continuous baffles on sleeping bags: a practical way to adjust temperature?

[Ashley Brown]

Just wondering if there are many folks out there that regularly shift the down around in their sleeping bag to make it cooler or warmer as the conditions dictate. Is it easy to do, or do you end up with cold/hot spots? Do you just shake your bag or do you need to push the down with your hands? And is the difference worth the effort?

[Brett .]

I don't need to because I never have 'too much' bag. I adhere to the light backpacking concept of taking a sleep system which includes my base clothing layer, my insulation clothing layer, bag, etc.. I adjust for temperature by unzipping or maybe removing a clothing layer; I never have to shift down.

Another concept I use are segmented lateral elastic baffles along the entire length of the bag, every 10" or so. Each circumferential ring attached to the inner lining squeezes the dead air out of the bag, and continuously maximizes loft without any effort from me. This is a patented feature on some Montbell bags.

[Kyle Rosenberger]

I use a sleep system similar to Brett, adjusting your clothing worn inside the bag is the best way to change your systems temp range. The montbell bags are super efficient!

[Lynn Tramper]

I'm with the others here. I used a WM Versalite and Ultralite for many years, and fiddled with the fill depending on temps. Then I finally figured out it was a waste of weight to carry down that I was basically going to lie on top of. Now I use a WM POD, with down only on the top, and adjust temp with clothing or zipper.

[dennis davitt]

I've had two sleeping bags with continuous baffles and the light one with about 12 ounces of down and 5 plus inch baffles I had some issues with cold spots from shifting down that were probably made worse by using it in a bivy.
I removed the zippers/draft tube and after adjusting the down sewed a couple of lengthwise seams and turned it into a great performing quilt but not necessarily a cheap one.
I also use layers and a montbell down liner/jacket as necessary and even before cutting it up could go well below the 30 deg rating if I used a proper pad underneath.

[Ashley Brown]

Thanks for your feedback guys. The reason I was asking was I'm trying to work out whether I can get away with a single bag across a wide range of temperatures. I understand that it makes most sense to start with a cooler and lighter bag, and then add clothing as necessary. But adding +- 10 degrees to your bag by shifting down would be handy too.

I don't really have a fixed location/climate where I do most of my camping and hiking (since I usually do it when I travel). So I'm looking for maximum flexibility in temperature ranges from 15-60 degrees F.

I'm thinking that a 25 or 30 degree bag might do the trick if I could shift some of the down when necessary (to make it cooler). A 30 degree bag like the WM megalite might be good, but I'd prefer something with a full down collar for sub-zero temperatures. Maybe a montbell SS down hugger #2 (25 deg)?

[Brett Tucker]

I agree with your reasoning Ashley. I think a lot of PCT thru-hikers might concur as well.

[Kyle Rosenberger]

Super stretch bags are great! but will not allow you to shift the down.

[Lynn Tramper]

I'm not sure I understand the reasoning behind shifting the down (after years of using these bags). Basically you get the warmest bag you will need, and if the weather is warmer than that, you a) wear less clothes, or b) unzip the bag and use it like a quilt or c) use it like a quilt and stick you feet and arms out, or d) lie on top of you bag if it's absolutely steamy. A fully zippered bag is as versatile as you can get, with or without down shifting capability. Having said all that, the Ultralite or Versalite are supreme bags for just about any conditions. We've even used the Versalite in spring/summer as a two person quilt.

[Ashley Brown]

You're a lucky camper then Allison! I'm very sensitive to temperature when I sleep. Too warm or too cool and I sleep very poorly, waking up every half an hour. Some people can get away with sticking their arms or leg out of the bag but it doesn't work for me. Unzipping the bag doesn't work great either since I sleep on my side a lot… I end up with a cold front and a sweaty back, or vice versa. Using it as a quilt works fine though, and certainly makes things cooler by a few degrees.

Basically I'm just a really fussy sleeper. I have about 6 layers on my bed at home, so that I can get it just right depending on the temperature of the night. My girlfriend on the other hand, just sleeps with everything on (the hotter the better). When she eventually over-heats she sticks her leg out, which I have always found hilarious!

Anyway, it seems not many people shift their down around, so "continuous baffles" must be mostly for the purposes of marketing (ie. an extra 'feature'). I might give it a go when I get a new bag with continuous baffles though because (in theory) it could be quite handy for a fussy sleeper like me.

