: Of course! How did I overlook that?

I use a 13½ foot Cheap Canoe for running shallow rivers. The rocker is about perfect for dodging rocks on mild rapids and the plywood is capable of ricocheting off rocks or dragging bottom with minimal damage. But the bottom does get gouged from contacting submerged rocks on the rapids. I eventually glassed it to make maintainence easier.
With a skin-boat in similar circumstances the question will be can the hull covering survive. I had an old Folbot that could withstand a lot but it was covered with 2 layers of heavy vinyl covered cloth. The skin weighed as much as the frame. You're really going to put that nylon to the test if you hit something submerged when the current has a grip on your boat in a fast section.