2 bag or not 2 bag?

[sallysparkle]

Hi,
I have just been having a debate with my lovely boyfriend about sleeping bags. We have trekked EBC twice, Langtang/Helambu and Annapurna Circuit and santuary. [yes I know we are very very lucky bunnies].
Anyway, we have always taken good quality 4 season down sleeping bags i.e. Rab summit and the likes.
However I have alway been feezing cold at night-camping or lodges - even with all my clothes on including hat. The cold just seeps through to my bones and as for my feet!!
So, we are off once again next week to trek Manaslu and I have thought of taking 2 sleeping bags instead which the accumalative weight is the same as my 4 season. one is a very light down fill bag, the other is a primaloft fill. I'm reckoning on the science of layers being more effective just like they are for clothing.
My boyfriend thinks I will be even colder. Is he right?
So I'm putting it out to you guys. Anyone with experience in using 2 bags?

[Petrus]

For the same weight one bag is warmer. If more layers of fabric would be warmer than down or Primaloft, sleeping bags would be constructed from fabric only, no?

There might be some reason for 2-layer combo being warmer, if the construction of a heavy single layer bag is not good; down can sift too much and leave cold spots. The thickest expedition bags do have either a internal 2 layer (3 fabric layers total) construction or AVAVAV -type (if you get the idea) down tubes which aim to keep the down thickness constant.

I have used double bags sometimes. The main advantage is the possibility of having 3 different combinations (light, heavier, double) depending on the temperature. Still the total weight is more than just one really warm bag.

By the way: it is not ideal to try to put one bag inside the other, as usually normal sized bags would be too small and squeeze the inside bag making it loose its insulation value (I have a special combo bag with overlarge overbag). It is better just to throw the overbag over the inner as a quilt, loose fillings are warmer than squashed. Insulation from below must be handled with matress(es), as sleeping bag has very low insulation at the bottom anyway.

I would and do just take one fairly warm bag, but not overkill. For the coldest nights I wear long underwear, maybe also fleece (never wear too much to bed, first you think you need it, but when the bag gets warm you sweat...). One good idea is to use your open down jacket as a quilt also.

[rich]

As said above try wearing just thermals to bed. That will help the bag to work as intended. ie: using the heat that your body radiates to warm the bag. Will also reduce your getting hot and sweaty in the middle of the night if thats a problem.

[Spaceman347]

Agree with the others, I can't see 2 bags being warmer. More flexibility yes, but warmer no.

If you suffer from cold feet, try to get yourself some down (or synthetic) booties. I have a pair and they are nice and warm and give your feet a break from your other footwear. Try to find some with a good closed cell foam base on them, some have no, or very little base (more like a sock) and are no good to walk around in.

[sallysparkle]

OK, so it looks so far that my theory of layers doesnt work with sleeping bags,[much to my dismay as trying them out in my warm kitchen they felt great!!] I guess that I will be taking my expedition 4 season flock of geese bag.
Some of you mentioned getting too sweaty etc.... I'm sure I'm from another planet as I have never had that problem. I wear thermal leggings and big woolly sox, base layer, down jacket and hat in my sleeping bag [which is one of the warmest you can get without installing an oven] when up in the high Himalayans and just about keep to a body temperature level above freezing that I can sleep in!
Thanks for the replies so far. It's all a bit of fun really. If I was brave enough I would take the challenge and try my theory out next week in Manaslu but the thought of freezing to death for an experiment doesnt sound too appealing right now as I'm looking out of my window to a dark, cold and wet Scottish november day.

[Landfall38]

Sounds to me like you are wearing too much when in your sleeping bag! It is much warmer to wear only a thin layer (at most) when in the bag!

A good place for your down coat would be over the bag and you once you are in.

[James]

I use a two bag system from Big Agnes and give it very high marks. As previously suggested it provides five combinations light bag, light bag w/ heavy bag over the top, heavy bag, heavy bag w/ light bag over the top and heavy bag in light bag. Given the temp extremes from the valleys to the really cold mountains you are set for all the possibilities.

The light bag is an oversized synthetic bag rated to 40F and the warm bag is down and combine for a rating around -15F. I have never had the occasion, but I think they can even be zipped together The bags are very light given there is no insulation in the bottom, which is fine given that all the lodges have mattresses.

It is more expensive, but worth the investment.

[Sharon]

Do you have a good sleeping pad? that helps.

[sallysparkle]

Do you have a good sleeping pad? that helps.

Hi Sharon, Yes, as I have mentioned it in my mini-monologues above.

James, at last someone who has had success with the 2 bag theory, your combination is exactly as mine and the 2 bags combined weigh in at 1.8kg, exactly the weight of my big one....now you have got me thinking again about trying them.

Sounds to me like you are wearing too much when in your sleeping bag! It is much warmer to wear only a thin layer (at most) when in the bag!


A good place for your down coat would be over the bag and you once you are in.

Thanks Landfall, I have tried less but had to resort to retreiving clothes in the middle of the night to put on but you are right in theory as usually if you wear too much your body heat does get generated around the inside of the sleeping bag. Perhaps I will try again with just my baselayers.

Well, 2 bag or not 2 bag is still the question.

I will reveal all upon my return!

Thanks everyone for your contibutions, much appreciated.
Sally

[julia]

I also agree with the not wearing too much in the sleeping bag.

Also, get into bed warm, if you are cold before getting in you will never warm up. I also have a metal drinks flask that I fill with boiling water, put it in the sleeping bag for 10 mins or so before getting into it, cover the flask with your socks and keep it close all night, toastie! The socks are usually still warm in the morning. Maybe put on the socks you have warmed up and then put another one on the flask so not to burn yourself on the flask. Another tip is to not wash your hair in the evening, only in the afternoon when it has time to dry properly, I made the mistake of washing my hair early evening and it took ages for me to warm up again. Hope this helps.