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PA Boating Handbook
Cold Water Shock / Hypothermia

Cold water shock is a major factor in boating fatalities. It happens when someone is suddenly immersed in cold water. The water does not have to be freezing; cold water shock often occurs in water temperatures above 50°F.

The body’s first response to cold water shock is usually an involuntary gasp (torso reflex). Hyperventilation (rapid breathing) and breathlessness follow. The person may feel claustrophobic, panicked and confused. Cold water greatly reduces the victim’s ability to hold his breath, control breathing and impairs the ability to swim.


Hypothermia is the lowering of the body’s core temperature. It is a factor in many fatal boating accidents. Cold water robs the body of heat much faster than cold air of the same temperature.

Hypothermia begins with shivering and a loss of feeling in the extremities. Cold, blue skin, decreased mental skills and slurred speech are common symptoms. Unconsciousness can be followed by death. Warm layered clothing, a life jacket and eating high-energy foods will help prevent hypothermia.


Cold water shock is a rapid development of a number of shock responses caused by cold water immersion that can result in sudden drowning.

  1. Initial cold shock (first 3-5 minutes). Sudden immersion in cold water causes the gasp reflex, this can result in water inhalation, hyperventilation, changes in heart rate and rhythm and blood pressure, and panic. All of these reactions may result in death, especially for those with pre-existing heart conditions.
  2. Short term swim failure (3-30 minutes). Cold water saps energy and arms and legs become weak. Movement is difficult and slow. Death can occur by drowning, as the victim can no longer stay afloat.
  3. Long term hypothermia (30 minutes +). The body losses heat to cold water 25 times faster than cold air. The body becomes hypothermic when it loses heat at a rate faster than it can generate heat. Continued exposure leads to unconsciousness and death. At this stage death may occur without drowning.
  4. Post immersion collapse. The stage occurs during or after rescue. The body is still hypothermic and death may occur due to complications from inhaling water or lowered body temperature.


  1. Get the person out of the water or weather as quickly as possible.
  2. Replace wet clothing with dry. Wrap the person in blankets to warm them slowly.
  3. Handle hypothermia victims gently and do not give anything by mouth if they are unconscious. Never give alcohol to a hypothermia victim.
  4. Get medical help as soon as possible.


  • Wear a life jacket. Flotation coats also offer insulation from the cold.
  • Wear clothing that still insulates when wet such as wool, fleece or other synthetics.
  • If you know you are about to fall into cold water, cover your mouth and nose with your hands, so you don’t inhale water.
  • Do not remove your clothing.
  • Get back into or climb on top of the boat.
  • If you can’t get out of the water and shore is too far, get into the Heat Escape Lessening Posture (HELP).
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