Survival in cold water depends on many factors. The temperature of the water is only one. Others include body size, fat, and activity in the water to name a few.
Large people cool slower than small people. Fat people cool slower than thin people. Children, because they are small, cool faster than adults.
By swimming or treading water, a person will cool about 35% faster than if remaining still. The "drownproofing technique" requires putting the head into the water and will cause a person to cool about 82% faster than if floating still with the head out of the water.
An "average" person, wearing light clothing and a PFD, may survive 2 1/2 to 3 hours in 50 F water by remaining still. This survival time can increase considerably by getting as far out of the water as possible and covering the head. Getting into or onto the boat or any thing else that floats can be a real life saver.
In case of accidental immersion in cold water, remember that water removes heat from the body many times faster than air. Most boats will float even when capsized or swamped. Therefore, get in or on the boat to get as far out of the water as possible.
Wearing a PFD is a MUST. It will keep you afloat even if you are unconscious. (Only certain types will keep you face up if unconscious.) Remaining still if possible, assuming the fetal, or, heat escape lessening posture (HELP), will increase your survival time. About 50% of the heat is lost from the head. It is therefore important to keep the head out of the water. Other areas of high heat loss are the neck, the sides, and the groin. If there are several people in the water, huddling side to side in a circle will also preserve body heat.
Should you swim to shore? This is a most difficult decision. It depends on many things. Some good swimmers have been able to swim 8/10 's of a mile in 50 F. water before being overcome by hypothermia. Others have not been able to swim one hundred yards. Furthermore, distances on the water are very deceptive. Therefore, stay with the boat. Even a capsized boat is easier to see than a person in the water. This will make it easier for rescuers to spot you.
Do not swim unless there is absolutely no chance of rescue and you are absolutely certain that you can make it. If you do swim, use a PFD or some other flotation aid.
Incorrect treatment of hypothermia victims may induce a condition knows as "After Drop." This is caused by improper rewarming, allowing cold stagnant blood from the extremities to return to the core of the body. When this cold blood returns to the core of the body it may drop the core temperature below a level which will sustain life. For the same reason, hypothermia victims must be handled gently and should not be allowed to walk.
1. Move the victim to shelter and warmth as rapidly as possible.
2. Gently remove wet clothing. The feeble amount of heat energy the victim has left must not be expended on warming and drying wet clothing.
3. Apply heat to the central core of the body(head, neck,sides, and groin). Place the victim on a hard surface, this will allow the administration of cardiopulmonary resuscitation should the need arise.
A. Rap warm moist towels - or other textiles around the victim's head, neck, sides, and groin. As the packs cool rewarm them by adding warm water (about 105 F). Check the temperature with the elbow, it should be warm but not burning.
B. Hot water bottles and heated blankets can also be used.
C. An effective field measure is for one or two of the rescuers to remove their own clothing, using their bodies to warm the victim's naked body. A sleeping bag or blanket should be used to conserve the body heat.
D. If the victim appears dead, heart massage and mouth to mouth resuscitation should be administered. Never put an unconscious victim in a bathtub. In cases of mild hypothermia, dry clothing and shelter may be all that is needed before the victim appears normal. However all hypothermia victims should be seen by a doctor.
"The United States Coast Guard knows how quickly cold water kills. And with the average body temperature of 98.6 Fahrenheit, the water does not have to be all that cold to be very dangerous.
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from Sea Gear catalog
contributed by Joseph Seluga