Wooden Boat Buidling: Working with Epoxy and Resin
Rule 1: Epoxy and Resin. Don’t overdo it!
Limiting your epoxy and resin use is the best way to ensure that you build a lightweight boat. Epoy is easy to overuse. Here’s how to ensure that you use only enough to seal and waterproof the wood and bind the fiberglass to the wood.
First, consider that if you overuse epoxy and resin (hereafter referred to as epoxy) – the most common error among first time boat builders – the fiberglass ends up floating on top of hull rather than adhering to it.
Second, not only does a too-thick layer of epoxy between fiberglass and wood add unnecessary weight, it compromises the strength and durability of your boat by lifting the fiberglass cloth away from the hull. You want your wooden hull to do its work of providing beauty and low weight; allow the epoxy and the fiberglass to do their work of providing strength and durability.
In short, as you apply epoxy to the fiberglass and hull, first wet out the hull with a squeegee or foam brush. Both tools drive the epoxy into the grain of the wood, sealing it. Then lay the fiberglass on top, which adheres the fiberglass to the hull. Then apply over the fiberglass with either foam brush, foam roller or autobody trowel just enough epoxy to render the fiberglass cloth transparent.
Finally, to ensure that the fiberglass lies in contact with the wood, dress the epoxy.
To dress epoxy, spread it over the fiberglass with an auto body applicator. In particular flatten and spread any epoxy pools which may have formed on flat surfaces.
Dressing saves weight, even more so when you apply the subsequent coats of epoxy wooden boat building requires come time to filling the weave of the fiberglass cloth. Take care to thin and smooth the second and third fill coats and you’ll be reward with both a lighter boat and a easily sanded surface come time to paint or varnish.
Any areas you can’t dress with the auto body applicator dress with a jabbing motion with the tip of a chip brush.
As you dress the epoxy, be to smooth and flatten any sags, drips, gobs, or ripples. You’ll reduce, again, not only weight but the amount of sanding come time to pain or varnish your hull.