If you enjoy boating during the cold-water months, you should be more concerned about dressing for the water temperature than you are about the air temperature. Your chance of surviving a fall overboard into cold water drastically decreases as the water temperature declines. Any water that is less than body temperature (98.6° F) can be hazardous depending on how long you’re in it, but water temperatures around or below the 70° F range can become deadly. Dressing for water temperature involves wearing a properly-fitted life jacket and layers of clothing because that helps insulate and protect you from losing body heat if you suddenly enter cold water. Many people think hypothermia is the only risk in cold water, but there are stages of cold-water immersion that are more likely to result in death prior to hypothermia happening.
The first initial stage is called cold shock and it happens in the first few minutes of being immersed in cold water. During this stage, you can inhale water from involuntary gasping, hyperventilation, panic, and sometimes vertigo. In addition to that, cold water also increases your heart rate, so if you’re prone to blood pressure or heart rhythm problems your chances of cardiac arrest are high. If you’re wearing a life jacket it can help you survive this stage and gain control of your breathing.
Swim failure or cold-water incapacitation is the second stage of cold-water immersion and it happens anywhere between 3 to 30 minutes. Muscles and nerves in your extremities (i.e. hands, arms, and legs) cool quickly. Even strong people lose their ability to swim or pull themselves out of the water back into a boat so without wearing a life jacket your chances of surviving through this stage are slim.
Hypothermia happens in the third stage of cold-water immersion, after 30-minutes or more in the water. The specific amount of time for hypothermia to happen depends on water temperature, clothing, body type, and your behavior in the water. Hypothermia can happen anywhere that the body loses heat faster than it can produce it, but in cold water it can happen 25 to 30 times faster than cold air. Swimming or treading water can cause you to lose body heat even faster so it’s critical to stay calm. Wearing a life jacket is the only way to survive hypothermia because once it occurs, you can lose consciousness and death can happen with or without drowning. It is estimated that in 40 to 50 degree water, it can take 30 to 60 minutes before someone loses consciousness and wearing a life jacket can help someone survive those temperatures between 1 to 3 hours.
Many people mistakenly think that layers of wet clothes will weigh you down in the water. The fact is wet clothes only weigh you down when you’re getting out of the water. This concept is often difficult for people to understand unless they have experienced it themselves. Advanced lifesaving training involves learning to stay afloat and swim for long periods of time fully clothed, including shoes. My experience in doing that proved to me that my clothing and shoes actually helped me to float, as long as I didn’t use any swim strokes above the water surface. Numerous times after a cold-water drowning incident, I’ve heard self-proclaimed experts mistakenly report on the news that a person drowned because their clothes or boots pulled them down underwater, implying they had no chance to even attempt to get out of the water. Dispelling this misconception could help people realize it is possible to survive cold-water immersion.
The fourth and final stage of cold-water immersion is called post-immersion collapse. To those of us not trained in treating these medical emergencies, it’s somewhat surprising that this can happen after someone has been rescued. The fact is these people are in great danger of experiencing collapsed arterial blood pressure, which can lead to cardiac arrest. Also, inhaling water can damage your lungs and cause heart problems to develop as cold blood from your arms and legs is released into the core of your body.
Hopefully, now that you know more about the risks associated with falls overboard into cold water it will help you realize how critical it is to always wear your life jacket.