John McCann - Stay alive -- survival shelter and protection from the elements eshort learn about your bodys thermoregulation, what protection it needs and how to build a storm shelter for protection

There has been rigorous debate about whether fire or shelter is the first priority for survival. I see them as equal in importance, and as two options where, ultimately, one is chosen depending on circumstances. If you are in a warm climate and it looks like rain, a shelter would be an appropriate course of action. However, if you are in the northeast in the winter and it is below zero, you need a fire, especially if you fall through the ice and get wet. You have a very short time to get warm and dry, or youre going to die. Once you are warm, youll be able to build a shelter for protection from the elements. Again, the situation will dictate which of the two is the priority.

Since we covered fire in the previous chapter, lets now examine the ways your body heat can be transferred to the environment, and how a shelter protects you from the elements and helps prevent that loss.

The ways that heat from your body can be transferred to the environment are called heat loss mechanisms. In a cold environment they can all be detrimental, but in a hot climate some of these mechanisms can be used to your advantage.

Radiation

Radiation is the primary cause of heat loss. Our body radiates heat to the environment much like the sun radiates heat to the earth or a campfire radiates heat to keep us warm. At 50 degrees F, 50 percent of the bodys heat can be transferred to the environment through an exposed head and neck. We can also lose heat from our wrists, hands and feet. Have you ever had your mother or father tell you if you want warm feet to cover your head? Wearing a hat, scarf, wrist-overs or gloves can help eliminate loss of heat through radiation from your head, neck and wrists. A shelter can help reduce loss of body heat to the environment by holding it inside the shelter.

Conduction

Conduction is the process by which we lose heat through direct contact between objects. This can occur when sitting on a cold or snow-covered stump or rock, when wet clothes come in contact with your body, by touching cold objects with bare hands, or by kneeling on the snow to build a shelter. Avoid these situations to prevent conduction of heat from the body to other objects. This is another reason to insulate between yourself and the ground in a shelter. In the winter, I carry a small closed cell foam pad, cut from an old military sleeping pad, in the back of my pack. I use it to insulate myself from a cold object when sitting down.

Convection

Convection is loss of body heat due to movement of air or liquid across your skin. An example of convection is wind chill. Through radiation, the human body is always warming a thin layer of air next to the skin. The temperature of that layer of air is usually equal to that of the skin. When this layer of warm air is undisturbed, the body stays warm. However, if this warm layer is removed by convection, the body quickly cools down. In cooler environments, clothing is your first line of defense, as it helps hold that thin layer of warm air near your skin.

Evaporation

Evaporation is a process whereby liquid changes to vapor, during which heat from the liquid escapes to the environment. In a cold environment, it is essential to wear fabrics that breathe. If water vapor from perspiration cannot evaporate through clothing, it will condense, freeze and reduce the insulation value of the clothing. This will cause your body temperature to go down. However, in a warm environment evaporation can be used to your advantage. Have you ever, on a hot day, worn a wet T-shirt or a wet bandana around your neck? This is also evaporation at work, because as the water is evaporated it pulls heat from the body, cooling you. It is called evaporative cooling. At our camp, we use this method in the summer by placing wet towels on water containers to keep the water cool.

Respiration

We lose heat through our normal breathing process. You can observe this when you see a persons breath on a cold day. This is heat from the body lost to the environment. It is also difficult to prevent this loss, as we have to breathe.

Hypothermia

Often called the killer of the unprepared, hypothermia is a real threat to survival. The three main elements leading to hypothermia are cold, wind and wetness. Keep in mind it isnt necessary for temperatures to be at or below freezing for hypothermia to occur. Many instances of hypothermic death have taken place in temperatures over 50 degrees F. Hypothermia is heat loss at the body core, and it results from exposure to cold with the addition of other heat-loss mechanisms or natures elements.

Normal body temperature is 98.6 degrees F. If core body temperature drops below 95 degrees F, your body will not generate enough heat to maintain normal body functions and hypothermia sets in. If your body temperature drops below 92 degrees F, you wont be able to help yourself survive!

In the case of mild hypothermia (between 91 and 95 degrees F), normal shivering begins and ranges from mild to severe. You might have a cold sensation and have goose bumps, your hands can be numb and you might not be able to perform complex tasks with your hands.

In moderate hypothermia (between 82 and 90 degrees F), shivering becomes intense. There is an obvious lack of muscle coordination and movements become slow and labored. Violent shivering continues, and speech, thinking and gross muscle movements become difficult. The use of hands often ceases and stumbling becomes frequent. This is a serious situation.

In severe hypothermia, below 82 degrees F, you are in major trouble. All shivering stops and exposed skin becomes blue or puffy. You are confused, unable to walk and muscles become stiff. You lose awareness of others, if present, and the pulse and respiration are erratic. At this point, unconsciousness occurs and death usually follows.

A good survival kit should contain the items you need to avoid falling prey to hypothermia. You need to be prepared in order to protect yourself from the cold and effects of hypothermia.

Hyperthermia

Hyperthermia is elevated body temperature which occurs when the body fails at thermoregulation; and the temperature control system becomes overloaded. The body is normally able to cool itself through sweating, but under some conditions sweating is not enough and body temperature can rise rapidly. If the temperature continues to rise, it can damage the brain and other vital organs and result in death.

There are three levels of heat related injuries: heat cramps, heat exhaustion and heat stroke. Heat injuries are a serious matter.

As indicated earlier, normal body temperature is 98.6 degrees F. When your temperature is between 99 and 100 degrees F, you are at risk of heat cramps, the least serious heat injury. Heat cramps normally result from over-activity in a hot environment and are connected to dehydration and poor conditioning. Initially, youll begin to feel cramps in the abdomen and legs. Youll have hot sweaty skin, may feel nauseous or dizzy, and may have a headache. When this happens, rest, drink water and, if possible, move to a shady, cool environment. Evaporative cooling, discussed above, and staying hydrated can help prevent this stage.