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Winter Bivy Sack Guide

Winter bivy sacks have been first developed as solo shelters for mountaineering and climbing the place members have been desirous about light-weight and extremely compressible tenting gear. Bivy Sacks are additionally a sexy possibility for backpacking hunters, backcountry skiers, and winter backpackers who need the lightest and smallest shelter they’ll carry for in a single day or emergency use.

Should you’re a backpacker, bikepacker, or path runner, searching for a three-season bivy sack see our Ultralight Backpacking Bug Shelter Primer which spells out the forms of shelters accessible and methods to choose the most effective one on your wants. 

Winter bivy sacks are totally different from three-season bivy sacks which are sometimes used along side a tarp for insect and splashback safety, the place rain hitting the bottom can bounce again and moist your quilt or sleeping bag.  In distinction, a winter bivy sack is meant as a standalone shelter all by itself or along side a snow shelter corresponding to a trench or snow cave. Winter bivy sacks are usually a lot larger in quantity to carry winter-weight sleeping baggage with out compressing the insulation and work greatest in dry and chilly circumstances the place precipitation is within the type of snow.

Winter Bivy Sacks – Benefits

The most important benefit of a winter bivy sack is the power to make use of it wherever you need to cease and sleep. Most fashions don’t require tent stakes or tent poles they usually pack up very small which is a bonus if you need to hold your winter gear light-weight and compact. Most winter bivy sacks are made with waterproof/breathable prime materials to assist cut back inner condensation and waterproof base materials to maintain your sleeping bag and pad dry. Insect netting can also be accessible in some chilly climate bivy sacks and could be helpful once they’re utilized in spring circumstances when bugs start to emerge,

There are a lot of benefits to sleeping in a water-resistant bivy sack over a tent. It’s simple to discover a place to place a bivy sack at night time because it solely requires as a lot area as your sleeping pad and sleeping bag. Merely unroll your bivy sack, slip your sleeping pad and sleeping bag inside, and crawl in. This makes them appropriate for sleeping on slim mountain ledges or in forested glades the place there’s simply sufficient area to lie between two timber.

Bivy sacks can be set up just about anywhere without the need for tent guylines or stakes
Bivy sacks could be arrange nearly wherever with out the necessity for tent guylines or stakes

There are not any tent stakes to freeze into the bottom so you will get inside at once and get heat. Being waterproof, you don’t must lie on prime of a groundsheet both, for the reason that backside of a water-resistant bivy sack is designed to maintain you dry. Bivy sacks additionally add a couple of levels of insulation to your sleep system and make nice emergency shelters for solo winter hikers, supplied you carry a sleeping pad and sufficient insulation to get via the night time.

Winter Bivy Sacks – Disadvantages

Bivy sacks are far more confining than tents, with solely sufficient area for you and some small private objects. You’ll be able to’t actually do something inside one besides take heed to podcasts or fall asleep. It’s awkward to alter out of your moist garments or placed on dry garments inside relying on the kind of bivy sack you’ve, it may be rattling onerous to place in your boots, even to go for a pee at night time. There’s no place to retailer your backpack and the remainder of your gear will probably be absolutely uncovered an evening with none cowl.

Bivy sacks are additionally extra susceptible to inner condensation than a tent, even when manufactured with waterproof breathable supplies. You’re greatest off preserving them open or unzipped at night time to cut back the temperature differential between the within of the bivy and the skin which causes condensation to type. Tent condensation happens for a similar motive however tents have higher air flow and extra quantity, so it’s simpler to maintain your sleeping bag dry when it happens.

Regardless of these disadvantages, I’ve buddies who swear by their winter bivy sacks as a result of they’re so quick to deploy in comparison with a tent or tarp. I’ve used winter bivy sacks and may recognize their strengths, however winter nights final a really very long time and it’s good to have a bit additional area to alter your garments or sleep along with your gear inside your tent. Whichever you select although, actually is dependent upon what you’re attempting to perform.

The Outdoor Research Helium Bivy has a clamshell design that you enter and exit from the front
The Outside Analysis Helium Bivy has a hooped design that you just enter and exit from the entrance.

