Yesterday for the first time I turned my canoe over, then I tried to get back in it. I have been thinking about adding a sail to my canoesail to my canoe and now that I know a bit about sailing, I know I need to plan on being able to right the sailing canoe and get back in it. So I took the canoe to the lake to practice self recovery (solo) with just an empty canoe.
I have a 17 foot two person plastic canoe as seen in my answers to this questionas seen in my answers to this question it has built in flotation at both ends. With the canoe empty, just me in a life jacket and a wood paddle. It turns out will float the canoe just barely if the canoe is full of water it floats until I get in. The flotation will not support me and the canoe, I was sitting in the canoe floating by my life jacket with the canoe 2 feet under the surface. When I get out it surfaces with the sides just breaking the surface.
There is a cool video of a guy doing solo recovery at Solway Dory, but he is in a smaller lighter canoe, I think he is wearing a dry suit, and he has added side flotation. I watched that video before going to the lake to try it myself.
Real life me and my canoe (big & heavy). I can't throw it and have it land empty! (no surprise) Best I can do is turn it over slowly which results in it being half full of water when right side up. I was not able to get back in without filling it the rest of the way with water.
Later I took the canoe to shore emptied it and a couple of attempts to get back in the canoe when it did not have water in it. By this point I was tired, and could not make it happen. I know it is possible, but it is difficult, if I could not do it in warm water while a bit tired, I don't want to bet my life on it in other scenarios. In sailing class I was easy able to get in a Sunfish without difficult, but that is a very different boat.
When people take canoes white water rafting they add A LOT of flotation (image below), essentially the canoe is all flotation except room for one person. At that point you might as well get a kayak, what is the point of the canoe? All it holds is you and flotation.
So I want to add some flotation, at least enough so that I can get in over the side as long as I have enough strength to turn it back over. Optimally enough so if I am caring my normal loadmy normal load or if I have a sail I can get it upright and get in. I don't want to fill it with float bags. The point of a canoe is that you can put a lot in it.
How do I decide out how much flotation I need, and where it needs to be?