[Lynn Tramper]

Ashley, it would be good if you could borrow a baffless bag to try. I think you'll find it impossible to pick just the 'right' amount of down to have on top so that you will be comfortable all night without having to re-adjust the down. This is not a trivial exercise in the middle of the night as you really need to stand up and shake the whole bag to move the down. If you're in a tent or tarp you will have to go outside to accomplish this. Since the night usually starts off warmer and then cools through the early hours of the morning, I suspect you will be expecting too much from this style of bag. Sounds to me you might be better off carry 2 much lighter bags that you can trhow on or off without much effort.

I'm definitely a 'stick your body parts out' kinda gal. At home I even sleep with a fan to rapidly cool my feet when I stick them out!

[Pamela Wyant]

Good point on the requirements to shift the down. It will work, but it does take a good bit of effort (and space) to shift the down.

Ashley might be happiest with clothing layers (including insulated jacket and pants and a down quilt so she can add or remove layers as needed. Or even a light bag plus a light quilt for maximum versatility.

[Ashley Brown]

Thanks for the heads-up Allison. I wouldn't be looking to adjust the down during the night, but when I am travelling I would at least be able to make it a little cooler depending on location. Some trips it's hard to know in advance exactly what the temperature is going to be like (eg. a heat wave on my last trip in France) so even if I had a large selection of sleeping bags to choose from I still need to choose one before I leave and make the best of it.

Two lighter bags would be much more flexible… I guess it's a comfort/weight tradeoff as always. A lighter quilt instead of a second bag would probably be a good idea.

[Anonymous]

Hi Ashley,
Another possible technique would involve purchasing a bag with a double zipper. That would allow you to vent from the foot of the bag without exposing your upper body to cold air
during the night as you turn from side to side. Unfortunately, WM bags don't have that feature, at least my Ultralite and Summerlite don't. But there are lots of other good bags out there to evaluate if this idea appeals to you. Interesting problem.

[Eric Noble]

Ashley, before I got my quilt my only bag was a Western Mountaineering Versalite. I would shift the down to adjust the temperature. There are two approaches to this that I used. One was to shake the bag while standing. The other was to sweep my forearm across the bag in the direction I wanted to move the down. The later approach can work while in your average shelter. Using the bag as a quilt is a good approach as well. The last time I did this was on a week long outing in the Rockies. It never got below 40° F. The Versalite is a 10° F bag. I did struggle a bit to not over heat but it did work. If you are tying to make one bag cover a very wide range this is workable though a little fussy. If weight is your primary concern then a quilt for above freezing temperatures is hard to beat in my experience.

[Eric Blumensaadt]

AShley,

I have a Western Mountaineering Megalite down bag W/ continuous baffles. I do shake the down to move it from top to bottom or the other way….howsomever the 850 fill down is so fluffy it is difficult to move as much as I'd like. It does help though. I can reduce or increase thickness in the top by about 25% and on a hot or cool night and that helps.

My favorite way of dealing with a hot night is to unzip the bag full length, (full length zipper required, of course)then hook the bottom of the bag over the foot of my Thermarest UL full length mattress and use the bag as a quilt. This is VERY comfortable. Like sleeping at home.

Eric

Eric

[Brett Tucker]

Also keep in mind that a bag with continuous baffles can, in theory, allow you to move all the down to the top of the bag where it does the most good, meaning such a bag can be made significantly warmer than its stated temperature rating. Not so for a bag with a more complex baffle pattern, for example the Montbell Superstretch Downhugger #3. In such a bag, the amount of insulation in a given square of baffling is fixed, and all of the down on the underside of the bag is permanently underneath you and compressed by body weight. In a bag with relatively low fill weight such as this, those individual baffles can also be fairly unlofty, and any aberrations in fill content between baffles can lead to noticeable cold spots for which there is no remedy.

In a winter bag, discontinuous lateral baffles are an important design feature, keeping the down from accidentally shifting out of place (to the sides and bottom) during the night, which can sometimes be an issue with continuous baffles that becomes problematic in cold temperatures. Outside of winter conditions, discontinuous baffles reduce the flexibility of the bag and can mean carrying a heavier bag than is necessary for a given set of conditions.

