On a slightly off topic note, I went on a similar ride in Wisconsin Dells (Wilderness), and right before the drop one of my friend's swimsuit bottoms was falling down. She only just got her hands back on the handles before we entered the bowl.
Look back on that ride, it had only four seats, and the bottom was not only a larger hole, but also didn't have that bottom layer. If it is just a matter of a bad tube design, that's easy enough (and relatively cheap, in comparison to other alternatives) to swap out.