Hypothermia: The Cold Killer

Cold water robs the body of heat 25 to 30 times faster than air. When you lose enough body heat to make your temperature subnormal, you become hypothermic. Safety experts estimate that half of all drowning victims actually die from the effects of cold water, or hypothermia, and not from water-filled lungs.

Sudden immersion in cold water cools your skin and outer tissues very quickly. Within 10 or 15 minutes, your core body temperature (brain, spinal cord, heart and lungs) begins to drop. Your arms and legs become numb and completely useless. You may lose consciousness and drown before your core body temperature drops low enough to cause death.

Cold water does not have to be icy. It just has to be colder than you are to cause hypothermia. The rate of body heat loss depends on water temperature, the protective clothing worn, percent body fat, other physical factors like alcohol in the blood, and most importantly, the way you behave in the water.

Different activities in the water consume varying amounts of body heat. The more energy (heat) you expend, the quicker your body temperature drops, reducing your survival time. As shown in the chart above, wearing a lifejacket or PFD adds hours to your survival time.

*Drownproofing is a warm-water survival technique. To conserve energy, you relax in the water and allow your head to submerge between breaths. This technique is NOT RECOMMENDED in cold water, since about 50% of heat loss is from the head.

Body "Hot Spots"

Certain areas of the body are "hot spots" that lose large amounts of body heat faster than other areas and need special protection to prevent hypothermia.

• The head and neck are the most critical.
• Sides and chest are major areas of heat loss.
• The groin area also loses large amounts of heat.

To Increase Your Odds of Survival in Cold Water:

• Wear the right lifejacket for the activity, location and water temperature.
• Don't swim unless you can reach a nearby boat, fellow survivor or floating object. Swimming lowers your body temperature.
• Try to get out of the water. Climb onto the boat or a floating object. Cold water depletes body heat much faster than air.
• If you are alone and if you are wearing a lifejacket, slow down body heat loss through the Heat Escape Lessening Position (HELP). Cross your arms tightly against your chest and draw your knees up towards your chest as well. Remain calm and still.
  
  
  

• If there are others in the water, HUDDLE together for warmth. HUDDLE with everyone's chests and sides close together. Intertwine legs and extend your arms around the people next to you. Keep a positive outlook. It will improve your chances of survival.

Prepare for and Prevent Hypothermia

• Wear an approved personal flotation device (PFD). Some PFDs provide better insulation against cold water than others.
• A pealess whistle attached to your PFD or clothing can be used to signal for help.
• In cool weather, wear a hat, rain gear, and/or wool clothes under your PFD.
• Be alert to changes in the weather that could influence your safety.
• Always tell a responsible person where you are going and when you plan to return.
• Avoid the use of alcohol.

Note: Information on this page is based on Boat Smart from the Start – A Family Guide to Safe and Responsible Boating, produced by Blaicher Marketing International Inc. in partnership with Reader’s Digest.

Source: http://www.ibc.ca/en/BeSmartBeSafe/Boating_Safety/hypothermia.asp#prepare