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Sleeping bags
Wanna have sweet dreams?
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No matter where you trek or what outdoor activity you pursue, your comfort at night depends mostly on the choice of sleeping bag you use. It will become a constant companion, and a welcome refuge at night. Like many other items, a shrewd choice will greatly appreciate your enjoyment of trekking, so that while others shiver the night away, you can wake warm and refreshed in the morning. Nothing beats snuggling down inside a trusty bag as the splash of rain or the patter of snow beats a rhythm on your tent’s flysheet.
A sleeping bag is made of three things. An inner bag take makes sleeping comfortable, an outer bag that gives some form of protection from wind, and sometimes rain, and some insulating stuff between the two. Inner materials are either cotton or some man made fibre. Cotton is comfortable, but a bit heavier. Nylon or other fibres are lighter, but can be a bit uncomfortable. If one uses an inner bag, the type of inner fabric is not very important.The outers are almost always a man made derivative, mainly nylon. More expensive bags may have breathable water resistant fabrics, that make the bag a little more weather proof, but not water proof. Filling (the insulating stuff) will be either a hollow fibre material, or down. Hollow fibre is cheaper, more abusable, but has a shorter life and is bulkier and heavier. Down is expensive, lighter and needs special care, but should last 3 or 4 times as long as hollow fibre. There are various types of both down and hollow fibre. Generally you pay more for more loft in both. Loft is the amount that the stuff expands to create an insulating layer. The more loft the fill has, the less is needed to create a layer of given thickness and warmth. Down has more loft than hollow fibre. People often point out that hollow fibre is warmer when wet, which isn't exactly true. Both hollow fibre and down are miserable when wet, but a hollow fibre bag retains its structure when wet, and dries infinitely quicker However, what separates the horses from the mules in sleeping bags is how the whole package is put together. The insulation material needs to be held in place so as not to allow it to slip and form cold spots. There are various ways of doing this, but as always, the better ways to do it are more complicated, and thus expensive.
The standard sleeping bag most people are familiar with is the rectangular
bag that zips out to form a duvet type thing. Great for the kids in Kruger,
but not the most weight or warmth efficient way of designing things. The extra
space around the feet area is another space to warm up, and extra material to
carry. Hence the semi-mummy bag. This tapers to the feet, making it a little
lighter and warmer than a similar rectangular bag. Full mummy bags go the
whole hog, tapering the feet and narrowing the whole bag. The idea begin that
any free space is space that you have to needlessly heat and extra bulk that
you have to needlessly carry.
Hoods are also found on more advanced bags
and are well worth having to keep cold drafts off your head. Drawstrings and
baffles around the entrance further add warmth by keeping the warm air in and
the cold air out. All these features, unfortunately are a little more costly
to make and hence cost extra. It is also important to have a bag of the right
length. Short men and many women often have standard length sleeping bags.
This can mean that up to the last quarter of the bag is useless, merely extra
weight and bulk to lug around and cold air to heat up at night. Tall people
often have to pull the bag taut to get right down in it, and this results in
inefficient insulation. The bag should be pretty much as long as you plus a
little bit. Inside you should be able to get right in, including your head. A
hooded bag can be slightly shorter, but the hood must totally cover your head.
A very useful accessory to your sleeping bag. The main function of an inner is to collect all the grime that the inside of you sleeping bag would other wise be fouled with. As sleeping bags, especially down ones, are difficult to wash and it does them little good this simple measure will greatly lengthen the life of your bag. In addition, it can provide a little extra warmth, and on those balmy evenings, can be used instead of the sleeping bag itself. Although you can buy inners purpose made, out of such exotic materials as pertex or silk, an old sheet sown in half to mirror the size of you sleeping bag works just fine. It does help if the inner is 20 or 30cm longer than the sleeping bag, especially if you have a hood.
Sleeping bags are often the bulkiest thing to go into a backpack. Most come with their own stuffsack, but often this doesn't have compresson straps. A good compression sac can reduced the volume you sleeping bag takes to as little as half, and hence is well worth considering. Just remember not to store your bag in its stuff sack, and hence never leave it in a compression sac other than whilst trekking.
Bivies are not very well known in South Africa. Essentially a bivy is an outer shell made of a breathable waterproof material such as Goretex. They are mainly used by weight fanatic trekkers and backpackers to replace a tent. The only use I could see for them would be in shallow caves (Ifidi springs to mind) or as an emergency measure on treks done without a tent. However the cost of a decent one is utterly absurd, and non breathable ones are badly prone to condensation.
There is much that could be could be written on the virtues of closed cell foam pads, what we often call gaper mats, versus the luxury of self-inflating mats (thermarest) In the end it all boils down to cost and weight versus comfort. Thermarests are definitely more comfortable, but not as much as your bed at home. However, they weigh more, cost a lot more, and can't be conveniently strapped to the exterior of the backpack. If you visit a good outdoor store, they will probably have a selection of various lengths, thickness’ and densities of both types of sleeping mat. In caves with straw and camping on lush grass in summer one can get away with almost anything. Come winter and a gravely site on the high berg, extra length, thickness and density will be well rewarded with addition warmth.
Ideally one could have three bags for the berg. A light 5 degree bag for summer little berg strolls, a -5 bag for all year little berg and 2-3 season high berg walks, and a -15 bag for those high berg trips in the depths of winter when the cold fronts roll in. Of course, few of us can afford this, so a compromise is sort. The 3 season -5 bag seems the best to have, provided you are prepared to have the old really cold night in some high berg campsite. A good down bag to -10 or so should negate this, but then those summer strolls could see you have uncomfortable warm nights. Having an ultralight inner bag for the summer strolls, makes more sense as a second bag, as this can be taken along in winter to beef up the 3 season bag. Me. Well, I have too many sleeping bags, so choose by conditions, although it is almost always the RAB -15 down monster(its really comfortable to sleep on top of when the weather is warm)