sleeping bag warmth specifications?

[kaite]

I saw KMart has down sleeping bags quite cheap, they say down to +5, which in my case means a tropics sleeping bag, probably. But if i would get two, and stick them into each other for cooler times... ?
How are the warmth specifications determined for sleeping bags?

[Moondog55]

Aldi did have but I can't find a down one at K-Mart online
Nominally it is the thickness of the insulation that determines warmth but the EN rating is determined by mannequin measurement under controlled circumstances

[Gadgetgeek]

The EN rating uses some science, the other systems are mostly just marketing. For example, I have a katmandu EN rated bag that is supposed to be comfortable at 11C. For me its comfortable at 18 or so. So if the EN is that far out, whats a non-scientific bag going to be?
Also putting bags inside each other tends to add a lot of compression to the loft, which limits its value.

Not saying any of it is a bad idea, I would guess they would handle tropical nights just fine, just don't plan on a warm sleep on a frosty desert night.

[Moondog55]

But if i would get two, and stick them into each other for cooler times... ?

Doubling bags is an old technique but it only works if one bag is much bigger that the other
Do a search here and you will find a few threads but that is what "Expedition cut" refers to, an Extra wide Extra long bag to be used as an outer bag over another one

[slparker]

EN ratings just reflect degree of heat loss in a human shaped form in controlled conditions, so far as i know.

because there are a number of physiological and climatic variables in any given evening for any given sleeper the EN value should be a guide, rather than accepted as an absolute ceiling.

If you're well fed, if you're not exhausted, if you're not wet, if you have a good mat, if you're not camped in a damp hollow, if you're not in a cold breeze than the EN rating will reflect a type of average that you should be comfortable, or survivable at.

I imagine it would be a peculiar form of idiocy to go, for example, to high altitude depending on the survival EN rating of a bag to keep you alive, when all it takes is one of the variables above to render you hypothermic.

[Chris-Toms Outdoors]

Hi,
I've attached a pdf with a good explanation of the EN ratings and suggestions for what range to use a bag in. The biggest variable is the actual person. EN ratings at least give you a way of comparing bags and seeing if it will meet your needs.

[Gadgetgeek]

A factor to keep in mind with EN, its based on sleeping on a 1 inch foam pad, that's a pretty significant amount of insulation, and thermals, another variable. But at least you should be able to rate two EN13537 bags side by side, rather than guessing how each manufacturer defined comfort. Which in the Kmart case, its anyone's guess. But it would be worth experimenting with.

[kaite]

strange, i did reply and thank you all for comments and info but not sure where it all went...

Yes it seems i need to go for a quality bag rated about -7 for comfort, which means i'm not likely to get away with something under kg 1 and a bit...
Was surprised how F or M appears to rate stronger than body mass and age.

I am in the tropics and have a system of two bags over each other depending on height and time of the year, they are getting a bit thin.
But i am gathering some gear for a Tasmania trip, not quite sure yet when, but not in winter or snow..

[Franco]

The Western Mountaineering Ultralite is rated (fairly accurately according to many and myself too...) at -7 comfort.
It is about 800g for the 6' version, not inexpensive though.
(you need many nights inside one before it starts to sound like a reasonable amount of money to spend on it)

[Moondog55]

What's your budget? Without being rude what size and shape are you? \I ask as there is a WM bag for sale here that is good to 2C to 8C but can go lower if proper clothing or an overquilt used
viewtopic.php?f=13&t=21853

http://www.westernmountaineering.com/sl ... /highlite/

Adding one of Simons LW quilts would take you down to below 0 -7C and be a very versatile and LW combination

And the price is excellent value

And yes posts do vanish I lose a few every now and then

[kaite]

900 bucks is too much.
Actually, that highlite is very appealing! My budget, ...well,... was considering $69.- bag...But have decided to invest in a good bag which I will use till I die, - I hope....
Am F, 1m64, ranging from kg 55-59, ...- and, hm... well, old.
So, wondering if highlite (in here) is warm enough...rated +2C... am seriously considering though.
Quilt as a double-up might work (even for tossing and turning ppl) but would increase cost and weight. Maybe warm jacket...

