Well, this certainly contradicts part of my thinking. Thanks.
(I always hike with a large black plastic trash bag. Curl up in that and you can be warm anywhere. On the water, the bag would have to be a lot thicker and maybe connected to a inflatable ring).
Coast Guard advice is based on a lot of experience--most of which I'd like to know about but not experience.

Swimming to shore is another matter.

I once attended a teacher training session. It was about group decision making
The groups were to decide the order of importance items to be taken into life rafts in the Southern Pacific 1000 miles from land.
At the end she announced that 'according to NASA' the most important item was 5 gallons of gasoline, next was matches.

I asked NASA, really?
Well, no.
Why Gasoline? To make a signal fire on the water, while we wait in a rubber raft.... Funny I can't remember reading any life boat survival stories about teacher trainers......

: From USCG RESCUE AND SURVIVAL SYSTEMS MANUAL, pg 2-23:
: "Contrary to popular belief, the survivor should not swim
: around in efforts to keep warm. This will only increase the rate
: of heat loss and speed the onset of hypothermia."
: http://www.uscg.mil/directives/cim/10000-10999/cim_10470_10f.pdf

: Though a lot of the USCG manual pertains to liferaft conditions, it
: does make for an interesting read........