Surviving in cold water
If you find yourself in cold water, you may not have long to react. Cold water shock happens faster than hypothermia.
Sudden immersion in cold water can cause:
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heart failure within a few minutes
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very fast breathing leading to dizziness
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rapid cooling of muscles which could cause a person to lose the strength to board a life raft or operate a flare, within minutes.
Even a fit person can:
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lose the ability to keep themselves afloat
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drown in under 10 minutes, long before hypothermia sets in.
How the body reacts in cold water
The body must keep the vital organs in its inner core – such as the heart and lungs – at about 37.6°C so they can function normally.
At normal temperatures, heat generated by the body is carried by the blood to all regions and extra heat is released through the skin.
As the environment cools:
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the outer layers of the body cool first
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the body reduces blood circulation to these outer regions, to protect the inner core
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hands and feet feel cold because less blood reaches them
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shivering begins to generate more body heat.
If cooling continues:
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the inner core temperature drops (this is the start of hypothermia)
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the body further reduces blood supply to the outer regions to protect the vital organs
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shivering may slow or stop
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as the brain cools, control reduces and consciousness is affected
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further cooling of the core causes organs to stop working
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without correct treatment, consciousness is lost and death will follow.
What should you do before you go out?
1. Put on layers of clothing
If you need to enter the water, do not get undressed. A person wearing two layers of woollen clothing will lose less heat than someone in a swimsuit.
If possible, wear several layers of wool and add a waterproof outer layer. This helps trap warmer layers of water close to your body.
2. Wear a lifejacket
A good lifejacket helps keep your head and airway clear of the water, even as your strength and mental capacity decrease. It also makes it easier to float in a way that reduces heat loss and increases survival time.
Avoid alcohol
Safer boating and alcohol do not mix. Conditions can change quickly on the water and everyone on board needs to stay alert.
Alcohol may make you feel warm but speeds up heat loss. It dilates blood vessels and pushes blood closer to the skin.
For more on why alcohol and boating do not mix, see the alcohol guidelines below.
Your situation on the water can change suddenly and without warning
Surviving the unthinkable
Survive: See the effects of going overboard
What to do if you end up in the water
1. Float first and try not to panic
Concentrate on floating and try to control your breathing. Panic can affect breathing and speed up drowning.
Hyperventilation often occurs when a person is unexpectedly immersed in cold water but should ease over time.
2. Get out of the water if you can
In water, the body loses heat 20 to 30 times faster than it does in air.
Even if you feel colder out of the water, try to climb on top of your overturned boat or any floating wreckage. A boat or large pieces of wreckage are also easier for rescuers to spot.
3. Think carefully before attempting to swim for shore
Stay with the boat unless you are sure you can safely make it to shore.
Tests show an average person wearing a lifejacket and light clothing might swim about 1.85 kilometres in 10°C water. In one Canadian case, a 20-year-old strong swimmer drowned within 5 minutes in 10°C water.
When deciding whether to swim for shore, consider:
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how far is away the shore is and what the shore conditions are
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your swimming ability
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the weakening effects of cold and anxiety
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the extra heat loss that swimming will cause.
Heat escape lessening posture:
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Hold your arms tight against the chest.
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Press your thighs close together.
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Raise your knees to protect the groin region.
Huddle posture
To adopt the huddle posture:
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Press the sides of the chests and lower torsos together.
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Hug around each other’s lifejackets.
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Twist your legs around as much as possible and talk to each other.
