I’m going to come right out and tell you something that almost no one in the maritime industry understands. That includes mariners, executives, managers, insurers, dock workers, for certain – fisherman, and even many (most) rescue professionals:

It is impossible to get hypothermic in cold water unless you are wearing flotation, because without flotation – you won’t live long enough to become hypothermic.

Despite the research, the experience, and all the data, I still hear “experts” touting – as wisdom – completely false information about cold water and what happens to people who get in it. With another season of really cold water approaching, I feel compelled to get these points across in a way that will change the way mariners behave out there on (or near) the water. What follows is the truth about cold water and cold water immersion. I know that you think you know all there is to know about hypothermia already (and maybe you do), but read ahead and see if you aren’t surprised by something. When the water is cold (say under 50 degrees F) there are significant physiological reactions that occur, in order, almost always.

You Can’t Breathe: The first is phase of cold water immersion is called the cold shock response: It is a stage of increased heart rate and blood pressure, uncontrolled gasping, and sometimes uncontrolled movement. Lasting anywhere from 30 seconds to a couple of minutes depending on a number of factors, the cold shock response can be deadly all by itself. In fact, of all the people who die in cold water, it is estimated that 20% die in the first two minutes. They drown, they panic, they take on water in that first uncontrolled gasp, if they have heart problems – the cold shock may trigger a heart attack. Surviving this stage is about getting your breathing under control, realizing that the stage will pass, and staying calm.

You Can’t Swim: One of the primary reasons given by recreational boaters when asked why they don’t wear a life jacket, is that they can swim. Listen up, Tarzan; I swam for a living for the better part of my adult life, and when the water is cold – none of us can swim for very long. The second stage of cold water immersion is called cold incapacitation. lacking adequate insulation your body will make its own. Long before your core temperature drops a degree, the veins in your extremities (those things you swim with) will constrict, you will lose your ability control your hands, and the muscles in your arms and legs will just flat out quit working well enough to keep you above water. Without some form of flotation, and in not more than 30 minutes, the best swimmer among us will drown – definitely – no way around it. Without ever experiencing a drop in core temperature (at all) over 50% of the people who die in cold water, die from drowning perpetuated by cold incapacitation.

(Read the entire article at gCaptain.com)