Princeton University Outdoor Action Program
Winter Camping Seminar
The information in this workshop is taken from a number of excellent sources which are referenced in several bibliography sections throughout. The information provided here is designed for educational use and is not a substitute for specific training or experience. Princeton University and the author assume no liability for any individual's use of or reliance upon any material contained or referenced herein. When going into cold weather conditions it is your responsibility to have the proper knowledge, experience, and equipment to travel safely. The material contained in this workshop may not be the most current. Copyright © 1995 Outdoor Action Program, Princeton University.
Exploring the wilderness in winter is a wonderful experience. You are far from the crowds, in a hushed tranquil world of white. At the same time you must realize that this environment can be extremely dangerous. If you aren't aware of the hazards and of the proper precautions, skills, and equipment to have you can be at great risk. The greatest dangers in the winter environment are hypothermia and frostbite. These are covered completely in the Hypothermia and Cold Weather Injuries lecture.
Hypothermia - results when the body looses heat too rapidly. At a certain point the body's heat producing ability cannot keep pace with the heat loss and the core temperature-the temperature of the internal organs begins to drop. Once core temperature begins to drop the body can no longer reverse this trend without aid-either food, warm clothing, fire etc. Generally it is impossible to self-diagnose hypothermia once it is past the beginning stages. Without recognition and proper treatment it leads to death.
Frostbite - is the freezing of body tissue. It begins at the skin surface and can move to deeper tissues. Proper rewarming and treatment must be given or tissue may be lost. In extreme cases limbs are lost.
1. TRIP PLANNING
Planning a trip in the winter means spending a good deal of time researching areas and conditions to determine where, when, and how the trip will work. All of these factors will interact to determine what your daily pace and mileage can be.
Keeping all these factors in mind, set up a Time Control Plan for your trip. Keep in mind that everything takes "twice" as long in the winter (setting up camp, breaking camp, cooking, going to the bathroom, etc.). Look at your proposed route for potential campsites for each day. Also look to see where you could camp before your planned site if you can't make it. Know what your emergency and bail out options are if conditions deteriorate or you have problems. Talk to area rangers about permits and camping restrictions. Find out about snow levels, avalanche danger, safety of ice crossings, etc.
2. PERSONAL EQUIPMENT
The essence of staying warm in the winter is having the proper clothing layers and knowing how to use them effectively.
The body basically acts as a furnace, producing heat through chemical reactions and activity. This heat is lost through conduction, convection, evaporation, radiation, and respiration. As physical activity increases so does heat production and conversely as activity decreases so does heat production. The key to keeping warm is to add insulation to the body.
The thermal insulation of clothing is proportional to the thickness of the dead air space enclosed. Dead air is defined as any enclosed unit of air that is small enough that natural convection currents would not arise in it. Such currents have been detected in units as small as 2 millimeters in diameter. The dead air next to the skin is heated up by the body and provides a layer of warmth around the body. The clothing is not what is keeping you warm it is the dead air. This is because the denser a material the faster it can transfer heat through conduction, the density of air is obviously minuscule compared to a piece of a fabric. The "clo" unit was developed to provide a measurement of insulating effectiveness. One clo is roughly equal to the insulating value of an ordinary wool business suit. Each inch of thickness of conventional insulating materials (wool, pile, down) provides a theoretical value of about 4.7 clo or a practical "in use" value of 4.0 clo.
The Layering Principle
The key to providing this dead air space is through having a number of layers of clothing. Each layer provides a certain clo value of dead air space. This allows you to add or shed layers to increase or decrease your accumulated dead air space as the temperature changes and/or as your activity level changes. Remember, your body is the heat source, the clothing layers only serve to trap the heat and slow down your heat loss to the cold environment. If you have too much clothing on, you will overheat and start to sweat. You need to find the proper heat balance between the number and types of layers and your activity level.
Example 1: You are snowshoeing up a steep incline with a 50 lb. pack. The air temperature is 10 degrees Fahrenheit and you are dressed in wool pants and a lightweight polypro shirt. As soon as you stop for a rest, your heat production slows. If you stop for more than a couple of minutes, you will begin to chill. So you need to have an outer layer handy to put on.
Example 2: You are skiing along the flat. The air temp is 25 degrees and you are dressing in light polypro tops and bottoms, a down vest, and a windshell. You come to a long steep hill and have to push hard to get up and over. You start to sweat as your heat production increase with the increased muscle activity. To prevent overheating, you pull off the vest and stick it in your pack.
Why not just have lots of layers on and sweat? Heat loss from a wet surface can be up to 25 times greater than a dry surface (due to the higher density of water). If you sweat and get soaked, you will lose heat much more quickly through evaporation of the water. Also you are loosing an incredible amount of water through sweating since the air is so dry. Too much water loss leads to dehydration which significantly increases the risk of hypothermia. So you want to control your layers so as to be warm at the activity level you are in but not sweating profusely.
Thus, traveling in the winter is a constant process of adjusting your layers to keep comfortable. This means having a number of layers you can add or subtract and allowing for versatility within layers. Convection may account for the greatest amount of heat loss under most conditions. In order to properly insulate, you need to have an outer layer that is windproof.
Example 3: You are standing on a windblown summit in a wool sweater, the wind will penetrate through the openings in the sweater and quickly carry away the warm layer of air next to the skin.
Another convective factor is the "bellows action" of clothing. As you move a bellows action occurs which tends to pump your accumulated warm air out through openings in your clothing and sucks the cooler air in. In some conditions this action can reduce your body's personal insulation by 50% or more. Thus, it is important that all layers have effective methods of being "sealed" (i.e. buttons, zippers etc.) Openings in layers allow you to ventilate, to open the "chimney damper" if you are beginning to overheat, without having to actually remove a layer. So opening and closing zippers on a jacket, or armpit zips will allow you to either ventilate if you are getting too hot or seal up if you are getting chilly, all without having to add or take off a layer. With clothes that are too loose, the bellows action pumps warm air out through the openings. You need to have clothes that fit properly but not tightly. Too tight, and the clothes compress and actually reduce dead air space in layers below as well as restricting body movement.
