-- Last Updated: Oct-31-12 7:55 PM EST --
Thanks for all the tips and war stories, folks.
After getting lots of good points of view from both the "repair it" and "it's toast" camps I've decided to give the repair a go. I did take some good whacks on the hull with a sledge hammer, which bounced off each time (thankfully!). I've decided it's worth repairing it and seeing what happens.
So far, I've beveled (using a dremel grinder and random orbit sander with 80-grit)the edges of the cut and put the first layer of epoxy on the inside to stabilize the hole. I peeled the wax paper off the first side after one day so I could add a second layer of GFlex to a few areas that didn't get enough the first time. I left the wax paper on the outside while I was doing the second coat. When I went to peel the wax off from the outside, much of was stuck to the epoxy that seeped through the cracks. I have had good luck peeling the wax paper away from GFlex in the past (and during this repair from the inside). I'm not sure what happened this time. I guess I'll have to sand it off because if I use a chisel, I'm afraid I'll take off to much of the GFlex that is doing what it's supposed to do.
Anyway, the repair is pretty solid so far. Now I plan to use more GFlex on the outside of the hull all along the crack to finish stabilizing the hull in preparation for the patches. I've ordered kevlar and s-glass material for the inside and outside patches, respectively.
I'll post more pictures once I do the patches. In the meantime, here are a few of the crack stabilizing GFlex process:
More tips are still welcome!