I found another issue with the canoe. There is a strip of aluminum on top of the keel join, inside of the hull. This has a number of corrosion holes. I am assuming there is a layer of some sort of bedding compound underneath. I think water or salt water sat in the the boat and wicked into the joint. It looks to be a non structural issue, and I'd be surprised if it leaks from the out side. Because of the bedding compound I will not use a torch and brazing here, so Epoxy might be the best option. Of course I will probably just use concrete crack repair caulk, which as far as I can tell is grey 5200 at 1/3 the cost.
One bit of trivia I learned about working Aluminum, is that it oxidizes very quickly, as in seconds count, so what ever you want to to stick to it has to be applied immediately after cleaning/abrading the surface down to new metal. I've used west system acid etch for epoxy repairs on aluminum before, but didn't get a chance to see how they held up long term in a marine environment.