Who makes use of bivy sacks? Individuals who:
- Steadily journey solo within the backcountry.
- Climb big-wall routes that require greater than a day to finish.
- Camp throughout long-distance biking journeys.
- Critically need to shed each potential ounce from their masses.
- Go winter tenting in snow caves.
This text covers the fundamentals of bivy-sack choice.
Bivy Fundamentals
Bivy sack is brief for “bivouac sack.” It was invented to serve climbers who wished light-weight emergency climate safety for sleeping baggage throughout multiple-day ascents, significantly on large partitions.
Early bivy sacks had been little greater than waterproofed nylon slipcovers for sleeping baggage—good for shielding sleeping baggage from rain, not so good when ventilating vapor produced by physique warmth.
Bivy design right now entails 2 tiers of cloth:
- The backside tier sometimes consists of a sturdy grade of nylon coated with urethane to make it waterproof. This is identical materials used for many tent flooring.
- The prime tier is often fabricated from ripstop nylon (a lighter cloth) and handled with a water-proof, breathable laminate reminiscent of Gore-Tex®.
For an additional pound or so, a tent-like bivy shelter provides 2 options not accessible with conventional bivies—an expanded space of shielded headspace and a full enclosure to dam out unhealthy climate and bugs. These extras have helped bivy shelters develop in reputation, significantly with ultralight hikers.
Bivy Sacks vs. Shelters
A conventional bivy sack is meant primarily for mountaineers or dedicated minimalists. It performs 2 fundamental capabilities:
- It retains a camper’s sleeping bag dry.
- It will increase its warming capability by about 10°F.
A bivy sack’s head opening means moisture can probably discover its method inside. You possibly can reduce that danger by pulling the headhole’s drawstring very snugly. This tends to show the headhole into extra of a nosehole, which some individuals discover far too restrictive. Many minimalists, although, are keen to make this sacrifice.
Options price contemplating:
- A number of zipper sliders can help you create armholes so you possibly can kind gear or prepare dinner whereas being protected by the bivy.
- Full-length zippers present a number of air flow choices.
- Manufacturing facility-sealed seams for waterproofness.
- Straps that allow you to safe your sleeping pad in place.
Bivy shelters are low-rise tents that embrace mesh panels connected to the top opening, plus poles or hoops that raise cloth off your face. They can help you shut out bugs and rain, although downpours could require cautious venting to remain dry.
Shelters are greatest for ultralight backpackers and touring cyclists. Their fortified wedge of head house gives simply sufficient of a consolation zone to make a bivy’s restricted air house really feel acceptable. In wet areas, bivy shelters lose a few of their enchantment; it may be robust to attend out a storm inside a shelter that gives no sit-up house.
Bivy Concerns
Is a bivy too tight for you? Each sacks and shelters require a Spartan mindset. However do not dismiss this type of shelter too rapidly. Whereas a tent gives a roomier, roof-over-your-head sensation, a bivy is nearly like sleeping beneath the celebs—a really liberating expertise. On the similar time, you might be protected against bugs and rain by a really light-weight barrier. Nonetheless, if tight areas make you uneasy, you might be prone to really feel uncomfortable inside a bivy. In that case, transfer as much as a tent.
How does air flow into inside a bivy? Breathable/waterproof laminates reminiscent of Gore-Tex® cloth make it potential for vapor produced by physique warmth to be pushed by way of (and out of) the material. This works greatest when a heat, humid physique is resting someplace cool and dry. In wet situations, it is best to sufficient overlapping materials and zippers so it’s unlikely you’ll have to utterly zip them shut. Manually venting a zipper or flap helps keep a suitable inside humidity degree.
Can condensation be an element with a bivy? Doubtlessly, sure. A bivy is principally a single-wall tent. When vapor escapes out of your physique or lungs, it rises to satisfy colder air. In some unspecified time in the future, the air can no lengthy carry all this moisture, so some could acquire on the inside wall of the handled bivy cloth. In 2-walled tents, in contrast, this moisture passes by way of the cover and settles on the rainfly.
Will a bivy actually hold a sleeping bag dry? When moist, Gore-Tex cloth generally produces a clammy feeling when it touches your pores and skin, however it’s simply that—a sensation, not a soak-through. Good air flow helps reduce this situation.
How minimalist can I am going? In heat situations, some individuals skip a sleeping bag altogether and easily sleep contained in the bivy shell.
Store fitnessinf’s choice of bivy sacks.