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Old 26-11-2015, 16:04   #46
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Re: If go overboard, how can one keep still in cold water?

Pioneering research by Drs Michael Tipton and Frank Golden in the United Kingdom, and by Canadians Drs Chris Brooks and Gordon Giesbrecht (among others) has painted a very clear picture.

Cold Shock
On falling into cold water, cold receptors in the skin cause immediate physiological responses, the first of which is a “gasp” reflex. If this happens when your head is under water, you are in deep trouble.
Next, you begin to hyperventilate, within seconds, your heart begins to race, and your blood pressure spikes. Hyperventilation may make it difficult to get air into your lungs, leading to panic and further hyperventilation.
These symptoms can trigger cardiac arrest in susceptible individuals. Even healthy individuals will have difficulty keeping their airways above water without a flotation aid while undergoing these major physiological stresses.
The effects of cold shock normally peak within the first minute and stabilize very soon thereafter.
Cold Incapacity
After a few minutes, the muscles of your limbs are affected. Neuromuscular activity slows and body fluids literally congeal in the muscles.
You feel the effects first in your hands and fingers. Then the deeper tissues in your arms and legs cease to operate properly. It becomes more and more difficult to perform any tasks requiring manual dexterity, such as using flares or other survival equipment.
Survivors have reported that after a few minutes it was impossible to open a package of flares or to tie a knot in a line.
After ten minutes immersion in very cold water, your arms and legs will no longer respond to your will. Even experienced swimmers have difficulty co-ordinating breathing and swimming strokes; short swims may be impossible.
In heavy weather you have difficulty keeping your face out of the spray and you may not be able to avoid inhaling water.
You will certainly have difficulty keeping your airway above the water without the assistance of a flotation aid.
During these two periods, the major risk of death is from drowning, caused by the body’s reaction to cold water. Any water less than 15o C (59o F) will trigger these physical reactions, though the colder the water, the more severe the response. Some experts suggest that if you are in water that is warm enough not to trigger these physiological reactions, then your biggest problem will be shark attack instead. Cheers
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Old 26-11-2015, 16:29   #47
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Re: If go overboard, how can one keep still in cold water?

Quote:
Originally Posted by OBXSkipper View Post
Pioneering research by Drs Michael Tipton and Frank Golden in the United Kingdom, and by Canadians Drs Chris Brooks and Gordon Giesbrecht (among others) has painted a very clear picture.

Cold Shock
On falling into cold water, cold receptors in the skin cause immediate physiological responses, the first of which is a “gasp” reflex. If this happens when your head is under water, you are in deep trouble.
Next, you begin to hyperventilate, within seconds, your heart begins to race, and your blood pressure spikes. Hyperventilation may make it difficult to get air into your lungs, leading to panic and further hyperventilation.
These symptoms can trigger cardiac arrest in susceptible individuals. Even healthy individuals will have difficulty keeping their airways above water without a flotation aid while undergoing these major physiological stresses.
The effects of cold shock normally peak within the first minute and stabilize very soon thereafter.
Cold Incapacity
After a few minutes, the muscles of your limbs are affected. Neuromuscular activity slows and body fluids literally congeal in the muscles.
You feel the effects first in your hands and fingers. Then the deeper tissues in your arms and legs cease to operate properly. It becomes more and more difficult to perform any tasks requiring manual dexterity, such as using flares or other survival equipment.
Survivors have reported that after a few minutes it was impossible to open a package of flares or to tie a knot in a line.
After ten minutes immersion in very cold water, your arms and legs will no longer respond to your will. Even experienced swimmers have difficulty co-ordinating breathing and swimming strokes; short swims may be impossible.
In heavy weather you have difficulty keeping your face out of the spray and you may not be able to avoid inhaling water.
You will certainly have difficulty keeping your airway above the water without the assistance of a flotation aid.
During these two periods, the major risk of death is from drowning, caused by the body’s reaction to cold water. Any water less than 15o C (59o F) will trigger these physical reactions, though the colder the water, the more severe the response. Some experts suggest that if you are in water that is warm enough not to trigger these physiological reactions, then your biggest problem will be shark attack instead. Cheers
I think that is junk science. I can recall deciding to swim to a beach on lake Champlain from Pops boat docked at Essex NY. I believe the water wasn't much over 40. I was one stroking 8 yr. old. Obviously I didn't suffer cardiac arrest. I was shivering walking back down the dock to the boat.
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Old 26-11-2015, 16:44   #48
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Re: If go overboard, how can one keep still in cold water?

