sleeping bag nesting

[outdoorgirl]

I have a number of sleeping bags for different 'seasons'. I'm a cold sleeper generally, so I usually find that I use a higher rated bag than others - especially my partner, who seems to be able to sleep in mid-winter in a 2 season bag... :shock:

Anyway, I've never 'nested' bags, having always just used the next rating up, and gone for wearing all my clothes for extra warmth.

How do you know how much more warmth you'll get from nesting bags?

For instance, I have a range of Snugpak Softies:

Softie 3 - rated comfort 5C, low 0C
Softie 6 - rated comfort 0C, low -5C
Softie 10 - rated comfort -7C, low -12C

What theoretical ratings could I expect from nesting various combinations of these?

What extra warmth do you get from a silk liner?

ack:

I have a 3 night trip at Merthyr booked up for the first weekend in April - I plan to test my new Hennessy and am expecting cold weather!

:chill:

 

[jakunen]

A silk liner (mmm, LOVE mine!, so soft, so silky..erm, oops!) will add about 5-7 degrees or more depending on its thickness.

If you 'nest' them, expect to go maybe another 5 degrees at least below the rating of warmer bag due to the extra loft, that is until you get too warm and start to sweat which wil actually take it back a few degrees as it is obviouls y more difficult for vapour to pass through the extra bulk of the outer bag.

Not being someone who normally perspires, I've not come across this effect, but I know old mates did on exercise on Dartmoor (or Dratmoor as we called it. LOL).

 

[ColdCanuck]

It is really hard to determine how much warmer you'll be when nesting bags inside one another. Sleeping bag warmth comes from how much loft you have, as well as the bag configuration. Quite often nesting bags will compress them reducing the loft of each bag. Unless the bag has been designed to function as a overbag. You might be able to get a reasonable guess at the temp range of the nested bags by measuring the loft with you inside them(nested). A silk liner won't add much warmth to your bag, but it will keep your bag clean and feel warm a bit quicker. Using a really good sleeping pad will add greatly to your warmth. Bags provide very little insulation on the bottom when you are in them as they compress.

 

[Carcajou Garou]

An idea maybe is to add a better bottom insulation to your sleeping kit and keep the frost (humidity) from traveling up to you. Twice as much on the bottom than the top will make a difference.
just a thought

 

[jakunen]

An idea maybe is to add a better bottom insulation to your sleeping kit and keep the frost (humidity) from traveling up to you. Twice as much on the bottom than the top will make a difference.
just a thought

VERY good point. Its the surface adjacent to the ground (or air in a hammock) that loses the most warmth, which is why some bags have more loft on the bottom than the top.

 

[Kath]

I'm a cold sleeper too. I've nested sleeping bags in the past (Vango Ultralights not Snugpacks) and to be honest I don't think it made a jot of difference! I haven't yet found a sleeping bag that keeps me warm! I've got a silk liner too. And a thermarest.

I just find that sleeping outside I feel colder. Partly this is because sleeping bags are more constricting than bed covers and so you might find you're colder because you are so still.

Also I've found I am cold because my head and face are exposed to the cold. It helps to wear a hat and , if below freezing, a balaclava (no cheeky comments please! :-D)

It also helps to eat some carb once you're inside the sleeping bag.

One of the most important things is not to get too cold before getting into your bag (often this happens to me while I'm getting the kids into their bags). The sleeping bag can only insulate and if you're cold already it will take much longer to get up to temperature. In those circumstance I've found it useful to snap a couple of the exothermic gel packs that produce heat (can't remember the name but here's a link) to warm up the sleeping bag. (They're very handy if you're camping with kids in the winter as you can never be certain how warm they are inside their bags and it's a good way not to have to worry that they're getting hypothermia! )

Hope some of these ideas might help ... :biggthump

 

[leon-1]

Kath are those the pads that have the little metal button in them, I know some have plastic type buttons in them because they are micro-waveable, but they are pretty good :biggthump

 

[wentworth]

VERY good point. Its the surface adjacent to the ground (or air in a hammock) that loses the most warmth, which is why some bags have more loft on the bottom than the top.

The fill on the bottom half of a sleeping bag gets crushed beneath you when you lie on it, giving absolutely no insulative value whatsoever. And heat rises, which is why it is important to have good loft above you.
But i certainly agree that it is highly important to have good insulation underneath you, perhaps in the form of one or even two mats.
Hammocks in particular are notorious for the cold! brrrr!

