UKH

Hi all,

I'm getting pretty bewildered by all the parameters there are in buying a new sleeping bag. I'm in the market because I'm headed to the Dolomites soon and the general logic seems to be that you need a warm down sleeping bag (although I'm not so sure now). 

I'm currently using a Snugpak Jungle bag which is a small synthetic bag and has a comfort of 7°C and a Limit of 2°C. Although combined with my down jacket and ME pad I think I've been fine down to 0°C. 

The new bag would hopefully be good for a summer bivvy in the Dolomites and some Scottish winter climbs if this is possible. I'm guessing this means going for a sub-0 rating, but I've also seen conflicting opinions about down Vs synthetic for these conditions. With some people also saying they use quilts or stack bags together.

If you were going to bivvy on the side of Marmolada in June or stay in a Scottish bothy in January, what would you take?

Thanks,

George 

Depends how long you're going to be out. If it's a few days I'd go syth with a good vapour resistant outer material. If it's just a couple of days then I'd use down.

If you're using bothies or alpine huts then down would be my choice as the damp shouldn't be an issue.

Sleeping bags can be a bit like boots, one item for all things is often a  compromise.

Like rucksacks the ideal number is n+1

Thanks for the reply!

I've read that overnighter = down, long trip = synth methodology elsewhere too. Is this because synth is far better when wet and therefore less of a risk on a long trip?

Haha, it's definitely looking that way!

It often depends where you're sleeping but in principle yes. You could spend 4 weeks in Scottish winter with a down bag, assuming you keep it in a dry bag and stay in a dry bothy. Use it in a bivy bag and you'll be lucky to stay dry and warm for more than 2 nights.

If you want a do it all bag, Mountain Equipment do a Klimatic lll synth at around 1200g that could work but I'd pair that up with a good insulated jacket incase the temps drop. A friend of mine uses a Mountain Hardwear Lamina he got cheap off Sportpursuit and that has kept him very warm for the weight. Keep in mind the use life of down lasts for much longer as synthetic compresses over time and loses it's loft.

What shelter are you sleeping in?

You can stack bags, but ... the rule is don't put a down as the inner one (unless the 2 bags are specifically designed to go together like that).

In particular don't put a nice fluffy high loft down one inside a synthetic bag as it tends to squash the down and you loose a lot of warmth from the inner bag. synthetic inside down is usually ok though, providing there's enough space 

But synthetic on the outside moves the dew point away from the more sensitive down. There are pros and cons to both

I used a down bag for a month straight in the Pyrenees last year. I think that if you're in a tent it's perfectly manageable, particularly in Europe in the summer where you can air it in the sun most days if needed.

I probably wouldn't go with a down bag with a bivi bag. I have in the past, and damp is definitely a problem - particularly in the UK. In a bothy in winter, again I would think it would be fine.

Actually, quite the opposite.  Always synthetic on the outside (as has been mentioned) to allow water vapour to pass the down before condensing.

Like many here I have multiple bags for often marginally differing needs (but buying gear for niche situations is always fun).

Almost every time I have opted for the lighter bag that just about matches the expected temperatures I have regretted it. Go for a bag that exceeds your minimum expected temperature and you'll have a decent nights sleep, subject to having good ground / mat insulation.

Any weight savings that make the pack feel better during the day are quickly erroded as you toss and turn all night thinking about that 200g heavier bag left on the shelf at home.

Don't know where you're based but you could a lot worse than head to a Alpkit shop. They have a good range of down and synthetic sleeping bags. Explain your needs they'll advise.

"Warm" and "down" are two different and independent decisions, though. How warm will depend on what overnight temperatures you're expecting to encounter. Down or synthetic really depends on how compact and light you need it to be. There's no reason why you can't use a synthetic bag in very cold temperatures - indeed, as others have said, it will be better at withstanding damp and condensation - but it will be bulkier and heavier than a down bag with the same temperature rating. 

If you are going to spend a  number of consecutive nights in a cold damp unheated environment - eg Scottish bothies , in a down bag consider using a vapour barrier liner. That will stop your sweat dampening the down and loosing insulation. The flip side is you wake up clammy in the morning, but it’s a small price to pay!

Hmm interesting, would wool baselayers not do a similar job by soaking up the sweat?

I'll check out the ME bag, thanks!

For the minute I don't own a lightweight tent so I'm just limited to my Bivvy bag and tarp which means that like you say, damp is a concern.

