Doubling up sleeping bags for winter?

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Sweep
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Doubling up sleeping bags for winter?

Post by Sweep »

I think this may have been covered somewhere but can't find

In short, does it work?

Have just got myself a new Snugpak sleeping bag for winter use.

Claims to have a comfort level of -12 or -15C which would do me just fine - no need for anything better than that.

But can't help but be slightly doubtful.

In case of issues am wondering about doubling up as I have a thin quality Coleman bag that will definitely fit inside OK without undue pressure.

Does this work or do you maybe get breathability/condensation issues because of the outer layer on the inner bag?

Any other thoughts on doubling up?

Would be handy if it did work as will only be doing a very limited number of deep winter camps.
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deejayen
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Re: Doubling up sleeping bags for winter?

Post by deejayen »

It should work as long as the outer bag is big enough to prevent compression. Some manufacturers make (or have made) combination bags and additional inner \ outer bags as accessories.

I sometimes use a tightly cut Buffalo synthetic fibrepile 'summer' sleeping bag inside a down one, and it significantly increases the warmth - from being cold to being comfortably warm.
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pjclinch
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Re: Doubling up sleeping bags for winter?

Post by pjclinch »

Sweep wrote: 28 Nov 2022, 7:02am I think this may have been covered somewhere but can't find

In short, does it work?
"Up to a point"

The usual problem is not enough space for the insulation to loft properly, which you seem to think isn't an issue here though it may be the case that the inner bag just doesn't have the space to fully loft up and unless the outer is really bigger than needed (which gives you space for convection currents as well as basically weighing/bulking more than it needs to) then it could get a bit constricted over night when it comes to scratching an itchy toe etc.

Personally, I'd take a set of warm PJs (e.g., fleece tights and a microfleece jumper) if I wanted to be warmer, rather than an extra sleeping bag. Probably lighter, more efficient, more comfortable, less faff, gives you some warm camp clothes to sit around in. There's also the option of a fleece or wool liner.

There have been setups designed specifically as double bags (the ones I've seen had, IIRC, a down inner and synthetic outer), but in those cases the inner is sized to fit in the outer. But they've never really been sellers.

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in4time
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Re: Doubling up sleeping bags for winter?

Post by in4time »

I was advised that because you would actually compress the underside of your bag/s then the advantages would be compromised. A Thermarest type mat with a good rating combined with a silk liner might be an option to consider. As ever with down; damp is the beast!
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Sweep
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Re: Doubling up sleeping bags for winter?

Post by Sweep »

in4time wrote: 28 Nov 2022, 8:00am I was advised that because you would actually compress the underside of your bag/s then the advantages would be compromised. A Thermarest type mat with a good rating combined with a silk liner might be an option to consider. As ever with down; damp is the beast!
surely you compress the underside of bags when lying in them anyway?
I take the point about needing some decent mat under you to insulate you from cold/freezing ground.
Am also hoping to avoid, if possible, a winter mat by using a normal thermarest and a dimpled foam thingy - more experiments called for once this unseasonably warm patch stops - the new bag was fine at +4 but still have my doubts - more tests over Christmas - will be close to home before risk it all in the true wilds.
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Sweep
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Re: Doubling up sleeping bags for winter?

Post by Sweep »

pjclinch wrote: 28 Nov 2022, 7:54am
Sweep wrote: 28 Nov 2022, 7:02am I think this may have been covered somewhere but can't find

In short, does it work?
"Up to a point"

The usual problem is not enough space for the insulation to loft properly, which you seem to think isn't an issue here though it may be the case that the inner bag just doesn't have the space to fully loft up and unless the outer is really bigger than needed (which gives you space for convection currents as well as basically weighing/bulking more than it needs to) then it could get a bit constricted over night when it comes to scratching an itchy toe etc.

Personally, I'd take a set of warm PJs (e.g., fleece tights and a microfleece jumper) if I wanted to be warmer, rather than an extra sleeping bag. Probably lighter, more efficient, more comfortable, less faff, gives you some warm camp clothes to sit around in. There's also the option of a fleece or wool liner.

There have been setups designed specifically as double bags (the ones I've seen had, IIRC, a down inner and synthetic outer), but in those cases the inner is sized to fit in the outer. But they've never really been sellers.

Pete.
thanks for thoughts pj, and others. - I do use some synthetic Aldi long johns and top but also have some merino stuff I could put under those since the Aldi stuff probably offers little thermal benefit and is mainly to make nightime exits of tent less problematical.

By the by I always use separate sleeping gear - would not use for sitting around camp in.

By the by two, I can recommend this Snugpak "sleeping" hat

https://www.snugpak.com/snugnut-hat

I also have a silk liner and another supposedly thermal liner.

Plus if gets desperate a Snugpak softie jacket - on the small size - bought for sleeping/sitting.
More thoughts on doubling up or experiences with welcome folks.
I will also report back with more experiences on the experiment - pretty much certain that nights where I will be over Christmas will be zero and below.
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Re: Doubling up sleeping bags for winter?

Post by jimlews »

For unheated indoor camping I use three bags + a bivvi.
The inner is a £ 5.00 thin, but washable synthetic from Tesco.
The mid is another, larger summer synthetic bag from Aldi.
The outer is a huge down & feather bag also from Aldi -
the latter was on sale a couple of years ago as part of their 'fishing range'.
In addition, I have a Gore-Tex bivvi bag that usually does service as a pillow
but is useful as an outer if the temperature drops to around freezing.

The only problem is locating and successfully undoing all those zips for unscheduled
nocturnal ramblings.
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Re: Doubling up sleeping bags for winter?

