Hazards
During winter or early spring canoe trip, one acts far more carefully than during the summer trips. The prospect of capsizing and immersing in the icy water is discouraging and restrain your ambitions effectively. Despite of this intensified carefulness, you are not completely safe. The kayak is an unstable boat and the accident may happen anytime. As a result, except from the obvious unpleasantness, we’re exposed to the real threat of the thermal-shock and hypothermia.
The thermal-shock
The thermal-shock (tremor) occurs, when the cold water has a direct contact with the body. Usually, it happens immediately after capsizing. The thermal-shock may occur even in the water with the temperature of 13°C, especially if the body is warm. The following effects are possible to occur after falling into cold water:
1. Loss of sense of balance. The cold water getting into nose and ears may cause, in the disadvantageous situation, the loss of consciousness or the instantaneous lack of orientation. Both situation are equally hazardous, because the person without the sense of orientation where is the top and bottom, is not able to perform the “Eskimo roll” or get out of the kayak.
2. Loss of breathing control. Immediate contact with the cold water make that kayaker subconsciously inhales the air deeply for several times. If the head is under the water at that moment, the water gets into lungs automatically. This may effect in aspiration of fluid or drowning. If the other group members don’t act quickly the accident may end fatally. Deep, uncontrolled inhalation is followed by the “hard breathing”. Such person breathes 4-5 times faster than averagely, which increases the risk of choking with the water. Additional danger in such situation is the disorder of blood circulation and as a consequence – the giddiness, stupor, fainting and cramps.
3.Lack of breath. Instead of the “hard breathing”, the lack of breath may occur – objectively - when the person is not able to take a breath, as well as subjectively, when the person has a sensation that the air is not inhaled at all or its portion is insufficient. Such situation may last even up to 3 minutes. The cramp of larynx and panic in consequence is a serious danger which may occur in such situation.
4. Breath holding disorders. It’s estimated, that in the water with the temperature of 15°C and less, the time of holding the breath shortens thrice, and with the temperature of 5°C it is even 5 times shorter. Therefore, in the cold water we have a considerable less time to perform the “Eskimo roll”, than, for instance, in the pool.
The basic principle in the situation of the thermal-shock hazard is the co-assurance among the group. If you notice, that your friend has just capsized and “stays under the water” for a long time, there is a danger of the thermal-shock and drowning. If the struggle seems to takes place under the water, the danger is equally serious. We have to come for the immediate assistance regardless of the fact, if the struggle is an effect of the problems with spray skirt or loss of sense of balance. We should react promptly when we tow someone on a cabin and notice “hard breathing” or problems with the breath control.
The quick help and reciprocal observation is possible only when the proper distances at the water are maintained. Therefore, during the foul weather, cold water (in relation to the air), and especially while canoeing in winter, the principle of the proper distance should be strictly obeyed. In case of the capsize, the aid should be given as quick as possible.
HYPOTHERMIA
Normal body temperature, 36.6°C, is necessary for human organisms to function properly. The normal body temperature is maintained thanks to thermoregulation of our organisms which is supported by the supply of energy and proper clothing. Paddling in low air and water temperatures may lead to disruption of this auto regulation. Chill of an organism (hypothermia) is the significant drop in the temperature of the human body caused by loss of thermoregulatory capabilities. Hypothermia may result from weariness, starvation and may occur when cooling of the organism is faster than its abilities to replenish the heat.
Chill of the organism can be divided into three stages of severity:
Stage of Freezing. Freezing, trembling of the muscles, shivers are typical for this stage. Legs and arms weaken, dizziness and confusion occur during this stage. Body temperature drops to 35°C.
Stage of Emaciation. Lack of irritability and stiffening of the muscles occur during this stage. The victim gets cramps, is apathetic, suffers from consciousness disorders. Body temperature drops to 34°C - 30°C.
Stage of Inertia. The victim finally loses his consciousness. Pulse and breath are hardly noticeable. Loss of pupils’ responsiveness to light is caused by the oxygen deficiency of the brain. Body temperature drops below 30°C.
If the body temperature drops below 24°C, death usually occurs.
CAUSES
You are obviously under threat of hypothermia in case of too long stay in the cold water, for instance after capsizing of the kayak on the large reservoir. The water conducts heat much better than air and chills the organism 25 times faster. The organism can level the chilling which is 25 – 500% (according to different sources) faster than loss of heat in the air. Anyway, it is less than 25 times.
Professional literature provides different numbers concerning time of survival in the cold water. In the water temperature below 10°C, a person without any professional suit, can for sure survive number of minutes equal to the temperature of the water: 4 minutes in the water temperature of 4 °C for instance. Proper clothing (neoprene suit, neoprene socks/shoes and tight jacket or dry suit) may increase the organism’s tolerance for cold water 2-3 times. This estimation is very careful, but it is always better to be overcautious than expose yourself to chilling.
Not only after capsizing we are at risk of hypothermia. Low air temperature, boosted by strength of the wind in particular, may bring about chilling of the organism too, even without any contact with the water. So called “wind chill” occur when we are exposed to the strong wind. Accelerated skin evaporation chills the organism. We should be especially careful when paddling on the large, windy and wavy reservoirs. The wind influences our feeling of temperature and “lowers” our subjective sensations: 3 degree wind in the Beaufort Scale brings about similar effect to the drop in temperature by 5-10°C, whereas 7 degree wind in the Beaufort scale is similar to the temperature lower even by 20°C at windless weather.
In the natural conditions, the whole body keeps the normal temperature, whereas in the critical situation thermoregulatory system protects only head and trunk minimizing the blood flow into over chilled limbs. Even if we are wearing a dry suit and only hands are exposed to the wind and water, the arms can quickly weaken.
AFTER EFFECTS
The shivers are basic and early symptoms of the chill. When the organism is not able to maintain the normal body temperature, it tries to produce more heat through the additional movements. Gradual weakening of the body is the first effect of the chill. If the shivers stop, the situation starts to be dramatic. Parts of the body directly exposed to water and cold, wet air, such as hands, are first to become weak. Later on, weakness goes into numbness which may be accompanied by cramps.
Moreover, the hypothermia influences the ability to properly estimate the situation. It is easy to miss the moment, when the situation gets out of control. In such situation, we need to rely on our friends who should notice our irrational behavior and slow reactions. During winter canoeing, it is necessary to observe the whole group. Every single bathe in the river may lead to the next one, and in the result, after few bathes, the paddler is not in a position to canoe further. Confusion changes into indifference which is extremely dangerous on the water. The victim stops to be concerned about security and stops to help the others.