how many coats of resin?

Discussion in 'Fiberglass and Composite Boat Building' started by Heynow999, Jul 20, 2020.

  1. Heynow999
    Joined: Jun 2020
    Posts: 7
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    Location: Toronto

    Heynow999 Junior Member

    hi, I'm building a 4 x 11 Jon boat out of 1/4 marine plywood. I will be glassing the bottom with 6oz cloth and epoxy resin. I am trying to make it light so I can load it myself onto a trailer.
    My plan is 60 inch cloth draping over the sides. I have 4 inch fiberglass tape, should I tape the outside corners of the boat first for extra strength?
    After the bottom has been wet out with one coat, is it neƧcessary to do a second coat to fill the weave for strength or is it merely cosmetic at that point? Frankly, as this is my first boat and I have a problem finishing projects, my goal is "quick and dirty" rather than a piece of art. I looking to skip cosmetic details and only do what is necessary for strength., Sure I will scrape off the glue drips but if a second or third coat of resin is not needed, I would prefer to skip it. The boat will be painted .

    thanks
     
  2. hoytedow
    Joined: Sep 2009
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    hoytedow Old Woodbutcher

    Welcome.
    Fill the weave for strength. Make sure the cloth looks transparent with no white spots. Tape the seams outside before laying the cloth. You may want to tape the seams along the seams inside too. Paint will protect the plastic from degradation by uv rays.
     
  3. hoytedow
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    hoytedow Old Woodbutcher

    Good luck.
     
  4. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    The weave is going to take a lot of beating.

    In conventional building, the seams are taped first. This is because the main glass does not do the curve well in all cases and in some cases, like a hard chine or dev panel, the tape is the only laminate on the edge. A jon boat is a hard chine, so tapes first.

    also, if you are less worried about appearance; you might consider an extra 6 oz tape on the edges for a wee bit of wear plate..the boat will get beat there
     
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  5. dinoa
    Joined: Oct 2007
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    dinoa Senior Member

    Wetting out gets you the strength. Filling the weave is cosmetic
     
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  6. hoytedow
    Joined: Sep 2009
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    Location: Guess.

    hoytedow Old Woodbutcher

    If any of the cloth looks white it has not been satisfactorily wet out.
     
  7. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Another thing to note is plywood can drysuck a 6oz laminate easily. What can happen is you wetout and walk away and over the next 30 minutes the plywood pulls the resin in and the laminate becomes dry. A couple ways to avoid this.. prewet the ply or also wetout about 100% of the weight of the glass in resin

    Also, fyi, typically canoes get two layers of 6oz on the bottom. But I understand you want to lighten the final, so the reason I suggest a wear strip on each edge.

    Good luck.
     

  8. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    You can fill the weave with epoxy with microballoons. That takes less epoxy reducing weight and cost, and allows it to fill more easily.
    You are already spending the money for epoxy / glass, make it last by filling weave.
    If you do this soon after laying the glass, you can do the whole thing in one day (glass/epoxy/fill).
    Painting makes this work well.

    Radius the outside edges of the plywood, so both the tape and the glass will wrap around the edge without separating.
    1/4" radius minimum.
    Have fun.
     
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