When I was involved in the boating incident were a perspective buyer was diving I was knocked out and buy only the grace of God did I end up still in the boat. The driver was ejected. Neither of us were wearing PFD's he was safed as well buy a couple of quick thinking guys in a Ranger who cut their lines because they seen what was about to happen. That person was still conscious but to my later surprise I found out he could not swim.
Needless to say I 've become an advocate for wearing a PFD ,Always make your passengers wear them as well. I never seen what hit us or what we hit I should say. I also am a good swimmer, but that doesn't help if your unconscious. (better save than soggy !)
MY 2 CENTS
Mark