Cold Water Immersion, Windchill, and Hypothermia

Rowing in cold temperatures, especially in small boats or when unaccompanied by a safety launch should be done with extreme care. The following charts illustrate the influence of wind, air temp, and water temp on potential hypothermia conditions. It should also be noted that hypothermia, often thought of as the initial killer in the event of an emergency, is preceded by events that are as life threatening, or more so, in the event of cold water immersion.

Take 1 minute to stop the panic – you’ve 10 minutes of physical ability to save yourself – and 1 hour of consciousness left.  Here’s why.

1 – The first phase of cold water immersion is called the cold water shock.  Data shows that roughly 20 percent die in the first minute.  They breath in ice cold water in that first uncontrolled gasp, panic and drown, plain and simple.  In some, the cold shock triggers a heart attack.  Surviving this stage requires you to stay calm and get your breathing under control.

10 – The second phase is cold water incapacitation.  Over approximately the next 10 minutes you will lose the effective use of your fingers, arms and legs for any meaningful movement. Concentrate on self-rescue initially.  Swim failure will occur within these critical minutes and if you are in the water without a life jacket, drowning will likely occur. You have between 5-10 minutes survival time in this stage depending on temperature.

“It is impossible to get hypothermic in cold water unless you are wearing flotation, because without flotation – you won’t live long enough to become hypothermic.”

The following is a chart showing the effects of hypothermia based solely on water temp:

Water Temp (degrees) Hypothermia Index Exhaustion or Unconsciousness Expected Survival Time
20 to 32 degrees EXTREME Under 7 minutes Under 7-22 minutes
32.5 degrees EXTREME Under 15 minutes Under 15-45 minutes
32.5 to 40 degrees SEVERE 15 to 30 minutes 30 to 90 minutes
40 to 50 degrees HIGH 30 to 60 minutes 1 to 3 hours
50 to 60 degrees CAUTION 1 to 2 hours 1 to 6 hours
60 to 70 degrees MEDIUM 2 to 7 hours 2 to 40 hours
70 to 80 degrees LOW 3 to 12 hours 3 hours to indefinite
Over 80 degrees NONE Indefinite