Airplane wings are designed to stall in particular areas first. I guess these foils are rather small for that.
If the horizontal surface cavitated, would the problem be limited to that area? Would it be possible for that to immediately ventilate the rest of the foil?
I don't know if it is a design thing or it is just the way it happens, but many aircraft wings will stall at the wing root first hence the areolons being outboard to still have authority to control the aircraft.
