This CAN happen!  This Souris River Wilderness 18 in kevlar was whapped into something so hard (flew off a canoe rack when some clueless individual didn't bother tying this 46 lb. canoe down) there was a big dent in one gunwale and a 14" stress mark in the side. The crack you see below did not leak a drop and the canoe actually went out on a 7 day canoe trip in the stressed condition which is way more than you can expect to see in other non-flexing, foam-core kevlars made with vinylester resin. The majority of name-brand, non-epoxy-resin canoes would have been unusable-until-repaired with this damage.  Nonetheless, this Souris River did need to be repaired to prevent further fiber breakdown in the future so here's how I did it using West System Epoxy resin that we sell here at Red Rock.  This is how you would repair most cloth-layup canoes with cracks or punctures as well, only you would need to apply the same patch on the inside (minus the plastic wrap).

1. Sand area of crack with 80 grit sand paper.	2. Cut a piece of kevlar to cover the cracked region.
3. Further refine your cut if desired to fit repair area.	4. Mix up some epoxy resin and apply with disposable brush evenly over entire patch area.
5. Stick on pre-cut patch. Make sure you center it over the damage.	6. Apply manageable amount of resin to patch.
7. Use a squeegee to wet the cloth completely with resin.	Be careful at the edges of the kevlar cloth because it likes to fray.
8. Cover patch with plastic wrap and stretch it tight with tape.	9. Roll out all the air bubbles by forcing them to the edge of the plastic with a little wallpaper roller. Let it sit to cure.
After 5+ hours, peel off the plastic. Wait'll tomorrow before putting it on the water. This patch turned out well with smooth "ramps" of resin along the edge of the patch, minimizing resistance in the water, or more importantly, obstacles such as rocks, etc.