LOL. They are tough but they are not indestructible. 12 oz nylon is probably the toughest fabric, it take a lot to damage it. But of course it has drawbacks but that is what I use if I have a boat that is going to see rough use.
Jack, in your case I would probably use the 12 oz. nylon from what you said. It takes a lot to puncture the skin but if you did, assuming it is something sharp it will cut it with ease. The good thing about nylon is it has a lot of stretch so it takes more to puncture it. If you do, pull it to the bank, pull out your emergency kit, dry it off and apply duct tape and off you go.
I have only damage one boat, I was running moving water, I hit something hard! It appear it pushed the skin up so far that it caught on one of the frames and the boat came to dead stop. I really thought it had broke a frame it stopped so hard. But instead it had pinched the skin and ripped it. My buddy was in a brand new plastic boat and he had some MAJOR gouges in his boat. We never did find what was in the water but it damaged both boats. Of course we shouldn't have been doing what we did but it was fun. :mrgreen: