Cold water immersion occurs when a paddler is unexpectedly immersed into cold water that is 15°F or below. When this happens, the body will go through the following four phases:
- Cold Shock (Initial Reaction)
This phase lasts for about one minute. A deep and sudden gasp will happen first and will be followed by hyperventilation and involuntary gasping. These actions can cause the person to inhale water and drown. During this time, the person overboard must concentrate on avoiding panic and controlling their breathing. Wearing a life jacket at this phase is absolutely critical to staying afloat.
- Swimming Failure (Short-Term Immersion)
This phase lasts for about 10 minutes. During this time, the person will experience swimming failure and lose the use of their fingers, arms and legs. A life jacket is critical to survival at this point—if they are without a flotation device and they are physically unable to swim, the victim will likely drown.
- Hypothermia (Long-Term Immersion)
The next phase is when hypothermia sets in. It can take up to an hour before the hypothermia victim becomes unconscious. During this time, the body organs are cooling and the internal temperature of the body will drop. If not rescued and treated immediately, the victim will die.
- Post-Rescue Collapse
Once pulled from the cold water, the person overboard will experience a phase during which their body is under extreme stress and at risk of cardiac arrest. The arterial blood pressure will change and the cold blood from the victim’s limbs will re-enter the internal body core, causing dangerous stress on the heart and the brain.
Always wear your life jacket. If a vest is thrown to you once you‘re already immersed in cold water, your muscles may already be paralyzed from the low temperature and you may be physically unable to secure the vest or to even reach for it. So put it on—you’ll never regret wearing a life jacket.