Originally Posted by Minnewaska
While I agree that immersion suits will substantially increase your life expectancy in water below body temp, the above is not correct. One will survive nearly a day in 80 degree water, but drops exponentially as water temp drops. 2hr survival is around the 50 degree mark, depending on conditions. Still the suit provides buoyancy, visibility and extended exposure even further.
If I'm going into 77 degree water in the middle of the ocean with no idea when I'll be rescued. I'll take the suit!!
Here's a USCG presentation on ditching and survival skills. Life expectancy is on page 12.
Note those survival times (as stated in the presentation) are in "good" conditions. At night with high winds, waves, and spray, the survival times should be reduced by quite a bit. Also the survival times as stated in the presentation should be reduced by 30% if you are not just floating motionless. In high seas you would probably be moving quite a bit just to get clear air.