Maritime New Zealand informs about techniques that everyone could do, in order to improve chances of survival in cold water. The guide includes some advice of possible immediate actions, in order to to maintain a conscious mind and to avoid cold water immersion, that could cause significant loss of heat in the body.
Martime NZ advises the following:
- Try not to panic : Panic can impair breathing and hasten the drowning process. Hyperventilation can occur when a person is unexpectedly immersed in the water. A mistimed breath can result in a laryngospasm, which sometimes results in loss of consciousness. A person who does not panic may simply have to cope with hyperventilation, which will eventually subside.
- Where possible, get out of the water : 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 clamber on top of an overturned boat or any floating wreckage.
- Think carefully before attempting to swim to shore : If you decide to swim for shore, consider that tests show an average person wearing a lifejacket and light clothing could swim about 1.85 kilometres in water of 10°C. In one Canadian case, a 20-year-old strong swimmer drowned within 5 minutes in 10°C waters.
When deciding to swim for it, consider:
- your swimming ability
- the weakening effects of the cold and anxiety
- the huge overall heat loss that the swim will cause.
If in any doubt, stay with the boat.
Martime NZ also provides some tips on how to survive cold water immersion :
- 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 a person wearing only a swimsuit. If possible, wear as many layers of wool as possible and cover yourself with a waterproof layer. This will help trap warmer layers of water closer to the body.
- Wear a lifejacket : A good lifejacket will help to keep the head and airway clear of the water, even when strength and mental capacity begin to wane. It will also make adopting heat-loss reducing postures easier.
- Avoid alcohol : Safer boating and alcohol do not mix. Things can change quickly on the water. All on board need to stay alert and aware. While alcohol may make you feel warm, it actually accelerates heat loss. It makes blood vessels dilate forcing blood closer to the skin.
Children in cold water should be sandwiched in the middle of the group, as they succumb to cold much more quickly than adults.
How the body reacts to cold The body must maintain the vital organs in its inner core – the heart, lungs, etc – at a constant temperature of about 37.6°C to enable them to function normally. At normal temperatures the heat generated by the body is carried by the blood to all regions of the body. The body automatically regulates its blood flow to control body temperature. Any excess heat is removed by transferring it to the outer layers for dissipation. As the temperature of the environment falls, the outer layers of the body begin to cool. The body now reduces blood circulation to these outer regions, so that the cooling is not transferred to the important organs in the deeper regions of the body. Hands and feet feel cold because of the reduced blood supply to these areas. Shivering starts, as an involuntary muscular attempt to generate more body heat. With further cooling, the inner core of the body now begins to cool. This is the beginning of hypothermia. The blood supply to the body’s outer regions is further reduced, as the body now takes drastic measures to maintain the temperature of its vital organs. Shivering may now decrease or stop. The organs in the core are now being affected. As the brain cools, there is reduced control and consciousness is affected. Further cooling of the core will cause the organs to stop functioning.
