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patching a new kevlar canoe

Jun 8, 2022
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Denver CO
this was the easiest patch job I've ever had with a canoe - it was brand new, and I talked to the builder about what he used to build the boat and what he prefers to patch with. No trawling through the historical forum posts to determine the best resin, which kind of composite to patch with..
It's Kevlar. John likes to patch on the outside with S-glass, on the inside with Kevlar. Resin is Raka thin with the slow hardener. I did get some of the fast hardener to take along on trips.

Boat is the SS model, number 22 made by Empty Canoes. The hull design is basically the old Dagger Caption royalex whitewater, usually paddled tandem but I liked to paddle mine solo for the big water trips. This SS is outfitted for solo too.

I borrowed it at the 2023 canoe slalom races at Washau WI and smashed it up but good..
me in trouble,
friend Jeff,
a tandem SS coming through the second drop,
jeff alyce 2.jpg

After all that it had a crack through the hull on the left side, and the nose stove in. The crack was patched with duct tape for the rest of the competition, the nose pushed back out and the builder applied a Kevlar patch inside as a stopgap stopleak. He has a rasp with a bent handle, purpose-made for roughing up the finish and exposing the Kevlar on the inside. Outside patches have the finish sanded lightly, not down to to the actual Kevlar.

Actually the hardest part of my repairs was getting that duct tape residue off, man what a mess.

Front patch with S-glass and peel-ply over the top to keep it roughly smooth. I should probably paint over as it looks a bit ragged, on the other hand I'll never see it while paddling..

ss patch.jpg

on the interior there were a number of cracks that had not broken the finish but were visible as stress lines. These got sanded with some aggressive sandpaper to get down to the raw Kevlar. There were 15 in all. I was in a hurry to get this done before it gets too cold to epoxy outdoors, went down and cut 15 patches of s-glass. After applying the first batch I thought, wait, I was supposed to be using Kevlar here.. oops. I'm fairly sure.. fairly.. the s-glass will be adequate. If not I know what to do at least.

ss sanded.jpg

I love to carry this boat as it weighs 40-some pounds, as opposed to the 70-some pounds of the old Dagger Caper I have (precursor to the Caption). But I love to paddle the Caper as it's bounced off many a rock in its long and happy life without needing any patching.
Slalom races are really hard on boats though, I don't expect to hit as many rocks as that in the rest of the boat's life. Says he hopefully.

This boat will be perfect for the class II-III North Platte run from CO to WY, a 3-day wilderness camping trip. With any luck we'll get the water to do it next year..
S fiberglass is a superior material to use for external patches as the edges of the patches can be feathered very smooth, it does not tend to "fuzz up" when abraded like aramid does, it has excellent strength in both compression and tension with a good tensile strength to weight ratio, and it takes up and binds to resin very well. Those same characteristics make it a good material for interior patches as well, and when fully wetted out with clear epoxy or resin, it is almost transparent.

I do agree that aramids like Kevlar are even better for interior patches if you don't mind the fact that they will be much more evident than fiberglass patches. Aramid has even better tensile strength and a better tensile strength to weight ratio than S fiberglass but it is not so strong in compression. That doesn't matter much for interior patches which are always subjected to tension when the outside of the hull is impacted. Aramid fibers do not bind to resins as well as fiberglass. While the fibers seldom actually break, they will tend to disassociate from the resin matrix when subjected to extreme tensile forces that would probably fracture fiberglass fibers.
Boat is the SS model, number 22 made by Empty Canoes.

Those Empty Canoes seem structurally similar to Millbrook whitewater canoes and are even more wildly aesthetic. The photos on the Facebook page are stunning.

We should probably have a thread dedicated to this manufacturer.
there are a lot of them at slalom Nationals these days..

the turtle boat,


John the builder in the bacon boat,