Many people have jobs that require them to be on the water during the freezing winter months. Others find the winter fishing season advantageous and some live in areas where being around cold water is part of their daily activities. While we hate to think of boats capsizing or people falling into the frigid waters, it does happen which is why it is so very important to learn about cold water immersion and cold water survival.
It is a common misconception that sudden cold water immersion means immediate hypothermia. In reality, there are a few physiological things that happen prior to becoming hypothermic. The first thing that happens is called Cold Shock Response, it only lasts one minute and it affects your breathing. You will automatically gasp as your body responds to the shock of the temperature change. Your arteries will narrow (vasoconstriction) which makes the heart work harder to pump the same volume of blood throughout your body. Cold Incapacitation occurs within 5-15 minutes in the water. Vasoconstriction reduces the blood flow to your extremities in order to protect vital organs. This causes your movement to slow and it will be extremely difficult to stay afloat. (This is just one of many reasons it is pertinent you wear a life vest or personal flotation device.) Hypothermia is the third physiological occurrence and can take up to 30 minutes to set in. Being aware of this could prevent life-endangering panic. See the graph below to understand the advancement of hypothermia.
The fourth and final stage is Circum-rescue Collapse and this occurs right before, during or after rescue. While your body is fighting for survival your brain is emitting stress hormones and your senses are heightened. When rescue is near you relax which causes blood pressure to drop and muscle failure. Rescuing someone who has been immersed in cold water presents its own set of obstacles as doing so improperly could severely affect their survival.
Come back next week for Part II which will focus on cold water survival.
To reduce risk of accident or injury, Carefree Boat Club performs regular maintenance and inspections on all vessels, equips all vessels with a ditch kit, personal flotation devices and a working radio, administers classroom and open-water training to all members, creates a comprehensive float plan prior to boat departure and provides current weather briefings.
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