Light cloth vs 3 coats epoxy

[54bullwinkle]

Getting ready to start my ECO 18 build 

For non structural waterproofing can one epoxy coat with 4 oz cloth substitute for 3 coats of epoxy?
Thinking of using it on non structural applications ( under deck, frames, under gunnels, ) for waterproofing in addition to 10 oz cloth where needed.  

[Captain Tim]

Three thin coats of epoxy might be less epoxy than what you would need to wet out the cloth.

Three coats of epoxy would have a better chance of full coverage with no voids

[54bullwinkle]

Gotcha.  Thanks

[Alan Stewart]

I wouldn't bother if it's going to get 10oz over it later but I am a fan of putting down 4oz on something if i need to finish it quickly but you still usually need a "fill coat" on top of the glass if you want it smooth. If you put too much epoxy then the glass just floats and you still get the weave. I find the best is to do a heavy coat on the bare wood and put the 4oz glass down and let it soak up the epoxy and let that set up then a few hours later come back and coat that again as a fill coat. OR use peel ply over the 4oz then it's a 1 step and done. It is heavier than 3 coats though. If the parts are flat on the table though you can just do a heavy flood coat but it's hard to know how much there is and easy to use a LOT. Sand the ply smooth with 220 before you coat if you want to try to do a one step flood coat for best finish else you could still get some wood grain/fuzz rough texture on it. 

 

 

[54bullwinkle]

Thanks Alan

[Andy B]

Forgive the possible stupidity, but can someone explain some of these areas need epoxy?  I'm thinking under the gunwales, seats, even the deck.  It seems to me they get wet so little that primer and paint, or varnish, would be enough.  What is the deciding criteria for whether epoxy is needed or not?

[Alan Stewart]

Epoxy always needed on everything everywhere. That's the best method. The epoxy is a barrier to moisture. Moisture makes wood shrink and swell. Shrinking and swelling causes cracks. Cracks let in more moisture. Full epoxy encapsulation of all wood is the best most long lived way. Okoume plywood is not very rot resistant at all. If it's wet it will rot in a couple seasons. The Gougeon Brothers built the adagio Trimaran in 1969 and she's still going strong. All epoxy and plywood bonded and i'm sure every bit is coated in epoxy.