Editor’s Note: At our recent Practice What You Preach outdoors gathering, we had several different companies send in gear for testing and evaluation by the participants. One of those was Cascade Designs. Doug Ritter of Equipped To Survive coordinated the efforts to obtain items from MSR and Platypus, both of which are divisions of Cascade Designs. We’d like to thank Doug for helping facilitate the acquisition of the different products, and Cascade Designs for sending those items for all of the attendes to use during the week-long outing.
Bivouac bags, or bivies, are somewhat controversial among outdoors-people. Designed for the military, they were originally marketed commercially towards climbers and adventure racers, and they have gained popularity with the bushcraft crowd. The original intention of the bivouac bag was to provide emergency shelter in case of an injury or if it would be unsafe to continue due to inclement weather. They became the ultralight shelter of the light-n-fast crowd, providing protection from the rain in lieu of a more traditional tent. Bushcrafters, often fond of a tarp or primitive natural shelters, found bivouac bags useful to protect their sleeping bag and add some extra warmth in cold conditions.
Typically, a bivouac bag consists of a waterproof material for the bottom, and either a waterproof or water-repellent material for the top, with various other trappings to make them more hospitable. The most basic function of a bivouac bag is to protect the sleeping bag from rain or other precipitation while remaining as light weight and small-packing as possible. Some bivouac bags have evolved into mini-tents, which are made from waterproof and breathable materials, have bug netting sewn in, and contain small poles to create a small dome around the head and shoulders of the user.
Advanced bivouac bags are often criticized for being cramped and nearly as heavy as small (but roomier) one person tents. Another common complaint is that bivouac bags can never be made breathable or waterproof enough to protect the user from both condensation (caused by perspiration) and precipitation. The MSR E-Bivy is not an attempt to be the ultimate compromise. Instead, the E-Bivy only intends to protect against precipitation. The E-Bivy is intended to act as an emergency shelter for climbers, hikers, bikers, or any other day-tripping Woods Monkey. The E-Bivy is also advertised as being suitable for regular use by ultralight enthusiasts, including adventure racers, thru-hikers, and peak baggers. Consequently, it is made as light as possible while remaining roomy and totally waterproof.
The E-Bivy comes “factory stuffed” into a soda-can sized stuff sack. This is so that it can easily be tucked into the corner of a daypack or climbing belt for emergency use only. It is almost impossible to re-stuff the Bivy into the factory stuff sack, so a larger stuff sack is provided for those that wish to use the Bivy regularly. I was just able to re-stuff the Bivy into the original stuff sack, but it was difficult and I don’t recommend trying. A cordlock is attached to the drawcord of the factory stuff sack, and there is none on the larger sack, though it is possible (and I recommend) to move the cordlock onto the cord of the larger sack. I had an extra cord lock laying around, so I used that instead. The larger stuff sack has plenty of room for a couple of additions such as extra cordage or perhaps a bug head net, as I’ve added to mine.
The construction of the E-Bivy is solid. All of the seams are taped, and the bag is advertised as being ready for use right out of the package. I was advised by a friend that even products that are so advertised often benefit from a seam-sealing, but I had no issues. The bottom, or floor, of the bag is made from a heavy grade of sil-nylon and the top of the bag is made from a lighter grade of sil-nylon. Both are waterproof, but the heavier base is intended to stand up to more abrasion and constant waterflow, so it is made from 40 denier silnylon with the addition of a Durable Water Repellent treatment (abbreviated DWR). The top, intended to shed rainfall but without the need to stand up to abrasion, is made from the lighter 30 denier silnylon. Both fabrics are “ripstop”, meaning that they are woven in such a way that there is a reinforced grid of threads inherent in the fabric that are intended to keep any tears from growing larger. The Bivy is made in the simplest form possible in order to reduce overall weight and simplify setup. It is essentially a squashed tube that is slightly tapered from top to bottom, with a flap to cover up the head opening and a partial length zipper to make entry and exit easier. The pocket created by the hood flap fits my small two day pack well, so that I can keep it dry and use it as a pillow at the same time.