[north-north-west]

900 bucks is too much.
Actually, that highlite is very appealing! My budget, ...well,... was considering $69.- bag...But have decided to invest in a good bag which I will use till I die, - I hope....
Am F, 1m64, ranging from kg 55-59, ...- and, hm... well, old.
So, wondering if highlite (in here) is warm enough...rated +2C... am seriously considering though.
Quilt as a double-up might work (even for tossing and turning ppl) but would increase cost and weight. Maybe warm jacket...

Female, 5'3", around 8 1/2 stone (yeah, I know, but I can never remember the metric versions), late fifties. Low BMR.
I have a Highlite and, while it's a very good bag, I only use it for summer coastal camping (and as part of a two bag system for sleeping in the car). I just sleep too cold to take it anywhere where I can't be sure the temps are going to stay high enough to be comfortable. Even with thermals, it's not warm enough for me at altitude except in warm weather, and as weather is so variable down here I don't feel it's worth the risk. Personal choice.

I think one of Mike's quilts would be good for you, although he hasn't started making the shorter ones yet.

[kaite]

ok I like the feedback of someone who seems a bit like me... still looks like I need something in the range of at least 1kg. I just doubt that quilts work for wriggly sleepers, but will google anyway..

[Mark F]

Kaite, you will find quilt far better than a sleeping bag if you are an "active" sleeper. I toss and turn a fair bit and I will never go back to a sleeping bag after using a quilt. If you can use a sewing machine you can make a quilt quite easily to keep the cost down and keep the weight well under 1kg. There are several threads on this the MYOG section, fabrics and down from tier gear (local) or many US suppliers.

[Moondog55]

It depends on the quilt kaite, those with fixed/shaped footboxes are better for wrigglers [ I am apparently a very restless sleeper] but I never woke up cold when using my own home made car camping overquilt
If you want a cheap way out of the temperature problem get a kids mummy bag from eBay and use it as a half sack inside another bag and wear your down jacket

http://www.ebay.com.au/itm/Kathmandu-Pi ... SwKtVWvQqL

http://www.ebay.com.au/itm/Coleman-Kids ... SwUuFWtt-n

The half bag plus duvet and an XL over bag has been my winter kit for decades and a 100GSM kids bag will add 20 degrees lower limit

I often use the combination of a SB plus quilt for camping, it's all about compromise, light, compact; warm; but not cheap or cheap and warm but bulky and heavy

[kaite]

thanks again for taking the trouble! Am chewing the idea of making a quilt over, I suppose I could sew close if I'd feel there was too much cool air coming through the gaps...
It certainly is about compromises, but not sure if economizing on warmth is smart in my case...

[roysta]

Kaite
My wife is about your height and found the WM Ultralite not quite good enough at -7.
I swapped it for my Marmot Plasma 15 which is -9 and she's now a happy camper.
Have a look at that bag.
I'm not sure about cost.


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[Moondog55]

I NEVER compromise on my sleeping warmth these days
But I use a system that can extend down very low
My own winter sleeping systems weighs about double most folks and it's bulky due to the fact that I still use CCF pads as well as the air mattress
My own system was weighed a while ago but I forget how much it weighs except "LOTS" maybe 4 kilos? Perhaps 5
Most people will not want that much warmth tho as my own is good to around -30C if I take the big down parka which is about a kilo on its own

[Hermione]

Hi Kaite,
I am a very cold sleeper and living in Western Australia not particularly used to cold nights. I generally choose sleeping bags based on how much down they have rather than the EN Temp rating which I don't find quite warm enough for me. Not that I've bought that many bags since they last a long time if you look after them, my original down sleeping bag is almost 30 years old (though getting a bit thin). One thing I have found with some of the cheaper down bags is that they don't always specify the fill weight so it can be hard to judge their warmth. We bought a couple of cheaper bags a while ago for our daughters to use but had to shop around for a while and they're fine but a bit heavy.
There's a quite good article here about sleeping bag warmth http://andy-kirkpatrick.com/articles/vi ... ags_warmth.
Both my sleeping bags came from the US but they're expensive to buy here, in Australia I'd probably look at Sea to Summit, Mont or One Planet bags. Not cheap either but maybe a bit than Western Mountaineering. Though as I said it is perfectly possible to be warm enough in a cheaper bag they are just generally heavier (and less compressible) that's all.

