The truth about cold water | Hacker News Reader

The truth about cold water

gcaptain.com

244 pointshelwr57 comments

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 hopeless. We spotted the lighthouse and started swimming towards it. Soon there was only the two of us left calling between us, but soon enough I stopped hearing any calls."

More amazingness: On his way to shore a ship came within 100m of him. He spoke to "múkki" an imagined sailor's friend on the way, told himself jokes and said some prayers. When he came to shore he had to hold onto a rock wall while waiting for the tide to recede. While walking he spotted a bathtub used for lifestock feeding he punched through a layer of ice to get drinking water.

Apparently he survived because he was fat.

http://books.google.com.au/books?id=rYIJJP7audkC&pg=PA26...

I can't find a citation for this now, but I recall reading somewhere that he had a higher ratio of brown fat than is normal. I.e. just being fat isn't enough, it has to be the right sort of fat.

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

However, a startling fact was discovered by the researchers from the University of Iceland: Guðlaugur’s fat is almost like seal fat. It is more solid and two or three times thicker than human fat.

"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/

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/

As as a swimmer, I know I'd much rather swim in cold water than warm, at least as far as pools go.

It's easier to maintain momentum and glide in cold water, whereas swimming in warm water feels like you're swimming in molasses.

Also, as my body heats up, cold water feels more cooling, obviously.

"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?

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/

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

What about after you're out of the cold water and on land? Take off the wet clothes and dry off naked, or leave them on for protection against wind chill? Or does it just depend on the wind chill and other circumstantial factors?

It depends entirely on what sort of clothes they are. Wool will insulate you even when soaked, but wearing a pair of wet jeans is worse than wearing nothing at all.

They don't provide insulation, and only serve to make you wet and extract heat from you. Just like a wet towel wrapped around a champaign bottle.

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.

Wetsuits are named wet because their operational concept depends the water they absorb. Maybe you intended to refer to a drysuit?

See: http://en.wikipedia.org/wiki/Wetsuit

". . .a thin layer of trapped water could be tolerated between the suit fabric and the skin, so long as insulation was present in the fabric in the form of trapped bubbles. In this case, the water would quickly reach skin temperature and the air in the fabric would continue to act as the thermal insulation to keep it that way. The suit did not need to be dry to be insulative."

No I meant a wetsuit. Wetsuits are completely waterproof aside from a select few entry points where water is allowed to seep through as you first get in the water.

The idea behind their operation is that you have a thin film of warm water around your body, isolated by a waterproof neophrene layer. So there's: The Sea -> neophrene -> Warm water that doesn't freely mix with the sea -> You.

That doesn't work (as deadmansshoes thought) if you're wearing normal clothes instead of a neophrene layer. In that case the water next to your body is constantly being replaced by new & cold water, faster than you can heat it up to provide you with insulation.

Both wetsuit and drysuits depend on there being a layer next to your body that you heat up. With wetsuits this is a layer of water that doesn't get swapped out, with drysuits it's a layer of air + rubber.

Do you have any links?

The article suggests you won't be able to swim so struggling to take your clothes off seems like very bad advice.

Several layers of clothes, and even a semi-waterproof jacket or anorak will trap water - and air which would help with bouyancy.

A fraction of a degree could be all important - there is a tipping point where a fraction means living or dying.

I live in Michigan's UP, and there was a sailor who fell out of one of the shipping boats... at night. Lake Superior is 40-45 degrees out there, at best. He swam to miles shore and managed to knock on the door of an elderly couple.

I'm impressed. That guy must be so fit.

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. Larger boats take at least an hour to turn around and at least 10-15 min for the rescue boat to hit the water. Then, only if your lucky, will they be able to find you as you bob in and out of view from the waves. All of this of course, relies on someone seeing you fall over in the first place. Never work on deck unless you are working with someone, have an immersion suit, or are attached by a safety chain.

Another problem arises when you are rescued as he points out, but the stories I have heard are about the survivors being put in showers to raise their body temperature back up and collapsing and drowning in a puddle of water in the shower.

The whole thing, on the other hand, seems fairly moot. It's like telling someone that when you get shot, it's not the bullet that kills you, it's the bleeding.

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 and Zed Shaw-like drama on HN, articles can be interestingly written without all that baggage. That someone such as yourself, who knows a lot about this, and someone like me who doesn't can both enjoy the article is a testament to the style.

[1]http://thelastpsychiatrist.com/2008/11/where_does_a_tree_get...

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

"Zed Shaw-like drama" :-)

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, but at night, in rough seas, making 10 kts, you're still in a LOT of trouble.

"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...

This is correct advice. Warming the person by hugging them inside of a sleeping bag is the best way to help. Now, rubbing them or massaging them is not a good idea because it does circulate the cold blood back to the core.

