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The truth about cold water

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Re: The truth about cold water

#31

Post by jedbrown »

cromulent wrote: post #24
jokull wrote: post #17

There's an Icelandic legend that beat all this crap in 1984. His ship sank with all his friends and co-workers. He swam to shore, walked bare feet on razor sharp lava and walked to town. Guðlaugur Friðþórsson. His descriptions are chilling. "When the ship sank from underneath us and we were submerged for the second time we decided [the three of us] to swim. We decided not to help each other which would have been hope…

Apparently he survived because he was fat. http://books.google.com.au/books?id=rYIJJP7audkC&pg=PA26...

"cold water is highly viscous and impedes swimming"

This is very size and speed dependent, but increased viscosity delays separation and can actually reduce drag [1], [2]. In any case, the viscosity difference is not huge and water temperature is normally not precisely controlled for swimming events.

"Most people [...] suffer from vasodilation in extreme cold."

Only when the core is doing well [3], the opposite (vasoconstriction) occurs otherwise.

[1] http://jeb.biologists.org/cgi/content/abstract/204/1/81

[2] http://www3.interscience.wiley.com/journal/120798746/abstrac...

[3] http://www.springerlink.com/content/l776704k04017q43/

Re: The truth about cold water

#33

Post by wallflower »

lkozma wrote: post #11

I wonder if people who have training with cold water resist significantly longer. I knew Finns who would go in mid January to swim for ten minutes in a hole cut in the ice of a frozen lake, then sit around for a while, dress up and go on with their day. And that was without sauna.

Lynne Cox, the only person to have swum a mile in Antarctic waters and to swim the Bering Strait.

"Dangerous marine animals aside, the [Gulf of 'Aqaba] swim was among Cox's most physically challenging. A battery of scientific studies done on Cox over the years has revealed some startling facts about her physiology. First, the muscle and fat in her body are so perfectly balanced that she has neutral buoyancy, meaning that she neither sinks in water nor floats. As one researcher told her, "You're at one with the water" - a critical energy-saving advantage during long-distance swims.

More remarkable, however, was the discovery that Cox's body is superbly adapted to cold temperatures. On entering cold water, a person's surface blood vessels constrict, forcing warm blood to the vital organs at the body's core. Normally, however, this is a stopgap that works for only a short time. By contrast, Cox's vital organs are insulated by an evenly distributed layer of insulating fat. Warm blood shunted to her core remains warm dramatically longer. So effective is this "internal wet suit," that Cox's temperature actually rises during a hard swim in cold water."

http://en.wikipedia.org/wiki/Lynne_Cox

Re: The truth about cold water

#34

Post by jokull »

avar wrote: post #26
jokull wrote: post #17

There's an Icelandic legend that beat all this crap in 1984. His ship sank with all his friends and co-workers. He swam to shore, walked bare feet on razor sharp lava and walked to town. Guðlaugur Friðþórsson. His descriptions are chilling. "When the ship sank from underneath us and we were submerged for the second time we decided [the three of us] to swim. We decided not to help each other which would have been hope…

"Múkki" isn't an imagined sailor's friend. It's the Northern Fulmar, an abundant sea bird. He was talking to the birds he saw overhead to pass the time.

Thanks for correcting me. Hvernig datt mér þetta í hug?

Re: The truth about cold water

#35

Post by cromulent »

jedbrown wrote: post #31
cromulent wrote: post #24

Earlier quoted context omitted.

Apparently he survived because he was fat. http://books.google.com.au/books?id=rYIJJP7audkC&pg=PA26...

"cold water is highly viscous and impedes swimming" This is very size and speed dependent, but increased viscosity delays separation and can actually reduce drag [1], [2]. In any case, the viscosity difference is not huge and water temperature is normally not precisely controlled for swimming events. "Most people [...] suffer from vasodilation in extreme cold." Only when the core is doing well [3], the opposite (vaso…

The Mythbusters checked the increased viscosity myth (opposite presumption, same speed is possible) and found it plausible.

http://mythbustersresults.com/swimming-in-syrup

Re: The truth about cold water

#36

Post by ciupicri »

jokull wrote: post #17

There's an Icelandic legend that beat all this crap in 1984. His ship sank with all his friends and co-workers. He swam to shore, walked bare feet on razor sharp lava and walked to town. Guðlaugur Friðþórsson. His descriptions are chilling. "When the ship sank from underneath us and we were submerged for the second time we decided [the three of us] to swim. We decided not to help each other which would have been hope…

Guðlaugur was dressed in jeans, shirt and sweater, with nothing on his feet. He did not know that wet clothes draw heat from the body 20 times faster than dry ones. [1]

I'm curious what should I do if I fall into cold water: should I really take my clothes off or not? The first option sounds a bit counter intuitive to me.

By the way, how can people swim in jeans or other clothes? I find it very hard, it's like dragging some weights.

[1] http://www.vikingrune.com/2009/03/true-viking-grit/

Re: The truth about cold water

#37

Post by ra »

drats wrote: post #10
TGJ wrote: post #4

A very good article that shows some perceived misconceptions about cold water survival. I spent 4 years on 20 different large marine seismic exploration boats with most of them operating in the North Sea. I have taken 3 North Sea Survival courses and a many safety meetings for good measure. Every person that I have worked with has been well aware of the consequences of falling overboard in water barely above freezing…

I particularly like the tone in "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" given that someone actually downvoted me when I took exception to the line "whatever you just said, it's wrong" in the "Where Does A Tree Get Its Mass?" article[1] when it was posted to HN. There is no need for all the hyperbole…

"Zed Shaw-like drama" :-)

Re: The truth about cold water

#39

Post by ciupicri »

tomjen3 wrote: post #25
pclark wrote: post #18

So the advice to survive in cold water: wear a life jacket?

Absolutely (though it may not be enough), but not just for the reasons you think: a life jacket will keep the back of your head out of the water - which will help prevent damage to the brain. You don't want to know where this research comes from, believe me.

Maybe he doesn't want to know, but I'm curious.

P.S. I'm also curious about what kind of damage can occur to the brain and from what exactly?

Re: The truth about cold water

#40

Post by drats »

ErrantX wrote: post #13
drats wrote: post #10

Earlier quoted context omitted.

I particularly like the tone in "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" given that someone actually downvoted me when I took exception to the line "whatever you just said, it's wrong" in the "Where Does A Tree Get Its Mass?" article[1] when it was posted to HN. There is no need for all the hyperbole…

You should have read on; it was just an attention grabber :)

I don't want to offend anyone but that article was extremely boring (I did end up reading it). I suppose I'd seen the Richard Feynman video on fire and trees quite recently beforehand and was in an intolerant mood. But it's impossible to stay in any kind of negative mood if you watch Feynman, his love of knowledge is just infectious.

http://www.youtube.com/watch?v=N1pIYI5JQLE

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