Should I use a bivy bag under my tarp?
I've got a Bibler Betid tarp, and looking for some extra protection for my Mountain Hardwear sleeping bag (down with Conduit SL shell). I don't want to carry the Betid's floor since it is a bit heavy, and doesn't offer the protection I want. Please suggest a sleeping bag cover or bivy that will allow my bag to breathe, yet shed any moisture from condensation or the occasional exposure to rain. I'd prefer not to break the bank on this, as well. Dennis Staley Englewood, Colorado
Yeah, I’ve got a recommendation. It’s called a “tent.” Keeps rain and snow off your sleeping bag, doesn’t require a tarp or other sort of floor, and eliminates the need for a bivy bag when you’re already lugging a piece of weather protection.
In other words, it sounds as if you’ve hit the limitation perimeter of the Betamid ($98), a single-wall, single-pole, floor-less tent that saves a bunch of weight (it’s just over two pounds) but forces you to do without some niceties. Add the optional floor, and you’re close to four pounds, which is close to tent weight.
The only other option, as you suggest, is to add a sleeping-bag cover. The best bet would be a simple Gore-Tex bivy bag, such as Outdoor Research’s Standard Bivy Sack. But that weighs as much as the Betamid floor, and is expensive at $230. A good option: Mountain Hardwear makes a bag cover out of the same Conduit fabric that already wraps your bag. It’s called the Conduit SL Bivy, and costs a more reasonable $109. The drawback: Two waterproof layers right next to you, which are apt to trap moisture inside the bag, or between the bag shell and bivy. And that could be bad, depending on conditions.
Bottom line: It’s hard to find a place where price, weight and performance all intersect as neatly as you might desire. I suppose you always could by some 4 mil plastic poly sheeting, cut an 8X8-foot chunk, and wrap yourself in that when it gets nasty. That’s what campers did in the good ol’ days after World War II - take a chunk of military surplus waterproof sail cloth, and roll up in it when the rain fell.