Winter Camping And Backpacking

Transcription

1 Winter Camping And Backpacking Cold Weather Dangers Hypothermia - is a condition in which core temperature drops below the required temperature for normal metabolism and body functions which is defined as 95.0 F. Frostbite - is the medical condition where localized damage is caused to skin and other tissues due to extreme cold. 1

2 Deciding What to Bring Check the local weather forecast for the time period you will be in the backcountry wet, dry, wind, temperature extremes. Consider where you will be going in the backcountry water front, mountains, alpine. In dry weather, the temperature drops about 5.5 F per 1000 feet in elevation gain (3.2 F for moist weather). Consider how long you will be in the backcountry. Consider your own sensitivity to low temperatures. Consider the extent of your physical exertion at the end of the day. Mechanisms of Heat Loss Conduction Convection Radiation Evaporation Respiration Combination of convection and evaporation 2

3 Insulation Thermal conductivity, k, is the property of a material's ability to conduct heat. Heat transfer across materials of high thermal conductivity occurs at a higher rate than across materials of low thermal conductivity. Materials of low thermal conductivity are used as thermal insulation. Thermal conductivity Material [W/(m K)] Vacuum 0 Water (vapor) Air (sea level) Silica Aerogel Polyurethane Foam Feathers Fiberglas Wool Polystyrene Foam Cotton 0.04 Hollow Fill Fiber Insulation Paper Polyester 0.05 Straw 0.05 Felt 0.06 Wood Mineral oil Particle Board 0.15 Neoprene Rubber 0.16 Snow 0.16 Polypropylene 0.25 Teflon 0.25 Sand 0.27 Cement, Portland 0.29 Water (liquid) Thermal grease Glas s 1.1 Soil 1.5 Concrete, stone 1.7 Water (ice) 2.2 Sandstone 2.4 Mercury 8.3 Stainless steel 14 Titanium 21.9 Lead 35.3 Steel Iron 80.2 Aluminum 237 Gold 318 Copper 401 Silver 429 Diamond 895 Insulation Thermal resistivity, R, is the product of the material thickness and reciprocal of the thermal conductivity. Good thermal insulators have large R values. An insulating material will have a large R value when the thermal conductivity of that material is small and the thickness is wide. In layered materials, R-values can be added. 1 t R t k k 3

4 Insulation 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. 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. The Layering Principle The key to providing this dead air space is through having a number of layers of clothing. 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. 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. So you want to control your layers so as to be warm at the activity level you are in but not sweating profusely. 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. 4

5 The 3 Layer System The Base Layer - wick moisture away from the body allowing you to remain dry and warm. The Middle Layer -provide thermal protection from the wind and the cold. The Outer Layer -protect against rain and wind, but allowing you to breath. Extremities - heads, hands and feet. Up to 40% of the bodies heat can be lost through the extremities. No Cotton - Cotton Kills! Cotton is basically useless in winter time. Problems with cotton occur when the cotton gets wet. Cotton absorbs this moisture and the water occupies the space previously occupied by dead air. When water occupies the space previously occupied by dead air, cotton loses all insulating properties. Because cotton holds so much moisture, it can hold that moisture against your body and sap body heat from you by high evaporative cooling and conduction. This can quickly lead to hypothermia. A cotton garment is almost impossible to dry out. Cotton becomes abrasive when wet. 5

6 Natural Fibers Silk loses its insulating properties when it gets wet and does not wick like modern hydrophobic fabrics. Wool insulates relatively well when wet. But while some weaves do shed water for a period of time, it will eventually absorb a great deal more moisture than comparably weighted synthetic garments and become very heavy. All of these natural fiber fabrics take much longer to dry once wet than comparably weighted synthetic fabrics. Base Layer Light Weight Capilene 2 Medium Weight Capilene 3 Expedition Weight Capilene 4 6

7 Mid (Insulating) Layer Fleece, made from polyethylene or other synthetics has many of the features of wool, but is lighter. It provides good insulation even when wet, absorbs very little moisture, and dries quickly. 100 Weight 200 Weight 300 Weight Mid (Insulating) Layer Down Fill has very good warmth to weight ratio, and can be packed down (squeezed) to take very little room. It is expensive, makes a thick garment, dries slowly, loses its insulating properties when wet or compressed, and stops lofting properly after being washed several times. 7