Another general rule is that the efficiency of clothing is proportional to the diameter of the body part it covers. Thus a given thickness of insulation added to your trunk will be more thermally efficient than the same thickness added to your arm or leg. It will also help maintain that body core temperature. This is why vests work well to maintain body heat. There is an optimal thickness of insulation for each body part. Beyond that the added bulk tends to be more of a hindrance in movement than the added insulation is worth.
Have you ever noticed that your hands feel colder after putting on a thin pair of gloves? This is because when insulation is wrapped around a curved surface, the cross-sectional area of the insulation through which the heat may flow is greater as is the surface area from which the heat may be lost. This means that the total insulation efficiency of a given thickness progressively decreases as curvature sharpens over a surface. In addition, small cylinders, such as fingers, show a paradoxical effect. The addition of a thin layer of insulation actually increases heat loss until a thickness of about 1/4 inch is reached. This heat resistance gains as additional thickness is added. However, added thickness beyond 1/4 inch increases warmth very little in proportion to its thickness. This is one reason that thin gloves don't keep your hands particularly warm.
Some of the different types of materials for winter clothing and insulation are discussed below.
1. Wool - derives its insulating quality from the elastic, three-dimensional wavy crimp in the fiber that traps air between fibers. Depending on the texture and thickness of the fabric, as much as 60-80% of wool cloth can be air. Wool can absorb a fair amount of moisture without imparting a damp feeling because the water "disappears" into the fiber spaces. Even with water in the fabric wool still retains dead air space and will still insulate you. The disadvantage to wool is that it can absorb so much water (maximum absorption can be as much as 1/3 third the garment weight) making wet wool clothing very heavy. Wool releases moisture slowly, with minimum chilling effect. Wool can be woven in very tight weaves that are quite wind resistant. An advantage to wool is that it is relatively inexpensive (if purchased at surplus stores). However, it can be itchy against the skin and some people are allergic to it.
2. Pile - is a synthetic material often made of a plastic (polyester, polyolefin, polypropylene etc.). This material has a similar insulative capacity as wool. Its advantages are that it holds less water (than wool) and dries more quickly. Its disadvantage is that it has very poor wind resistance and hence a wind shell on top is almost always required. New versions of pile have a middle windproof layer. Pile is manufactured in a viartu of different weights (thicknesses) to offer numerous layering possibilities.
3. Polypropylene - is a synthetic, plastic fiber which offers dead air space and a fiber which cannot absorb water. The fiber is hydrophobic so it moves the water vapor away from the source (the body). Polypropylene layers are extremely effective worn directly against the skin as a way of keeping the skin from being wet and reducing evaporative heat loss. As the water moves away from the body it will evaporate, but each additional millimeter of distance between your skin and the point of evaporation decreases the amount of body heat lost in the evaporative process.
4. Vapor Barrier Systems - another way to stay warm in the winter is through vapor barriers. The body is always losing water through the skin even when we are not active. This loss is known as insensible perspiration and occurs unless the air humidity is 100%. This insensible perspiration goes on at the rate of nearly half a quart every 24 hours. It takes 580 calories per gram to turn liquid water into water vapor. This heat is constantly being lost by the body. A vapor barrier is a clothing item which is impervious to water. When worn directly against or very near the skin it stops the evaporative heat loss and slows dehydration. A vapor barrier sleeping bag liner will permit you to sleep comfortably in temperatures 10 - 15 degrees colder than in the bag alone.
5. Polarguard, Hollofil, Quallofil - these are synthetic fibers which are primarily used in sleeping bags and heavy outer garments like parkas. The fibers are fairly efficient at providing dead air space (though not nearly as efficient as down). Their advantages are that they do not absorb water and dry fairly quickly. Polarguard is made in large sheets. Hollofil is a fiber similar to Polarguard but hollow. This increases the dead air space and makes the fiber more thermally efficient. Quallofil took Hollofil one step further by creating four "holes" running through the fiber.
6. "Superthin fibers - Primaloft, Microloft, Thinsulate - the principal behind these synthetic fibers is that by making the fiber thinner you can increase the amount of dead air space. For example, take an enclosed space 5 inches wide and place 2 dividers into that space, each 1 inch thick. You have an effective air layer of 3 inches. If you take the same 5 inch space and divide it with 4 dividers, each 1/4 inch thick you now have an effective air layer of 4 inches. You have gained one inch. Under laboratory conditions a given thickness of Thinsulate is almost twice as warm as the same thickness of down, however, the Thinsulate is 40% heavier. Thinsulate is made in sheets and therefore tends to be used primarily for outer layers, parkas and pants. New materials such as Primaloft and Microloft are superthin fibers that are close to the weight of down for an equivalent fiber volume.. They are now being used in parkas and sleeping bags as an alternative to down. They stuff to a small size and have similar warmth to weight ratios without the worries about getting wet.
7. Down - feathers are a very efficient insulator. They provide good dead air space for very little weight. The major problem with down (and it can be a major problem) in the winter is that down absorbs water. Once the feathers get wet they tend to clump, and lose dead air space. Using down items in the winter takes special care to prevent them from getting wet. For example, a vapor barrier sleeping bag liner in a down bag will help the bag stay dry. Down is useful in sleeping bags since it tends to conform to the shape of the occupant and prevents convection areas. Down is very compressible, which is an advantage when putting it into your pack but also realize that your body weight compresses the feathers beneath you and you need good insulation (foam pad, etc.) underneath you, more so than with a synthetic bag. Some people are allergic to down.
8. Radiant Barriers - some portion of body heat is lost through radiation. One method of retaining this heat is through use of a reflective barrier such as aluminum. This is the principal used in "Space Blankets" and is also used in some bivy sacks and sleeping bags.
