Bivy sacks were first developed as solo shelters for mountaineering, climbing, ultralight backpacking and adventure racing where participants were interested in light weight and highly compressible gear. The original bivies were little more than waterproof sleeping bag covers that protected extreme athletes from rain or provided them with a temporary emergency shelter.
However, in recent years, a new class of bivy sacks has evolved that incorporates high tech breathable fabrics like Gore-Tex and eVent with elements of ultralight tents such as mesh screening and collapsible vestibules. Initially, these more advanced bivies were manufactured by a few specialist and cottage brands such as Integral Designs, Outdoor Research and Bibler (acquired by Black Diamond), but mass market manufacturers such as Marmot, Big Agnes, Mountain Hardware, REI, The North Face and MSR have introduced models in recent years, reflecting an increased audience for this class of solo shelter.
This video illustrates the first stage of the bivy’s evolution into a more comfortable solo shelter with the addition of a mesh screen and collapsible poles to improve ventilation and keep the screen off the user’s face. This bivy has a Gore-Tex top to reduce moisture built-up in your sleeping bag from sweat. This is particularly important in winter when trapped sweat can significantly reduce the thermal efficiency of your bag.
This final video illustrates the most recent evolution of bivy bag architecture by a mainstream gear manufacturer, Big Agnes, with the incorporation of an external vestibule over the wearer’s head. The top of this bivy is also made with highly breathable eVent fabric which is reputed to be even more breathable than Gore-Tex.
Sleeping in a bivy sack is an acquired taste and not for everyone. Given their space constraints, there’s not much to do except sleep once you’ve gotten into one. Still, they provide an excellent way for you to eliminate the weight and bulk of a tent, particularly in winter, if you are mountaineering or climbing, and need to carry a lot of other gear and food.
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Good article! I've found that a good bivy bag + lightweight tarp is a great way to go: lots of "living space" (as long as it's not crazy-windy) but your sleeping bag stays bone dry, even with the bivy bag half-open: also avoids the claustrophobia issue and provides for a much better sleep in a downpour (BTDT: rain can be amazingly loud when it is pounding 1/4 of an inch from your ear).
Depending on the bivy and pad you use, some pads won't fit inside of some bivys … although having a $20 foamie between your $300 bivy and sharp rocks is maybe not a bad idea. In my totally unscientific experience, having the pad inside the bivy bag seems a little warmer: any idea if this is true, or just my imagination?
I often use a bivy, but I chose the alternative to waterproof materials, which is a DWR type made of Momentum. For me a bivy is to protect my down quilt from spindrift rain or snow, usually while under a minimal sized tarp. In this case it doesn't have to be totally waterproof, just water resistant. The Momentum is windproof, but allows considerably more breathability than an eVent type material. When rain isn't a threat, then it makes a quick setup shelter on it's own. A big advantage of this type of bivy is the very low weight (around 7 or 8 ounces) and a very small packed volume.
I'm not advocating that this type of bivy is better than a waterproof one, but I've found that if significant rain is occurring I'd rather be under a minimal tarp with this type of bivy than exposed with a waterproof one.
Photo of my MLD Soul Sidezip bivy (open), Nunatak quilt, and NeoAir pad.
http://i444.photobucket.com/albums/qq164/Quoddy1/…
Quoddy – I'm working on a followup post to this that explains in english the difference between the different bivy tops fabrics. Momentum and Pertex are top choices in the non waterproof category.
Tim – having a pad inside you bad would probably be warmer. Think of the bivy as a vapor barrier and you'll see how it would retain the extra heat.
Being a full time stealth camper I have been using Bivy's exclusively for the past 20 years or so and will remain forever with my beloved GoreTex which has yet to fail me when all the others have.
In my experience I set up my camp a bit differently than advertised in that I carry a 12×12 Camoflage Tarp (27 oz.'s) with gromments every two feet and set up my Bivy underneath on half of the Tarp and the other Half is over my head as like a small leanto which I fix up with sticks and Cord made for Catfish fishing or what they call Setline, 330lb # test 300 ft for less than $8. and does not strech when wet… Cheaper than most Store prepared Trip cords and Paracords and really stands up to water. (if I find a good set of sticks I may carry them with me for the rest of trip)
This set up allows me to keep the mouth of the Bivy sack open which has solved all my inside condensation problems as well as puncture problems from various sharp items on the forest floor, like those innocent looking but extremely guilty Pine needles, they are sharp enough at just the right angle to puncture the bottom of my bags and Sleeping Pads. Yes, putting the Pad inside the tents keeps things warmer and cleaner, nothing like Pine pitch spotted all over the Pad for sticky fun..Though it does keep the pad from sliding around a lot when layed on a tarp or groundcloth or inside the Bivy..