Comparability Desk

Kinds of Winter Bivy Sacks

There are three forms of winter bivy sacks to select from:

  • Hooped bivy sacks
  • Sleeping bag covers

The hooped design has a gap on the entrance, often supported by a curved fiberglass hoop. You’ve gotten crawl into it feet-first, and head-first, in your palms and knees, to get out. The entrance entrance is often screened with a strong cowl that may be zippered closed for heat or to dam wind or rain. This design supplies good air flow on your head and helps to expel the water vapor contained in your breath. Whereas the additional room above your head additionally makes a hooped bivy really feel much less claustrophobic, in addition they are usually the heaviest kind of bivy bag accessible. The Outside Analysis Helium Bivy is an efficient instance of the hooped design

The Black Diamond Bipod Bivy has a snorkel design that provides head protection and is entered from the side.
The Black Diamond Bipod Bivy has a hooped design that gives head safety and is entered from the facet.

One other variant of the hooped design supplies a coated rear-facing compartment for the top utilizing a hooped pole.  This makes it simpler to get out and in at night time and to place in your sneakers. You can too open up the highest of the bivy sack for higher air flow to mitigate inner condensation. The Black Diamond Bipod Bivy and the Large Agnes Three-Wire Bivy are good examples of these bivy kind.

The MSR Pro Bivy is shaped like a sleeping bag with a simple slit to get in and out of.
The MSR Professional Bivy is formed like a sleeping bag with a easy slit to get out and in of.

The best and lightest weight winter bivy sacks are little greater than sleeping bag covers. Some have drawstrings that you may pull closed over your head, some have formed mummy-style hoods or easy slits above the face for air flow. Whereas not as livable or well-ventilated because the clamshell or snorkel-style bivy sack designs described above, they do get the job finished if you would like a extremely compressible, ultralight climate safety on your sleep system. The MSR Professional Bivy and the Black Diamond Twilight Bivy are consultant examples of the sleeping bag cowl design.

Methods to Select a Winter Bivy Sack

There are a number of options and trade-offs to contemplate when selecting a winter bivy sack.

Waterproof/breathable prime cloth

Having a water-resistant/breathable prime cloth is necessary to vent water vapor and assist decrease inner condensation that may make your sleeping bag moist. Nevertheless, not like rain jackets, most bivy sack producers don’t checklist the laboratory measurements used to fee waterproofing (hydrostatic head, abbreviated “HH”) or breathability (movable water transmission fee, abbreviated “MVTR”). That may make efficiency comparisons between totally different bivy sacks tough.

Extra headroom

If headroom is necessary to you, think about getting a bivy shelter with a hooped design. These bivy sacks include a versatile fiberglass pole that slides into the hood space to create extra quantity round your face and shoulders. The tradeoff is that they are usually heavier than extra minimal bivy sacks.

Extra quantity

Winter bivy sacks are usually excessive quantity to suit chilly climate winter sleeping baggage and inflatable pads with a excessive R-value. When selecting a bivy sack you need to ensure that there may be sufficient room on your sleeping bag to totally loft and that it’s not compressed by having a decent match.

Entrance and exit

It’s a lot simpler to get out and in of a bivy sack that has a zipper alongside the facet than one which solely has a “hatch” on the head finish, to crawl out and in off. You’ll keep drier if the bottom is roofed in snow and it’s a lot simpler to placed on and take off your sneakers.

Insect netting for hotter temperatures

Should you plan to bivy in early spring when biting bugs emerge, make certain to get a winter bivy sack with a mesh panel over the face so you possibly can sleep with out bugs biting your face at night time. Should you solely plan to sleep in a bivy sack in winter or in snow caves, a mesh panel will probably be much less necessary. For hotter climate use, I’d encourage you to put money into an ultralight bivy sack or bug shelter fairly than a winter bivy sack, since they’re a lot cooler to make use of. See our 10 Greatest Backpacking Bug Shelters for our really helpful three-season bivy sacks.

Weight and Packed Dimension

Don’t overlook to contemplate the burden of the bivy sack and its packed measurement, since one of many chief advantages of utilizing a bivy sack is gear weight and measurement discount. There’s usually a tradeoff between options and weight/measurement, however some winter bivy sacks are surprisingly light-weight and compressible.

Sizing and Match

When unsure, order a bivy sack (verify the retailer’s return coverage) and lie in it at house to see if it suits. This may in all probability let you know much more about whether or not it would be just right for you than evaluating the specs of a number of fashions listed on-line. Verify to just be sure you can suit your sleeping pad and sleeping bag inside, and that the foot field is massive sufficient on your ft.

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