The nylon layer of a tent that lies between you and the outdoors disappears leaving you completely immersed in your surroundings. Starry skies, the sunrise and the breeze on your face are completely open to your view and only enhance the experience with a liberating sensation of what it is to be in the true ‘outdoors’.
A bivy bag can add an entire world of versatility to your outdoor experiences. If you’re wanting to camp inconspicuously or in a rocky ledge, heavy wooded area or on a climb, it can give you the freedom of limited space that which a tent cannot, not to mention the fact that they are light, packable and fast to set up for any extreme or leisurely situation that may arise.
These are excellent for any bug out bag, car emergency kit and even for the urban survivalist. Survival blankets can be awkward, bulky and inefficient in varying elements.
Bivy bags are a multi-use, packable, reusable, life-saving items that can cost you as little as under $10. Bivy bags are in the form of a body in which they’re less bulky and more efficient in warming you rather than an alternative or survival blanket.
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What is a bivy bag and why do you need it?
A bivouac sack or bivy is a waterproof or windproof layer used to seal your sleeping system in place of a tent. Many people use them as a simpler form of light travel or in case of emergencies.
Simply slip the bivy bag over your sleeping bag or ground pad to protect yourself from the wind chill, rain and winter conditions while they can add an additional 5 to 10°C of additional insulation.
Basically a single wall tent, bivouac sacks were originally created for mountaineers and climbers in need of lightweight protection in case of emergency.
Now, after years of modifications and added specs, you can enjoy the pleasure of owning a bivy for just about anything from an emergency situation, TEOTWAWKI, camp trip to an extreme expedition.
Disadvantages of a Bivouac Sack
Before I romanticize too much, there are situations in which can make a bivy bag less comfortable. Rainy conditions and condensation can make you feel like sleeping in a Ziploc.
The condensation that your breath and rain cause can seep into your sleeping bag over time, forcing you to dry it out on longer trips. Trying to dry your once warm down sleeping bag can take ages. In addition, it will freeze solid into ice in cold conditions, adding an immense amount of weight to your pack load.
When vapor leaves your body, usually in the form of breath or sweat, it meets the cold air in which it eventually forms as frost or moisture along the walls of your tent. In a double-walled tent, the moisture can pass through the canopy and settle on the rainfly layer, making moisture much easier to manage.
I caught up with world renown polar explorer Lonnie Dupre to ask him a few questions regarding his bivy sleeping systems used over the last 25 years of his arctic exploration, ranging anywhere from circumnavigating Greenland by dog sled and kayak, dog sledding in Siberian winters to the far reaches of Alaska and beyond.
Photo by Lonnie Dupre
His most recent claim to fame was the first-ever Denali (the tallest mountain in North America) solo summit this past January 2015, where he would sleep in snow caves and depend on his lifesaving bivy bag for the critical summit day.
Dupre’s advice on a bivouac sack is simple and straightforward where he advised me that, “In winter camping, you don’t want a waterproof, GoreTex® bag because you’re going to end up clammy, damp, and ruin the insulation of your sleeping bag, which will just get wet.
It’s better to use a breathable, wind-resistant bivvy bag. I’ve had a very hard time finding one of these actually on the market, so I made my own out of Tyvek fabric, which worked on Denali wonderfully.”
Bivy Shelters vs Bivy bags
Types vary from the actual bivouac sacks to bivy shelters, a small, low-rise tent usually constructed with hoops or poles that lift the fabric from you, providing more sit-up space.
While some would feel claustrophobic or confined in just a bivy bag, the shelter can provide you with more space to move about, without the weight and conspicuousness of a tent. It can be much more comfortable to wait out a downpour or storm inside of a bivy shelter vs a bivy bag.
Bivvy Bags for Various Situations
Most bivouac sacks are made of similar material of a tent i.e. urethane coated nylon and a top layer of ripstop nylon treated with a waterproof laminate like GoreTex®, which allows some of the humidity and condensation to pass through the all the while protecting against most of the water from outside.
Consider the use of your bivy bag or shelter. Are you using this for winter camping, survivalist scenarios, ultralight backpacking or to simplify your outdoor sleeping system?
What type of sleeping conditions are you in need of? Are you a light sleeper in need of more room or can you sleep solidly in a crowded or smaller space?
Bivy bags are a standalone product, however for overnights or longer backpacking trips, I suggest a combining a weather-appropriate sleeping bag and ground pad. Quick drying down synthetic sleeping bags can be just as warm as down and easier to dry. Even the simplest of ground pad can leave you feeling much warmer than sleeping directly on top of the ground.
As Dupre mentioned before, finding a wind-proof, breathable bivouac bag to save you from the condensation that can arise from a waterproof sack is preferable.
Marmot offers their Alpinist bivy which is windproof, compressible and weighs less than a pound. A windproof bivy bag combined with a down synthetic sleeping bag can be the perfect combination to keeping you dry and warm even in the most extreme cold.
Bivy bags come with a hefty price tag, but will weather through the storm for you for years to come.
A sturdy, waterproof and roomy bag all combine into an excellent shelter that is both lightweight and packable.
These are usually constructed with an added pole to make for more room inside the bag along with more durable materials for extreme weather. They can add more weight, but are still lighter than a tent and will keep you comfortable and safe even in severe conditions.
If you’re an ultralight hiker, alpinist, climber or even an occasional backpacker needing to shed extra weight off your load, you don’t need the added features like poles that can increase your carry load.
Rab’s Survival Zone Lite bivy bag is an ultra-light sack weighing in at just 200 grams. It’s made of Pertex Endurance, a waterproofing fabric that is breathable, leaving you feeling less clammy and preventing mass condensation.
Warm or Buggy Conditions
Lighter and easier to carry than the waterproof bivy bags, bug bivy bags are made to keep you from swarming insects. Jungle traveling, lake areas or warm conditions can cause buggy conditions and ruin any camping trip in a heartbeat.
Bivy bags like Outdoor Research’s Bug Bivy are made to combat any kind of insect made with its nylon bug net. This bug bivy among most others will need a separate waterproof shell that you can put on top to protect you from changing weather.
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The Army Goretex is both affordable and durable. It makes for a great addition to your bug out bag or survivalist kit with its waterproof and resilience to foul weather.
If you’re in need of a good backup emergency shelter you can get an orange survival bag for next to nothing which will keep you mostly dry and warm throughout the night. You’ll wake to realize just how much condensation your breath and sweat alone can produce while these bags are not breathable in the slightest.
This breakdown of different shelter bivy bags and sack types you can bivy with should give you a good idea of what is current on the market no matter what your budget is, for a variety of conditions.
Don’t forget that with just a few materials at a cost next to nothing, you can make a durable and efficient bivy for almost even the most extreme conditions.
You can prepare for any emergency situation with even the simplest of bivy bags. Just by spending under $10 on a survivalist sack can be an excellent add-on to any bug out bag or car emergency kit.
Before you buy one, consider what you might be using it for and in what type of conditions. Insects, thunderstorms, wind, snow and heat all play a major role in what type of bag you want to pack with you. Also try to keep in mind what kind of space you would require to sleep comfortably through the night or wait out a strong storm.
I’ve been in love with the freedom and versatility that my bivy system has given to me over the years. Tired of the weight, time and energy spent on tents in the past, my bivy bag and I don’t look back, just up to the open sky and landscape that surrounds.