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Know-How – the dangers of cold

Hypothermia, the cooling of your core temperature, can occur in air or water, though cold water chills the body 25 times faster than air. If your core temperature drops to 86 degrees, you will lapse into unconsciousness; below 77 degrees and you’re likely dead.

Hypothermia, the cooling of your core temperature, can occur in air or water, though cold water chills the body 25 times faster than air. If your core temperature drops to 86 degrees, you will lapse into unconsciousness; below 77 degrees and you’re likely dead.

Your body is a heat exchanger, and your blood carries the heat. The large blood vessels in your groin, armpits, throat and head are extremely efficient heat exchangers, so it’s important to reduce heat loss from these areas. As the body loses heat, it tries to maintain core temperature first by friction from shivering, then by reducing blood flow to your extremities.

Survival in cold water depends on several factors, including water temperature; the victim’s age, physical condition, body type and fat content; and what he or she is wearing. This is one area where fat is a plus, as it provides insulation. You can survive about 15 minutes in freezing water, but as a general rule a 50-year-old person has a 50-50 chance of surviving 50 minutes in 50-degree water. Practice your man-overboard techniques, wear insulating clothing if the water’s below 60 degrees, and wear a life jacket.

1. Create an insulating layer of warm air or water next to your skin. Wool and certain polyester fabrics are good insulators. In fact, some polyester wicks moisture away from the skin so you feel dry. Wool provides insulation even when wet. However, it retains water, is heavy when soaked, and can smell like a wet animal. Before polyester, we used to carry oiled wool sweaters. Don’t wear clothing that binds.

2. Cotton can kill; it absorbs and holds moisture, and has no insulating value when wet. Silk has insulating properties. We carry it on cruises because it can get cool at night and you can suffer hypothermia in cool air, which won’t kill you directly but can slow your reactions.

3. Your head is a major source of heat loss. Wear a wool or polyester watch cap when on cold water and in cold weather.

4. A survival suit will keep you afloat, dry and insulated, but most of us don’t keep them on board. Float coats with neoprene “beaver tails” are good, then come flotation jackets, polyester sweaters and fleece, and wool.

5. If you’re in the water, don’t panic. Pray the crew is well-rehearsed in MOB tactics and start survival floating techniques. You must conserve heat, and attempting to swim or thrashing about simply causes more heat to be lost and accelerates the onset of hypothermia. A PFD will keep you afloat and allow you to remain still.

6. To conserve heat assume the fetal position, with your legs pulled up and arms crossed. If you’re in company, huddle together; it will increase survival time.

7. Stay with the boat, if possible, and get as much of your body out of the water as you can. Around 50 percent of heat loss is through the head, so keep your head dry and wear that watch cap.

8. First aid depends on how profoundly the victim is suffering from hypothermia. Keep in mind that core temperature can continue to drop for a half-hour after rescue. If the victim is unconscious but breathing, treat to prevent shock. Remove wet clothing and slowly warm the victim by wrapping in unheated blankets. Don’t massage the limbs or face; it draws warm blood from the core to the skin, where it cools and circulates back. Breath into the victim’s face as he inhales, or carefully waft steam from a kettle of boiling water toward him.

9. No booze. Alcohol can speed hypothermia and cause dehydration.

10. Don’t give up if the victim is young and appears lifeless, even if he was face down in very cold water. The body can shut itself down in what’s known as the “mammalian diving reflex.” I learned at a safety-at-sea seminar to never consider anyone beyond help unless they are warm. Many victims of the Titanic may have been revivable. Most who died when she sank died of hypothermia, not drowning.

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