Bivy Bags

Most people who buy Bivy bags for 'an emergency' would be better off buying a bothy bag instead. A bothy bag will be lighter and more practical for emergency use. Best of all a large bothy bag can take up to 12 people.

An overview of Bivy Bags

The bivy bag was originally invented to serve the hardest of the hardcore climbers. These are the people who wanted to sleep on a ledge that was several hundred feet up a cliff on a multi-day climb and still stay warm and dry. When you are that hardcore the little niceties like comfort don't really matter and the only things that do matter are functionality and weight. So, from the outset a bivy bag was designed as the absolute minimum that you needed to stay warm and dry when sleeping in an exposed place.

Of course, since those early days lots of people have started to use bivy bags as ultralight shelters as an alternative to tents. But, it is a big initial step to move from a tent to a bivy bag. If you want a little bit of fun then you can recreate the joys of bivy bag camping in your own home.

A bivy bag can be used anywhere at all - especially in places where it would be impossible to pitch a tent. They are ideal for places like exposed mountaintops where there is no shelter from the wind and the rain, for snow caves and alpine conditions and also for beautiful warm summer nights.

I'm personally a big fan of Bivy bags and the bulk of my wild camping will be done with either a bivy bag or a tarp or both. I like the freedome that it brings and accept the resultant compromises when compared with the luxury of a tent.

Bivy Bag designs

There are still specialist bivy bags out there that are designed for hardcore big-wall climbers but most are designed for ordinary people doing ultralight camping or camping in hostile terrains. Materials will vary with price as will weight. The most important thing to bear in mind is that there is no longer much difference in weight between a typical bivy bag and an ultralight tent. In fact some ultralight tents are actually 100-200g lighter than a typical bivy bag. So the question really becomes "What sort of camping do you want to do?"

There are three basic designs of Bivy Bags:

• Sleeping Bag Cover
• Fully enclosed
• Hooped

Bivy Bag design - Sleeping bag Cover

This is the 'classic' design and is still used extensively by climbers, by summer users and by many armies around the world.

The design is very simple. A zipped bag that has a drawstring opening for your head. On some designs this opening may be closed down to a small hole. In the rain this hole will let in water.

You can find many 'army surplus' examples of this design that are 100% Gore-Text, work very well and cost a fraction of the 'commercial' models. The only downside of the military ones is that they only come in green and tend to be on the large side - for a soldier and gear. However, if you are on a tight budget I would buy one.

With this design the best place to use it is where it is possible to have some cover for your head or when no rain is expected.

Many people will have a cheap bivy bag for summer use. The cheapest one that I found was by Khyam and cost £17.50 for a 'breathable' nylon bag that was waterproof. A more professional version that is much more breathable is the Rab Survival Zone at around £50

Bivy Bag design - Fully Enclosed

This design is basically a fabric coffin. You will be warm and dry but it can also be claustrophobic.

The bag will have to be made of a very breathable fabric such as Gore-Tex or eVent. The current state of the art seems to be with eVent and it is the fabric that Rab have used to replace Gore-Tex. Naturally it is expensive.

All of these bags will feature a zip somewhere. It may be around the head area of the bag (a crocodile zip), or accross the bag in either a straight or a diagonal line. Some will have a zip along the length of the bag. Just remember that a zip is a source of leaks and so it should be well protected from driving rain and puddles.

A typical bag is the Terra Nova Discovery Lite which weighs under 500g and uses the latest Gore-Tex Flo2 fabric.

The only real issue with a fully enclosed bag is that moisture in your breath can overwhelm some of the older and cheaper Gore-Tex fabrics. Both eVent and Flo2 are alleged to overcome these issuse. I haven't yet tested that fact.

A fully enclosed bag is probably the best one to go for if you are going to be using it in anything less than perfect weather. Just remember that lying in a coffin listening to the rain is not a lot of fun even if you call it an 'adventure'.

I personally like to use a bag like this with a micro-tarp so that I can at least stick my head out and not get it wet. Read more...

Bivy Bag design - Hooped

This is now the 'luxury' end of the market where the bags are designed for 'extended' use. What you are now buying is a mini-tent in which you still cannot cook. They are however a lot less claustrophobic than a fully enclosed bag.

The cost of all this 'luxry' is in the extra weight of poles and pegs and of course in price. For winter use I think this is the only option for a Bivy Bag user if you really cannot use a tent. A hooped bag is on my shopping list for this year and only the price is slowing me down.

Bivy Bag Fabrics

One of the ironies of most bivy bags is that they weigh as much as an ultralight tent even though they enclose far less space. The reason for this is very simple. Gore-Tex and other fully breathable fabrics tend to be quite heavy when compared with the modern ultralight tent fabrics.