 

[sandbender]

I use a Buffalo sleeping bag, these bags are intended to be nested which sadly makes them heavier and bulkier than other designs, however a person can 'live' in a Buffalo bag for weeks even in permanently damp conditions and always be comfortable.

I use a 'Superbag' on its own during the summer months, I have an older lightweight buffalo bag which I use as an inner in early spring and autumn and have the ridiculously cosy '4S inner' for the depths of winter.

http://www.buffalosystems.co.uk/ssthumbs.htm

 

[outdoorgirl]

Many thanks for all these replies, guys!

I have two thermarests - an old 3/4 length one, and a new full length Expedition. I plan to use the full-length one, but if I'm cold the first night I may add the 3/4 as well following your comments on base compression.

I also plan to take a goretex bivi bag - while I won't need the waterproof features (hopefully - as long as I set my rain fly up properly!), it should also help the warmth rating.

For those who use liners - do they tie inside the bag, or are they loose? Do you find that you twist them up (as you turn over) when you sleep or not?

Kath - I always wear a hat when sleeping outdoors in cold weather. I often also keep my thermal layer on. An old trick I learned as a kid for keeping warmer when getting into the sleeping bag was to first take off boots and trousers, then sit in the bag. Then remove top layers and snuggle in. The bag gets warmer quicker because your bottom half starts it warming before you slide your top half in, and your top half stays warmer longer because you keep your top layers on until the last possible moment.

You're right about staying cold in a bag if you're already cold when you get in it - I've found that it pays dividends to move around (run on the spot if necessary) so that my body warms up before I get in. Otherwise I either don't sleep at all, or wake up freezing in the middle of the night...

 

[Wink]

Just cos no-one else has mentioned it, make sure you use whatever bag you're using properly! If you pull the drawcord snug on the chest baffle and hood, and avoid breathing into the bag, you will make the most of the insulation you have already. It amazes me how many people will go to incredible lengths like wearing their waterproofs in bed (I kid you not), when all the warmed air is just escaping from the open end of the bag! I reckon that has to be worth an extra 5 degrees at least.

Also, last thing at night, boil a kettle full of water on the fire and put it in a water bottle with a good seal (hydration pack flexi bottles/Sigg are ideal) and stick it in or under your bag. In the morning you have purified water ready to brew, and keeps you warm in the night. Even if you aren't cold, this can be worth doing to dry damp socks etc in a tent. Just wrap the socks around the hot water bottle and leave until morning.

 

[greg2935]

I am also a cold sleeper and have tried numerous ways to keep warm, mainly to no avail.

So far the only method that has proved successful for me (but is bulky) is to fold a blanket into three sections longways, and put this into your sleeping bag so that the middle fold is facing up, and the outer two folds are facing down (and therefore underneath you when you are in the bag (i.e. you are lying on the two folds so the blanket cannot unravel and you have one fold above you)). The excess air gets trapped in the bag and blanket, the blanket provides a lot of warmth and because it is wool both acts as insulator and traps lots of air: therefore you keep warm. The obvious downside is carrying a blanket (bulky and heavy). I now wrap the blanket in a waterproof covering and wrap it round the top of my A-frame ruck sack, with the sleeping bag slung on the frame underneath. I hope that helps

Greg

 

[Ravenn]

It may nbot be a substancial help, byt placing a space blanket, foil side up under you will reflect body heat. I've used the wool army blanket method with success too, bulky to be sure, but warmer.

 

[woodrat]

what I finally did for my strictly backpacking gear was to use a 2 bag system . I have a 1 1/2 lb. bag and a 4lb. bag. the 4lb. is a long and so the 1 1/2 fits inside well. I have a friend with a korean war artic bag and based my set-up on it. it is a long size mountain mummy w/ regular size insert. so far this has been a very flexible yearround system. I should add that for realy cold temps. I have what is called a t.p.a. ,[thermal protective aid], they are part of the survival gear that comes in a commecial life raft, its a mummy style bag w/ sleeves and mitten hands, they are large so as to fit over your floatation gear and is made from heavy duty space blanket material . I have put my dual bag inside it and theres plenty of room, but i have not used it yet on a campout. I dont know if there available in u.k. but if anybody wants source info they can p.m. me, I know of at least one distrib. over here.