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Improving temp performance of sleeping bag

Discussion in 'Kit Chatter' started by emm dee, Jul 9, 2019.

  1. emm dee

    emm dee New Member

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    Im a bit of a bodger and I was wondering

    My local store has a 1 season snugpak synthetic bag rated comfort +11 to +7. Its very light, portable and slinky.
    It almost has the dimensions of the smaller down bags without the thermal performance.

    I also noticed that 2 of these were smaller and lighter than a vango 250 rated comfort -4. So much so that I was thinking about getting 2 of them and putting one inside the other to see how far I could push the rating.

    It isn't exactly rocket science two have got to be much warmer than 1.

    Has anyone ever tried this?
     
  2. Alan De Enfield

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    Just remember that even to achieve those ratings they are taken assuming that the subject is using a sleeping pad, tent and is wearing a base layer of thermal underwear.

    The tests are to the EN 13537 Standard

    Yes - two will be warmer than one but I doubt 'twice as good'

    Lying on the ground in an open sided 'tarp' in just your undies and you will be cold even at the stated temperatures.
     
  3. Janne

    Janne M.A.B (Mad About Bushcraft)

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    Yes, I have used two sleeping bags wintertime in Scandinavia. Fjallraven did a two bag system, which I copied.
    If you get two bags with different ratings, you get three sleeping systems.

    Works well but think of this:
    More difficult to get out in a hurry, make sure the inner bag zip is somehow connected to the outer bag zip. I used those metal/plastic plastic bag closers. The bags I used tended to rotate to each other.

    Another negative aspect is that the available inside space is much smaller within the inner bag.
     
  4. Robson Valley

    Robson Valley Full Member

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    I used pairs of cheap sleeping bags before I could afford a top-line bag.
    Back in the city, they were quilts on my bed.
    Hindsight says I was more comfortable (more padding) and just about as warm.
    Car-camping, I had a canvas cover bag that did stop heat loss for a good night at 0C.
     
  5. Billy-o

    Billy-o Settler

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    As above, insulation from the ground and the kind of clothes you are wearing in the bag are very important. I'd up that first. Also, if you are well insulated from below, any heat lost is going out through the upper side of the bag. Maybe a light down quilt from Ikea cast over will be a practical option (or maybe a cashmere throw :lol:). A few nappy pins or a bit of velcro to make sure it doesn't slide off.

    Otherwise I'd start looking at the Western Mountaineering or PHD websites ... and trafficking in something in order to pay for one :) A second bag is heavy and bulky ... as my eldest knows. Until we rustled up the cash to get him something decent, he got stuck with the 0C and -10C swedish army bags; one of which fits inside the other. Warm yes, but a royal pain to cart.

    As to roominess, you don't really want that in the cold. Its just more air to heat up
     
    #5 Billy-o, Jul 9, 2019
    Last edited: Jul 9, 2019
  6. Woody girl

    Woody girl Full Member

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    I remember camping in Wales in November somewhere near pen-y-fan. It was cold as heck and not having a winter bag I made a cotton liner from a sheet and took a wool blanket. I was the only one who woke up toasty!
    I have used a couple of cheap aldi one season bags one inside the other in the summer. I got all twisted up, so now I use one as a quilt over the top of the other. Much less hassle. Just as warm as putting them together .and less hassle.
     
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  7. Deekin

    Deekin Full Member

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    I want one of those blankets like John Wayne. Sleep out in all conditions, no problem.
     
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  8. The Lord Poncho

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    I seem to recall that many years ago, the Softie 3 'merlin' was designed slightly 'oversize' in order to fit outside of another sleeping bag in order to create a two bag sleeping system without crushing the filling (and thereby denting the thermal performance) of whatever bag was used on the inside. Worth noting that the British Army and many other forces these days use a two bag sleeping system, some of which have ties on the bags to enable them to be tied together to minimise twisting.
     
  9. jimbo75

    jimbo75 Settler

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    Just fill your water bottle with hot water and put it in a sock, then stick it down by your feet. Works a treat.
    If you have a jacket with you, pull the jacket over your lower half with it zipped up for extra insulation.
     
  10. Kaesar

    Kaesar New Member

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    If it has the tie-ins, which it should, then buy one of the sleeping bag lines (e.g. fleece) from snugpak
     
  11. Old Bones

    Old Bones Settler

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    'It almost has the dimensions of the smaller down bags without the thermal performance.'

    Exactly. Most sleeping bags are made to fit you, and although that sizing can vary, they are simply not generally designed to allow one inside the other with any great comfort, and of course the inner ones loft and possibly the outer, are diminished. Oversized bags are rare, and are either designed as part of sleep systems (mostly for the military, who have slight different criteria from civilians), or they are just special large sizes.

    As Billy O says, carrying two bags is even more bulky than carrying one.

    You can get liners, like cotton (which keeps the bag clean), silk (warmth as well) and fleece. But not everyone likes them, and they only make a bit of difference. A decent mat will often give more for your money. And Billy O's suggestion of an extra quilt is a good one, but you still have the problem of extra bulk and weight.