[kaite]

That is a good article Hermione, I didn't realize how inefficient moist down is. Specially as it comes of water birds,( I guess they oil it...still..).
So it does come kind of back to weight... no getting away from that.
All up it doesn't seam such a bad idea to stick with a double up compromise, a synthetic one for on the outside. Even though the Marmot Plasma 15 sounds wonderful, they call it the Ferrari of sleeping bags! I would like one more than a Ferrari, - a modest wish surely....
As for camping in -30, for me, not without a fire or a team of Malamutes, or both...

[Moondog55]

Actually the lowest I've made it is -25C but that night I was using a half bag and overbag only, deep cold makes down more efficient because no moisture to sap the insulation value

[Moondog55]

Actually this is considered the Ferrari of sleeping bags

http://featheredfriends.com/snowy-owl-d ... g-bag.html

and If I had $1700- AUD I may consider it if I was headed to Antarctica or the North Pole in winter

[Giddy_up]

deep cold makes down more efficient because no moisture to sap the insulation value

This is why I use a vapor barrier all the time. Even in warm climates the transpiration from your body through the night into your down is staggering and the cumulative effect over a few days can make using down a falsehood.


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[kaite]

Ahw Moondog that one is way too blue to be a Ferrari.... but yes i did notice the weight...you would have to have a good reason.
Vapor barrier..._ hm interesting, had to read up on that one, it sounds a bit soggy... however worth a try...
so: light thermals, under thin rain clothes, inside down bag, inside synthetic bag, inside backpack up to knees, on top of foam and anything flat,(compass ,flattbread), under all spare clothes, inside tent (which in rainy conditions i cover with painters drip plastic).... might check out Alaska yet!

[Kingsleythelost]

Ive never used a vapor barrier but imagine the good of keeping out external moisture would be quickly offset by the internal moisture it would hold.

[Moondog55]

Ive never used a vapor barrier but imagine the good of keeping out external moisture would be quickly offset by the internal moisture it would hold.

Actually no
When your skin moisture level reaches optimum insensible sweating stops, so inside the VB you only wear UL synthetic underwear, and even a partial VB such as my Tyvek SB cover works
The VB goes against your skin inside the sleeping bag and you can get a trial one at any decent bed shop for $5- a LW single bed mattress cover, or a council bin liner at Safeway for $2- which may or may not last the night
A VB adds about 10C to any bags rating in my experience and I've used them a lot, I don't use them when I am wearing insulated clothing but I have used my old Moonstone VB shirt like this
Said VB shirt needs a replacement after 30+ years as does the cheap golf top which did the same job a heck of a lot cheaper [ $2- Op-Shop find]

[Giddy_up]

Spot on MD .

My quilts have Cuben on the inside which is my VB. You sweat up to a point but as MD has said its finite. It's not the outside moisture that is really detracting from your down efficiency (assuming you haven't had your bag in the rain or up against a tent wall all night with the condensation pooling against it) it's the moisture that your body puts into the down that is the problem. You are 70% moisture after all and you are a semi-permeable membrane. The outcomes are all known with this scenario

[kaite]

ok guys if you say so, VB underwear, will try.

[Giddy_up]

Really good article about it all from some people who know their stuff!

http://warmlite.com/vapor-barrier/


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[Moondog55]

ok guys if you say so, VB underwear, will try.

Good luck with those, they have become very rare beasts but luckily if you can find any they are cheap as chips no gravy, a pullover shirt works best BTW and try the golfing shops for those and cheap rain pants for the bottoms