Uh-oh... I think I'm in trouble

Discussion in 'Wooden Boat Building and Restoration' started by MaddMatt, Apr 2, 2022.

  1. MaddMatt
    Joined: Oct 2020
    Posts: 13
    Likes: 0, Points: 1
    Location: buffalo ny

    MaddMatt Junior Member

    I am building a catamaran starting with the center. I figured this was smart as if it doesn't turn out great, a) it won't be as noticeable as the hulls and b) as its the part that doesn't touch the water, I'm not going to sink.

    Well, I primed the plywood with epoxy and after it was tacky, I starting laying on fiberglass, pushing it down into the tacky epoxy with a squeegee. I left it to dry and when I went back the next day, quite a bit of the mat has pulled away from the plywood as it dried. The stuff that's down is REALLY down but half is floating above

    Is there a way to save this? And if not, how do I fix it?

    Keep in mind, this part of the cat isn't "in" the water although it will get wet sitting 24" above the water.

  2. MaddMatt
    Joined: Oct 2020
    Posts: 13
    Likes: 0, Points: 1
    Location: buffalo ny

    MaddMatt Junior Member

    So I think I know what may have contributed to the delay.

    I'm using west 205 hardener for colder temps but I've made sure its warm. I also stuck a heater under the cabin/cockpit. Im wondering if the cooler 45-50 degree temps plus the warmed wood and epoxy cause the issue.

    The bigger question is how to fix it. Ive gone thru a bunch of Google searches and can't seem to find a solution.
  3. Rumars
    Joined: Mar 2013
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    Location: Germany

    Rumars Senior Member

    Give us a better description of what you did. Right now I understand you used Chop strand mat pushed into tacky epoxy.
    1. Don't use CSM.
    2. Don't let the epoxy go tacky on the ply, give it a coat, wait to soak in, rewet dry areas, put on cloth and wet out thoroughly until transparent.

    To repair there is only one option, take it down and refiberglass (cut, grind). If you use heaters the wood can outgass and the cloth will bubble. Always work on a falling temperature gradient, that way the epoxy gets sucked in and you don't get bubbles.
    Skyak likes this.
  4. AlanX
    Joined: Mar 2022
    Posts: 113
    Likes: 20, Points: 28
    Location: Perth, Western Australia

    AlanX Senior Member

    My too cents.
    I live in a hot/dry climate so the epoxy going off too quickly is my problem.
    Still out gassing of the plywood is a problem if the temperature is rising, or it is outdoors and the sun shines on the plywood.
    However, I would never try to do the nominal two pre-coats and the fibre layer in one pass.
    I always have to do some sanding of air bubbles on the pre-coats.
    As far as the floating of, and bubbles in fibre glass, it will be much easier to manage if you do this as a separate layer.
    Fixing, just sand off the problem areas and put a patch over it. Fibreglass is practically invisible under epoxy (and paint).

    Finally don't paint too much epoxy on each layer, runs are damn annoying.


  5. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    Based on what I am hearing, you precoated the wood, but failed to rewet the substrate and used mat glass with perhaps biax above it and failed to achieve an adequate wetout. Now the mat that stuck is barely holding and you are delaminating easily.

    If so, the job must be torn off; the glass is garbage.

    Take pictures, submit them, ask us how to wetout your specific glass.

    Epoxy can be used for mat backed glass. But mat backed stitched glass is resin thirsty and demands a lot.

    If so, you can shear the glass away easily and sand off the mat fibers all off with 40-60 grit papers. Wear gloves and a face shield and haz suit or you'll itch for days
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