Half Bag?

A so-called elephant foot bag was popular forty years ago among climbers. They would normally have a big down parka for the torso, so they would wear it with the half-bag for the bottom half. An elephant foot bag typically weighs about half of what a full bag weighs, and it is much more compact.

–B.G.–

Or half in the bag? I have always been skeptical of this approach, as everything I have read suggests that the weight from a heavy parka is better invested in the weight of a down bag. It seems to only make sense if you are required to carry a really heavy parka for some reasons, like a beefy belay jacket for climbing. I guess temperature ranges and conditions are also a factor. Some forum members use the Feathered Friends Vireo, a cousin of the half bag, with a light down parka like the FF Daybreak, because they always bring the down jacket anyway so why not pair it with a bag and save some weight? Nunatak has a nice half bag/Parka combo I have pondered but passed on. Let me know how it works out for you!

I picked up a half-bag from Wild Things off a BPL member. It's rated at 30º, with enough length to reach almost to my armpits. I'm interested in using it with a synthetic jacket (Arcteryx SV) for wet 3-season trips with temps down to near-freezing, but not below. I also want to use it with the same jacket inside my 15º MH bag for deep-winter trips. I can get by with just the MH bag and the jacket, but figured the half bag would be a boon.

Part of me thinks "A full bag will only add a few ounces and be far warmer" due to the trapped air effect, but I am not 100% sure. I am mostly excited with this purchase as a chance to test out another alternate sleep system; nothing brings me joy quite like shivering in the dark, learning about gear.

"It seems to only make sense if you are required to carry a really heavy parka for some reasons, like a beefy belay jacket for climbing."

Check out the old 1975 Clint Eastwood movie, the Eiger Sanction. All of this shows up about three-quarters of the way through the ascent.

–B.G.–

I had a Wild Things bag like that. The math looks good if you are carrying a puffy anyway. It's more of a summer thing. It should make a good pairing with a quilt for winter, keeping the drafts out. Should work good with a bivy too.

It's kind of a developed taste thing: you have to like sleeping in a jacket. We're used to wrapping a blanket (or buffalo robe) over us. I wake up more from being too hot than cold.

Can't say I've ever been in near-freezing temps and thought to myself, "The top part of my quilt sure seems useless right now."

Nothing quite soothes me to sleep like the knowledge of saved ounces.

I've been using my Viero inside my WM Alpinlite since it's gotten colder, saves me a pound since my winter bag is by itself heavier. Once it gets below 18 degrees at night here I'll have to switch to the heavy bag and deal with carrying the extra pound.

I think a good rule of thumb is to have at least the same amount of loft in your parka as the elephants foot bag.

I used a vireo on the northern half of the PCT and found it warm with a heavy down jacket (Marmot ama dablam) and baselayer down to 30 degrees or so, after that I would have to add a bag liner and all my hiking clothes. Considering the vireo is rated 25/45 I don't think a daybreak alone would be enough. The loft in the 25 degree section of the Vireo is about the same as my marmot jacket + the 45 degree, so that's where my rule of thumb comes from.

I'm tempted to try it. I'm a stomach sleeper at home and sleep with my arms above my head. This doesn't work well with a quilt (arms get cold), so I've been thinking that a half-quilt with a super warm jacket would let me comfortably sleep on my stomach like at home.

For a backpacker, I don't think there are any weight savings with a half-bag. It will always be lighter to just carry a warmer, full-length bag.

I agree that a full bag is lighter, but if you're already carrying the jacket… multi-use.

This is definitely one sleep system where utility comes before comfort. I don't think half bags are going to fill a void of warmth and comfort for anyone over a full length bag or quilt.

"Part of me thinks "A full bag will only add a few ounces and be far warmer" due to the trapped air effect, but I am not 100% sure"

In my experience this is correct, making the half bag a rather flawed concept. If you'll always have a fairly heavily insulated parka, something with variable insulation like the Vireo makes sense, but with the traditional mid to light insulating jackets used by hikers a normal bag or quilt is by far the most efficient option.

Can anyone comment on where the Arcteryx SV plus a Patagonia Micro-D fleece falls on the "tons of insulation" spectrum? I don't have any experience with super puffy down jackets, as this combo plus a raincoat takes me from 30º to -20º.

Thanks!

A 100 g/meter synthetic parka plus the 8 oz fleece would be just enough to take the 45F rated upper part of the Vireo down to the 25F part of the lower (assuming no insulated opants), maybe a bit lower.

When I say big insulated coat I think of 160+ g/meter of synthetic or a baffled down parka.

With 100g/m^2 of PL1 (now Primaloft Gold) the Atom SV is the warmest lightweight or midweight puffy that often gets talked about. Most others are 60g/m^2. It's warm enough at 20ºF for me for short periods of no movement, but longer than a half hour and I get chilled, easy. I definitely couldn't sleep in it unless we are talking the warmer side of 40ºF.

That said, my jacket of choice for winter backpacking and ice climbing is the DAS parka, which combines 60g PL1 and 120g PL Synergy. I could almost sleep in that comfortably around 30ºF with just a t-shirt if I had the appropriate leg covering. I could see using a half-bag with it as being a practical choice since I need a thick jacket anyway to stay warm in camp and at stops.

Brilliant is it is I now leave the Atom SV at home for this warmer, heavier belay jacket. With the DAS, there rarely a need to layer up for stops and camp, although you are still welcome to.

What position do you sleep in?

I could see it as an alternative for the mummy-haters.