The sleeping bag is designed to eliminate drafts. You will sleep warmer in a bag than you will with blankets of equivalent weight. Sleeping bags come rated for temperature, and in a variety of shapes, sizes, and construction. A mummy bag is warmer than a rectangular bag due to less heat loss around your feet and shoulders. Most mummy bags also come with hoods, as up to 70% of your body heat is lost through the top of your head. While warmer, mummy bags take some getting used to. For example, it's a little harder to roll over in a mummy bag -- you'll have to roll the whole bag!
The outside fabric, or shell, of the bag is often made of nylon. Loft (space to hold heat) is created by filling the shell with a variety of natural or synthetic materials. Partitions sewn into the shell hold the filler material in place. In less expensive bags, the partition seams may go straight through the shell, which makes it easy for cold air to creep in. In better bags, mesh or nylon walls, or baffles, divide the shell into compartments that keep the fill evenly distributed without lessening the loft, thus preventing cold spots. The best bags also have tubes of fill material backing the zippers to keep warm air in, and will probably have insulated hoods that can be drawn tight around the sleeper's face.
Bags come temperature rated for 45°F to -10°F and beyond. It is possible to add range to a less expensive bag by adding a cotton sheet (-5°) or a flannel sheet (-10°), or by sleeping in sweats (-10° to -15°). A tarp or extra blanket added around the bag will make it even warmer. Matching the range of the bag you buy to the temperature you expect to use it in the most is very important. It is also important to change into clean, dry clothing before getting into your sleeping bag. Moisture on your body from a busy day will quickly cool you and your sleeping bag down, which may make it very difficult to sleep comfortably. A stocking cap is a must, unless your bag has a hood already. Small bodies in long bags will be warmer if the bottom of the bag is folded up and tucked under.
If you don't have a bag, you can make an envelope bed using two blankets
and a ground cloth. Lay the first blanket on top of the ground cloth
(half on and half off). Put the second blanket half on and half off
the first (in the opposite direction). Fold the first blanket into
the second, then fold the remaining half of the second on top of the first.
You should have four interlocked layers -- two for the top, two for below.
Fold the bottom of the blankets up to size, and secure with large clips
or blanket pins.
Sleep Bag Terminology
Box Wall - Prevents fill from moving around inside the shell.
Double Quilting - Two quilts fastened together in an offset manner to eliminate cold spots. Material tends to be heavier.
Goose down - Actual feathers from geese, grown next to the skin. Ounce for ounce, the best insulator, but it is very expensive, and when it is wet, it will lose its loft and will not keep you warm. Requires careful laundering.
Ground cloth - Commercially available, or 4- to 6-mil plastic, an old shower curtain, or a water bed liner will work. This will be your moisture barrier from the ground, and is essential.
Overlapping tube or V-baffle - Very efficient, but tends to be heavy.
Simple Quilting - Loses heat where stitching passes through the fabric.
Slant Wall - Prevents down from moving around and gives it room to expand.
Synthetic fibers - Made from petroleum by-products by a variety
of manufacturers. Heavier than an equally rated down bag, but will
retain its insulating value when wet. They are easier to clean and
quite economically priced.
Sleeping Bag Construction (Sections through wall of bag
illustrate how filling is kept in place.) (Graphics taken from www.mec.ca.)
|Sewn-Through or Simple Quilting (Synthetic or Down bags)
- Loses heat where the stitching passes through the fabric.
- Used in lightweight or warm-weather bags.
- Inexpensive to construct
- Cold spots at quilt lines.
|Offset Quilt or Double Quilting (Synthetic bags only)
- Two quilts fastened together in an off-set way to eliminate cold spots.
- Material tends to be heavy.
- No cold spots at quilt lines.
- Less expensive than shingled construction.
|Shingles or Slant Wall (Synthetic bags only)
- Most warmth-to-weight efficient construction.
- More expensive than offset quilt construction.
- Gives it room to expand.
|Baffles (Down bags only)
- Mesh partitions at quilt lines prevent cold spots and keep down from migrating through bag.
- Expensive, but very warm.
Caring For Sleeping Gear
If you expect wet weather, place your sleeping bag in a garbage liner before stowing it in its stuff sack. After your trip, and on nice days during extended trips, air out your bag thoroughly. Hang it in a closet or store it in a loose cloth sack to preserve the loft of the fill material. Clean it when it becomes soiled, according to manufacturer's instructions. Use of a bag liner will extend the life of the inside of the bag. Many campers find that the convenience of a light bag outweighs the use of sheets and blankets. Take care of it, and it will take care of you! Your sleeping bag is probably the most important piece of camping gear you will own. If you don't sleep well, the rest of the trip will not be fun.
Disclaimer: Taken from "Appendix G", but the original
source is unknown. If this is your copyrighted material, I will give
you credit or take it off the site. Thank you.
Last Updated: 07/28/2005
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