Cold Water

[Larry H]

Check this out.



Page two



These images are in the Nancy H photo album.

[Hunkydory]

[thataway]

Why wear the life jacket? First, it will help prevent the first dangerous phase of cold water shock. It should keep the head above water, and avoid aspiration of water (leading to drowning, as part of the cold water shock-this includes a gasp reflex which aspirates water into the lungs, as well as the affect of cold water ceasing or markedly decreasing respiration). Some people will hyperventiallate, with shallow respiration (could lead to unconsiousness), others will be unable to hold their breath for more than a few seconds--again a reflex due to the cold water. Also if you have a good fitting vest type of type III PFD, it will also give you some cold protection of the torso. This does not totally remove the danger of high blood pressure (high peripheral vascular resistance due to vaso constriction)--but does help some. Also a lot of cold is lost thru the head (highly vascular scalp), and a head gear which helps to revent heat loss will also aid in this phase. The increased heart rate and arrythmias, as part of the reflex can also be reduced by decreasing the sudden cold reflex. All of these can lead to a heart attack and sudden death.

I have a personally built vest type of jacket, which has foam all around the torso, down over the upper abdomen and up into the collar. I have used it for many years--it is not stamped coast guard approved, but has over 22 lbs of floatation and gives me excellent rib protection and conservation of body temperature. If I have been in very cold weather I have worn it with an 1/8" neoprene wet suit vest, with hood--which helps further with the head and neck protection. A beaver tail (groin flap) would also greatly increase survival (as many float coats have).

I wonder if any of us are predisposed to develope the physiological response (if we had the time and inclination) to resist cold water effects by acclimation? I have jumped into icey water after a sauna etc when younger---but I would be reluctant to go into ice water unless under very controlled circumstances.

I certainly agree with the comments about survival suits--but one has to look carefully at both the type of insullation, water intrusion protection and full body protection (including hands and feet) as noted by several posters. The reality is that most of us will probably not wear such gear on the docks, unless we were working there. Yes, you would if fishing etc.

The mention was made of getting part of the body out of the water--this actually is of great benefit. Water conducts heat away from the body at almost 30x the amount as air does. So just getting your upper body out of the water would markedly increse survival.

The H.E.L.P. (heat escape llessening posture) position: This minimizes any activity, with hugging your arms against your sides and across your chest, with legs tight together and up toward your chest as much as possible-and must be used with a good floatation device. This position decreases your body surface exposed to the coldest water outside of the area of your "Hug".

Some tables from Minnesota sea grant site on hypothermia:

Water Temperature Expected Time Before Exhaustion and survival

(°F)temp Time before exhaustion Time or survival

32.5° ----- < 15 minutes --------------- 45 minutes
32.5–40----- 15 – 30 minutes ------------- 30 – 90 minutes
40–50°------ 30 – 60 minutes -------------- 1 – 3 hours
50–60° ----- 1 – 2 hours -------------------- 1 – 6 hours
60–70° ---- 2 – 7 hours --------------------- 2 – 40 hours
70–80° ----- 3 – 12 hours ------------------- 3 hours – indefinite
> 80° ---- Indefinite ------------------------ Indefinite

Situation & Equipment Predicted Survival Time in 50° F Water

Without flotation device
Drown proofing 1.5 hours
Treading Water 2 hours
With personal flotation device (e.g. vest or collar-type PFD)
Swimming 2 hours
Holding Still 2.7 hours
H.E.L.P. position 4 hours
Huddling with others 4 hours

With hypothermia prevention equipment
Insulated flotation jacket (float coat) 3 – 9 hours
Survival Suit indefinite