PD-
I do not have any personell experience in rafts and I do not have alot when it comes to being pinned on rocks and such but I have had a couple nasty experiences.

The Pac 900 because it sits so high in the water it slides right over rocks plus it has a very very low center of gravity so they are very difficult to tip. When I have rowed boulder gardens, I do not find it necassary to row around all the rocks. Many times I just give one hard push on the oars, hit the rock and spin off.

One time on the Upper Hoh, coming into the Upper Canyon, there is a very nasty short section where there is heavy brush against the one bank that has the good current and free of rocks while the the rest of it is littered with VW Bug sizes rocks. The drop into it is very steep yet shallow and has an incredible amount of flow.

Anyways, as I was coming down, I was planning the bst way to pick through the boulders. I was not paying attention to the oars and accidently lodged the right oar between two rocks. The boat spun broadsize to the current and totally pinned me against the oar with full current pushing against the left side of the boat. The left pontoon came completely out of the water and the boat pivoted around the oar almost 180 degrees and shot me into the run backwards.

After that experience, I realized these boats are incredibly difficult to tip especially considering they weigh around 50 pounds. The amount of current forced against that boat was incredible and if that boat was to of ever have tipped that would have been the time.