Cold Water Immersion

Cold water is very dangerous. Boaters should avoid cold water when possible and take extra precautions if you must go out on cold water. Cold water literally shocks the body, causing it to slowly shut down, which makes drowning much more likely.

It is important to understand what cold water does to the body and how to survive if you do fall in.

Stages of Cold Water Immersion

Falling into cold water causes the body to experience several responses depending on the temperature and time spent in the water.

Cold Water Shock

Stage 1 of cold water immersion is called cold water shock. When a person falls into cold water, it triggers the “gasp reflex.” This reflex includes hyperventilating and muscle spasms and can lead to inhalation of water. It can lead to changes in heart rate and blood pressure. This stage lasts about two to three minutes.

Short-Term Immersion

Stage 2 of cold water immersion is called short-term immersion. In this stage, the body starts to lose basic motor skills. In as few as three minutes, a person can begin to lose strength and sensation in the hands; this results in swimming failure and can easily cause drowning regardless of swimming skill level.

Long Term Immersion

Stage 3 of cold water immersion is called longer term immersion. After about 30 minutes in cold water, the body’s core temperature will drop below a safe level. This is called hypothermia. The body’s core temperature will drop until it has reached the water’s temperature, and the person will lapse into unconsciousness.

Post-Rescue Collapse

Stage 4 of cold water immersion is called post-rescue collapse. In this stage, a drop in blood pressure, caused by hypothermia, can cause a person to become unconscious or stop breathing, even several hours after the rescue. This is why it is critical to receive immediate medical attention after cold water immersion. 

Cold Water Immersion Prevention

Capsizing and falling overboard are the most common causes of cold water immersion. Capsizing is most often caused by unsafe boat handling, improper anchoring, overloading, or the loss of power or steering. Falling overboard can be caused by slips or falls while moving around a boat or by quick maneuvering.

  • Always stay low and stable while moving around the boat.
  • Safely load the boat to distribute weight evenly.
  • Use caution in bad weather.

Cold Water Immersion Survival and Recovery

It is critical to get yourself out of the water, however possible, as soon as possible.

Remember that your ability to swim may begin to be affected in as few as three minutes, and you’ll lose the ability to swim within 30 minutes. Stay calm, and try to conserve energy and maintain body heat.

The following advice will help you conserve heat and energy in cold water.

  • Always wear a life jacket or PFD. Without a life jacket, you will expend extra energy treading water. Your chance of survival in cold water is far decreased without a life jacket.
  • Use “HELP”—the Heat, Escape, Lessening Posture. This posture requires a life jacket, and it involves bringing your knees close to your chest and wrapping your arms tightly around them. This position will prevent some of your core heat from escaping.
  • If in a group, use the “huddle” technique to maintain body heat. Get close together so that the sides of chests are as close together as possible. Then wrap your arms around each other’s backs and intertwine your legs.

If you know you will be going out on cold water, wear additional protection such as:

  • A floater suit (a full nose-to-toes style PFD)
  • An anti-exposure work suit (a PFD with a thermal protection rating)
  • A drysuit used with a flotation device and thermal liner
  • A wetsuit (that traps and heats water against your body) combined with a PFD
  • A cold water immersion suit (used in extreme conditions and typically for offshore use)

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