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Hypothermia is a life-threatening condition you should be aware of when going out on the water. It occurs when the body loses heat faster than it can produce it. Body temperature that is too low affects the brain, making the victim unable to move well or think clearly. This makes hypothermia especially dangerous, because a person may not know it’s happening and won’t be able to do anything about it.

Also, while hypothermia is often thought of as a cold-weather or cold-water condition; it can occur at temperatures well above freezing, even in waters as warm as 80°. Whenever you go boating or swimming, it’s important to understand and look for the signs of hypothermia.

The first sign your body is losing heat is shivering. Other signs and symptoms of hypothermia include:

  • Slurred speech or mumbling
  • Slow, shallow breathing
  • Weak pulse
  • Clumsiness or lack of coordination
  • Drowsiness or low energy
  • Confusion or memory loss

If untreated, the victim will lose consciousness, then die.

  • Wear proper clothing. Different materials offer different levels of insulation. For example, synthetic fibers offer excellent insulation from the wind but don’t protect the wearer for long when they are wet. On the other hand, wool insulates the wearer better from the effects of hypothermia while both dry and wet.
  • Increase your energy reserve by having a good meal prior to going out on the water. This way, your body will have something to draw on in case of an emergency.
  • Keep dry and stay out of the wind. 
  • If you fall overboard, get out of the water and change out of wet clothes as soon as possible.
  • Avoid drinking alcohol prior to going out on the water. Besides the fact that operating a boat while under the influence of alcohol is illegal and dangerous, it increases the effects of hypothermia. Alcohol causes the blood vessels to dilate, which increases the amount of heat that is lost. 
  • Get out of the water as soon as possible.
  • If you can't get to shore or your vessel, do NOT try to swim. You lose more heat by swimming than by treading water. See the chart below to compare survival times associated with floating, treading water and swimming at various water temperatures.
  • Keep your clothes on. They'll insulate you from heat loss.
  • If you are wearing a life jacket, draw your knees up and make your body as compact as possible, unless you are wearing a Type III life jacket (it can turn you face down).
    • If you’re wearing a Type III life jacket, keep your legs together, arms tight to your side and lean your head back to keep your face out of the water.
  • If there are two or more people in the water, huddle together to conserve warmth.
  • Keep your head out of the water to prevent heat loss.
  • Get medical attention as soon as possible.


Survival Comparison Chart

Water Temperature Floating With Life Jacket Treading Water Swimming

70 degrees

18 hours 13 hours 10 hours

55 degrees

3.5 hours 3 hours 2 hours

35 degrees

1.75 hours 1.25 hours .75 hours