Given a water temperature at or around 54F the standard chart gives you an "Expected Time Before Exhaustion or Unconsciousness" of 1 to 2 hours and an "Expected Time of Survival" of 1 to 6 hours. :
http://www.seagrant.umn.edu/coastal_communities/hypothermiaThe range is 50F to 60F and 54F is certainly close to the lower end so it suggest both will end up on the low end of the range. Add in a degree of physical exhaustion, what seems to have caused the dunking, and those figures might be optimistic.
Then again our man wasn't completely unprotected so a bit longer makes sense. But, here again, he doesn't, by my eye, look overly plump and well insulated by fat. So that would suggest a figure more on the low side. Point being it is a hard call to make. I'm pretty sure even the same individual and identical conditions will vary in their survival times.
What scares me is that figure of one hour on the "Expected Time of Survival". As I read it that means that dead in an hour is not out of the question. An hour waiting for help is a long time. An hour left to live is always going to feel like too fleeting a moment.
If you have the time spend some time perusing that Seagrant site. Lots of good information. Things that bear repeating and being reminded of even if you have heard them before.
Another site with some interesting tidbits:
http://www.shipwrite.bc.ca/coldwater.htm
Previous Topic
Index
