drysuit alone
Actually a drysuit used alone will only keep you dry while you freeze to death. Has zero insulation value by itself. It does keep the insulation dry so it can work.
Bill H.
We aren’t talking about hypothermia.
We’re talking about the cold water or gasp reflex. And I don’t know what community you are in, but the whitewater community doesn’t lose several to hypothermia each year, and I doubt that the community of serious canoeists loses that many, either. We weren’t losing that many even in the 70s.
Individual differences
I suspect susceptibility to the gasp reflex does vary from person to person, as does susceptibility to hypothermia in general.
I know that my susceptibility to debilitation to cold has become greater with age, and I have heard some others say the same.
For my part, I never experienced a tendency to want to gasp upon immersion in cold water in water temperatures in the 50s or even the 40s, but I did when it dropped into the 30s.
I don’t think too many whitewater boaters die of pure immersion hypothermia because the bank is always relatively close by. I have, however, seen even young paddlers shivering uncontrollably for quite a few minutes after a long swim in cold water. And I strongly suspect that the weakening effect of hypothermia plays a roll in some of the flush drownings seen on some of the big, cold water, western rivers like the Colorado.
The reason I was in cold water for about
– Last Updated: Oct-30-10 1:04 PM EST –
8 minutes (surfacing to breathe occasionally) was that I had to swim to the bottom of a just-opened swimming pool in April to unscrew plugs in the filter lines. Water temp was in the 40s. I don't recall having hand control problems during or after I did the work. I certainly shivered for quite a while afterward. I think mental preparation helped with both absence of gasp and with keeping my hands working.
I've had to roll in winter water, and in the earlier days I did not have a drysuit, so it was more than head immersion.
By the way, I have had self-terminating ("paroxysmal") atrial fibrillation episodes since I was 19, but never after cold water immersion. Causes of fibrillation episodes are very individual.
It does depend on the person
I was not going to chime in on thos post since the Op was looking for data, which I don’t have, but since you mentioned it, I’ll relate some of my experience on several different trips to Alaska.
The first was in Glacier Bay while we were kayak camping.
I decided to take a dip in Icy Straight just to see what it was like.
I knew if I tried to walk into the 39 degree water, I would never do it, so after sheading all but a bathing suit, I ran in and dove… It was shockingly cold, but I did not experience any “gasp reflex”.
Other than the cold temperature the only problem I had was making the mistake of opening my eyes underwater, and they hurt a lot, and when I came out, I had an ice cream head ache.
Then again on another trip to the Arctic circle and the Noatak river, at the end of each day, when others were taking a sponge bath with heated water, I would run into the river to bath. cold; -Yes, but absolutely no problem.
Jack L
not sure what you are asking
big difference between 40 and 50 degress, huge difference in responses depending on the person and their energy level at time of immersion. If a person is concerned with immersion then they have to take care of the head and hands as a warm core will only last longer to experience the situation presented by diminished capacity for self-rescue if head/hands are compromised.