Icy waters put us in a danger zone
Our cold waters mean proper safety gear is a life saver, writes
TASMANIA is an island surrounded by water – and for many months that water temperature is less than 15C and its effects can be deadly.
In this part of the world, sea temperatures range from 8C in winter to 18C in summer. Inland waters are colder, ranging from 2C to 17C. The risk of drowning increases almost five times if the water temperature is below 15C.
Studies have shown up to 60 per cent of fatalities from cold water immersion occur in the first 15 minutes before the body core temperature cools to hypothermic levels.
Boaters, kayakers and stand-up paddle boarders all need to be aware of the dangers of cold water immersion.
If you fall into the water, there are three physiological changes that occur – known as the 1:10:1 Principle.
1 MINUTE: Cold Shock Response
This happens immediately and your body undergoes a number of phases starting with the involuntary gasp reflex.
Within 10-12 seconds of entering the water, you will gasp for air – and if you are under the water or in waves, you can inhale water and this can lead to drowning.
This is why you must try at all times to keep your head out of water, which is why wearing a life jacket is essential.
The other two things that occur are uncontrolled, increased breathing and an increased heart rate, which can lead quickly to increased fatigue.
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 caused by 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.
Many people regard themselves as good or even strong swimmers. Sadly, the reality is that in cold water, that won’t matter.
Comprehensive testing on Olympic swimmers in such conditions has revealed that even the best swimmers could not maintain their swimming stroke and suffered muscle rigidity and loss of coordination in both their arms and legs (swim failure).
Wearing a life jacket greatly reduces the possibility of drowning from swim failure.
1 HOUR: Hypothermia
When the body temperature drops below 35C (normal is approximately 36.5C), 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.
The hard facts are that if you are wearing only light clothing, between one and four hours later, you can go into cardiac arrest and die.
Dependent on water temperature, if you are wearing a wetsuit, you can survive for up to 16 hours and if you have the great fortune of wearing an immersion or “dry” suit, you can last for up to 30 hours.
It is important to remember that when you are in cold water, you lose heat about 25 times faster than if you are dry on land.
So if you are out on the water, understand the 1:10:1 Principle, wear appropriate clothing and make sure you don a life jacket.