> Another problem arises when you are rescued as he points out, but the stories I have heard are about the survivors being put in showers to raise their body temperature back up and collapsing and drowning in a puddle of water in the shower.

This problem shouldn't even be a problem, you shouldn't leave them alone when they are recovering! Well, IMHO.

It's still a problem, because raising the body temperature quickly can be dangerous in itself. To preserve core temperature, the body centralizes circulation, i.e. circulates blood only through the vital organs. If you're warmed up suddenly, it can cause this centralization to end prematurely, mixing still-too-cold blood from your extremities with the core blood and dropping your core temperature suddenly and fatally.

I had something like this happen - except for the 'fatally' part of course.

I was in a canoe race on a cold spring day in cold water. At the beginning of the race I ended up jumping into the river in waste deep water. My jeans stayed wet the whole race. My legs were cold wet and immobile for over an hour while my upper body was 'working out' paddling the canoe.

All was good until the race ended. I got out of the canoe to walk the 1/2 mile back home. As soon as I started walking I felt the cold blood from my legs rush up to my torso & started seriously shivering. Continuing to walk made it worse. Made it home anyway & collapsed under a hot shower. I felt at the time that if I'd have tried to walk much further I'd have had a real bad day.

> mixing still-too-cold blood from your extremities with the core blood and dropping your core temperature suddenly and fatally.

Unlikely. there will be very little of that cold blood to mix. Very little. Adding heat will cause your core temperature rise. What is more likely to happen is that the sudden vasodilation drops your blood pressure, and your heart, possibly still in it's stunned cold state, can't compensate with stroke rate or variability. Then you risk cerebral hypoperfusion in the face of increasing metabolic demand (warm cells run faster, burn more glucose, need more oxygen to burn that glucose)

In maritime navigation class, we were taught that artificially heating a person who has been chilled down (that is, heating by giving them something warm to drink, putting them in a hot shower etc.) sometimes result in something very similar to a cold shock response, a sort of "hot shock response" known to cause severe after-effects and apparently even death.

Tests carried out by the Swedish Sea Rescue Society along with data from over one hundred years of recorded incidents, showed that the safest way to sustain a person suffering a cold shock or near hypothermia is to simply uncloth them (if soaked in water), blanket them lightly, and let their body heat itself up to normal temperature, utilizing the time in parallel to make sure heart rate and blood pressure stabilizes in calm tempo.

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.

Much of the knowledge we have about the effect of cold water on the human body comes from the Nazi's human experiments.

http://www.jewishvirtuallibrary.org/jsource/Judaism/naziexp....

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

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.

Some practitioners of meditation, in particular Tummo, claim that they can change their body temperature which allows them to withstand extreme cold:

http://www.news.harvard.edu/gazette/2002/04.18/09-tummo.html

The world record holder for ice immersion (1 hour, 44 minutes) is Wim Hof who describes himself as a Tummo master.

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

http://www.youtube.com/watch?v=BpKXE2lm4t0

I know a couple of Finns that have swum everyday for decades, no matter what the water temperature (eg through ice). They claim it builds up brown fat. Maybe the ratio of brown fat has something to do with it.

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

There is certainly an amazing amount of adaptation going on when you start swimming in cold water. Swimming short amounts of time (10 mins) in cold water can be done safely with proper training & supervision. You can definitely learn to control or reduce the initial cold shock reflex (gasping for breath).

A good complement to the recent drowning-related post. In fact, it's the "prequel". Worth a read, followed by a warm bath.

For reference, the original Drowning Doesn't Look Like Drowning post:

http://news.ycombinator.com/item?id=1492835

Indeed. Why does HN suddenly want to make me a lifeguard?

Because the media wants to make you an idiot where drowning and cold water are concerned.

The video Cold Water Boot Camp linked to at the end of the article strikes home the points very nicely.

Volunteers jump into cold water and demonstrate the 1-10-1 rule of cold water exposure.

  1  : Initial cold shock will last for about a minute
  10 : Physical incapacitation will occur after about 10 minutes
  1  : Unconsciousness from hypothermia in about 1 hour

http://www.youtube.com/watch?v=J1xohI3B4Uc

The author, USCG Rescue Swimmer Mario Vittone, is a nut. He once submerged himself in Lake Erie in the middle of winter to prove that it takes about an hour for your body to reach hypothermic levels.

After he did it I asked him "How did it go?"

He replied. "I survived, but it was close!"

Reminds me of Dr Popsicle: http://www.youtube.com/watch?v=nH29uzBvR1s

Well - it wasn't "that" close - but it was pretty darned chilly.

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?

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).

wear a wetsuit

You have to watch this TED talk where Lewis Pugh swam in the North Pole. It's fascinating. http://www.ted.com/talks/lewis_pugh_swims_the_north_pole.htm...

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