8 Mid (Insulating) Layer Fill power is a measure of the loft or "fluffiness" of a down product that is loosely related to the insulating value of the down. The higher the fill power the more insulating air pockets the down has and the better insulating ability. Fill power is expressed as cubic inches per ounce (in³/oz). Fill power ranges from about 300 in³/oz for feathers to around 900 in³/oz for the highest quality down. A lofting power of is considered medium quality, is considered good, is considered very good, and 750+ is considered excellent. Technically speaking fill power is a measurement of the amount of space one (1) ounce of down (as shown on the right) will occupy in cubic inches when allowed to reach its maximum loft. For example, one (1) ounce of 800 fill power goose down will loft to 800 cubic inches. The higher the fill power the larger the down cluster. Larger down clusters will loft higher, last longer and sleep warmer. Mid (Insulating) Layer Synthetic Fill is polyester fiber (such as Polarguard, Hollofil, Quallofil) used similarly to down, but does not have as good a warmth to weight ratio. It is less expensive, provides good insulation (fairly efficient at providing dead air space though not nearly as efficient as down) even when wet, dries quickly, and absorbs very little moisture. Over time with repeated compressions, the fibers become damaged and become less effective as an insulator. Primaloft - the principal behind super thin fibers is that by making the fiber thinner you can increase the amount of dead air space in a given volume of material. Other super thin fibers include Microloft and Thinsulate. Down Primaloft One 8

9 Shell Layer Hard Shell these materials are waterproof and somewhat breathable. Their essential element is a thin, porous membrane that blocks liquid water, but lets through water vapor (evaporated sweat). The more expensive materials are typically more breathable. The best-known brand is Gore-Tex. All rainwear exteriors (also known as face fabrics) are treated with a durable water repellent (DWR) finish. Even rainwear classified as water-resistant (which includes soft shells) carries a DWR finish. Shell Layer Soft Shell these are water resistant materials only partially block water. On the other hand they are usually more breathable and comfortable than hard shells. Soft Shells use sophisticated stretch woven fabrics (Schoeller, for example) with tight layered weaves and durable water repellent (DWR) treatments to guard against wind, rain, and snow in all but the most severe weather conditions. 9

10 Foot Wear Insulated Boots Waterproof, synthetic fill, heel lip for snowshoes & crampons. Plastic Mountaineering Boots plastic shell mountaineering boots use inner boots made with wool felt or closed cell foam insulation. These can be very warm and easily used with ski bindings, crampons, and snowshoes. Depending on the inner boot, you may need insulated over boots to add enough insulation to keep your feet warm. High Gaiters Waterproof and breathable fabric Socks wool or synthetic Microspikes Snowshoes More Foot Wear Down Booties Camp Slippers Insulating Insoles 10

11 The Rest Gloves and Mittens Head protection Face protection Poles with Snow baskets Glacier glasses with side protection Goggles Sleep System Pad Always use a pad under your sleeping bag in the winter. Many people suggest two pads. One should be a full length 1/2" thick closed cell foam pad. The second pad can be either a closed cell pad or an inflatable pad. Insulating yourself from the ground is more important than insulating yourself from the cold air. THERMAREST INFLATABLE PADS: 2.0" Luxury Edition: 4.1 R-value 1.6" Camplite: 4.1 R-value 1.5" Guidelite: 3.8 R-value 1.0" Ultralite: 2.6 R-value 1.75" Standard: 5.8 R-value 2.0" Basecamp: 6.1 R-value 1.5" Explorer: 4.7 R-value NeoAir All Season: 4.9 R-value THERMAREST CLOSED CELL FOAM PADS: 0.75" Z-Rest: 2.2 R-value 0.75" Ridge Rest Deluxe: 3.1 R-value 0.625" Ridge Rest: 2.6 R-value 0.44" Ling Rest: 1.9 R-value 0.75" Ridge Rest Solar: 3.5 R-value 0.375" (3/8") Gossamer Gear Thinlight Insulation Pad Made of Closed Cell Evazote Foam: 1.42 R-value 0.375" (3/8") Blue Closed Cell Foam (quality varies, but best has 9 % EVA (Ethylene Vinyl Acetate): 1.35 R-value Camplite " Thinlight Closed Cell Foam Pad: 5.5 R-value NeoAir All Season " Thinlight Closed Cell Foam Pad: 6.3 R-value EXPED DownMat 9: 8.0 R-value 11

12 Sleep System Sleeping Bag 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. EN 13537:2002 Requirements for Sleeping Bags is the official European Standard for the testing and labeling of sleeping bags. Couples often want to be able to sleep together. If a couple sleeps close together, say spooned, they should be comfortable in temperatures which are F colder than they would be comfortable in under the same insulation without someone else. Sleep with a stocking cap or balaclava on your head to help hold in your body heat. Cinching up your mummy bag so that only your eyes, nose, and mouth are exposed is another way to hold in heat. Don't breathe inside your sleeping bag at night. Moisture from your breath will wet your sleeping bag and reduce its insulating ability. Methods You Can Use To Improve the Bag Rating You can opt for the expedition bag which is rated to -30 F or you can use a three season bag rated to 0 F and augment it with: A vapor barrier liner (adds 5-10 degrees) Vapor barrier liners should only be used in temperatures well below freezing. A bivy sack (adds 5-10 degrees) An overbag (adds degrees) An overbag is a summer weight bag that fits over your mummy bag. Make sure it is big enough to fit over the mummy without compressing it. Also, you can supplement performance by wearing clothes and booties to bed. Keep in mind that each of these options has advantages and disadvantages in terms of price, weight, and volume taken up in your pack. 12

