Cold Water Immersion When Riding Your PWC: It’s not cold in the summer, so what’s the problem? Well, in Idaho, even summer water temperatures can hover around 50 degrees Fahrenheit. Our body’s response to immersion into 50-degree water is something we don’t have a lot of control over.

Cold water immersion will play out in four stages:

1. Cold Shock Response – first 3-5 min
2. Cold Incapacitation – 5–30 min
3. Hypothermia – 30+ min
4. Circum-rescue Collapse – during and after rescue

Cold Shock Response – You just fell overboard! The shock of the cold water causes you to gasp for air. It takes your breath away! With all this gasping, hyperventilation will kick in, which can reduce blood flow to the brain and your oxygen supply. This may cause dizziness and confusion. Along with the hyperventilation, there is a claustrophobic feeling of not being able to get enough air and this increases the potential for panic. And if that’s not enough, the ability to hold your breath is almost impossible! And your respiratory problems are just the beginning. In addition, your Cardiovascular Responses can then include rapid heart rate (up to double or more of your normal heart rate) and some irregular heartbeats. This increased workload on the heart puts even the healthiest individuals in danger of a heart attack.

Cold Incapacitation – Very soon after immersion, the cold water can impair your ability to undertake critical survival activities. You might not be able to put on your life jacket, hold onto a floatation aid, re-board your vessel, climb a ladder, hold a rescue line, swim, or stay afloat. Swim failure can happen even to “good” swimmers. Many classed as “good” swimmers in a heated pool are unable to swim even short distances in cold water, even to save their life. This loss of manual dexterity is not caused by a low core body temperature (hypothermia.) Hypothermia is the next step.

Hypothermia (Deep Body Cooling) – Once you are immersed in cold water, your core body temperature begins to decline and hypothermia can set in as quickly as ten minutes. This rate depends on water temperature, clothing, body type, and your behavior in the water. Cold water robs the body of heat 25 times faster than cold air. In many cases, you may lose consciousness and drown before your temperature drops low enough to cause death.

Circum-rescue Collapse – This occurs during or after rescue. Once rescued after you have been immersed in cold water, you are still in danger from collapse of arterial blood pressure, which can lead to cardiac arrest. Also, inhaled water can damage your lungs, and heart problems can develop as cold blood from your arms and legs is released into the core of your body.

Your chance of surviving cold water immersion depends on having the ability to swim, to keep your head out of the water (even without floatation aids), and the ability to avoid panic. You need to have sufficient flotation in order to keep your head above water, control your breathing, have a timely rescue by yourself or others, and to retain heat. Prepare for boating in cold water conditions by always wearing a secured life jacket (PFD) and wearing layered clothing for insulation.

More Info see http://parksandrecreation.idaho.gov/recreation/boating/boatersafety.aspx