Note: Cotton is basically useless in winter time. It has good wicking properties, but unlike polypropylene, cotton absorbs moisture and the water occupies the space previously occupied by dead air. This means a loss in dead air space, high evaporative cooling, and a garment that is almost impossible to dry out.
The Body and Clothing
1. Head - because the head has a very high surface to volume ratio and the head is heavily vascularized, you can lose a great deal of heat (up to 70%) from the head. Therefore, hats are essential in winter camping. The adage - if your toes are cold, put on a hat - is true. A balaclava is particularly effective and versatile. A facemask may be required if there are high wind conditions due to the susceptibility of the face to frostbite.
2. Hands - mittens are warmer that gloves because you don't contend with the curvature problem described above. Also the fingers tend to keep each other warm, rather than being isolated as in gloves. It is useful to have an inner mitten with an outer shell to give you layering capabilities. Also "idiot strings" are important to keep you from losing mittens in the snow. However, gloves are always essential as well in winter because of the need for dexterity in various operations.
3. Feet - finding the right footgear depends a great deal on the activity you are involved in as well as temperature and environment. The two general modes of travel are skiing or snowshoeing (in areas with only a few inches of snow you can hike in just boots).
Cross-country skiing - you need a boot that has some ankle support due to the extra weight of a backpack. Also you may need a ski overboot to give you additional insulation over the ski boots.
Snowshoeing/Hiking - regular backpacking boots are not sufficient. They simply do not provide the necessary dead air space. The options for boots include:
Socks - one of the best systems for keeping feet warm is using multiple layers. Start with a thin polypropylene liner sock next to the skin to wick moisture away followed by 1 - 2 pairs of wool or wool/nylon blend socks. Make sure the outer socks are big enough that they can fit comfortably over the inner layers. If they are too tight, they will constrict circulation and increase the chances of frostbite. Keeping your feet dry is essential to keeping your feet warm you may need to change your socks during the day. Foot powder with aluminum hydroxide can help. High altitude mountaineers will put antiperspirant on their feet for a week bfore the trip. The active ingredient, aluminum hydroxide will keep your feet from sweating for up to a month. (Some medical research has suggested a link between aluminum and Alzheimer's Disease but small exposure currently does not appear to be a problem).
High Gaiters - are essential for winter activity. They keep snow from getting into your boots and keep your socks and pants legs free from snow.
Polarguard Booties - are very nice to have to wear in your sleeping bag at night.
Camp Overboots - are shells with an insulated bottom. These can be worn over polarguard booties for traipsing around in camp. Also for those middle of the night visits to the woods.
4. Outer Layer - it is essential to have an outer layer that is windproof and at least water resistant. In some cases it may be best to have the garment waterproof. It also needs to be able to be ventilated. There is a big trade off between waterproofness and ability to ventilate. A completely waterproof item will keep the water that is moving through your other layers trapped, adding to weight and causing some heat loss. However, in wet snow conditions, if the garment is not waterproof it can get wet and freeze. Gore-tex and other similar fabrics provide one solution. These fabrics have a thin polymer coating which has pores that are large enough to allow water vapor to pass through but too small to allow water droplets through. Nothing is perfect, however, and although Gore-tex does breathe, it doesn't breath as well as straight cotton/nylon blends. If you opt for a straight wind garment, 65/35 blends of cotton and nylon work well. The other approach is to have a waterproof garment with sufficient ventilation openings to allow water vapor to escape. This provides the ability to work in wet snow without worrying about getting the garment soaked. Part of the basis for making the decision is the area and you are traveling in. If you are in the dry snow of the Rockies you needn't worry so much about waterproofness. If you are in the northeastern mountains where freezing rain is a possibility or very wet snow, you need to be prepared to be wet.
5. Zippers - are wonderful accessories for winter clothing. Having underarm zippers on jackets can greatly increase your ability to ventilate. Having side zippers on pants can allow you to ventilate and to add or subtract a layer without taking off skis or snowshoes.
6. Miscellaneous - knickers with knicker socks can make a good combination. You have the option of ventilating by opening up the bottom of the knickers and/or rolling down your socks. Also bibs are helpful (both pile and outer waterproof layer) because they prevent cold spots at the junction between tops and bottoms. Underwear is also available in the traditional union suit design which accomplishes the same thing. Snaps on jackets etc. can be a problem because they fill with snow and ice and fail to work. Velcro works much better as a closure.
Internal vs External Frame:Internal frames tend to be better for winter use. They have a lower center of gravity and hug your body better. When skiing or snowshoeing, the weight moves more with your body allowing for greater freedom of movement. This is especially important when you are on skis. External frame packs have a higher center of gravity and tend to swing a lot, sometimes throwing you off balance.
In order to carry all the winter gear for a multi-day trip (large sleeping bag, lots of clothing layers, tents, lots of food and fuel, etc.) you need a pack with a capacity of 5,000 cubic inches or greater.
Sleeping bags for winter camping should be rated to temperatures below what you will likely experience if you want to be comfortable. If the nighttime temperature can drop to -15 F, then your bag should be rated to -30 F. There are a variety of different fills for sleeping bags: down, Primaloft, Microloft, Qualofill, Polarguard, etc. The bag itself should be a mummy style bag with a hood. It should also have a draft tube along the zipper and a draft collar at the neck. In sleeping bags, you want the bag to snugly conform to your body. If the bag is too big, you will have large spaces for convection currents and you will be cold. In a bag that has too much space, you may need to wear clothing layers to help fill up the space. You can opt for the expedition bag which is rated to -30 F or you can use a three season bag rate rated to 0 F and augment it with a vapor barrier liner (adds 5-10 degrees), a bivy sack (adds 5-10 degrees), and/or an overbag (a summer weight bag that fits over your mummy bag - adds 15 - 20 degrees -make sure it is big enough to fit over the mummy without compressing it). Keep in mind that each of these options has advantages and disadvantages in terms of price, weight, and volume taken up in your pack.