The Bivy is about 20 inches wide at the foot, just wide enough to fit my sleeping pad inside the bag to keep it from moving around. The only time putting the sleeping pad inside the Bivy would be advisable is on soft grass, leaf duff, or other areas that rocks and dirt would not be able to rub on the floor of the Bivy. At hard-packed camp spots or on rocky terrain, it would be best to keep the sleeping pad outside of the Bivy to protect the floor from unnecessary abuse. In terms of actual use, the Bivy is roomy and soft to the touch (a concern when it is used without a sleeping bag). It makes an excellent waterproof shell to protect a sleeping bag from rain, snow, or common dew. I used the Bivy as my only shelter for a few nights out in the woods. In one case, I set up in the woods beneath plenty of overhead leaf coverage. This prevented any dew from reaching me, and protected me almost entirely from a light drizzle that night. I set up with my sleeping pad on the outside of the Bivy, and only suffered very minor shifting in the middle of the night. Level site selection is key when using the pad outside of the bag.
The other nights I had the opportunity to place the sleeping pad inside the bag, keeping everything together very well, eliminating the risk of sliding off the pad and waking in the middle of the night with a cold back. One of the nights I slept out in the open, without any overhead leaf coverage. The outside of the bag collected dew, but my sleeping bag was dry and ready for me when I went to bed. That same night, there was a little bit of a rain shower.
Typically, I had got into the habit of sleeping with my head resting on top of the hood of the Bivy, with a pillow item on the inside. When it began to rain and I woke up, I shifted my head inside the hood and pulled the hood down to cover the opening. I quickly discovered that if the hood was loose enough to allow adequate ventilation it was also open enough to allow a few rain drops inside. This is perhaps the most prominent weak point of the E-Bivy. It does not allow one to comfortably shelter their head while laying horizontally. In foul weather, if the E-Bivy is your only shelter, the hood could allow some water into the bag if you are not careful, but the main concern would be trapping the moisture from your breath inside the bag.
In all cases, I had an accumulation of moisture on the inside of the bag from the water vapor given off by my body during the night. This was not an issue, however, because the water clung to the inside surface of the Bivy instead of penetrating my sleeping bag. Most modern sleeping bags, mine included, are built with a water resistant shell material that surely helps reduce the amount of moisture absorbed. In the mornings, I simply turned the Bivy bag inside out and let it air dry. Typically, within five minutes there was no trace of moisture.
In my experience, this product would work best as part of a system. My own system incorporates a 4.5×7′ poncho that acts as a tarp to cover my upper body in bad weather, while the Bivy will act as both protection for my lower body and as a groundcloth that will keep all water from reaching me. In many cases, it is not necessary to pitch the poncho as an extra measure of protection, because the Bivy works wonderfully to shed light rain and dew. To provide some living space and better protection from precipitation for the head and shoulders, the poncho can be set up simply and quickly in a lean-to fashion.
Pairing the Bivy with another item causes the pro-tent crowd to shout, “Ha! By adding that tarp you are bringing the weight up to a per-person amount for a two man tent, with reduced comfort!”
This statement is thwarted, though, as the poncho pulls double duty as raingear, as well as only weighing 10 ounces after counting the stuff sack and guylines. Combined with the carry-weight of 10 ounces for the E-Bivy (including stuff sack and bug head net), my total shelter weight comes to 20 ounces, or just over a pound. This is still less than my share of a large number of ultralight two person tents, and I have far more flexibility. With my combination, I can lay right down on the ground in the E-Bivy, or I can string up the poncho for foul weather cooking, sitting, or sleeping.
Sleeping in only the E-Bivy bag is an incredible experience. I have often slept in open-air shelters such as under a tarp, but nothing compares to having the head exposed to all of the night air. With only the lightweight Bivy as my shelter, I felt suddenly liberated. All of my camping life I had felt a need to create my own “space”, a place that I could retreat to when the sun went down and the stars filled the sky. I wanted a separate place to keep my gear and to sleep in, some modicum of protection and partition from the environment. Then I used the E-Bivy, with my head right out in the open, and I could see all around me, hear all around me, and feel all around me. The scant 10 ounces that the Bivy weighs makes it easy to carry a totally waterproof shell to protect against nature while allowing a total immersion in the same nature from which it protects.
The MSR E-Bivy has a couple of weak points, but mending them would mean ruining its strengths. The Bivy makes for an excellent all-in-one shelter if one is willing to put up with tricky ventilation in rough weather and relatively small headspace (when compared to more conventional shelters). The totally waterproof material and construction will seal out storms of all variety, at the same time boosting the warmth of your sleeping bag by greatly reducing convective heat loss caused by wind. The Bivy allows a true feeling of freedom with its small pack size, weight, and a feeling immersion in the environment when used as a sole shelter. For total weather protection during casual outings, it is best to pair the Bivy with a tarp, but as an emergency shelter the Bivy would work wonderfully!