Ply on frame epoxy schedule

Discussion in 'Materials' started by bobbrown, Nov 21, 2021.

  1. bobbrown
    Joined: Jul 2021
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    Location: SE Georgia

    bobbrown New Member

    Ply on frame to be used in the marsh in southern Georgia. Lots of oyster shell banks.
    Now, these shell banks are in shallow water so should not be hit at speed but rather while poling or using trolling motor on slow speed. Recommended lay up is 2 layers of 6 oz cloth.
    My concern centers around the sharp shells on the epoxy bottom.
    The question then is…..would it be worth the $ to sandwich some Kevlar or carbon fiber between layers…how about S2 all around.
    Centainly a strong consideration is tape on all seems.
    Thanks for any help
     
  2. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    I am assuming that you will cover the bottom with 2 layers of 6 ounce cloth with epoxy, in addition to taping the seams?

    If so, then I doubt that you will sustain any hull damages if you encounter shells at poling or trolling motor speeds.
     
  3. philSweet
    Joined: May 2008
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    It depends what the boat weighs and how much power it can carry. For a 16' skiff with a 70hp, I'd go a bit heavier - 2 x 9 oz or 2 x 10 oz. For the vee bottom seam, an additional 3 layers of 9 oz tapes. I'd use at least 10 inch wide tapes staggered about 1.5 inches. Same with the chines, three layers, but 6" tapes would do. For abrasion resistance, use Dynel. But it really soaks up the epoxy. You would do two layers of tape on all seams staggered 3 inches, then bog and fair, then the two drapes of glass cloth with overlapping seams along the centerline, bog and fair the centerline, and don't sand the bog all the way down to the glass where the last layer goes on. This is a sacrificial, and you want to be able to remove it. Then put the last layer of tape over all the seams. This boat will last 30 years in the tropics with minimal care.
     
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  4. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    Second Phil. Hard to disagree, but I will reinforce.

    2@6oz I have on a canoe and it would never do oyster beds well

    it is weak along the keel and should have had more glass tape and I only lake paddle onto rocky shores-once varnished, you can't go back

    some guys swear by graphite and epoxy neat coats for oyster beds
     
  5. bobbrown
    Joined: Jul 2021
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    Location: SE Georgia

    bobbrown New Member

    Thanks guys…..how about flat bottom? Look like beefier is better
     
  6. bobbrown
    Joined: Jul 2021
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    Location: SE Georgia

    bobbrown New Member

    Forgot….13’ skiff about 150 pounds.
     
  7. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    Re the flat bottom, I presume that you will have a keel along the centreline?
    Apart from helping with directional stability, and reducing the effect of winds on the beam wanting to blow you sideways, a keel would also be more likely to be the first point of contact with something on the sea bed.
    Although I appreciate that the side panels could be vulnerable - they could have some protection in the form of additional longitudinal keel strakes, one on each side, perhaps a couple of inches deep? They would also help to stiffen up the flat bottom, in addition to the internal framing.
     
  8. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    Back away from Phil's advice, but jist a bit.

    Add two tapes to chine and keel and aim for 20 oz of woven fabrics on bottom.
     
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  9. Tops
    Joined: Aug 2021
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    Location: Minnesota

    Tops Junior Member

    +1 to double layer everything and a little paint, to help with pinholes, cracking along seams, and UV degradation.

    I am learning this retroactively, the hard way, from single layer glassing and unpainted epoxy over budget plywood failing after a few years of weather on my 8-footer. Once the plywood starts wicking it is a rapid decline.
     
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