Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The truth about cold water

gcaptain.com

Post reply on HN
Print view View original

41–50 of 62 posts

Re: The truth about cold water

#41

Post by avar »

ciupicri wrote: post #36
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 draggi…

Yes you should take your clothes off. They impede your movements and provide you with no insulation.

Re: The truth about cold water

#42

Post by Alex3917 »

gaius wrote: post #23
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…

The best way to warm someone up with hypothermia is for someone to get into a sleeping bag with them. I've done the sea survival training for offshore racecrew and it's the same: you're in your suit, wearing a lifejacket and harness, and attached to a jackstay. There are radio tags you can get now, about the size of a matchbox, you wear one and if it goes out of range of the basestation a MOB alarm goes off. Clever,…

"The best way to warm someone up with hypothermia is for someone to get into a sleeping bag with them."

Don't ever do this. The cold blood in their arms and legs will rush to their heart and kill them. You are supposed to leave them out in room temperature and wrap their core in blankets until the blood near their heart is able to reheat their limbs.

Re: The truth about cold water

#43

Post by deadmansshoes »

avar wrote: post #41
ciupicri wrote: post #36

Earlier quoted context omitted.

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 draggi…

Yes you should take your clothes off. They impede your movements and provide you with no insulation.

Are you sure about this? Surely they keep a layer of warmer water nearer your skin - the same way wet suits work.

Once someone is out the water wet clothing should be removed.

Re: The truth about cold water

#44

Post by stan_rogers »

ciupicri wrote: post #39
tomjen3 wrote: post #25

Earlier quoted context omitted.

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?

I believe he's referring to this: http://en.wikipedia.org/wiki/Nazi_human_experimentation

Much of that has been confirmed more recently by somewhat more humane (and more than somewhat more voluntary) experimentation by folks like Gordon Geisbrecht (U of Manitoba) and the Canadian Defence and Civil Institute of Environmental Medicine (DCIEM).

Re: The truth about cold water

#45

Post by avar »

deadmansshoes wrote: post #43
avar wrote: post #41

Earlier quoted context omitted.

Yes you should take your clothes off. They impede your movements and provide you with no insulation.

Are you sure about this? Surely they keep a layer of warmer water nearer your skin - the same way wet suits work. Once someone is out the water wet clothing should be removed.

Wetsuits are made of neophrene, they only work because neophrene is completely waterproof. That's not the case with a pair of jeans and a sweater.

New cold water will seep through much faster than your body can warm it. Even if you gained a fraction of a degree from tightly fitting clothes you'd lose much more than that through lack of mobility.

Re: The truth about cold water

#46

Post by pge »

A great rule of thumb I learned in Wilderness First Responder training: "1 minute, 10 minutes, an hour"

It's catchy and easy to remember, and it means: * 1 minute to deal with the panic response (i.e. first keep yourself alive for the first minute, you have plenty of time, and lots of people die quickly because of panic and inhalation.

* 10 minutes - that is roughly the amount of time you have to get yourself in a stable position before you lose motor control. Get yourself in a position with your head out of the water that doesnt require active support anyway you can - flotation, freezing yourself to an ice shelf, etc).

* 1 hour - that's how long you'll live (roughly) in 32F water. You may have a lot longer depending on water temp and your body.

There's a prof that did a lot of this research on his poor grad students (and you thought your thesis advisor was hard on you!). http://www.umanitoba.ca/faculties/kinrec/research/people/gie... He's the source for much of the recent research.

Re: The truth about cold water

#47

Post by alex_stoddard »

cromulent wrote: post #35
jedbrown wrote: post #31

Earlier quoted context omitted.

"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

It has been a long running debate which way viscosity would affect swimming. Higher velocity increases resistance to forward motion but also allows for more propulsive force from the swimmer - which will dominate?

It turns a research group at UMN actually was crazy enough to do the test - it looks like the effects balance for a human swimmer.

http://it.umn.edu/news/inventing/2004_Winter/goingforthegoo....

http://www.cems.umn.edu/research/cussler/pool/

Re: The truth about cold water

#48

Post by gaius »

Alex3917 wrote: post #42
gaius wrote: post #23

Earlier quoted context omitted.

The best way to warm someone up with hypothermia is for someone to get into a sleeping bag with them. I've done the sea survival training for offshore racecrew and it's the same: you're in your suit, wearing a lifejacket and harness, and attached to a jackstay. There are radio tags you can get now, about the size of a matchbox, you wear one and if it goes out of range of the basestation a MOB alarm goes off. Clever,…

"The best way to warm someone up with hypothermia is for someone to get into a sleeping bag with them." Don't ever do this. The cold blood in their arms and legs will rush to their heart and kill them. You are supposed to leave them out in room temperature and wrap their core in blankets until the blood near their heart is able to reheat their limbs.

On a racing yacht at sea there is no "room temperature"!! Ambient temperature inside the hull might be slightly warmer than the sea, but barely. You can't even go into a cabin and close the door, because there are no cabins and doors, there're berths above stowage compartments or in the sail locker.

Once you get cold and wet out there, you aren't going to get warm and dry again until the race is over and you're back on land, which might be days and hundreds of miles away. So we train for that. Similarly in our first aid, the "rules" on moving casualties are different. 'Cos you can't leave them on-deck...

Re: The truth about cold water

#50

Post by mahipal »

wallflower wrote: post #33
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…

But apparently she had been swimming for decades -- a lot of it in (progressively colder?) ocean water -- and she was studied "over the years." So it seems pretty possible that her physiological adaptations were a result of, not a cause of, all that cold-water swimming.
Post reply on HN