I've been reading an old Andy Kirkpatrick article (https://www.andy-kirkpatrick.com/articles/view/double_up) where he talks about the 'ideal' system of using a lightweight down bag/quilt inside a synthetic bag with a good waterproof coating for when it gets really cold. This system sounds pretty interesting because in warmer seasons the synthetic bag can be used for bivvying and the down bag/quilt for tent camping and then in winter both can be combined to get a bag that's good down to hopefully below -5°C.

Wondered if anyone had any thoughts on this?

I use a system a bit like that - have a cheapish 1 season synthetic bag, and a phd Minim 300 I bought when there was no need to sell a kidney to do so. 
 

I also have pretty warm tent gear - OMM insulated trousers and a light down jacket. 
 

the three sets together sees me through Scottish winter nights, and its mix and match able across the year.

Don't agree with that; you want the down bag inside, so that the dew point falls within the outer synthetic bag.

[edit: beaten to it...]

If you're sweating that much your bag is probably too warm.

More seriously, wool is permeable - even while it was soaking up moisture some would still be passing through into the down.

Does anyone else feel uneasy with the use of the word "need" when kit is being debated? Just got the spring edition of Summit through the post today with the usual two pages of what kit I "need".

Sorry, rant over, just being grumpy... 🙃

George - a vapour barrier works by preventing moisture getting into the bag to start with so the down stays dry. Wearing woolen undies or smelly helly undies inside a vapour barrier is a good idea to stop you getting too clammy. (For vapour barrier read waterproof)

But this would mean that down is unsuitable for bags in general. Imagine you were in very cold conditions and had a single bag which was a thick down one. In that case the dew point would fall inside the outer part of the bag. Never heard anyone say not to use down for this reason (excepting: some damp bivi conditions when synthetic is advised)

Tom - that's why you use a vapour barrier!

You make a very good point. I think this edition of Summit was my first and yes, I agree, the gear advertisements/suggestions were pretty over the top. Gear always has been a distraction from just getting out there and you're right 'need' is probably the wrong word, especially in the current climate.

Thanks for the explanation. VBL still confuses me I think though. I thought the whole logic of layering systems was to prevent sweat from building up against your skin because this makes you cold. Hence the constant marketing of breathable waterproof shells. Maybe it's different when you're sleeping but doesn't getting into a waterproof bag cause exactly this issue?

Edit: I've also read that VBL stuff is just for extreme cold, like arctic temps. Are you guys using a VBL liner all the time?

Thanks, that's great to know. I think I might go for something like this given the snugpak bag I already own. 

Yeah I looked at the PHD stuff to see what all the fuss was about but immediately turned away the price!

Edit: do you know the ratings of both your bags? Just out of curiosity.

Understood and I see where you're going, but if you had a vapour barrier liner (nasty, but agree sometimes necessary) then the dew point issue mentioned as a reason not to have down on the outside would also be avoided 

Yes; that's exactly what happens, and why down bags accumulate moisture from insensible perspiration. And why VBLs are used with down bags for longer use in cold climates.

If you're going to layer down and synthetic, certainly put the synthetic outside.

You're not supposed to be sweating (sensible perspiration) in a sleeping bag. If you are, you are too hot, and need to reduce insulation. You should only be losing insensible perspiration (essentially, water escaping our bodies through the skin). The VBL reduces IP, as it creates a humid microclimate within the VBL. Feels a bit clammy, but stops the down bag getting wet.

Sweating is intended to cool us down when we are exerting ourselves. It is supposed to evaporate, dissipating energy. If your clothing prevents this, sweat accumulates, and you overheat. When you stop exercising, the trapped sweat then evaporates, and continues to escape, so you get cold.

I think the PhD is down to 0 degrees C not a model they sell at the moment but the 200 is down to 5 or 6 and the 400 down to -5.

the synthetic bag (mammut kompakt summer) is rated to 10 degrees. It’s nice and big so let’s the phd bag loft well.

I don't think I have a problem with "need". If it were "want" it might be problematical.

Second hand bag on Facebook for £100. They turn up quite a lot second hand but will need washing as per instructions.

I think that there's a lot of marketing 'want' as 'need'; "this year's 'must haves'"

I camped a week in Arctic Norway - night temperatures down to -28. Didn't use a VBL, didn't have any problems. I've camped a lot in Finnish winters, down to maybe -30 at absolutely coldest, and lots of -10 to -20, never used a VBL. I think it's nuts suggesting you need one for the usage you've ask d about. 

