Originally Posted by Limey Linda
... Sea anchor and drogue are different appications of the same piece of kit.
I'm not sure about that. A drogue would only need to be about the size of a big bucket but a sea anchor needs to be many feet across. Also, a drogue really needs to be fitted with a tripping line. Anyway, it's just imaginings, as Pete says, I would expect your rib to fill up as the first sizeable wave passed by then your boat would weigh about 5 tons. That would be fun.
I'm not sure about the flooding hull thing. In my canoe surfing days, a boat full of water was very unstable. In fact, if one got trounced and had to get out of the boat, it could then just be inverted to empty it using one hand.