You also need to insulate yourself from the underlying snow. Foam pads (Ensolite) or inflatables (Thermarest) work well. Your insulation should be a least 1/2 " thick (two 3/8 " summer pads work well, or use a Thermarest on top of a 3/8 " foam pad). It best to use full length pads so that all of your body is insulated.
Stoves vs. Fires
In most cases you will be taking stoves and fuel for cooking. Fires are possible in some locations, but in high use areas, it is best to rely on a stove as firewood can be difficult to find in the winter. Your stove should have good heat output. In order to insulate the stove from the snow (so it doesn't melt itself into a hole) place something underneath it like a pot lid, or a piece of fiberboard. Since the burner is usually significantly smaller than the pot bottom, placing a metal pot lid on top of the burner can also help spread the heat more efficiently to the pot. Wind shields are also helpful in the winter to concentrate the heat. Priming stoves in the winter can be difficult. It is best to use alcohol or lighter fluid rather than trying to prime the stove with white gas.
Fuel - plan on 1/4 quart per person per day if you need to melt snow for water. Plan on 1/8 quart per person per day if water will be available. Make sure you have at least a day's surplus of fuel in case of bad weather, water being unavailable, etc.
Planning food for winter activities must take into account the great demands the cold weather and physical activity placed on the body along with the difficulty of preparing foods in the winter (it takes time, stove fuel) and having a menu which appeals to the group). Appetite is generally reduced during winter activity even through the food needs of the body have increased. If the meal isn't appealing, it won't get eaten. In some situations you literally need to force yourself to eat.
All foods are made up of varying proportions of the three basic food types - carbohydrates, fats, proteins, and water, vitamins and minerals. Each of the three major types can be converted into simple sugars and burned by the body to produce energy but the time required for conversion increases as the complexity of the molecule increases, so carbohydrates are quicker to convert than proteins and proteins quicker than fats.
Vitamins and Minerals - are generally found in most foods we eat and for a trip less than 7-10 days no special resources are needed. For longer trips and expeditions vitamin and mineral supplements are necessary. See a physician to get specific recommendations for expeditions.
General caloric requirements increase in the winter due to the energy expended in keeping the body warm. Caloric requirements for different activity levels are summarized below.
Activity Caloric Requirement (kg-cal/day) Basal metabolism 1,500 calories Sedentary occupation 2,500 - 3,000 calories Three season backpacking 3,500 - 4,000 calories Winter backpacking 4,500 - 5,000 calories
Keep in mind that there are definite individual variances on these figures based on age, body metabolism, health, etc.
Avoid taking fresh food in the winter (fresh fruit, vegetables, eggs). These all contain water and weigh a lot (and you have enough to carry). The exception to this is cheese, butter, or meats (needed for their high fat content). Take mostly dry foods (cereal, pasta, rice, wheat, oatmeal,) baked goods (brownies, cookies), or freeze dried foods (expensive but very lightweight and quick to cook which can save on stove fuel).
1. Breakfast - should not be a complicated meal but should be a complete one since it supplies the foundation for a full day's work. Time is also a factor since you probably want to get up and moving. Just standing around in camp in the early morning (cold) hours only leads to cold feet and bodies. Since the easiest thing to cook is water it is best to go for items which can be made in each individual's cup. Suggestions include: Instant oatmeal with hot milk & margarine, Hot Tang, Granola with hot milk, Hot Jello, Hot chocolate with extra milk & margarine.
It is best to supplement some of these items with extra powdered milk to add additional protein and margarine for fats. This is the meal to be careful not to dump too much sugar into the bloodstream at once, but rather to eat a good mix of all three major food types. The sugars will get you started and the proteins and fats will keep you going through the morning.
2. Lunch - There are two approaches to lunch on a winter trip. One is to stop for a traditional lunch and take a long break. This means cessation of activity which can lead to people getting cold. Additional layers would need to be put on and taken off. All of this adds up to a lot of time. But this also allows time for exploring an area and taking it easy. You can break out the stove and cook up a hot meal if you like. The other approach is carrying a personal lunch which can be eaten throughout the day, at scenic points, water stops, clothing breaks, etc. The second approach minimizes the amount of time people would be standing around, but also doesn't provide a mojur rest stop. In both cases you should include all the food groups by having some of the following items: meats, cheeses, nuts, dried fruit, raisins, cookies, candy, granola bars.
In the case of an "eat through the day lunch" a general formula is to take the following per person per day:
1/2 - 3/4 lb. Gorp - raisins, peanuts, M&M's, sourballs coconut, chocolate morsels etc.
1/4 - 1/2 lb. Lunch Meat and/or Cheese - cut into bite size chunks so you don't break your teeth
Other items include cookies, brownies, peanut butter, bagels, etc.
3. Dinner - It is often good to start dinner with an instant soup or a hot drink that can be made in each persons' cup. This gives some internal warmth while waiting for the main course. In the winter, the main dish is usually some form of one pot glop/stew. This is to save time and stove fuel. A glop starts with a soup or gravy base, and includes a starch (rice, noodles), some vegetables (frozen veggies keep well on winter trips), whatever protein you are carrying (lunch meat, cheese, canned chicken, tuna). This should be spiced to make it tasty. Remember, at the end of the day you will be more tired than hungry and having an interesting meal is essential to get you to eat.
The other approach to dinner is freeze-dried foods. These have the advantage of simply adding the dish to boiling water so less fuel is needed and they weigh very little. There are a number of companies offering these items. They are generally more expensive than what you would pay for basic staples like rice & noodles. Be aware of portion size. Some companies give an unrealistically high estimate on how many their meal pack will feed.
The meal is concluded with hot drinks (tang, tea, hot chocolate, jello etc.) and possibly dessert. At the end of the meal water should be melted/heated up for personal water bottles at night. (See water section below).