Makes sense, thanks for the explanation

Yeah great tip thank you! Although ironically a lot of the bags on second hand sites atm are 700-900g fill down bags which are way too warm for my needs or most people's I'd imagine. I guess people over estimate what they need, which is what I was doing before I came to ask on UKC. Or maybe people buy bags for single trips I guess.

Hmm interesting, thanks! I think I'm going to go this route, seems the most flexible option. Do you have any idea what the lowest temp is that you've slept comfortably with that setup?

I'm yet to get into Scottish Winter activities but I know that occasionally temps get get down to -10°C and so my only concern is that I don't want to be caught out with a system that is only just capable of keeping me warm should temps drop suddenly.

I agree that for around 0 deg or just below, VBLs arent very helpful.  The best thing one can do is pack & compress the sleeping bag the moment you get out of it (so all the moist air is expelled before it cools and the moisture condenses).

However, in general, VBL use depends on the person and situation.  I've had a big -45 rated down bag collapse after just a few nights due to moisture (it was almost -40 to be fair, and my base layers were slightly sweaty... my error).  Moisture management is a huge challenge for me in the cold, less so for others.

Also, bear in mind that 1 person in a big tent will have significantly colder air temps around the bag than 2-3 people in the same space.  Often with a few people in the tent, the temperature inside is barely below freezing even when the temps outside are -20.

If someone isn't very sweaty and doing a shorter trip, yeah, no VBL needed probably.  However, I know that as someone who is quite a sweaty person, and loves going solo in extreme cold, I most certainly need a VBL for even a few days, let alone multi-week.  I learned the hard way.  Even with the VBL, my bag still starts to lose loft after a few weeks.

Also a bit puzzled by some of the responses he's had but perhaps they have understood what he wants from a new sleeping bag. I’m not clear.

George, what do you want from this new bag? More warmth? Less weight? Both? What do you mean by "on the side of the Marmolada." ?

Last time I was in the Dolomites, wild camping in the Sella pass at about 2300m in July, I used a £10 basic synthetic bag rated to 15C. This was warm enough in a small tent with a thin closed-cell sleeping mat. Your current bag sounds like it is warmer. I'd have thought it would be good enough for a day or two, depending on exactly where you're sleeping and what the weather is like.

It's a long time since I've been in a bothy in winter but I would guess it would be colder than the Dolomites in summer.

I think when I made the post I didn't really know what I wanted, but now maybe I have a better idea.

Effectively I have this Snugpak bag which has served me well, and will continue to. It's well made and packs down very small. However, now that I'm starting to do more serious outings I am considering getting a bag that is potentially more fit for purpose (but maybe I'm just falling for marketing crap).

By fit for purpose I mean a bag that will give me a larger margin of safety for colder climates like the Dolomites and Scotland i.e. a warmer bag. But also one that is lightweight and packs down small.

I'm heading to Marmolada and hoping to bivy on the halfway ledge of the Don Quixote/Swallows Tail route, so that means a bivy at approx 3000m. From research, in June I don't expect it to get below -2°C. Currently my bag is rated to 2°C and I could probably get by with using it plus a down jacket and clothes but I have been considering purchasing something that will future proof me for more (and potentially colder) adventures in Scotland etc. So I came here to get everyone's two pence.

Thanks for the info about your bag on the Sella pass, that's pretty reassuring.

Mind you, I wouldn't ever trust Snugpak's temperature ratings, as they don't seem to use the standard EN/ISO lab test procedure at all, only stating some – potentially just shite marketing bullshit – "comfort" values without doing any accredited lab testing, unlike the more respectable manufacturers. And being a pretty big brand, they could certainly afford that £400 accredited lab test per a bag type, yet they don't...

The EN/ISO rating standard for sleeping bags exists for a reason – it lets you compare different sleeping bags, based on a common, standardised laboratory test, iterated and improved upon through the decades. While it had its share of quirks at first, it's still the best temperature rating standard for comparing sleeping bags independently and scientifically.

It works pretty well even for people with different comforts (everybody sleeps differently) – if you know you feel cold in a EN/ISO ~5°C comfort‑rated bag on a 5°C night, it's highly likely you'll also feel cold in a different EN/ISO -10°C comfort‑rated bag on a -10°C night, being a cold sleeper (or the reverse of that, for warm sleepers).

Unlike trying to do a comparison with some numbers of totally unknown provenance like theirs. Pretty hard to compare your Snugpak to a properly EN/ISO‑rated down bag when shopping for a warmer, different one, if all you are basing your previous 'comfortable or not' experiences on is just their own in‑house marketing rating, as nobody knows what's that based on (guesses? CEO's mood?)