Reglassing 50' cat hull bottoms - overhead?!

Discussion in 'Fiberglass and Composite Boat Building' started by tevake118, Mar 18, 2023 at 10:41 PM.

  1. tevake118
    Joined: Jan 2013
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    Location: Goodland, Fl.

    tevake118 Junior Member

    Hi, Yes I am going to have to apply 3 layers of 17 oz biax/epoxy to the entire underwater area of my composite one-off, hard-chine cat after haul-out.
    I have many years of wood- fiberglass construction experience, but NOT fiberglassing against gravity. I have done a smaller portion a few years ago, when I applied 3 wetted-out coats over each other, but there were some delamination spots.
    This time, together with 2 helpers, after thorough sanding of the original surface, 1) wetting out a 50"+ width of one hull side, and overlapping the small keel rub strip, 2) wet out a suitable biax first layer on a piece of peelply, over a sheet of Visqueen, 3) wait for the two mating surfaces to get gelled over, 4) using 6 hands lift the 'sandwich' into place, while it can still be adjusted into gapless skin, 5) after epoxy hard remove peel ply, 6) repeat for 2nd and 3rd, final layers, 7) continue by overlapping down the hull and over onto the other side. Estimated time, daily 2 hrs, for a month.
    I have used in the past about 250 gal of laminating epoxy, and about 3 rolls of biax...
  2. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    This sounds like a major project for sure!
    But you certainly have the experience for it, not to mention the enthusiasm.
    Please do keep us updated (carry on with this thread?) re your progress over that month of work - and everybody loves to see photos as well of boatbuilding and repair projects, so please do post some to show your progress.
  3. kapnD
    Joined: Jan 2003
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    Location: hawaii, usa

    kapnD Senior Member

    You are very brave (or?) to even attempt that. Have you considered vacuum infusion?
    wet feet and bajansailor like this.
  4. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell . . . . .

    Good thing it's not a tri.

    Wouldn't this be a great application for vacuum bagging?
    I've never used it, and it seems like a real hassle, but worth it in this case.
    Or even inflating air-bags under the hull to press the e-fiber.
    bajansailor likes this.
  5. wet feet
    Joined: Nov 2004
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    wet feet Senior Member

    I share those thoughts, but would suggest a small practice area first. Or even a simulated hull section. I would not be keen to try such a major project as a first attempt at infusion without gaining a little experience. Which should make it at least bearable, even if the subsequent fairing and finishing is arduous and messy. The end result may justify all the effort.
    bajansailor likes this.

  6. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    I am sorry, but this is a terrible idea, with a capital T.

    17 oz biax I have about ?50 yards experience and it is really your friend with gravity and contours, but a horrible enemy on vertical or upside down is snaky and two sided wetout means it can't go on dry.

    I have done a lot of wet bagging, never upside down and would not bother.

    This job is made for infusion all the way.

    You can layup all the laminates with spray glues, bag it, test the bag, and pull the job. No snaky biax errors need to end up in the final, and 6 hands will not be enough and cost way too many days.

    If you insist on handwork, I can tell you how. You make jigs of the bottom, cover them in ship tape and lift them to hold the dry then wet snakes in place, but it is a nightmare. You may need some of these jigs to hold the glass even prepping for infusion. Making the jigs will also be hard to do..but if you use mold wax and partall; it can be done with 1708x4 pieces, they need not be real wide 6"? and it may cure your dreams of laying up 1700 upside down.

    Another idea is 1700x3= 5100, two layers of 1708 = 5000 and hardly likely you gain much one versus the other, 1708 will hold its shape. Neither fabric will wet upside down and through, so the problem is the substrate needs a lot of resin which makes it a greasy mess.

    There are other, wiser contributors here than me, but I have done enough to tell you the plan is bad. The glass will not cooperate and you'd need like 15 hands.

    I wonder if @ondarvr or @rxcomposite have seen these attempts.

    But the idea you propose is terrifying and I have 300 gallons epoxy work as well.

    Another issue is biax may not be best.. the problem is wetting cannot be done through glass stuck on. If you used a different glass, you might be able to spray and stick the glass on alone and then roll it on while it drips all over you. Yuk.

    Infusion is your friend, please believe me.
    bajansailor likes this.
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