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The truth about cold water

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Re: The truth about cold water

#51

Post by SkyMarshal »

alex_stoddard wrote: post #47
cromulent wrote: post #35

Earlier quoted context omitted.

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.…

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.

Re: The truth about cold water

#52

Post by SkyMarshal »

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.

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?

Re: The truth about cold water

#53

Post by adolph »

avar wrote: post #45
deadmansshoes wrote: post #43

Earlier quoted context omitted.

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."

Re: The truth about cold water

#54

Post by avar »

SkyMarshal wrote: post #52
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.

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.

Re: The truth about cold water

#55

Post by avar »

adolph wrote: post #53
avar wrote: post #45

Earlier quoted context omitted.

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…

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.

Re: The truth about cold water

#56

Post by unofficial »

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!"

Re: The truth about cold water

#57

Post by deadmansshoes »

avar wrote: post #45
deadmansshoes wrote: post #43

Earlier quoted context omitted.

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.

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.

Re: The truth about cold water

#58

Post by Ixiaus »

gaius wrote: post #48
Alex3917 wrote: post #42

Earlier quoted context omitted.

"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…

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.

Re: The truth about cold water

#59

Post by code_duck »

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…

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.

Re: The truth about cold water

#60

Post by nas »

unofficial wrote: post #56

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
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