This boat is going to get wet and stay wet for days at a time. I plan to seal the interior with epoxy to give it at least some protection from the elements. My main concern was with the plywood. That is sealed well with the fiberglass cloth. The keel, gunnels, and ribs will be sealed by caulking the seams where they meet the plywood with thickened epoxy and coating the rest with unthickened epoxy.
I imagine a builder could use silicone caulk to seal the joints, but I’m using epoxy since it will last just as long as the rest of the boat.
Start with epoxy that is thickened like this.
Plop the epoxy into a 1 quart bag that has the corner nipped off. I use a smooth plastic scraper to move the epoxy into the corner of the bag with the hole.
Squeeze the bag to lay a bead of epoxy on your seams. You need to squirt that epoxy in a timely manner since 3 ounces of epoxy in such a thick blob could cook off pretty quick and it’s too expensive to waste.
I cut the edge of a scraper to make a custom scraper of a small radius to spread the epoxy evenly. These beads of epoxy will help prevent water from getting under the keel and the ribs. I applied thickened epoxy to the ribs prior to applying the plywood, so the underside of the ribs are protected.
Painting on the Epoxy
The plywood is already coated with fiberglass and the seams inside are caulked. Next, the rest of the interior is coated with epoxy that is applied with a chip brush. There’s nothing special about this and it’s pretty much a drudge task. However, timing is something to consider. If you brush epoxy on your caulk seams before they are cured enough, they could run. If you paint the epoxy on at just the right time, it may smooth out any rough areas along the caulk line.
It looks like I’m obtaining satisfactory coverage with two coats of epoxy. Some would advise more, but I own a well-used kayak that I built in 1996 that is doing just fine with two coats. Hopefully I’ll be too “smart” to duck hunt 20 years from now!
I’m not neat at this paint work. I got lots of epoxy on my sleeves and some on my pants. Here they are curing before I can bring them upstairs!
In the next installment, I’ll show how to keep the anchor pole holes from leaking through the hull.
-- Mark, Minnesota