheres well with only epoxy. Or just some durable and compatible with epoxy cloth and a hard surface finish. Any sound advice?
  2. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    A keel strip can be approached a few different ways. Metal (half oval for example), plastic strips (HPDE, etc.), and wood are the usual options. Plastic strips have to be screwed on, mostly because they don't glue well. Metal is often screwed on, though with an accurate bend, it could be glued with an adhesive/sealant. Wood is an old school technique and it can also be easily glued. All of these are sacrificial in nature and replaced when sufficiently beaten up.

    To solve the screws through the laminate problem, you could epoxy a strip of hardwood, to the bottom of the hull, then screw on whatever you'll use as the rub strip. I like half oval metals, by HPDE works well too. You also could "bond" the fasteners to prevent leaks.

    Lastly, you could just bulk up the centerline with Xynole or Kevlar tape. Bond it on, fair it in and know it'll be torn up eventually, but no leaks as a result of attachment.
  3. jonr
    Joined: Sep 2008
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    Location: Great Lakes

    jonr Senior Member

    It would be interesting to try alcohol wipe+flame treating a HDPE or ABS strip and then gluing it on with G-Flex.

  4. SukiSolo
    Joined: Dec 2012
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    Location: Hampshire UK

    SukiSolo Senior Member

    I'm with PAR on this one. On some hard used GRP Dorys, one of the best solutions was/is bond on a timber 'keel' or keel extension then run a brass part arc rail on it called a keelband. This is screwed in with S/S screws but only long enough to be all in the timber. Good for taking the scuffing on concrete slips on tidal waterways. The polymer strips can also be pinned but screws are much more secure. The aluminium strips are also quite good, it just depends on the service conditions.

    BTW always put varnish down the screw holes on assembly. Also if repairing the wood part later you can rip out the screws if they are 'soft' ie timber wet, and glue in cored plugs to take new screws - just like new.
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