Bivy bags, also known as bivvi, bivvy, bivouac or any other form, is essentially a sleeping bag cover, which means it is simple, usually very light and very, very discreet. If you don’t know, camping (in non marked camping grounds) in England is illegal and requires the land owner’s permission (pretty much all of England belongs to someone). The limited camping options leads to a fair amount of “illegal” behavior in order to enjoy a night or two outdoors and requires more discreet means of camping – hence the bivi.
A little about bivys – the word bivy is a shortening of the word bivouac, which comes from an old French (assumed to be Swiss French) bivauc, or beiwacht – by watch. The term was used for temporary shelters that Swiss soldiers used while watching enemy movements, very similar to the way we use bivys today – a simple waterproof cover over insulating clothing.
The term, shape and basic concept of the bivy hasn’t changed much, but who uses it and which materials are used have. Bivys today come in two main categories: sleeping bag cover and mini one person tent construction.
Sleeping bag cover
Very light and simple construction, it has the same shape and build of a sleeping bag, but with no insulation and made from a robust waterproof bottom (the tub/bath) and a lighter waterproof fabric at the top. It has a hood with a draw string and may be able to accommodate a sleeping mat inside (but not always). The most important thing with regards to the cover is how breathable it is – if it’s not breathable, we might as well sleep in a bin liner.
One person tent construction
The bivys in this category are relatively heavy (500-1500g), have a way to use stakes to hold them in place, room for a sleeping mat and a bag, a fully closable hood (some times with a bug net) and a loop to hold the hood away from the head. The reason they are like a one person tent is because they almost are a one person tent, you just can’t sit in it; you can only lay down, raise your head a little, and maybe read a book.
Breathability of bivys
The most important (or 2 most) features of a bivy is how waterproof and breathable it is. Since its role is to protect the sleeping bag from humidity, being waterproof is pretty self explanatory – protect the bag from rain, snow, mud and other “wet” elements (and of course, protect you in it). The breathable part is what most people miss when it comes to bivy bags – you pesperate through sweat and breath, a lot, especially when sleeping. Usually when out in a colder environment, we tend to use a natural down sleeping bag that is very sensitive to humidity. When we persperate at night in a bivy bag that isn’t breathable enough, humidity get caught in the bag, seep into the sleeping bag and ruin the down, reducing its loft and making it colder, resulting in a worse night for you.
When considering a bivy, I recommend looking at the breathabilty and waterproofing to get a good one to protect your sleeping bag and your good night sleep first, then look at the rest of the features.
Back to my story – I’ve been using a simple sleeping bag cover style bivy for more then a year now, usually combining it with a tarp to protect my head and gear. The bivy is the Hunka by Alpkit (combined wit the Rig 7 by Alpkit), it is very simple and was amazingly cheap (£30/$45) and very light. I bought the Hunka and Rig setup to see if I’m into bivying and could enjoy it.
My experiences were a mix of really enjoying see the sky when going to sleep (which I hadn’t done in many years), but also realizing that in a wet country like England (and will be true for any wet place), bivys are only good when combined with a tarp, and in that case the level of “stealthiness” is reduced, along with the weight loss (gain?) of not carrying a tent. One person tents today easily come in under 1 kg (2lbs), and so there is no need to carry a mix of bivy and tarp to save weight.
At the end of the day, I think I will start looking for a good, light, one person tent. The exposure and better contact with nature while bivying is amazing, but I find that in wet conditions it becomes mainly a struggle to avoid being covered in mud, rather than sleeping comfortably looking at the sky.
I do hope to try and use the bivy in more appropriate conditions, such as snowy places or arid places, where humidity as less of an issue.
Do you have any good experiences with bivys? Maybe even in the conditions that I tried, but with better results?