Cold Water Shock – RNLI
For sailors heading into cooler waters, cold water shock is a serious danger not to be overlooked. Wearing a personal flotation device will help to save your life in this situation. Immersion in water below 15°C can rapidly incapacitate you leading to fatality.
There is no avoiding cold water shock. If your head and body are suddenly exposed to cold water it may cause involuntary bodily reactions which are known collectively as ‘cold water shock’. It cannot be prevented; it is fast, and it is very deadly.
What is Cold Water Shock?
Whereas hypothermia is a slow process, cold water shock occurs within the first minute of immersion. It is far more dangerous than hypothermia, but less understood by many sailors. Hypothermia is when heat is conducted away from the body over a period of time, leading to a slow decline in core body temperature, eventual unconsciousness and death. Cold water shock can be life threatening within a minute. It can effect the respiratory system, increasing your heart and blood pressure which may result in cardiac arrest (even for the fittest).
If you become immersed in water below 15°C, you may exhibit an involuntary gasping reflex and inhale as you submerge. This will cause drowning without surfacing. You will find your ability to hold your breath underwater is drastically reduced by cold water shock. You may also experience vertigo; causing confusion underwater about which way is up or down. You may not be able to swim due to instant muscle paralysis.
How to Minimize the Risk of Cold Water Shock Fatality
- If you are wearing an automatically-inflating personal floatation device (lifejacket) it could save your life by bringing you to the surface.
- Avoid panic and control your breathing to avoid hyperventilation.
- Make sure you have your harness clipped onto the safety lines if the weather and sea conditions are adverse.
- Make sure your crew are briefed and trained to respond to a man overboard situation.
- Take precautions to avoid capsizing your vessel.