Don't fool yourself into thinking the cold water you sail over is dangerous only when it contains pancake ice and glacial runoff – you could be dead wrong. In fact, water temperature as high as 60 degrees Fahrenheit can kill you just as easily.

But your chances for survival will be greatly improved if you understand what happens to your body when you are suddenly immersed in cold water and if you know what actions to take to rescue yourself.

Gordon Giesbrecht, a noted hypothermia expert, uses a "one-10-one" approach to explain the body's cold-shock response and the rough amount of time in the sequence of events that take place when you fall into frigid water: one minute of gasping, when you need to control your breath; 10 minutes of meaningful strength to pull yourself out of the water; and one hour before you lose consciousness.

Actual times may vary slightly, depending in part on the water temperature, but how you use the time can be the difference between drowning and surviving.

CONTROL YOUR BREATHING

Sudden immersion in cold water affects breathing, heart function and muscle strength. This is called the cold-shock response. The initial series of reflexes peaks during the first 30 seconds in the water and lasts up to two to three minutes.

PA3 AMY THOMASFive swimmers, playing the role of "victims," cry for help to the nearby 41-foot rescue boat during a training exercise in Cape Cod Canal.During this time, blood pressure, heart rate and the workload of the heart all increase, making the heart more susceptible to life-threatening rhythms and heart attack.

Simultaneously, gasping begins, followed by rapid and deep breathing. This seemingly uncontrollable overbreathing creates a sensation of suffocation and contributes to feelings of panic. It can also create dizziness, confusion, disorientation and a decreased level of consciousness. Accidental inhalation of seawater can occur, leading to drowning. (In fact, deaths that occur during the first few minutes after falling into cold water are usually caused by drowning, rather than hypothermia.)

It is important to realize that this initial phase of the cold-shock response is brief and that these reflexes will pass, so try to calm yourself and don't panic. The key is to keep your head above water and to consciously slow your breathing.

EXPECT LOSS OF STRENGTH

Over the next 30 minutes, the muscles and nerves in the extremities cool, and swimming becomes arduous, weak and ineffective, even for experienced swimmers.

Loss of muscle strength also makes it difficult to perform basic survival procedures, such as reboarding the craft, getting into a life raft, climbing the ladder of a rescue boat or simply grasping a rescue line. In icy water, you have only 10 to 15 minutes of effective muscle strength.

If you fall into cold water, be prepared for violent shivering and intense pain. At this point, there are several things you can do – and things you should not do – to help slow your rate of cooling and increase your survival time.

Contrary to popular belief, do not undress; the added weight of clothing and boots is negligible and will not impair your ability to float. Clothing traps water next to the skin where it is warmed, retarding heat loss, similar to the protective effect of a diver's wet suit. Clothing also traps air, which provides some insulation and buoyancy. (The exception is if a short swim is your best chance of survival; in that case, removing any extra clothing and footwear will reduce drag and improve agility.)

Of course, you should not venture out to the water without a life jacket. If wearing a life jacket, cross your hands over your chest and press your arms closely to your sides; draw your knees up toward your chest and cross your ankles. This so-called Heat Escape Lessening Posture (or HELP) facilitates maximum heat retention by protecting the most vulnerable areas of the body.

If you don't have a life jacket, you can't float and simultaneously use the HELP technique. Instead, move slowly and tread water using slight movements. Exercise wastes precious energy and accelerates the rate of cooling by increasing blood flow to the extremities. Activity also flushes cold water through protective clothing, increasing heat loss.

If possible, reboard the swamped or capsized boat or climb on top of it and await rescue. Once out of the water, stay out, no matter how cold the air temperature or how chilled you may feel. You'll survive longer out of the water because the rate of cooling in water is 25 times greater than in air at the same temperature.

If you must swim, pace yourself with an easy stroke that keeps your head and face out of the water, such as the breast stroke. In 50-degree water, you have a 50-50 chance of successfully swimming half a mile.