Post by simonineaston »

I tried it once & found it an uncomfortable and dispiriting experience. Always a sleeper who preferes less rather than more, as well as being fond of winter outings, I found myself in a difficult spot, especially as was student at the time. Resolved it by buying a second-hand ME Lightline, from a cyclist from Swindon... have used serial Lightlines ever since.
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Sweep
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Re: Doubling up sleeping bags for winter?

Post by Sweep »

jimlews wrote: 28 Nov 2022, 9:45am For unheated indoor camping I use three bags + a bivvi.
The inner is a £ 5.00 thin, but washable synthetic from Tesco.
The mid is another, larger summer synthetic bag from Aldi.
The outer is a huge down & feather bag also from Aldi -
the latter was on sale a couple of years ago as part of their 'fishing range'.
In addition, I have a Gore-Tex bivvi bag that usually does service as a pillow
but is useful as an outer if the temperature drops to around freezing.

The only problem is locating and successfully undoing all those zips for unscheduled
nocturnal ramblings.
Ah remembered. I do also have a british army gore bivvy myself but things would probably be getting a bit desperate if I used that on top of layering in a tent. It has also when used outside, fields and woods etc, produced a bit of condensation.
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Re: Doubling up sleeping bags for winter?

Post by pjclinch »

Sweep wrote: 28 Nov 2022, 9:02am
in4time wrote: 28 Nov 2022, 8:00am I was advised that because you would actually compress the underside of your bag/s then the advantages would be compromised. A Thermarest type mat with a good rating combined with a silk liner might be an option to consider. As ever with down; damp is the beast!
surely you compress the underside of bags when lying in them anyway?
Yes, but synthetic insulation is usually hollow fibre and so there is usually some air trapping within the fibres even when compressed, so a synthetic loses less from not having a mat than a down bag (there was an ultralight trend a few years back of down bags with no insulation on the bottom and just a sleeve for a mat, reasoning the mat would be doing all the heavy lifting of under-body insulation. I think the issue was then it was difficult to avoid dead space between the mat edges and the sleeper which meant cold spots there, but whatever the idea seems to have largely died a death).

Silk liners tend to be over-rated for their thermal effect. A liner will generally keep you warm to a similar degree as PJs made from the same thing, so unless it's pretty thick silk (which is available, but bag liners tend to be quite fine silk) it won't make a huge difference. Various synthetic and wool thermal liners are available. Most silk liners are primarily about keeping the bag clean rather than the occupant toasty.

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pedalsheep
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Re: Doubling up sleeping bags for winter?

Post by pedalsheep »

As others have said it works well if the inner bag fits nicely in the outer. Years ago I took part in the Everest Marathon and used a Mountain Equipment Dewline (quite a small bag) inside a Mountain Equipment Green Dragon (quite a large bag) as these were the bags I already had. It worked perfectly with the down lofting nicely to give a big fat bag that kept me toasty on the trek.
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Re: Doubling up sleeping bags for winter?

Post by pjclinch »

Sweep wrote: 28 Nov 2022, 9:08am
By the by I always use separate sleeping gear - would not use for sitting around camp in.
Each to their own, but the main point of PJs camping is to stay warm & comfy and maybe keep the bag clean, and sitting around in a tent doesn't generate much in the way of sweat or dirt that will compromise that. And given there is a bulk and weight cost to everything you carry, might be worth considering sleeping in your camp clothes if you feel you need the warmth boost of PJs.

Bit different in summer where you're more likely to be outside in camp for extended periods, but on a damp & gloomy winter night changing out of damp cycling gear in to something to sit around in and then changing again to night wear seems like a change you can by-pass.

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boblo
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Re: Doubling up sleeping bags for winter?

Post by boblo »

Re: No Fill/Lower Fill bases (AKA differential fill) . All good until you turn over. Rarely does the bag stay in place when you spin, it usually tracks you so you end up with a cold back which wakes you up.

If you've a bag that goes to -12°C, how much lower are you going? Occasionally it might get colder than this in Scotland or perhaps you're touring further afield? Short days/very long nights in severe cold are not much fun. You'll spend most of your time in your bag(s), in your tent, on your back contemplating your navel as everything around you gets damper and damper. OK for one or two nights, not much fun for much more.

If you're planning going to Scandahooligan Land or some such, get one bag that copes with expected temps and make sure it has a dryline or similar outer to keep the condensation off. IIRC, one of the biggest issues of multiple bags beyond compressing the insulation is the margins between the bags encourage condensation to form and this makes the bags damp. If it's just a few degrees you're after, a silk liner, a good hat and fleece clothing should sort it.

Oh and in winter, 'camp clothing' and 'sleep clothing' will be the same thing as you won't be sitting around outside admiring the view.
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simonineaston
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Re: Doubling up sleeping bags for winter?

Post by simonineaston »

Forgot to add the most importnat point, which is at low temps ie around freezing, what you sleep on is as important if not more important than what sleep under. A good deep insulated mat will almost certainly mean the existing bag is enough...
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Re: Doubling up sleeping bags for winter?

Post by jimlews »

simonineaston wrote: 28 Nov 2022, 10:35am Forgot to add the most importnat point, which is at low temps ie around freezing, what you sleep on is as important if not more important than what sleep under. A good deep insulated mat will almost certainly mean the existing bag is enough...
Yes,

1/3 above 2/3 below IIR.

Sometimes boost my Thermarest with a cheap closed cell foam mat. Strap the two together with elastic.
Also helps to protect against punctures.
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