Does it flex at all there? I'm not sure of what's on the inside at that spot, but I would repair a crack with a layer or 2 of the same fabric that's on the inside, kevlar or that hybrid fabric. You can buy similar fabric, probably the exact same stuff from the manufacturer of your canoe. They probably have piles of scraps. If you have a foam core there on the inside, then your repair will have to be on the outside. In both instances, you may want to patch it with glass on the outside to make it less visible. I'm sure the people who made that canoe have a good answer on exactly what to use.
Mark