Increasing Bag Warmth

[Whisky]

Other than the obvious, buying a warmer sleeping bag, what are some options a guy can do to use a 15-20* bag in colder temps? I can only pack in so many clothes. I have a BA Mystic SL 15. It's very possible I'll be using it come Nov in ND and it will be mighty cold. I think I read somewhere about guys using a bivy sac (??) inside of the bag to increase the warmth?

What are my options and what has personally worked for you?

Thanks

 

[smalls13]

A bivy sac is used on the outside to keep you dry from rain. I don't think mine would add any warmth. Most of them don't sweat either so you would be soaked if you had it inside your bag. I bought a small fleece sleeping bag that i put inside of my mummy bag if the weather is cold. It probably only adds 5 to 10 degrees though.

 

[Chippy Hacky]

I add a fleece sleeping bag to mine too. It is great in cold temps but it is heavy! I found some "backpacker" fleece bags that can be used for a bag or liner, however this one was $29. I purchased it but am not impressed with it, it seems cheap and am thinking of taking it back. It says on the label that it can give you "up to" 10* (whatever that is worth).

Now, I am thinking of going to the fabric store and buying a bulk piece of fleece. I will update when I get down there but I think that I may be able to save some weight with no zippers, cords, stitching, etc.

 

[tdub24]

I have a 15 degree rated bag and bought a liner which adds up to 15 degrees of warmth. So far I haven't met an environment that is too cold for this set up, and I am cold blooded. Below is a link to the liner I have.

http://www.cabelas.com/product/Sea-To-Summit-Reactor-Thermolite174-Liner/714584.uts?Ntk=AllProducts&searchPath=/catalog/search.cmd?form_state=searchForm&N=0&fsch=true&Ntk=AllProducts&Ntt=sleeping+bag+liner&WTz_l=Header%3BSearch-All+Products&Ntt=sleeping+bag+liner&WTz_l=Header;Search-All+Products

 

[Bitterroot Bulls]

A bivy will certainly add warmth. The USMC GTEX bivies add noticeable warmth, in my experience.

 

[Sawfish]

Big 5 has lightweight fleece sleeping bags that can be used as a liner. $19.99 regular, or $9.99 on sale at times.

 

[Whisky]

Thanks for the info so far guys. That Sea to Summit liner looks to be one of the more convenient options thus far, considering packability and comfort anyways. I didn't realize them bivy sacks are that heavy.

 

[jjenness]

I use a Cabela's XPG Bivy bag and it definitely ads warm to my bag. I only use it when I know the weather is going to be cold, or rainy.

 

[Ikeepitcold]

A bivy will certainly add warmth. The USMC GTEX bivies add noticeable warmth, in my experience.

BB is that bivy added to the inside of the bag? Or as intended on the outside?

 

[Bitterroot Bulls]

outside.

Adds warmth just like a jacket shell, more dead air space.

Not all bivys are heavy. I have a 9 ounce tiGoat bivy. It doesn't add warmth like the heavy USMC bivy, but it adds a few degrees of warmth, and acts as a groundcloth and spindrift protection in a floorless shelter.

 

[NorthT]

Ditto on the cabelas xpg. I have a marmot hydrogen 30 bag. One night the temp dropped down to teens and thought i was going to freeze. Next night stuff bag inside of bivy and stayed toasty warm all night. Make sure that your bivy doesnt cover your face or it can cause condensation between the bivy and your bag.

 

[NorthT]

Meant to add that I also have used the fleece liners, They work and are cheaper but feel like the bivy worked alot better for me. Mine I think is 11 oz.

 

[ivorytip]

+ 1 on the tigoat. also... i have a couple of the military issued bivi sacks that work great too.

 

[VTBwana]

Liners & bivies work..I alway have a few disposable hand warmers on hand; 'bombing' the bag w/hand warmers really helps and nasty cold nights. I am in the 3-172nd Mountain Infantry BN and we sleep in the cold regularily. Last winter I bombed my bag (in bivy bag, no tent) on a -12F night and was toasty while others bitched about freezing their stones off.

 

[JMSZ]

I got a couple of Thinsulate poncho liners, I always have one with my bag. It's a two-part bag and rated to 30 degrees with both parts and lower with clothes on, but my feet get cold when it's in the 30s.

The poncho liner helps out a lot, the only problem is that it likes to slide around inside. On the upside, I can pull it out and use it separately when I just want to wram up and I can leave my bag part way open on cool, but not cold, nights.

Gotta try the bivy, though.

 

[Bitterroot Bulls]

Sleeping in clothes removes that airspace and kills bag warmth.

There are differing opinions on this. In my experience, I always stay warmer in the bag with extra layers on, as long as I don't have so much bulk in the bag that it starts to compress the loft of the insulation.

 

[Whisky]

There are differing opinions on this. In my experience, I always stay warmer in the bag with extra layers on, as long as I don't have so much bulk in the bag that it starts to compress the loft of the insulation.

I've wondered about this.....Two different opinions on it already.

My bag is not a true mummy bag. It's the Mystic SL from BA, think they call it a rectangular bag. It seems I have plenty of air space in that bag. I did sleep in my clothes as well as layered up on the merino tops. Nothing too bulky. Although if I was to give that liner a try, that is a mummy fit.

 

[mnhunter]

+1 on VTBwana's reccomendation. I do the same thing and it works slick. A weeks worth of handwarmes weighs alot less than the heavier bag will.

 

[arrowslinger21]

Bivy sacks add good warmth by allowing for the air around your down or other insulation to be less affected by colder air. A good sleeping pad with a high r-value helps too, like some of the great mats from exped. Other than that I would say to eat and drink hot food and fluids before bed, layer up a bit, and crawl into your bag on a good pad. Should make for a much better night.

 

[crumy]

Maybe this is a bad idea since nobody else has said it, but here is what I do and I have never had a problem with being cold. I usually have a 15-20 degree bag. Based upon a recommendation from a friend I started throwing a hand warmer pack into the bottom of by bag. I don't wear any extra layers and don't wear socks so that I don't sweat in them. Does a great job. I did just upgrade to a zer degree kelty but i imagine I will keep doing it. It does make it really hard to get out of the bag in the morning because it is so warm but I like it.