Testing New Gear - Bivy Sacks

[Erica]

I recently spent a few days on the Peace River trying out a number of new gear type items. My goal is to discover the minimum amount of gear I can bring and still be safe and reasonably comfortable. For this post, I am giving my impressions of two bivy sacks. One is from Outdoor Research and the other is, I think, Army surplus.

A couple of years ago, I tested an OR bivy sack on the Suwannee River. It was great, totally waterproof, comfortable. But...the hoop that keeps the fabric off your face kept falling down onto my head. After I got back, I called OR and was told that, yeah, they knew that was a problem and I should return it (to REI) and then buy the next version.

So, it's been a couple of year and I bought the most recent OR bivy. They have figured out, amazingly from my point of view, how to keep a half circle standing up without ties or stakes.



The bivy weighs less than a pound. It is totally waterproof, but breathable. The face screen is smaller than on the older bivy sack, which is disappointing to me. But the hoop keeps the fabric off my face and that trade off is worthwhile. The sleeping pad slides in easily and the sleeping bag on top of it. The combination was toasty on a very cool south Florida night (probably in the low 40s. When I unzipped the screen, I could see my breath, which does not happen very much where I live.)

I am about 5 foot 5 inches tall and there was plenty of room for me. I can see a larger person feeling squooshed on the head to feet axis. There was enough room for me to have a flashlight, a glasses case, a knife and a book.

The four sections that comprise the hoop are made of some kind of plastic that feels pretty flimsy. The pole is very light weight, but slips in easily. All in all, it takes about 30 seconds to set up the bivy. Another couple of minutes to slide in the sleeping pad and bag. And presto, you are warm and dry.

The other bag was some sort of army surplus. It weighs considerably more (about 3 pounds) and is sturdier. As you can see, there are two poles that create a sturdier frame for the head end. There is also a zipper about half way down one side, which would make it easier for taller people to get in and out. There is a second screen on the back side of the head space which probably helps with ventilation. The fabric is tougher (and heavier.) It is supposed to be waterproof, but I did not test it.



It might be a good bivy, but for 3 pounds, I can get an actual tent with more space. It also takes longer to set up this bivy, although not by much.

Finally, here is a picture comparing the two bivy sacks rolled up and in their drawstring bags:

 

[Bothwell Voyageur]

Get a lightweight, breathable (non-waterproof) bivy from someone like Katabatic Gear, Borah Gear or Oware and use a 6 x 9 silpoly tarp. Would weigh less than a pound and a half.

 

[dogbrain]

I gave up on using a bivy long ago. My biggest problem is with the condensation that builds up between the bag and the sack, but it can be managed successfully. We used to use a vapor barrier with a bivy in the winter to keep the sleeping bag dry. For summer use, I did make a breathable bivy and small tarp setup as BV suggests, but there are many solo single wall tents that weigh in the same 1 to 1.5 lb. range, or even less than a pound if you want to spend big bucks, that will keep you and your gear dry even in driving rain. Single wall shelters also have issues regarding condensation, but it can be managed effectively with experience. Also, I would only use a bivy if it was actually raining or there was a heavy mist or dew expected. On a clear night, camping under the trees will reduce or eliminate condensation. All my opinion of course.

Mark

 

[Erica]

I've used the OR bivy in cold weather and in pouring rain. Moisture does not condense on the inside walls. It is made of breathable fabric.

 

[Sweetfancymoses]

Fear not, I'm not posting to bash the whole idea of bivy bags.

I carry a mylar/aluminum emergency bivy bag that packs down to fist-size. I bought one after seeing a report about a lady who got stuck in a snowstorm in the high alps. She was on the cell phone to call for help but because of the darkness and the snowstorm they couldn't help her. She was underdressed for the temperatures and her body was recovered the next morning. The mountain rescue volunteer held a bivy bag in the camera and said she would have survived had she had one. Weighs nothing, packs down to nothing, and costs almost nothing. He made me a believer.

I also own a 1990s vintage woodland camo, military surplus, breathable bivy bag. I don't carry it anymore but for a person afraid of getting their sleeping bag wet in the tent, it might be just the ticket.

 

[Johnny 5]

Fear not, I'm not posting to bash the whole idea of bivy bags.

I carry a mylar/aluminum emergency bivy bag that packs down to fist-size. I bought one after seeing a report about a lady who got stuck in a snowstorm in the high alps. She was on the cell phone to call for help but because of the darkness and the snowstorm they couldn't help her. She was underdressed for the temperatures and her body was recovered the next morning. The mountain rescue volunteer held a bivy bag in the camera and said she would have survived had she had one. Weighs nothing, packs down to nothing, and costs almost nothing. He made me a believer.

I also own a 1990s vintage woodland camo, military surplus, breathable bivy bag. I don't carry it anymore but for a person afraid of getting their sleeping bag wet in the tent, it might be just the ticket.

I also have lightweight compact mylar bivy bags for moisture protection. Condensation management is necessary with all bivy systems regardless of fabric construction. VBL and vapor management article.

 

[Erica]

I read the article. If I am understanding it correctly, it is saying that I should be wearing a VBL garment next to my skin when sleeping. Or possibly over just a thin garment. From the description of the VBL fabrics, I doubt I would be able to tolerate the feel and the noise and stiffness of them. That's just me. Others might not find it objectionable.

