The effects of falling into cold water can be serious
- In Tasmania, sea temperatures range from 8 degrees Celsius in winter to 18 degrees in summer
- Inland waters are colder, ranging from 2 degrees Celsius to 17 degrees Celsius
- The risk of drowning increases nearly five times if the water temperature is below 15 degrees Celsius
- Studies show up to 60% of fatalities due to cold water immersion occur in the first 15 minutes before the body core temperature cools to hypothermic levels
- Cold water carries heat away from the body 25 times more quickly than air with the same temperature
1:10:1 Principle | Three phases of Cold Water Immersion
1 Minute: Cold Shock Response
The body’s response to cold water is to increase breathing to a rapid rate which can cause you to inhale water. A sudden shock of cold water immersion can also cause a heart attack in some people.
10 Minutes: Cold Incapacitation
After 10 minutes, cold water can cause swim failure which is due to blood vessels in your arms and legs constricting, which makes it difficult to keep your muscles moving properly. This then makes it difficult to wave for help or grab a throw ring which can quickly lead to drowning.
Wearing a life jacket greatly reduces the possibility of drowning from swim failure
1 Hour: Hypothermia
When the body drops below 35 degrees Celsius (normal is approximately 36.5 degrees Celsius), hypothermia occurs which results in uncontrolled shivering and mental confusion. If body temperature continues to drop, unconsciousness will occur, followed by death.
Survival will depend on wearing appropriate protective clothing and flotation.