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The straps are rated to keep the PFD on in the water. They are NOT rated for the impact force of a fall on a tether or recovery. Just ask them (I did, researching for an article). They would have to be 5000-pound rated. Which would hurt.
Just ask who?

5000 Pound is 5 tons we are talking sailors and not elephants arn't we?

You are partially correct, but PFD's with built in harness's are made for both recovery and falls to a Standard. I just think it's odd that whilst some of the pfd's that can be purchased with 'crotch' straps, I doubt they are of that much benefit. There is no doubting that pfd's with built in harness, that also have built in crotch strap certainly do meet a solid requirment.
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Old 26-11-2015, 16:47   #49
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Re: If go overboard, how can one keep still in cold water?

Quote:
Originally Posted by Cadence View Post
I think that is junk science. I can recall deciding to swim to a beach on lake Champlain from Pops boat docked at Essex NY. I believe the water wasn't much over 40. I was one stroking 8 yr. old. Obviously I didn't suffer cardiac arrest. I was shivering walking back down the dock to the boat.
Cadence, you seriously shouldn't be criticising or calling the science junk based on your own personal experience. That's not very good 'science' to do that.

Shock Syndrome is the most common reason people go in and don't come up.
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Old 26-11-2015, 16:51   #50
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Re: If go overboard, how can one keep still in cold water?

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There are also some combined pdf+harness models available. Maybe a nice combination for some sailors.
yep. I've got one for me. In future I intend to replace all of mine with combined harness types. It just saves so much mucking around.

The other thing I have is my wet weather jacket also has an inbuilt harness. But I don't think it has a crotch strap. I'll check that next time I'm on the boat.
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Old 26-11-2015, 17:02   #51
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Re: If go overboard, how can one keep still in cold water?

Quote:
Personally, I think it is criminal for inflatable PFD's to be sold without a crotch strap. It took considerable effort to locate some straps when I found this out on a purchase some years ago.
Until recently, CHILD/ BABY pfds on airliners would NOT keep the child floating face up. UFB really.

One has to wonder WHO the brain surgeons are that certify safety equipment.
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Old 26-11-2015, 17:40   #52
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Re: If go overboard, how can one keep still in cold water?

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Originally Posted by Rustic Charm View Post
Just ask who?

5000 Pound is 5 tons we are talking sailors and not elephants arn't we?
5000 pounds of force (weight) is actually two and a half short tons...but still a lot of force.

The force on tethers occurs when the tethered person stops when the tether extends to maximum length and stops. The force generated by the deceleration of the person attached to the tether can be very much greater than the weight of the person while at rest (a measure of the effect of gravitational acceleration).

One way to think of how big the force due to the deceleration can be would be to compare what the deceleration might be in "boundary" cases such as deceleration after falling a foot or two and deceleration after falling several stories off a tall building. In the second case, the tension (force) in the tether as it comes up tight would be immense.

Tethers should be able to take a LOT of force, and optimally be stitched to allow progressive extension to minimize the impulse when at maximum extension.
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Old 27-11-2015, 09:22   #53
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Re: If go overboard, how can one keep still in cold water?

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Cadence, you seriously shouldn't be criticising or calling the science junk based on your own personal experience. That's not very good 'science' to do that.

Shock Syndrome is the most common reason people go in and don't come up.
You are right. If I tried it today I probably wouldn't come up. Poor choice of words on my part.
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Old 27-11-2015, 09:53   #54
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Re: If go overboard, how can one keep still in cold water?

I don't have wisdom to add to this thread. But I can attest that there shock is very real and could be very deadly. The only time I have been dumped was white water rafting in midst of category 4 rapids (intense). I actually passed out when I hit the water. My life jacket a helmet saved me then but I was in the water another hour and hypothermia was setting in when I was pulled out. I had the shakes so bad afterwords!
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Old 27-11-2015, 10:56   #55
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Re: If go overboard, how can one keep still in cold water?

Around here, near Ottawa, Ontario, Canada, the consensus is that when you hit the very cold water you have an involuntary inhalation and if under water start to drown.
Bill
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Old 27-11-2015, 11:06   #56
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Re: If go overboard, how can one keep still in cold water?

Quote:
Originally Posted by Rustic Charm View Post
Just ask who?

