Originally Posted by panicman
I don't think I would stick by that 100 stuff. 50 water and 55 air is still cold for a swim and I bet hypo potential. add some clouds and that ratio becomes much colder.
That's "hypothermia zone" stuff. Under "100", immersion protection is a "must".
Cold water is cold water if you can't quickly get out of it. Your fingers get numb, you lose your breath, and you get tired fast....a self-rescue is a lot harder even if you're not hypothermic. Avatard's "130 total" would be a lot more reasonable--or even 120. Above that, a dunk is less of a big deal and hydraulics--not cold--would be your primary concern.
I'd suggest that from 100-120, it's not a "must", but it's still a good idea.