Dehydrated foods (which are different than freeze dried are not recommended because they require large quantities of water to rehydrate them.
4. Food for sleeping - you need to take some of your lunch for the next day to bed with you. This allows fresh items like the meat and cheese to thaw. If you wake in the middle of the night and are cold (or just before you go off to sleep) it is best to eat proteins. The protein will be broken down more slowly so the heat will be released over a longer period of time. If you eat a sugar, you will get a quick "heat high" and then your body temperature will drop back down, sometimes falling below its previous level.
5. Utensils - all the personal utensils you will need is a large plastic cup (insulated if possible) and a plastic spoon. (Do not bring metal utensils in winter). It is also recommended that you tie an idiot string between the cup and the spoon. Cleaning these utensils is generally only scraping out the remainder with snow. Anything left will be part of your next meal.
6. Food Packing - You will need to repack you food to minimize the amount of trash you bring in with you. It is best to combine food items by meal or type into separate stuff sacks (breakfast bag, lunch bag, dinner bag, hot drink & dessert bag). Label them or color code them so you can easily distinguish them.
4. WINTER WATER
5. WINTER SHELTERS
In many cases you will be traveling to areas without shelters, so you need to bring your own. There are a range of tents available. The key factors are:
Tips for Tents
Keep the following factors in mind when choosing a winter camp.
Setting up Camp
When you first get into camp, leave your snowshoes or skis on and begin to tramp down areas for tents and your kitchen. If possible, let the snow set up for 30 minutes or so, this will minimize postholing once you take snowshoes or skis off. Set up your tents with the doors at 90 degrees to the prevailing winds. Stake the tents out. On a cold night you can build snow walls on the windward side of the tent. Mound the sides of the tent with snow (have someone inside pushing out on the tent to keep it from collapsing. When the snow sets up you will have a hybrid tent-snow shelter which will have better insulation than the tent alone. Dig out a pit in front of your tent for a porch. This makes taking your boots off much easier. Put your foam pads in the tent and unstuff your sleeping bag and place it in the tent so it can "expand" from it's stuffed size.
If the snow is deep, you may want to dig out a pit for your kitchen. Dig a pit at least 6 feet in diameter (for 4-6 people). You can mark out the circle using a ski or a rope. Dig down about 2-3 feet and pile the excavated snow around the perimeter. Pack the snow at the perimeter of the hole with your shovel. This will give you a 4-5 foot deep area, protected from the wind. You can carve out seats and benches, put your skis or snow shoes behind the pile as backrests, carve places for stoves, etc.
General night sequence - after dinner, getting warm water for water bottles, and putting gear away, it's time for bed. This is a general sequence:
The following snow shelters are also useful in winter. Keep in mind that there is great potential for getting your clothing wet while constructing these shelters. You should be dressed accordingly.
Snow Mound Shelter (Quin-zhee) - If the party does not have the experience or the snow conditions aren't good for an igloo, a snow mound shelter can be made. In a selected spot, place an upright marker (ski pole, ice axe, etc.) to mark the center. Tie a cord to the marker and scribe a circle in the snow to indicate the pile size. The rule of thumb for size: if the snow in place is not to be dug out, the radius should be the interior size plus about 2 feet; if the snow in place is to be dug out, about 1 foot can be subtracted from the radius for each foot of in-place snow. Piling the snow for a two person shelter will take two people about an hour. Pile loose snow within the marked circle with shovels, tarp etc. Don't compact the snow. When the mound is the right size and shape, do not disturb it; allow it to compact naturally - minimum time one hour. Chances of collapse are greatly reduced if you let it settle for two hours. Thirty-five degrees is the natural angle at which loose snow rests. Be sure to allow the snow to settle at this angle. Otherwise you will have thin spots or a buckling roof when you excavate the interior. After compaction you are ready for digging. The entrance direction should be away from the prevailing incoming weather. From the entrance point start digging toward the marker. Pass the snow out to helpers. As soon as you reach the marker, do no not disturb it. This is your guide for excavating the interior. Clear out the inside to the intended radius. To check on wall and roof thickness, measure with a stick poked through. When the dimensions check, remove the marker and trim the interior. Then install a vent in the roof. Get rid of waste snow promptly before it hardens. The process is a wet one so make sure you have waterproof gear on and good shovels for making the mound and digging out.
Snow Cave - A snow cave can be dug into a hillside. Dig the entrance up so that the door is below the sitting level. Also there are natural snow caves formed by the overhanging branches of trees covered with snow. By digging down you can get into the cave beneath the branches. In both cases you should poke a ventilation hole and keep it clear.
Igloo - can be constructed if there is snow of the proper consistency to pack into hard blocks. Keep in mind that building such a shelter takes a great deal of energy and time. Two skilled persons can build a two person igloo in 2-3 hours with proper equipment and good snow. Obviously several such structures would need to be built to hold a larger group. Building an igloo is a process that requires a certain amount of artistry, but is less of an energy expenditure than a snow mound shelter. In general, rectangular blocks roughly 24" by 18" by 6" are cut and stacked in an ascending spiral. The rectangular blocks are placed vertically and the bottom shaped so that only the two bottom corners are supporting the block. Then the block is tilted inward and the vertical edge contacting the adjacent block is cut away until the weight of the block rests only on the upper corner. The weight of the block is supported by the diagonally opposite corners, while the third corner prevents rotation. Once the first row is laid you shave off the tops of several blocks ( 1/4 - 1/3 of the circumference) to create a ramp and build upward in a spiral. Once the structure is complete, snow is packed into all the open joints. (See the Off Belay reprint Igloo.)