Also, it seems to apply primarily to people who are winter camping or mountaineering. I get that in more extreme environments, more care and protection are needed when considering what to bring.

Within the weather and season parameters I travel in, it shouldn't be a problem.

I don't carry it anymore but for a person afraid of getting their sleeping bag wet in the tent, it might be just the ticket.

My thought also. Thank you for not bashing.

 

[recped]

I have two old Outdoor Research bivies, I still use them as an outer bag to protect my down sleeping bag when I'm camped in wet conditions and on the rare occasion when it's not bug season and I want to sleep "under the stars".

I'm glad to hear they have improved the hoop system, having the mesh drape on my face was annoying and it doesn't stop mosquitoes from drilling through and sucking the blood out of my face (it will stop black flies).

I gave up using it for anything other than an emergency shelter (and above) after having to spend several night turtled in non-stop rain, I could not handle being stuck inside for hours (being in a two person tent for 48 hours is bad but tolerable).

The other problem I had is that I don't like to sleep on the narrow pads that will fit inside and using the thick pads I prefer consumes too much inside space.

There are some oversized bivies that offer much more space, especially headroom but can still be used in those tight situations like having to camp out on a narrow portage trail.

For me bivies are for the ultralight crowd or for emergency backup rather than everyday use. Too each his/her own of course, I had a paddling partner for 10 years that never used anything other than a bivy and he was quite happy with it as long as I brought my large shelter to hang out in and only use the bivy for actual sleeping.

 

[Johnny 5]

I read the article. If I am understanding it correctly, it is saying that I should be wearing a VBL garment next to my skin when sleeping. Or possibly over just a thin garment. From the description of the VBL fabrics, I doubt I would be able to tolerate the feel and the noise and stiffness of them. That's just me. Others might not find it objectionable.

Also, it seems to apply primarily to people who are winter camping or mountaineering. I get that in more extreme environments, more care and protection are needed when considering what to bring.

Within the weather and season parameters I travel in, it shouldn't be a problem.



My thought also. Thank you for not bashing.

Erica, I am not suggesting that a VBL is the best or only method of managing moisture while using a bivy bag. Some people are unaware of the mechanics involved in controlling moisture and condensation and I felt the article would provide some useful information.

The dew point as well as body moisture impact moisture and condensation issues with the clothing, bivy bags and tents that we use. Understanding the cause and effect can help us use make informed equipment choices and help us use the items more efficiently.

The fabric and construction of the bivy bag as well as the environment and procedures we employ will effect the function. I agree that under certain conditions little or no moisture issues will occur and many bivy bags will function well on their own. I only introduced the mylar bivy for those considering an inexpensive VBL to control moister in extreme conditions.

I appreciated your reviews.

John

 

[Chip]

I’m kind of grossed out by the VBL article. I’ve never done activities for prolonged periods in extreme winter weather. So, I can’t argue with the VBL guy‘s moisture management practices, but geez, it sounds sloppy. Wearing a waterproof layer next to your skin undoubtedly keeps the perspiration from wetting outer layers, but what happens to all that sweat? I’d expect to end up with multiple cups of sweat sloshing around inside the garment. Does it come equipped with drain holes? It must be like the fictional stillsuits of Dune, minus the filters.

I have occasionally used a bivy bag in below freezing weather, always for single nights of camping. Most times I put up a tarp. Mine is by Mountain Hardware, is a breathable fabric and does not have the little tent over the head.

While the bivy saves weight, I don’t like going to bed in the rain. While the rain falls, you’ve got to get out of your wet gear, get into the bag and do something with what isn’t going into the bivy with you. Everything ends up wet, making the breathable aspect of the bag even more important. Also, I like to have a place to put stuff removed from my pack. So, I brought a small HW-store tarp as a ground cloth, and a tarp for overhead and, geez, not really saving any weight over a small tent. But, on bugless winter nights, I still like it for the space and open-ness. No zipping tent fly. No bending over to get through the tent door, and, I like being able to see the camp site.

On the limited duration trips where I used the bivy, I’ve never had moisture accumulation issues, except when tarpless and I accumulated a layer of dew, but that was on the outside.

 

[Bothwell Voyageur]

Provided you can keep the fabric of the bivy bag warm enough it will stay breathable. Uncoated non-waterproof bivys are less of a problem than coated or laminated fabrics. In colder weather breathability drops and in really cold weather you'll get ice on the inside. A really warm bag can make things worse and it prevents body heat from reaching the bivy. The moisture in the bag issue is a similar thing. As long as there's enough heat reaching the surface of he bag it will carry any water vapour out to to the surface, too much insulation or too cold and the vapour will condense or even freeze within the bag. The most important role of the bivy is to keep the outer surface of the bag warm enough to at least stop vapour from condensing inside the bag.
Chip highlights the biggest problem of a bivy bag though. Without a tarp for some coverage life can be pretty miserable. Even a small tarp over the head end can be enough to make things bearable.
For me the main reason for a bivy/tarp combination is I like sleeping in the open. When forced to used a tent I will only close the doors as a last resort.