Solo shelter systems like the bivvy has evolved considerably with the growing sophistication of ultralight camping. There are a variety of choices and designs available to anyone determined to keep their loads as light as possible.
The main function of a bivvy is to keep the user’s sleeping bag dry and to increase the warming capacity by at least 10 degrees. Bivvies are for people who travel solo in the backcountry, are on hiking trips that take longer than a day to complete, camp during long-distance biking trips, want to shed as much weight as possible and don’t mind sleeping in limited spaces. They’re perfect for summer ultralight backpacking.
The bivvy sack was originally made for climbers who wanted an emergency shelter to protect themselves from the weather on multiple-day climbs on big walls. Bivvy is short for bivouac sack and sometimes “bivvy” is spelled with only one “v” i.e. “bivy”. They look like a sleeping bag modified as a shelter.
In fact, early bivvies were only a single layer of waterproof fabric designed as a slipcover for sleeping bags to keep them protected from the rain. The biggest problem with bivvies in the old days was condensation due to poor ventilation of body heat.
The modern bivvy normally involves Gore-Tex or other breatheable material as the inner shell and commonly a durable nylon coated with urethane for waterproofing for the outer layer.
However, the bivvy is still in need of a opening for breathing but when the rain falls some water can potential leak into the sack through the unprotected opening. You can minimize this risk by pulling the headhole’s drawstring snugly.
Some things you might want to consider when choosing bivvy sacks:
– Armholes on the side that allow for cooking while staying warm and protected inside the bivvy
– Full length zippers for easy ventilation
– Factory sealed seams
– Included stuff sack
– Straps for securing sleeping bag in place
– Integrated camping sleeping pads
There’s also something called the bivvy tent or bivvy shelter which is a modification of the original bivvy sack to have tentlike characteristics for an extra pound or so. This adds two features not available with tradional bivvies – a full enclosure to block out bad weather and insects and an expanded area of shielded headspace.
Bivvy tents are very popular with ultralight backpackers. They usually have mesh panels and some poles that lift the fabric off the face and body. You can get yourself fully enclosed and shut out bugs and rain with this type of bivvy.
Bivvy Inspired One-man Tent
Then there’s the bivvy-inspired one man tent like Kelty Clark Tent, NEMO Gogo and The North Face Solo 12 Tent. This type of tent can weigh as little as 2 pounds 8 ounces. Standard bivvies weigh about 2 pound or less but the bivvy inspired tent has more room for sitting and general comfort. This type of one-tent is the main choice for recreational explorers.
The bivvy is unfortunately for for everyone. Although it is a good option for ultralight backpacking, not everyone is comfortable with the limited space. If space is an issue for you and you don’t mind the joys of sharing then go for a dome tent. It’s a lot heavier but you can share it between few people. Other members of the groups would have to carry some of the gear of the guy who’s carrying the tent.