Hmmm I don't recall seeing many wooden, fibreglass or plastic rafts on the rugged parts of the Colorado River. Seems like they were neoprene-coated fabric - some over frames but most just inflated.

: I was on a canoe trip a few years ago with a man who had a very nice
: PVC-skinned double kayak. There were no true rapids on the trip, but in
: negotiating a bit of fast water between two sections of the river, he
: holed his boat on a rather innocuous bit of rock. He was able to apply a
: patch very quickly, as he had come prepared, but he admitted that his boat
: wasn't really meant for any kind of fast water.