[Lynn Tramper]

"Also keep in mind that a bag with continuous baffles can, in theory, allow you to move all the down to the top of the bag where it does the most good, meaning such a bag can be made significantly warmer than its stated temperature rating"

To a certain extent this is true, but I feel continuous baffle bags work best the other way, i.e. shifting the down from the top to make things cooler. Baffle height will ultimately limit how efficient it is to shift ALL the down to the top of a bag. If the bag is underfilled for it's baffle height then it will make a bigger difference than in a bag like a WM which has ample fill to begin with. The baffles can be over-inlfated with down to some degree, but beyond that all you are getting is an increase in down density instead of loft.

Good point, though, that continuous baffled bags can have the down shift in the night, especially if you move a lot. The tendency is for the down to move towards the bottom of the bag (gravity sucks). This can be a disadvantage in winter conditions!

[Brad Groves]

The most important factor when trying to take the "one bag does it all, I'm gonna shift the down" is how well constructed the bag is. Here's the thing. I've got a WM Antelope DL that was my only bag for years. It's awesome! (Also a bit heavy at 2# 13oz, but it's a 5 degree bag, too.) The reason I say construction is so important is that many, many bags on the market don't start out with enough down in them. If there isn't enough down in the baffled chamber to start with, (1) you'll have difficulty eliminating cold spots and getting even loft at any time, and (2) when there's less down in the chamber, it tends to shift more on it's own accord and without your explicit blessings and encouragement.

I've spent far too much of my life on the retail end of this industry, and from the non-mail-order companies, Western Mountaineering and Feathered Friends are consistently on top of fill levels. Many other companies skimp on the down.

As far as practicality is concerned… Shifting the down is very easy. Open the zipper full length. Grab the bag at the zipper on the side you want to move down out (i.e., grab the top of the bag side zipper to shift down to the bottom). Shake vigorously. Check the bag visually, and feel loft with your hands. Adjust as necessary. Very easy process. But not one you're ever likely to do during the night. Shifting down is something you'd do either pre-trip or before bed. Incidentally, if you want to get the bag back to its original temperature rating for "factory" loft, most companies rate their bags with 60% of the down on top and 40% on bottom.

As long as you sleep flat on your back, this is eminently practical (not particularly from the perspective of weight, but of versatility in temperature range and ultimate cost). If you tend to sleep on your side, you generally should roll with your bag so that you aren't exhaling all your humidified air into the bag and reducing your loft. Bottom line, I wouldn't plan on shifting all the down to the bottom, and if you did, I'd plan on spending at least part of the night on your back when you get cold.

I know that a whole lot of people on this site would disagree with my following statement, but here it is: I'd probably suggest a zero degree bag for ultimate versatility, given that this is a system you want to use in winter. Generally you can add 10 degrees to a manufacturer's rating to get to a warm n' comfortable range. If you're out in summer, shift a bunch of down to the bottom. No big deal. It really depends on how much of your time you'll spend doing what. If you'll spend 80-90% of your time in 3-season use, just get a 20 degree and layer up in winter.

Thinking back to your original post, MAYBE the ultralight option would be best. What I'm thinking, honestly, is "Holy $%^#! Six layers on the bed?" If you need that much fine tuning at home, get a large-cut 30 degree mummy (Feathered Friends Kestrel, perhaps Osprey–Grouse is the women's cut, not sure if it'd be big enough– or Western Mountaineering MegaLite, maybe their semi-rectangular MityLite-40 d- or Sycamore-25 d-) , and in that large-cut, cool-ish bag wear a bunch of layers you can strip off at will, definitely including a down jacket, perhaps preferably with hood.

Anyhoozit, that's my couple cents

[Franco Darioli]

Whatever works for you…
With both my JRB No Sniveler and Ultralite ( open on quilt mode), if I feel the need I hold up the sides shake the down towards the middle and (particularly with the No Sniveler) I get a higher loft where I want it. Both bags are wider than I need them so the last few inches at the edge are not in use. This works for me because under a quilt I can turn without shifting the top, inside a zipped up bag I wake up either because of the cold spot from the temporarily compressed bottom or because I'm all twisted inside the bag ( I use a silk liner…)
A friend of mine falls asleep on demand (army training) and sleeps on his back all night. For him a continuous baffles zipped up bag would work more efficiently as well.
Franco

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