Is this the correct process for repairing this fibreglass crack?

Discussion in 'Fiberglass and Composite Boat Building' started by UtahSignature, Jun 5, 2021.

  1. UtahSignature
    Joined: Jun 2021
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    Location: Planet Earth

    UtahSignature Junior Member

    I actually have 3 of these on my canoe. But here's one as an example.


    NOTE: Gunnels have been removed since this picture was taken. They were rotten and basically ant farms.

    This is all new to me, and folks here have been a MASSIVE help. Here's how I plan to repair the above:

    1. Sand down both sides as much as possible
    2. Cut away crack into small rectangle, per the red lines above
    3. Clean area and remove dust
    4. Use fibreglass cloth with either 105/206 West System epoxy and hardener, or Bondo system (still undecided - open to be swayed!). I'll add the cloth to the inside of the canoe
    5. When dry, fill in the gap on the outside of the canoe (the small "dent" from the existing hull to where the new fibreglass cloth us) with epoxy and Wesy System 406 Colloidal Silica
    6. These areas will then be ready for sanding and, when the rest of the boat is sanded, gel coat and eventual paint

    As I mentioned, I'm totally new to this. So feel free to tear my process apart. I've likely made some assumptions and errors!
  2. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    Don't cut anything out.

    Sand it down, taper the edges of the crack to a thin edge, but leave it all in place.

    Bondo brand stuff is next to worthless, West Systems will work fine.

    Build it up and sand off anything that doesn't look like a canoe.
  3. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

  4. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    Also, you may not remove all paint through sanding as the glass is quite rough. Don't sand it all off to flat. You can either sand it mostly off or use a stripper in the area of the patch. Make sire the stripper is neautralized.

  5. kapnD
    Joined: Jan 2003
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    kapnD Senior Member

    Looks like the old gunnels were incorrectly jointed, inner and outer strips should have had generous overlap, but were nearly adjacent to each other, allowing damage to the fiberglass from the joints flexing and eventually failing.
    The proper rebuilding of the gunnel may be more structurally important than the fiberglass repair.
    DogCavalry likes this.
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