I was tubing once and wiped out so hard that hitting the water felt like I was hitting concrete. The side of my ribcage was actually bruised from the impact, and it knocked the wind out of me. Thank goodness for my life jacket!
I have experienced riding in a boat with some friends that capsized because there was so much movement that it became unbalanced. Luckily, we were all wearing life jackets and were still near the shore.
Wow, I know wiping out is tough. You bruised your ribs? That stinks! I've never really had any bad wipe-outs so far. You know just the occasional falling out of the boat or off the tube.
I don't think I've ever wiped out that badly. I am sort of afraid of water anyway so I'm not much of a daredevil in the water. I can swim, just not well, so I don't take many chances.