how many layers needed?

Fiberglassing over plywood and one-off fiberglass methods. See: "Boatbuilding Methods", in the left-hand column of the Home page.

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Denon Osterman
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how many layers needed?

Post by Denon Osterman »

im fiberglassing my tnt...but i dont really need it for abbrasion resistance, i just want a thin layer of epoxy to waterproof the whole hull, with a layer of fiberglass to stiffen it up a bit. my plan is to go
1. bare plywood
2. thin layer of epoxy
3. fiberglass cloth(anyone know how heavy it should be??)
4.thin layer of epoxy
5. paint

im sure theres somethign wrong with this plan of mine... anyone want to tell me what it is? if it IS in fact an ok idea, does anyone know how much epoxy/ epoxy ill need? as well, what weight of cloth should i use?

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Graham Knight
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Post by Graham Knight »

The fibreglass will hardly stiffen it at all, even if you use quite a heavy cloth, weight for weight thicker plywood is much more effective.
7oz - 10oz cloth is typical depending on what's available.
Graham in Shepperton, England

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DanH
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Post by DanH »

The fiberglass cloth will add puncture resistance to the hull surface. I think it is worth doing.

John K
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Post by John K »

I know that a lot of people use 6 oz or better cloth, and that is what I use to use. I have gone to 4 oz. It shapes easier and takes less epoxy to fill. The strenght of the boat is really in the plywood, so the fiberglass is a sealing and protective layer only.

If you are using it to cover the deck where you may want the deck wood to show, the 4 oz also is clearly - again easier to fill, so the weave does not show.

Denon Osterman
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Post by Denon Osterman »

the lake i run in is very deep, has no "obstales", i wont be trailering it, and its never very wavy so banging the dock wont be a problem. the only real reason i wanted to fiberglass the hull was to waterproof it, but nowthat i think about it...couldn't i just cover the hull in a few layers of epoxy?

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Graham Knight
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Post by Graham Knight »

Yes you can, but just as with paint, cracks will eventually appear as the wood moves, a sheathing of glass/epoxy has more integrity than a coat of paint or resin, if nothing else it will reduce maintenance.
Graham in Shepperton, England

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capt jake
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Post by capt jake »

Epoxy by itself can be brittle. It flexes a bit but you will relieve the streses by using epoxy with a cloth. The cloth will spread out any stresses that are created. The cloth also enables you to get a thicker layer of epoxy on the hull, increasing the effectiveness of its waterproofing capability.

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