13 Shelter 4 Season Tent Strength to withstand both wind and snow. Four season tents typically have stronger poles to hold snow loads and extra tie downs to hold up in high winds. Ability to shed snow - the tent must have a roof line that allows snow to fall off. Room - you need lots of internal space on a winter trip for all the bulky gear you are carrying. Single vs. Double Wall Snow Stakes On snow set tent stakes deadman style. Tie into the center of the stake then bury it horizontally in snow or under rocks. The line and stake together should make a T. Be sure to bury the stake several feet deep or the stakes will melt out! Buried snow stakes might get frozen in the snow ice axe comes in handy for extraction Snow Shovel Prepare a spot in the snow for the tent Igloo Shelter 13

14 Snow Cave Shelter Stoves Compressed gas vs. white gas Use canisters in liquid feed mode (in other words, the canister is used upside down) Use a wind screen Use a base hot stove will sink into snow Don t set a pot in the snow and then put on the stove flame; you may snuff it out permanently 14

15 Stoves Compressed gas stoves systems are generally lightweight, more compact, quick to set up, and do not require priming (white gas stove). Cold causes less pressure inside the canister, causing less ability for the fuel to vaporize. The cold, not the altitude causes canister fuels to rapidly decrease in performance (Altitude can actually aid in the vaporizing of the fuels). You can warm the canisters by sleeping with them in your sleeping bag, or you can just elect to use a white gas stove system. Pure butane (n-butane) canister fuels do not work below 32 F. A canister of isobutane fuel can work at temperatures above 21 F. Pure propane will work at temperatures below 0 F. Propane requires a heavier gauge container that is too heavy for use in backpacking. Most canister fuels contain a mix of propane and isobutane to boost the performance in colder temperatures. Examples of these fuels are: Jet Boil JetPower (25% propane, 75% isobutane), MSR IsoPro (20% propane, 80% isobutane), Snow Peak Giga Power (15% propane, 85% isobutane) and Coleman Powermax (35% propane 65% n-butane). Note that the Powermax fuel has been discontinued. Water Bottles and Insulated Jackets The cap on the Hunersdorf bottle gives you more benefit in multiple ways. First, it is made out of the same pliable material as the bottle body and will not crack or split in extreme cold. Secondly, a Hunersdorf cap is much larger, has a much wider and thicker thread pattern, and has large ribs on the outside for ease in gripping (even with gloves or mitts on). The thicker threads aid in clearing ice on a frozen bottle such that they are much easier to open when frozen. Water bags or bladder systems may freeze. If your tent is set up on the snow, don t leave water bottles (even if they are in insulated jackets) in contact with the floor of the tent all night; the water will freeze solid! Put water bottles in your sleeping bag; make sure the lids are tight! Don t count on finding liquid water. It may all be frozen. You can melt snow in a cooking pot. Have a designated large stuff sack to scoop snow into for hauling that back to camp. This allows for using cleaner snow than from the immediate area around your camp. Take a larger pot than usual (2.5 liter) since a large volume of snow will need to be melted to get a useful volume of liquid water. If you have some liquid water already, start heating it and add snow gradually. This prevents scorching the pot before liquid starts forming. If there is liquid water available and you try purifying it with a filter pump, the pump may freeze at lower temperatures becoming useless. Water can also be purified chemically or by brief boiling. 15

16 Batteries Alkaline batteries stop providing power at very low temperatures while Lithium batteries continue to provide power down to -40 F. Lithium batteries weight about 40% less than alkaline batteries. While in use, lithium batteries last longer than alkaline batteries. Lithium batteries have more than 2 times the shelf life over alkaline batteries. Energizer AA Batteries Specifications Not This This Type Operating Temperature Range ( F) Weight (oz.) Shelf Life at 70 F (Years) Low Drain Service Hours* (50 ma Continuous at 70 F ) High Drain Service Hours** (1000 ma Continuous at 70 F ) Alkaline 0 to Lithium -40 to *Lithium lasts 1.3 times longer **Lithium lasts 4 times longer Hauling Your Gear Large Backpack Pulk (Sled) 16

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