With this little shelter I have with stood everything from 6 inches of Snow to Monsoonal 2 hour down pours, to a 39 mph + windstorm that caused a number of trees close by to fall, and I remained warm and dry..
To tack down the Tarp, I use 6 of the Small Blue Colored Easton Stakes instead of the Large 8 inch Gold ones and these work very well and are liteweight and almost unbreakable.
My favorite set up for a site if I can find one, is a Blowdown with the roots sticking up about 5 -6 feet tall and wide and in the air. Sometimes I have to knock some dirt off to fill the root hole up but most of the time it requires little preparation.
I setup the Tarp and Bivy about six feet away from the Root ball where I build a small fire, smaller than the insides of my baseball hat, the face of rootball reflects the heat back under the Tarp. Real cozy on a cold 30 degree night. And the space between gives me room to set up my kitchen in..Just remember to find one facing away from the wind, otherwise you'll have some red embers blowing back under the Tarp instead of heat…
I like the root ball tip. They are cool little ecosystems, especially if its a big tee. I camped next to one this spring in Vermont.
I don't understand why some of you guys are bringing a tarp AND a bivy… I bought a bivy to replace my tarp. Are your bivy's not waterproof? Maybe I'm missing something
Like Quoddy, I like a bivy around my sleeping bag when sleeping under a tarp to control rain splatter. What you say is correct, but I'm still in my tarp phase of going light. At some point, I'll probably move on too and go with just a bivy.
I recently made a change in the way I hold my Tarp in place.. Instead of tieing the rope or Twine, or Paracord, or in my case, Catfish line directly to the Gromment, I have been using sticks! After having a grommet or three torn out by the wind a thought came to mind about relieving all that pressure on that one Gromment.. I spied a couple of pices of twigs close by, about 1/2 an inch in circumance.. I then tied the catfish line to the stick and then ran line through the Gromment to the stake. It appears to me that all the wind and pressure is therefore consentrated on the stick and not the Gromment which I believe has prevented the Gromments from ripping out in some recent 40 mph winds during a thunderstorm. I also tried using a ten foot long thin branch instead of individual pieces of stick and had great results as well….I have never seen it done anywhere by anyone so I guess I got an original here..I am thinking of buying a Dowel Rod or two and cutting it up into 3 – 4 inch lengths with maybe a little groove in the center and just carry half a dozen with me in my Pack…
I think that's pretty original!
So Sam, I am on the market for a very lightweight, very breathable winter bivy sack that can fit a thick exped 7 sleeping pad and a -25 Western Mountaineering Puma sleeping bag. Do you have any suggestions? I'm looking to use this system in snow trenches during the winter.
Sorry Earlylite, I have no experience with bivying yet. I have yet to "loose my bivinity." I am waiting for my Rab Storm Bivy to arrive in the mail. It's a simple bivy design, no poles or hoods, just a waterproof, "breathable" bivy sack with a zipper. It's made of Hyperlite, the quality of which I am unsure of. My plan is to just use the bivy sack without a tarp. I do have a nice tarp (ENO DryFly)that I use in conjunction with my hammock, but like I said earlier, I bought the bivy to replace my tarp as it is some 5 oz lighter and much quicker to set up. Also, where I live (Utah) we go camping in the desert often, and there's usually nothing to tie the hammock and tarp to. So, I think this bivy will meet all my needs! I am anxious for it to come!
I don't know if they sell them anymore, but many years ago I bought a Gore-Tex Bivy sack from L.L.Bean, in a dark green color instead of one of the "Taco Stand" colors they use now, which are an eyesore, which I used for Winter cross country Desert Hiking in Southern California/Mexico in the Anza Borrego Desert area for many years.. The temperatures on average at night hovered near 36 degrees with a couple of lows of 28 degrees, along with a North Face Goose Down bag I was plenty warm…For a setting up at Tarp, I drilled some holes through my Homemade Hiking Staff which enabled me to thread the 250# Test Catfish line through which used to hold up and staked out to hold my small Tarp up with. Even in winter it is good to get out of the Sun for awhile, if anything just to rest the eyes from the sheen of the Desert glaze on the rocks….