Snow Pit - This structure can be created by digging a trench in the snow down to ground level (if possible). The structure should be a little longer than your body and 3 - 4 feet wide. Line the bottom with insulative material to insulate you from the cold ground (in an emergency you cna use 5-6 inches of evergreen boughs). A roof can be made of skis and poles or overlapping boughs and sticks then covered with a tarp and then loose snow or blocks of hard pack snow. The doorway will be a tunnel in from the side. This can be plugged with a door of hard pack snow. A ventilation hole must be poked into the roof for air flow. Keeping a stick in this hole and shaking it every so often will keep the hole open. If possible, the entrance should be lower than the level of the trench, this keeps the coldest air in the entrance rather than in the trench.
6. MINIMAL IMPACT CAMPING IN WINTER
Winter generally provides a blanket of snow which protects underlying soil and vegetation, the major concerns for minimizing impact. However, when thin snow cover is compressed and compacted in early or late season, snowmelt can be delayed, shortening the growing season. Also, early and late winter trips can run into melting conditions, where top layers of soil melted by the sun lie overtop frozen ground. Erosion, and destruction of plant life is extremely likely at these times, and winter travel is best avoided. Otherwise travel in small groups and visit either remote places where your disturbances won't be compounded by others following you (allowing for recovery) or high impact areas that have already been disturbed. Special considerations exist for high altitude and glacier conditions (see Soft Paths).
Backcountry travel and camping
7. WINTER TRAVEL
Travel in the winter depends a lot on what form of locomotion (feet, snowshoes, skis). There are some general travel techniques that are applicable to all forms of winter travel.
Coming up to a frozen or snow covered lake in the middle of winter raises sudden safety questions for winter travelers whether you are on foot, snowshoes, or skis. Will the ice hold? What happens if I break through? Here is a collection of information to help with both of these questions.
(temperatures based on fresh water)
As surface water on a stream or lake is chilled by the low atmospheric temperature, the water contracts and sinks to the bottom where it is chilled to the point of the greatest density of water, where molecules are packed as closely as it is possible for them to be. This critical temperature is 39o F (4oC). The dense, cold water sinking to the bottom displaces water at a higher temperature which rises to the top. Thus vertical convection currents are produced. This process continues until the entire body of water reaches 39o F. Then the water can no longer sink. Instead it is progressively cooled at the surface. As the water chills below 39o F it starts to expand, until at 32o F (0o C) it changes state and becomes a solid by expanding into a lattice structure that is lighter than the liquid state. From the description of this process, it is clear that flowing water will require a greater length of time to freeze than still water and that shallower depths near the shore of any body of water will reach a uniform 39o F sooner. Thus, ice on a small pond that can support a person's weight cannot be used to gauge the safety of ice midstream or in the middle of a lake.
Generally the first type of ice to form on a lake is called black ice. This is a misnomer because the ice itself is clear-it is the water seen through the ice that looks black. If a prolonged spell of clear, cold weather occurs after the lake first freezes, this black ice initially grows quite rapidly. However, as is thickens it insulates the water underneath from the atmospheric temperature, and ice growth slows.
As snow accumulates on the lake, the stage is set for a major change in the characteristic of lake ice. The snow cover, when it's deep enough, begins to exert downward pressure on the black ice, and pushes it beneath the hydrostatic water level of the lake. If a period of cold weather follows, thermal contraction of the black ice produces cracks, which allow the lake water to rise up and flood the surface. This is called a slushing event.
Since the lake is under pressure it spills out, and as it freezes, turns the snow cover to ice. The new ice layer contains many air bubbles between the snow crystals and therefore appears white. This white ice forms on top of black ice, and with further snowfalls and cold periods, the process may be repeated throughout the winter. When struck white ice gives a solid sounding "thump."
Because of the close link between snow accumulation and white ice production, it's not surprising to find a predictable pattern of ice types on a lake. Snow in the center of a lake may be redistributed onto the downwind sides of the lake and along the shoreline. Thus, it's not surprising to discover that these area also have the greatest thickness of white ice. A lake's snow cover is frequently much thinner than the surrounding shore's due to removal by wind and conversion of snow to white ice during slushing events, and may be a preferred route for snowshoers or skiers.
The following are guidelines which will help you determine which routes to follow across a frozen body of water.
Ice Safety and Rescue
As a general guideline, 1 inch of black or white ice will probably hold you up. Two inches is safe, and six inches will hold up a moose. Thickness of suspect ice can usually be determined quite quickly by using an ice axe or auger to drill through. However, for advanced trip planning, you can use the following formula to estimate the thickness:
Z = ice thickness in inches S = degree days accumulated below 32 oF A = a coefficient which varies as follows: (.8) - windy lake with no snow (.5 to .7) - average lake with snow cover (.5 to .7) - average river with snow cover (.2 to .4) - sheltered small river with rapid flow
S is calculated as follows: Suppose ice is formed December 15 and the mean temperature for December 16 was 5 oF. To find degree days, subtract 5o F from 32o F for a value of 27. If on December 17 the temperature is 4o F, subtract 4o F from 32o F for a value of 28. S would then have a value of 55 by December 17
(27o F + 28o F = 55). Next take the square root of 55 (7.4). To determine ice thickness, multiple 7.4 by the appropriate coefficient A (say .8 for a windy lake with no snow), and your answer is 5.9 inches of ice.
If you don't know the date of ice formation, you can estimate by the following technique:
AMC Guide to Winter Camping, Stephen Gorman, AMC Books, Boston, 1991.
Winterwise: A Backpacker's Guide, John Dunn, Adirondack Mountain Club, 1988.
Winter Hiking and Camping, John Danielson, Adirondack Mountain Club, 1982.
Outdoor Emergency Care, Warren D. Bowman, National Ski Patrol System, 1988.
Soft Paths, Bruce Hampton and David Cole, NOLS, 1988.
Snow Caves for Fun and Survival, Ernest Wilkinson, Johnson Books, Boulder, 1992.
Outdoor Action Winter Camping Leader Training Notes
Insulation - the Thick and Thin of It, Backpacker Magazine #36
Food for Winter Mountaineering, Appalachian Mountain Club Winter School
Clothing for Winter Mountaineering, Appalachian Mountain Club Winter School
Patagonia Products Literature
Igloo, Off Belay Magazine Reprint, 1975
Getting Winter Water, Backpacker Magazine, January, 1983.
