Steinman said cold water can nullify the most powerful swimmers. And myths about cold-water survival pervade the public mind. Many folks cast into cold water, for example, don't get out for fear that the wind chill factor will make them colder. You could be naked on top of a capsized boat and have three to five times more chance of survival than by staying in the water. Swimming failure in cold water is more common than you expect.
Swimmers can drown in a minute.
Gasping underwater can cause drowning, hyperventilation makes it difficult to breathe and swim, while rocketing blood pressure can trigger heart attacks, he said. Cold-water survival, however, is one area where heavy folks have an advantage over slim ones. Fat is a natural wetsuit, a good insulator with good buoyancy. Leaner folks can compensate by wearing life vests and getting as much of their body above water as possible. And fat or thin, anyone can increase survival odds three to five times by getting even 20 percent of their body out of the water by clinging to floating objects, Steinman said.