5000 Pound is 5 tons we are talking sailors and not elephants arn't we?

You are partially correct, but PFD's with built in harness's are made for both recovery and falls to a Standard. I just think it's odd that whilst some of the pfd's that can be purchased with 'crotch' straps, I doubt they are of that much benefit. There is no doubting that pfd's with built in harness, that also have built in crotch strap certainly do meet a solid requirement.
The manufacturer. Most have plastic buckles rated ~ 500 pounds.

(Mustang)


5000 pounds is 2.5 tons. This was a rounding, but climbing and fall protection standards specifiy 4500-5500 pounds, depending on the standard. The impact force of a fall with some shock absorption generally reaches 1200 pounds (4:1 safety factor) (UIAA and USAF parachute opening force limit), and can top 5000 pounds if attached to a hard point.

Is an ISO harness crotch strap secure in a fall? Yes, and no. A harness without a crotch strap can pass the ISO drop test, because the dummy has rigid wooden arm stubs. For example, and sailor can worm and slide out of a chest only harness by raising his arms, but the dummy will hold chest-only harnesses every time. Additionally, the sailor would suffer broken ribs (this has happened). Additionally, climbing harnesses are tested daily in real falls, whereas I will bet a fine dinner that no sailor has EVER taken any test fall in a sailing harness. VERY different from climbing harness design, so we should avoid broad assumptions. They are good, I am sure, but I would not assume lab testing translates into the real world. Another case of swimming pool testing.

(Spinlock Deck Vest leg straps. No way these can take full load, and they would fail any climbing or OSHA drop test)


So no, just ordinary sailors.
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Old 27-11-2015, 11:10   #57
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Re: If go overboard, how can one keep still in cold water?

To reinforce this point:
I fell off the boat (trying to rescue dog who fell in....Jack Russell doesn't swim very well) in CALM WARM WATER and couldn't get back on board.
Luckily in a canal, swam the 12 feet to shore.
Learned a valuable lesson.
Bill

Quote:
Originally Posted by oleman View Post
The chances of being recovered after going overboard at sea are less than 50:50 even when you do everything correctly with help immediately available.
We had a crew member go overboard near Singapore form a large ship where I was a crew member. The seas ware rolling at 6-8' swells. The sea water temp was probably 75F at least.
The crew member was a 22 YO in good health and a swimmer. He was not wearing flotation. The OOD, bridge crew and crew members knew we had a man overboard within 1 minute of another crew member observing the incident. Every technique we tried in the recovery process FAILED.
The final report was "Crew Member lost at Sea".
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Old 27-11-2015, 11:23   #58
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Re: If go overboard, how can one keep still in cold water?

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Originally Posted by anacapaisland42 View Post
Around here, near Ottawa, Ontario, Canada, the consensus is that when you hit the very cold water you have an involuntary inhalation and if under water start to drown.
Bill
I have heard that before. I got called earlier for my poor choice of words which was true. I cited diving in to cold water, as a kid, and it was not a problem. The difference might be diving or falling. When you are diving you expect it failing you don't so you may be more likely to have that involuntary reflex?
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Old 27-11-2015, 11:30   #59
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Re: If go overboard, how can one keep still in cold water?

Quote:
Originally Posted by anacapaisland42 View Post
To reinforce this point:
I fell off the boat (trying to rescue dog who fell in....Jack Russell doesn't swim very well) in CALM WARM WATER and couldn't get back on board.
Luckily in a canal, swam the 12 feet to shore.
Learned a valuable lesson.
Bill
It's surprising how we forget that we aren't using our bodies like we once did then suddenly we need them to work a certain way and they won't.

I had trouble reentering my boat once after diving (jumping) in for a swim while anchored. After that, I immediately added pull ups to my workout routine

but sailing offshore I'll still be wearing a harness and short tether. For some reason now at 8 miles out in the bay though I don't (in summer) but probably should
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Old 27-11-2015, 15:17   #60
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Re: If go overboard, how can one keep still in cold water?

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I have heard that before. I got called earlier for my poor choice of words which was true. I cited diving in to cold water, as a kid, and it was not a problem. The difference might be diving or falling. When you are diving you expect it failing you don't so you may be more likely to have that involuntary reflex?
I with you, through my adult life I have routinely jumped in and swam in water with ice floating in it or snow melt flowing into it. Specifically, on rivers in Canada and in Lake Superior. Shocking yes at first but never considered it life threatening.

Up here many of us cut a hole in the ice, fire up the sauna, and jump in the ice water. I don't count this as swimming as the preheat in the sauna takes the sting out.

No one I know of has died jumping into ice water although I can see where it would happen on occasion. I will admit that in my old age jumping into ice water is no longer on the priority list.
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