NOLS Minimal Impact Camping Practices
The information on ice crossings is taken directly from the following two articles.
How Thick Should the Ice Be?, Douglas Ayres Jr., Adirondac Magazine, January, 1987.
How Safe Is That Ice?, Keith Nicol, Backpacker Magazine, January, 1983. Graphics are scans of the accompanying illustrations by Peter Thorpe.
Winter: An Ecological Handbook, James Halfpenny and Roy Douglas Ozanne, Johnson Books, Boulder, 1989.
A Guide to Nature in Winter, Donald W. Stokes, Little Brown, Boston, 1976.
Types of Avalanches
Loose Snow Avalanches - These start from a single point incorporating more and more unconsolidated snow as they fan out. They are caused when the weight of new fallen snow succumbs to the forces of gravity. This occurs most often after periods of heavy snow (10-12 inches accumulation, or snowfall or 1 inch or more per hour) especially when piled on top of a smooth snow surface (from thawing, freezing, or rain) The smooth snow surface provides a slick ramp for the heavy new snow to run down.
Slab Avalanches - Are caused when well compacted and cohesive layers of snow aren't anchored to the slope. If there is a weak layer of snow underneath the compacted layer, the slope is primed to avalanche. Various forces, sun, wind, or a person can trigger the slab at the release zone.
Avalanche Sites - Open slopes between 25 and 45 degrees. Especially lee slopes (the direction toward which the wind is blowing) which get greater snow loads.
Crossing Avalanche Zones
AMC Guide to Winter Camping, Stephen Gorman, AMC Books, Boston, 1991.
The Avalanche Book, Betsey Armstrong and Knox Williams, Fulcrum Publishing, Golden, CO, 1992.
The ABC's of Avalanche Safety, E.R. LaChapelle, The Mountaineers, Seattle, WA, 1985.
Types of Snowshoes
There are a number of general types of snowshoes. The major design features are the following:
The particular size of the snowshoe depends on the weight of the person (including pack), the terrain, and the snow conditions. Cold, deep powder requires more flotation than hard pack. Open country allows for longer, faster snowshoes; deep forest or steep areas may require shorter, more maneuverable snowshoes. Keep in mind that smaller people will need narrower shoes otherwise they have to straddle too much. This can lead to an injury known as mal raquette which is inflammation of the front hip tendons.
Current snowshoes are either wood with neoprene lacing or aluminum frame with a plastic decking. The aluminum models are very strong and lighter weight than wood models. The decking also provides superior flotation over an equal area of laces. Remember that 1 pound on the feet is like 5 pounds on the back. So go with the lightest model that fits the conditions.
The two major bindings are the H Binding which wraps over the toe and the Super A Binding. The Super A binding is easier to put on and much sturdier. The H Binding allows too much foot play. The toe of your boot should fit through the toe hole of the snowshoe without catching (going out or coming back). In cases where you are going on hard pack snow or ice, you should have some form of snowshoe crampon attached to the snowshoe under the ball of your foot for traction. Aluminum snowshoes often have such a traction device built in.
Rising on the ball of your foot while going uphill tires the calf muscles. But letting the heal sag down flat on the snowshoe stretches the muscle. Either produces some leg fatigue. Alternating between the two may reduce repetitive stress syndrome. Stretching before travel, especially the hamstrings, will help reduce the chances of injury.
Wooden snowshoes can be splinted like a bone fracture using wood and lacing. Broken lacing can also be repaired.
Snowshoeing, The Mountaineers Books, Seattle.
Outdoor Action Handouts
Outdoor Action Winter Camping Personal Equipment List
Outdoor Action Winter Camping Group Equipment List
Winter Environmental Hazards
Winter Camping Trip Teaching Plan
All of the above can lead to Hypothermia, Frostnip, Windchill, Frostbite, Frozen Eyelashes/cornea
The general plan for the trip will be to hike in on snowshoes and set up a basecamp. Day trips and will be done from the basecamp which may include snow cave and igloo construction, cross-country skiing, ice axe self arrest training, roped climbing techniques, crampon techniques, and a peak ascent.
