Vettpaddler, the photo of the damage to your canoe brought back a strong memory of a sailboat I once had, years ago.
The Cal 21 was a 1960s era MORC racer. They were built light. They were also built very quickly, I think. The gelcoat would sometimes ‘cave-in’. It was as if during the squeegee stage of the building process they didn’t get all the bubbles out of the laminate. My particular boat must have had a lot of bubbles.
There was no way to correct for that deficiency after the layup was done. Once the resin sets, that’s the way things stay.
That Cal 21 sailed like a ‘witch’. I loved that good old boat. And I also learned to love Marine Tex (for that good old boat). Because it put me back on the water instead of in the storage yard waiting for gelcoat to cure.
Paddle-on.