If you are canoeing with the wind at your back on still water, try taking along a golf umbrella (or any other large umbrella) and simply open it. Lay your paddle down or just use it as a canoe rudder. It makes an excellent sail when you are canoeing, and talk about a conversation piece with your fellow floaters!
Sometimes we need to exercise a little nonsense on our canoe trips! Umbrellas are also great for keeping the hot sun off of you.