How to Use a Bivy Sack: Your Guide to Sleeping in Bivy Sacks!
Who doesn't like a night under the stars? One of the best ways of going ‘light’ while spending nights outdoors and getting close to nature is with a bivy sack! Some love it... others not so much. Here is how to make the most out of a bivy sack with your guide on choosing and sleeping in one!
Bivying is the practice of sleeping in the outdoors with only basic protection from the elements. A bivy sack (or bag) is simply a single layer material bag that you sleep inside.
Shortened from ‘bivouac’, a bivy can also refer to a temporary shelter, like under large overhanging rocks, in caves, under trees or anything else that can be found.
In this article however, we are just referring to the material sacks commonly used nowadays.
For the modern person sleeping in the wilderness, specialized bivy sacks can be found in almost every gear shop. There are distinct advantages and disadvantages over your tent setup which we will explore below.
WHO USES A BIVY SACK?
Anyone spending a night or more outdoors can use a bivy sack. Hikers, climbers and many more, use them to keep backpacks lightweight. In mountaineering for example, they are often carried even when not expecting an overnight stay as a backup emergency option should something happen and the need to bivy arises.
Anyone going on solo adventures may also be considering a bivy bag as a lightweight alternative to a one person tent. Before buying one, it’s important to know why you are buying one, its pro’s and cons, and how it should be used.
THE ADVANTAGES OF BIVY SACKS
Weight: One of the biggest advantages of a bivy sack over a tent (even a one man tent) is weight. Most bivvy bags weigh less than 500 grams (17.6 ounces), and more often between 300-450 grams. Carrying less weight always equals to a more enjoyable experience.
Warmth: Great for colder climates, they also usually add a few degrees or warmth. With the minimal air space inside, your body will heat it much quicker.
Space: Bivy sacks take up very little room, both in your pack and on the ground. You will need far less space than a tent and can set up in some pretty cool locations you wouldn’t otherwise be able to fit into!
Easy to use: With no guy lines or poles, they are very easy to set up. They can be used in seconds, which is great for those looking to have less chores to do at camp. Keeping things simple is always refreshing after all!
THE DISADVANTAGES OF BIVY SACKS
While it’s great to save weight (over a tent), this saving comes at a cost. They can be uncomfortable for some people who aren’t fond of them, especially with some bivy models lacking something to keep the head panel off your face.
Keeping all your gear inside the bivy sack, which is usually not an issue in tents with their larger internal space, becomes a hassle at times and requires some forethought on how to best approach it.
Also, very bad weather (like torrential rain) can be quite uncomfortable in the small space, and they are not as waterproof as tents often are. Condensation is perhaps the biggest disadvantage in bivy sacks. This needs to be considered when purchasing one.
So while bivy sacks may not be suitable for everyone, making sure to use them in the correct way is sure to improve your experience. Next up we will look at how to choose a bivy sack!
CHOOSING YOUR BIVY SACK
While there are many models of bivy sacks, there are essentially just a few things to really pay attention to.
Materials: With the advances in waterproof breathable materials like Goretex or E-vent, its best to stick with one of these as opposed to the older, non breathable bivy sacks. Since both warm and cold climates can cause condensation inside, you really want it to breath as much as possible, and getting a Goretex or E-vent type material is the best way to go.
Design: When looking at which bivy sack to buy, there are a few design features to look out for and consider.
Mesh panels around the head are a big advantage in that when the weather is fair, you can leave the Goretex hood off and will have next to no condensation while still protecting you from insects. Taking note of all the ventilation options is key when buying one, and can really make the difference in how much condensation you will get inside.
A small hooped tent pole is included in some design, and for a very small increase in weight (almost marginal), it can make bivying much nicer by keeping the head panel off your face.
Fit: While most bivy sacks will accommodate every sized person buying them, it's best to check beforehand if the dimensions will actually suit you. You may wish to allow for extra room for storing some gear in there as well. If you can see the bivy sack in a store this will make the process much easier. When buying online, try to gather as much information as possible to make an informed choice, and also check the return policy of the store you are buying from in case you need to return it.