    Ultimately, if you want a warmer bag, buy a warmer bag. It works out cheaper and easier than bodging. Study the market, and know what sort of temp you want to sleep at (all other things being equal), and then look at what would suit. You dont have to buy new (although if you are, Alpkit is your benchmark for good by well priced, and they have agood guide to buying bags, and lots of other things), but a good second hand down sleeping bag will be worth every penny. It wont be that cheap, but much better value than a synthetic bag for the same price. Much easier to pack (my son is going on a 2 day camping trip with the school this week, and the cheap Aldi sleeping bag he has is fine, but the compression sac is pretty big - his sisters Vango 350 is like a breeze block to try to get into its bag), much lighter and smaller in your pack. And it will last a lot longer.

    Once you know the market (Rab and Mountain Equipment will be key brands to look out for, plus Marmot, Mountain Hardware, and even TNF, although rare in the UK) and the sort of ratings your are looking for (a bag will often have a number - 500 is roughly 3 season down to minus 4-6, 4 season will have a fill of about 700), you can do pretty well on Ebay (using Picclick can make things a bit quicker, although it wont pick up everything). On Ebay, you can set up automatic search that alert you when new items come on the market. Some seller specialise in seconds or used items.

    This ME Lightline might be fine for the money - a proper wash will cost perhaps £30-40 (worth it - it will fluff up nicely and its a faff), but for less than a hundred all in, good value. Hence the 12 bids...

    But if you can stretch to £170, this is a good deal for new with tags. And this is cracking - snap it up. And this Rab is well worth it at £70.

    Dont forget closing down sales, clearances and end of lines, and unusual brands that nobody recognises, which is why its worth doing your homework. If you spot PhD, Feather Friends, Western Mountaineering or Valandre in a jumble sale, etc, then just grab it, pay what it costs and thank your lucky stars - you got a huge bargain.
     
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  12. Lancer165l

    Lancer165l Full Member

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    To answer the OP, yes, I've combined two light sleeping bags and I had a good sleep. Next night I used a goretex bivi bag over them both and it upped the temperature a bit more. The combined bulk of all three items was less than my proper four season sleeping bag.
     
  13. MrEd

    MrEd Native

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    What about a cloud cover from alpkit? Use it as a blanket on top of a normal bag?
     
  14. Kaesar

    Kaesar New Member

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    Just to clarify on the liners as Old Bones is saying they won't add much (guess depends when you call much but a season or more from a liner is good imo). I solely created an account to reply to you because I had already spoken to Snugpak about their liners, their specific response was:

    The differences in heat retention for our liners are as follows:

    Fleece, adds about one and half seasons, the fleece is our warmest of all our liners but is heavy & bulky.
    TS1 liner, adds about a season and is extremely good a wicking moisture away and is lightweight.
    Thermalon, adds about a season and hugs and stretches to your body, warm to the touch but not as lightweight as the TS1.

    You can compare their weight and pack size but if you're dead set on buying that sleeping bag, I would imagine 1+liner is better than 2 of those bags for warmth, weight and size.

    I do agree with old bones in that it's better to spend more in the first place, buy well buy once. I've bought a Tactical 3 from Snugpak and left the option open for a liner should I want to add another season
     
  15. Old Bones

    Old Bones Settler

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    I have had a Snugpak for years (It even looks exactly the same as this!), and since its never been as warm as billed, I am skeptical as to just how much a liner adds. I have liners made from fleece, silk and cotton, but they are not that useful for extra warmth, although the fleece is better than nothing. And of course a 'season' is something of a notional measure - its very individual.

    People often dont like them, because they can feel restrictive and uncomfortable.

    The military use a modular system because it makes sense for the military - the extra bulk isnt a vast problem, and its cheaper than buying 3 or 4 different temp rated bags. But civilians dont need to worry about that - if you are camping during the summer, a cheap lightweight bag is fine, and if your going to the Arctic, you'll buy or hire one that will go down to expedition temperatures. We value comfort, and have the time and money.
     
  16. Kaesar

    Kaesar New Member

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    Well I'm quoting exactly what they said. Everyone's mileage varies, some sleep hot and some cold. Some will notice the improvement of a liner more than others. However, it's pretty much fact a liner plus the cheap bag will be better for warmth, weight, and size than 2 of those cheap bags put together if that's what OP is really set on. Like I said, it's best to buy a better bag in the first place. But you also have to remember not everyone wants to or has the budget to buy 2-3 different bags; that's why liners *can* be a useful option.
     
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  17. Old Bones

    Old Bones Settler

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    Yep - its each to their own. Liners are better than nothing, and if they are the tenner I paid in TKMaxx for my fleece liner, good value.
     
  18. petrochemicals

    petrochemicals Full Member

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    It's not worth it, the weight of the material zip, velcro, toggle and cord are a major part of a lightweight bags weight, compared two bags of different temerature!

    Thereis only so much you can do with insulation of the same weight, no matter how good your design and baffles, Chinese design bags of good fill power are pretty close to top rated bags.

    Look for goodinsulation and that will be a better bag. And choose natural as the micro plastics off synthetic insulation must be awful, only allowable for our serving armed forces in my opinion. Natural fibre insulation for me from now on.
     
  19. Ruud

    Ruud Full Member

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    I've just lately started using a Sea to Summit Extreme reactor with great success, lives in my bag from now on.
     
  20. Lancer165l

    Lancer165l Full Member

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    Ouch! What have you got against our armed forces?:)
     

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