Hi sam, good question. My OR micronight is not waterproof on top, pertex. I want a tarp because I also use a beyer moskito hammock. The condensation inside the foot box is bad enough without rain, but I use it mainly to keep bugs away. My only problem with a tarp or hammock is that I often don't want to stop bicycling to look for a good place to set up, so the bivy is more convenient. Above 80 F, I want a full mesh canopy 2 pole dome, because the heat and bugs can be too much.
James I think you are implying your looking for a Full Mesh canopy? Not sure of what your posting…But Adventure 16 in San Diego used to sell an excellent Bug House. I used one of theirs going back to when the old man first invented it and sold it via their catalog, but the kid took over the business in the 80's and well we see what happend to Rodale Press when the old man died…But they still might sell it in their stores, if their still open. I just checked and their still open but no Mail Order..dang kids ruined another great business. Oh Well! If you in or near or know someone who lives near one of their stores check them out…I bought my frist SEVA 123R from them in 1974 for $18.95 via mail order, shipping was like $2 bucks. The old man made their own line of excellent Backpacking gear he created while out on the trail, but the kid got rid of all the employees and I guess when to China or something and then shut down the Mail Order business..Well it is a source if that is what you are looking for.
eddie s,
I think the important thing with your "Grommet saving Stick Trick" is that the stick diameter be small enough so that the stick will break before the grommet will tear the fabric. We do something similar in most mechanical linkages. We design sacrificial piece as the weakest point so that the easily replaced part breaks first. Example – shear pin in snow blower
Tom,,,I just returned from a two week trip to are large western Georgia lake where we used a number of tarps in our group..On 4 occasions we watched a thunderstorm move across the lake coming right at us with winds in excess of 30 mph according to the Weather Station. The wind tore the grommets out of the corners of Two Silnylon tarps and one Plastic Tarp and One of those Survial Blankets or Sport Blanket tarps..My Sports Blanket tarp suffered zero damage being as all the stress was on that 1/2 inch stick which was about 4 inches long which was threaded through the grommet and attached to the ground with 235# Catfish line and Easton Stakes..My design idea is not based on reaching a breaking point but of spreading the stress..I'm working on a Patent idea now for it.
I have used an old survival aids goretex bivi on several patrols in europe. I always had to remember to knock the snow off in the morning before I unzipped. I recently found a surplus (canadian?) goretex bivi in green, very large I am thinking of adding netting and lift points since it is so large.
does anybody know if they make a waterproof sleeping bag with a flap or something over where your face is exposed? i dont see the point in having to pack a bivi sack and a sleeping bag separately. i would gladly sacrifice some comfort for the convenience of combining the two.
John G. boy does your question take me back to 1961 when Coleman made a bag like that!
It was good for keeping stuff from falling in your face should you set up under a tree but not in the rain…It was a tightly woven cotten top that was "water Repellent" due to the tight weave but we had to bring an extra piece of Canvas Tarp to put over the top of it to keep off the rain.
I haven't seen any over the years, the closest has been the various Bivy's now made and some of the high end Goretex bags, in fact I have seen any of those in a couple of years…They were very hot and your sweat did not evaporate as easily as one would expect with Gore Tex or what ever they were making them with…
So there is a project for you to do this coming winter…
I need to give a bivy a try, but the math doesn't seem to work since most bivies weigh about the same size as a lightweight, spacious tarp. So it seems that most backpackers would be better off with a tarp. But I haven't tried, so I must be missing something.
Actually a tarp and bivy go hand in hand. I mainly use a bivy for 3 season tarping to reduce splash back with a flat tarp or as a sheet/bug net combo in warm weather when I sleep with a very lightweight sleeping bag open like a quilt. I also use them in winter as an added insulation and waterproof layer on snow, again with a tarp. Mine weighs 6.5 oz and my tarp weights about the same. Adds a lot of comfort without a lot of weight. I used to carry a 2 oz headnet and a 3.5 ounce piece of polycryo for a ground sheet. It basically replaces those and adds function.
Good point: I could see the utility during bug season. However, outside of bug season, a bigger tarp and/or a lower tarp pitch might be good enough to solve the splash effect. But HYOH! :)
I use a MLD Superlight Bivy (CF bottom / M50 top) and when needed I use a 9×6 cuben fiber (0.34) tarp. Total weight is under 10 ounces.