Snow Travel Techniques
Ice Axe & Crampons
* Available from Outdoor Action
_____ * Wool/Pile Balaclava
_____ Silk Balaclava (optional - for sleeping)
_____ * Leather Face Mask
_____* Ski Goggles or Glacier Goggles with side screens
_____ 2 Long Undershirts - polypropylene
_____ Vapor Barrier Shirt (optional)
_____ * Wool/Polypropylene/Pile Shirt - medium weight
_____ * Wool/Pile Sweater or Jacket - heavy
_____ Wind Jacket with Hood - 60/40, nylon, Goretex-will double as rain jacket
_____ *Winter Parka with Hood - synthetic fill, nylon or Gore-tex outer
_____ Glove Liners - synthetic, polypropylene
_____ Wool Gloves
_____ * Wool/Synthetic/Pile Mittens
_____ * Mitten Shells (not needed if above mittens are shelled)
_____ Long Underwear - polypropylene - light to medium
_____ Vapor Barrier Pants (optional)
_____ * Wool/Pile Pants/bibs or Knickers - heavy
_____ * Wind Pants - nylon (Goretex-doubles as rain pants)
_____ Overpants - insulated, synthetic fill ski pants (optional)
_____ Liner Socks (thin) - polypropylene - 2+ pairs
_____ * Vapor Barrier Socks
_____ Wool/Pile Socks (heavy) - 4+ pairs (knicker socks if knickers)
_____ * Mickey Mouse Boots or Mountaineering double boots + overboot
_____ * Gaiters - coated nylon, large to fit over Mouse boots
_____ * Polarguard/Down Booties
_____ * Camp Overboots
_____ * Cross-Country Ski Boots (if skiing)
_____ * Ski Overboots (if skiing)
_____ Rain Jacket - nylon, Goretex - must fit over stacked layers
_____ Rain Pants - nylon, Goretex - must fit over stacked layers
Pack & Packing:
_____ * Large External Frame Pack - with frame extension or Large Internal Frame Pack (4500+ cubic inches)
_____ * Stuff Sacks of all sizes - all equipment in stuff sacks
_____ Pack Raincover
_____ * Snowshoes with binding & snowshoe crampons
_____ * Ski poles - 1 pair
_____ * Ice Axe
_____ * Crampons with binding and point protectors
_____ * Skis and boots (if skiing)
_____ * Synthetic/Down Sleeping Bag - rated to -15 or to 0 with overbag and/or vapor barrier liner, if down should have Gore-tex shell,
_____ * Ensolite Foam Pad - 1/2" or Thermarest Pad
_____ Plastic Cup - double walled recommended
_____ Plastic Spoon - should be tied to cup
_____ * 2 1 Quart Water Bottles - plastic, wide mouth, cap retainer should be outfitted in small stuff sack with webbing loops
_____ 1/4 - 1/2 pound meat & cheese per day
_____ 1/2 - 3/4 pound gorp per day
_____ Day Pack - for carrying extra clothing, water, lunch, camera, doubles as stuff sack
_____ * Flashlight - headlamp best, with lithium (best) alkaline (ok) batteries (workbetter in cold)
_____ Belt or suspenders
_____ Bandanas - the ultimate useful item
_____ Extra Glasses, Sunglasses, Glasses Strap, Antifog
_____ Toilet Articles
_____ Any Medications needed during trip
_____ Camera, film, books, games, paper & pen, etc. (optional)
_____ Cough drops or sour balls
Contact lenses can be a problem! Zipper pulls on all clothing and pack zippers. All clothing must be clean. Idiot strings on all mitts/shells. Nonfreezing laces on all boots. Defog all glasses and goggles. Develop method for hanging water bottles on body. Adjust and mark boots, snowshoes and skis before leaving. Figure out how you carry snowshoes or skis on your pack if the need arises. Figure out clothing arrangements: How will you organize glasses & face mask & balaclava ?
Additions to standard trip Group Equipment List
_____ Winter tent with fly
_____ Snowstakes for each tent (may need regular stakes e.g. Chouinard depending on conditions)
_____ Wisk broom - one per tent, one for Quinzee
_____ Thermos (metal) - one per tent
_____ Spare tent poles
_____ Stoves - Optimus 111 MF or MSR X-GK - 2/group of 8
_____ Fiberboard with ensolite stove platform - 1/stove
_____ Large nesting pots with lids - 1/stove
_____ Small nesting pots withlids - 1/stove
_____ Pot grippers - 2
_____ Fuel bottles with Fuel - figure 1/2 pint/person/day - ADD 1 EXTRA BOTTLE FOR EMERGENCY
_____ Funnel - 1/stove
_____ Plastic cooking spoons, other utensils
_____ Dip Cup
_____ Waterproof matches - strike anywhere - large supply
_____ Garbage Bags
_____ Screwdrivers - regular, phillips, posidrive (if ski)
_____ Ripstop & Duct tape - lots
_____ Sewing awl and heavy thread
_____ Regular needles and thread
_____ Hose clamps - 4
_____ Parachute cord - many yards
_____ 1/4" waterproof rope - 100 ft.
_____ Extra snowshoe binding
_____ Neoprene straps
_____ Epoxy glue - something good down to low temperatures
_____ Pack repair parts
_____ Stove repair parts
_____ Pole patch kits - 2 (ski or tent)
_____ Spare bails for XC bindings (if skiing)
FIRST AID KIT: (ADDED TO STANDARD FIRST AID KIT LIST)
_____ Throat lozenges
_____ Antacid tablets
_____ Heavy space blankets - 1
_____ Heat packs
_____ Hypothermia thermometer
_____ Snow shovels - 2 - packable
_____ Ice hammer (1-2)
_____ Goretex bivy sack
_____ Spare ski pole
_____ Lots of parachute cord
_____ Signal mirror
_____ Extra sleeping bag straps
_____ Oil lantern - 1/tent, oil
_____ Extra batteries/bulbs for headlamps
_____ Toilet paper & lots of ziplocks
_____ Alarm clock
_____ Extra spoon
_____ Extra garbage bags
_____ Guide book(s) & Maps
_____ Snowsaw - inside snow shovel (2 if igloo planned)
_____ 2 Throw bags with 1/4" polypropylene rope - 1 (for ice rescue, snow belays)
_____ Food - group gorp and extra days rations
_____ Clothing - balaclava, pile/wool pants, pile/wool mittens, goggles, face mask
DAY TRIP/SUMMIT EQUIPMENT:
Day packs - each person with appropriate extra clothing, food, water technical gear (ice axe,
crampons etc.), face mask, goggles, headlight - figure out how to get snowshoes, ice axe, crampons on
day packs if necessary - have enough straps. Extra Gear to be carried by group members:
_____Sleeping bag _____75 feet 1/4" rope _____Small ensolite pad _____Extra Balaclava _____Bivy sack _____Altimeter for peak climbs _____Heat Packs _____Extra mittens _____First aid kit _____Thermos _____Stove with fuel _____Pot with lid _____Matches _____Compass _____Map _____Shovel _____Candle _____Knife _____Whistle (each person)
VAN CHECK PRE-TRIP:
_____ battery _____ snowtires _____ oil _____ antifreeze _____ brake and transmission fluids _____ lights
_____ chains _____ flare kit _____ extra antifreeze _____ jumper cables _____ scraper _____ shovel, and sand
_____ have gas tank full _____ disconnect batteryThis page is maintained by Rick Curtis Director, Outdoor Action Program. Rcurtis@.princeton.edu
Copyright © 1995 Outdoor Action Program, Princeton University.