For those looking to go fast-and-light, the bivy sack is a classic…also, the easiest way to feel like you’re sleeping in a damp nylon coffin. Being claustrophobic, my few tests with other bivies always led to me waking up with a flap of nylon trying to suffocate me in my sleep. Your average smart person would give up on the bivy, but that ain’t how I roll. [Puts on sunglasses dramatically]
After doing a lot of research, I eventually decided to go with OR’s Advanced Bivy, and after a few months of testing at both ends of the weather spectrum, I can say I’m thoroughly happy with this sleep system.
The Advanced is constructed from a super durable, 30D Nylon ripstop and 3-layer Goretex Respiration Positive; while I do not have the exact stats on hand, it is a highly durable and highly breathable Goretex material that many of us know and love. The floor is constructed from a durable 70D nylon.
What makes the Advanced Bivy obviously stand out from others is its hoops. While not necessary for use, the user can place two hoops easily into snap-attached joints: one hoop will keep the hood off your face, raising it 20″ from the ground, while the other gives the hood some structural rigidity, letting you leave it open to vent while still protecting you from above. Now, other companies have hoops, but I found OR’s derlin poles to be light and easy to use; they don’t feel like the strongest poles out there, but truth be told they are luxuries rather than necessities. Also, most people won’t be abusing them too much, as they only come out of the pack during sleep time.
The bivy is mummy cut (as it should be), starting at 20″ wide at the feet and expanding to 26″ at the hood. At 87″ long (7’4″), you have to be pretty tall to fill this thing up. At 6’1″, I often toe the line of being too tall for some products, but I can only describe this bivy as exceedingly roomy. The bivy is just wide enough to slide your boots and a few accessories next to your pad on either side, which can be strapped down with the included velcro-closure straps. Broader folks may not be able to squeeze accessories next to them, but they should be able to fit in decently (albeit it might get a little cramped).
The Advanced also includes a removable no-see-sum mesh netting at the hood, and mesh vent in the footbox that can be unzipped to let air flow and prevent condensation. There are also guy-out and stake loops on the bivy; while I thought this seemed kind of strange at first, I found that staking out the floor of the bivy really keeps it from crumpling up, creating a neater, roomier feel.
All of this comes in at 39 oz’s, which is not the lightest bivy out there, but for the features I found the added weight well worth it. The price tag ($320) is steep, but if you’re going to invest in a bivy, this is the one.
I tested this bivy in deep-winter and snow conditions, in Spring/Fall temperatures, and in muggy summer weather, so I feel like I’ve experienced the gambit of temperatures. Unfortunately, I have yet to get a heavy rain while using it, but have dealt with snow, both wet and “dry.”
The Advanced definitely excelled in the winter: whether set up right in the snow on a 6* night in Danby State Forest, or in a lean-to in the Adirondack High Peaks it cut wind and snow, keeping me warm and dry. The obvious issue with a bivy is condensation, and let’s be clear, in the winter with a bivy you will get condensation. However, the condensation was not terrible in the Advanced, even when zipped up with just an inch of breathing room, and where there was any it was held off my down sleeping bag by the poles; I had light condensation around the hood of my bag, but this was likely due to me breathing right over it, and could be solved by placing a light windbreaker/piece of ripstop on the bag.
In Spring and Summer temperatures, even on humid nights, I didn’t have any issues with condensation–when I woke up in the mornings, the inside of the bivy was bone dry. I attribute this largely to the footbox vent and to the hood being held open by the poles. Similarly, I never found the bag to be uncomfortably hot, although I definitely wouldn’t love being in it in 70* or more; at 60* and down, though, it wasn’t clammy or hot.
Turning to the construction of the bivy, the “mouth” of the hood material is rigid enough to be supported without poles, although the poles do help it keep shape. If you are looking to shave ounces while maximizing comfort, leave that pole behind in lieu of the roof-pole. The only downside of the hood being so rigid is that it can be tough to pack down. I’d recommend ditching the included stuff-sack for packing the body of the bivy: I put mine in a XS Granite Gear Air Compressor bag, and still have room for a ultralight painter’s drop tarp that I use to keep the bottom of the bivy clean; you could very easily fit in a small sil-tarp for creating a lean-to over the bivy too. I place the poles in the included stuff sack in a corner of my pack running vertically up the back, along w/ a few lightweight guy lines and some tent poles.
When inside, I found there to be enough space to keep my book, pillow (stuff sack full of clothes), head lamp, and various odds and ends with me. If you’re going with an ultralight pack, you can likely slide the frame down into the bivy and keep the pack up with you by the head, but normally I keep it outside the bivy.
The one issue most users seem to have is the bug netting. While it does the job to keep the bugs out excellently, it is a one-way zipper that works from the interior. If you are outside your bivy but want to close the netting, and then get back in, you have to awkwardly work the zipper open. Of course, if I had thought it through, I would’ve just zipped the entire hood closed; after all, the bivy doesn’t have to breath when I’m not in it. But in warm weather I do like to keep it airy, because normally my smelly clothes/boots are inside of it. While the bug net zipper is initially annoying to work around from the outside, it’s pretty easy to work around.
But again, if I had to guess, it’s likely designed to have the entire hood closed when not inside.
Room for Improvement?
First off, the Derlin poles work fine, but I’m always a bigger fan of aluminum. But, that may just be me.
If the Advanced could be improved in any way, I’d say it’d be the pole system, namely the attachment points. The poles are connected to the body by attachable tips with snap closures that snap right onto the bivy; while they snap firmly, I found the face-pole often slipped out of the tip. I never actually noticed it was out during the night, so it’s not the biggest issue, but it’s good to have things in place.
Also, you can obviously lose the tips pretty easily. They include an extra tip with your package, which in a way is a bad sign: it kind of implies “Hey, you’re probably gunna lose one of these.” I’m sure OR, with their amazing customer service, would send you replacement tips free or cheaply, but great customer service doesn’t help too much on the side of a mountain.
The reason OR uses these snaps is so the hood can be adjusted into a variety of positions easily, and I can’t suggest an alternative design at the time. However, I noticed in warm weather when the hood is opened up so you can get a good sky view and air flow, it likes to flop back down slowly. This can be easily fixed: if a small fabric loop was included along one side of the interior snap closure, you could clip a small carabiner around it to keep it open. I jury-rigged this myself with a shoe heel-tab, but this could be easily included in the design for almost no added weight.
So, possible improvements: (1) Maybe make the poles out of aluminum, (2) Make the snaps built into the poles, (3) Small tab in interior to keep pole up.
The Advanced Bivy excels as a light, packable, easy-to use shelter; it is sturdy, weatherproof, and easy to use. If I had to guess, this bivy will get better as it is further designed, but even in the present it is a bomb-proof shelter built to last.