Hypothermia/cold shock

Falling overboard into the water can lead to the life-threatening conditions of hypothermia and/or cold shock. This page will help you understand the physical effects that can occur, and how to treat them.


Hypothermia is the effect of heat loss from the body’s core. Hypothermia occurs when a person’s body temperature is lowered to less than 35°C and affects your brain, heart and other internal organs.

While your body begins to cool as soon as you enter the water the full effect of hypothermia can take around 30 minutes.

Some of the effects of hypothermia are a reduction of blood flow to the hands, feet and surface of the body, intense shivering in the early stages as the body tries to maintain its core temperature and no shivering in the later stages.

To reduce the risk of hypothermia wear warm, preferably woollen, clothing under wet weather gear.

Various techniques have been developed to prolong survival time, including:

  • Huddle: By huddling close together with other people, so that your chest and arms are protected, you can reduce the rate at which your body loses heat and increase survival time by up to 50 per cent. This is the most effective method of reducing the onset of hypothermia if there is a group in the water.
  • HELP (Heat Escape Lessening Posture): Limit body heat loss by holding your arms down to your sides and up across your chest, and raising your knees and holding them together.

Cold shock

Cold shock is the sudden uncontrolled reaction when a person first enters cold water. Breathing and heart rates accelerate sharply and the person may have difficulty in avoiding inhalation of water. The effects of cold shock subside quickly but can be life threatening in the first few moments. Wearing a lifejacket gives a person support at such a critical time.

If you fall into the water, avoid panicking. Try to grab hold of the vessel or a floating object until you regain control of your breathing. Try to get yourself out of the water if possible. Stay with the vessel and only swim to shore if it is very close.

Treating hypothermia

Hypothermia can be mistaken for drowsiness. There are, however, some signs and symptoms which will allow you to make an immediate evaluation:

  • Adults: Cold to touch; pulse slow, weak or imperceptible; breathing slow and shallow
  • Children: Cold to touch; quiet and lacking appetite.

To treat hypothermia you must act quickly but gently. Never give the patient alcohol or an unwrapped hot-water bottle. The best method of treatment is to allow the patient to warm naturally where possible and you should:

  • Remove all wet clothing when warm, dry clothing or blankets are available
  • Allow the patient to warm gradually with the aid of warm towels and blankets or gentle sources of warmth, including body heat
  • Transport the victim to medical aid without delay. Their survival could depend on it
  • Keep an aluminium 'space blanket' on board.

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