Weight: Of course the whole idea of getting a bivy sack is to save weight over a tent, so make sure you are happy with the weight of the bivy sack you are looking at. You should definitely be looking at the bivy sacks weighing under 500 grams (17.6 ounces) as there are a few one person tent designs out there weighing in around the 700-800 gram mark.
My personal recommendation for bivy sack: Outdoor Research Alpine Bivy. This bivy sack has all the additions you need, is breathable, and is roomy!
HOW TO USE A BIVY SACK
Setting Up: The same rules apply to bivy sacks as for tents. Choose an area of flat ground that will not flood if it rains, is free of sharp objects, not in the path of humans or animals (like an animal trail), and is safe for you to sleep in for the night (away from a fire pit, out of avalanche zones in snow ect).
Sleeping Mat: Some models will have straps to hold your sleeping mat in place. Using a sleeping mat is recommended since you lose most of your heat through the ground. The straps help keep the mat in place as you toss and turn.
Turning in Your Sleep: Without straps for your sleeping mat, its essentially the same as if you are in your tent, but the bivy does tend to want to roll without. Lifting half your body and then the other, you can generally stop the tendency for the bivy to roll. If your bivy does not have straps, you can install some by using flat elastic straps and gluing velcro material on the middle ends to be able to adjust it, and then gluing each end to the bivy base.
Pack Contents: There are several ways with dealing with all the loose items that are left over after you have your sleeping setup inside. Depending on space, you can stuff the items around you, or leave them in your bag and use your rain pack cover to protect it. This is not very efficient in heavy rain however, so a large pack liner that your bag can also sit inside also works perfectly. Remember to keep food with you inside, or hanging it up in accordance with the local practice, depending on where in the world you are.
Dealing With Moisture: Generally, you always will want to leave the head cover off (using the mesh instead) and only cover up if it rains or snows. This allows the best ventilation possible. If it does rain or you have to cover up, still leave a small hole even though your bivy may have Goretex or similar and is said to ‘breathe’. In practice, it never does breathe as well as you think.
Sleeping on Snow: When sleeping on snow, make sure that you are in a safe place for the night, not under trees loaded with snow, or avalanche paths. You may find the condensation freezes overnight, and this leads to the Goretex being even less ‘breathable’.
Additional Improvements: Adding sleeping bag straps if they are not already in there is a nice addition that makes it easier if you tend to toss and turn alot.
To resolve bivy sacks that do not have a hooped tent pole for keeping the head cover off your face, some steel wire can be used and made into a tripod shape. This weighs about the same as a hooped tent pole. Remember to bend the wire ends back onto themselves so it won’t poke through the bivy sack! Some bivy sacks have a small loop for connecting a short single cord to a tree branch or hiking pole.
A small tarp, even just for your head (known as a head tent) can be great if expecting heavy rain. Consider this adds weight to your total setup, but by using small tarps, or a poncho even, you can still keep this well under a one person tent.
Using a water resistant sleeping bag is recommended as the issue of condensation becomes less of a problem. Most modern, high quality sleeping bags are made with these sorts of materials.
WHAT IS IT LIKE SLEEPING IN A BIVY SACK?
It’s the first question people ask anyone using a bivy if they haven’t tried it before. So what is it like sleeping in a bivy sack? Here is my review after spending many nights in one.
Having used my bivy sack in hot humid rainforests, on snow, mountainsides and many other places, and in many different weather conditions, its given me a good idea of what works and what it’s like.
Sleeping with the head panel open, and using either the mesh or just keeping it the whole thing open, is the best way when conditions are clear. I will usually do this even if I know rain may come later during the night, and just close it up when it does rain.
When I do have the head cover zipped up due to rain, I will still always keep a small hand length portion unzipped. Water does not usually splash up into it. A heavy downpour is not fun, mainly for getting in and out of the tent. I have a spare dry bag for my shoes, which are often very dirty, so I don’t have to put them in with my other gear.