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Epoxy crack repair

Discussion in 'Wood and Canvas' started by Mattg13, May 18, 2020.

  1. Mattg13

    Mattg13 Curious about Wooden Canoes

    I recently got this old town otca. And it has cracks it the epoxy. Was hoping y’all had some sage wisdom, for repairing. D259CFE9-6FF5-4557-90D8-0AA65C5A8EE8.jpeg 815B82CE-10E3-42DC-934F-A2611993F0E3.jpeg 7B3A91DF-A763-4972-AD1A-5A404F469698.jpeg 33ACD83F-F996-4A9C-A2BE-17F4504E57AB.jpeg 10290A28-A27D-4D90-AFDC-84F83F737DB5.jpeg
     
  2. MGC

    MGC Scrapmaker

    Hmm....neither sage nor wisdom are in my wheelhouse. Reckless ignorance is my specialty. I can dish a bit of that out.
    This hull appears to have been epoxied directly over the planking...without any woven cloth sublayers. The resin is cracking since there is no intermediary layer to absorb/distribute the force of impact. If you repair these cracks/chips you will soon find others appearing.
    You will never be able to achieve a cosmetically perfect repair. Anything that you do will be visible. So, with that in mind the mission becomes sorting the cracks to prevent them from leaking. You will need to push/force epoxy into the cracks to seal them. Since some of them are hairline cracks you will need to decide if you have the stomach for enlarging them so that you can inject epoxy. You will also need to decide if the water penetration to the wood is through the hairline cracks or the result of water working it's way in through some of the bigger wounds. If you think the source is the bigger gouges then you should very carefully use your Dremel to open them up enough to fill and repair them. If you think that the water is working it's way in through the cracks then you need to decide if you want to open them up to re-fill or if you want to see what happens if you coat the hull with a few layers of good UV resistant spar varnish. Keep in mind that whatever you do, more cracks are going to appear.
    If it were me, I would open the bigger wounds and using a syringe or small artists knife layer in epoxy. I would use a bondo leveling tool (little plastic appliers from the auto shop) to smooth the epoxy. I would then sand the entire hull before applying the noted spar varnish. Then I'd use it and see what happens. It is very likely that several layers of spar would be enough to seal the hairline cracks.
    You could also fill all of the wounds and then paint the hull....that way you'd never see the new cracks emerging.
     
  3. Dan Lindberg

    Dan Lindberg Ex Wood Hoarder

    When I was building my strippers, when I filled a void with resin, I put a small piece of waxed paper or even plastic sheet on the exposed resin to smooth it to minimize sanding.
     
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  4. Rob Stevens

    Rob Stevens Wooden Canoes are in the Blood

    IMHO varnishing or painting will not provide a durable solution.
    Since epoxy was applied directly over the planking, the only durable, waterproof repair is to apply a layer of glass cloth and more epoxy. Which will make it heavier.
     
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  5. Todd Bradshaw

    Todd Bradshaw Sailmaker

    Yep, somebody tried to resin-coat it without the fiberglass reinforcement that the resin demands for strength and it did not work and never will. Judging by the water stains around some of the cracks, I suspect that it isn't even epoxy resin, but polyester resin. Unfortunately, that will generally mean that the resin is even more brittle than epoxy and less well bonded to the wood. I really doubt that you have enough coating thickness to be opening the cracks up to fill them with epoxy and do any real good. Even if you did, the root problem is that the existing coating is neither strong or stable and it is just going to continue to crack elsewhere.

    That would seem to leave the options of either removing the existing resin and starting over (a nasty and very tedious job) or adding a better skin on top of what is there, be it a layer of fiberglass, or maybe even something like heat-shrink aircraft Dacron to keep the weight down.
     
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  6. OP
    OP
    Mattg13

    Mattg13 Curious about Wooden Canoes

    Upon closer inspection it looks like there is fiber mat under the resin. At a minimum on the bow and stern. I think this may be the factory finish? 5483E9F1-4B35-47CA-852A-F2C6AE6C2F1C.jpeg
     
  7. Dave Osborn

    Dave Osborn LIFE MEMBER

    Looks factory applied to me.
    Last fall I removed factory glass from an Old Town. It spent years in the sun and the UV destroyed it. To my surprise the glass came off very easily and also had two layers. Unfortunately the owner wants it glassed again.
     

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  8. OP
    OP
    Mattg13

    Mattg13 Curious about Wooden Canoes

    Ok I sanded the hull to get rid of the layer that was peeling. Also started grinding out the cracks and other damage. It does appear the prior owner put glass on the bow and stern only? On the damage I ground out, the resin seems decently bonded to the wood so I’m hoping it’s epoxy not poly. I’ll fill the areas with epoxy resin, Then spar on top, as suggested. Spar recommendations? I read helmsmen doesn’t hold up. I plan on swinging by west marine today. I’ll post progress pics here in a bit.
     
  9. OP
    OP
    Mattg13

    Mattg13 Curious about Wooden Canoes

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