I read somewhere that bags are rated at the temp you would be comfortable in naked. So I figure a 32 degree bag with a bunch wool/down layers should work. Anyone have experience?

Without knowledge of the specific bag/mfg it's hard to say how truthful the temp ratings are. For bags rated using the standardized EN 13537 scale the bag rating is based on a standard man at the lowest temp to have a comfortable nights sleep generally with some clothing. At the very most I would only push a bag 10-15 degrees below it's rating if you were wearing a insulated jacket, pants and balaclava. I would never attempt a full 30+ degree improvement. You may survive but you certainly won't sleep.

I'd actually heard test were done by people wearing long underwear and only sleeping for 8 hours.
Regardless of how they are done bag ratings tend to be optimistic. Some people actually recommend getting a bag that is rated tor temps 10-15 degrees colder then what you expect to encounter. Ultralighters push the ratings of bags by wearing puffy jackets (and occasionally pants) too bed. This might add 10 degrees to a bag's rating but definnately not 32 degrees.

> I read somewhere that bags are rated at the temp you would be comfortable in naked.

First, be careful about "rating". Some manufacturers just make up numbers. An objective standard is EN13537. I am pretty sure that for the testing, the copper manakin is dressed in mid weight long underwear and a hat. With EN13537 there are actually four different possible rating.

> So I figure a 32 degree bag with a bunch wool/down layers should work. Anyone have experience?

It is possible to use a 32F bag below freezing... but it's going to take VERY warm clothing. When sleeping you need roughly 2x the insulation you need standing around, and nearly 8x the insulation when doing "hard work" like going up a steep hill with a full load. So if you bring clothing that keeps you warm enough to just sit around for an extended period of time in sub zero weather, then that combined with a 30F bag would likely work. I have written up a bit about clothing insulation which has a table you might find useful as well as links to other information.

If you are using clothing that keeps you warm enough when active and then plan to get into you bag when the temp drops and you want to stop being highly active you are going to be very cold. I will use clothing + my 30F quilt in shoulder seasons... but if I really expect sub 0F temps I switch to my winter bag.

--Mark

it's the mountain hardware ultralamina 32. i just can't justify buying a completely new bag for just 1/2 night's worth of sleeping and the added bulk.

I've pushed an optimistically rated 15F bag down to low single digits on a DownMat 7 and inside a Hilleberg. The pad kept me well insulated from the ground, and the shelter read a good 10-15F higher inside than outside. I was wearing baselayers inside, and my torso was fine ... but my head and neck were uncomfortably cold even with a balaclava. The hood on the bag just wasn't up to the job. Do you have a four season shelter and a winter pad? Even so, like Randy, I wouldn't try a full 30F differential.

Based on what you said, your need for a bag for below zero would be for a short trip.

If that is the case, can you rent a zero degree bag from REI for this one trip?

Better to rent than to risk your safety and being miserable trying to get a 30 F bag to do way more than it was designed for.

I agree, trying to enhance the 30F bag to 0F is beyond what layering can do.

Even if you came close, you would likely not get much sleep....you would be miserable.

-Tony

i have the 32 bag, xtherm pad, 2 layers of down jackets and various wool/base for my top.

As far as I know all tests are done with the mannequin wearing long underwear and a balaclava/face mask or hat.
The exact type used is determined by the lab doing the test.
The other variable is the mat and again I don't think that there is a precise requirement but labs use whatever they think is an adequate mat for the temp tested.

Another aspect that the EN test does not consider is movement.
Every time you toss and turn you push out warm air and that is replaced by colder air.
Some sleeping bags may be better at handling that than others (see my allusion to this in the infamous ULA sleeping bag thread...)

If you put on enough layers, of course you could. But the amount of extra clothing you would need would be ridiculous and heavy. Weight wise, you would be much better off with a warmer bag. If you can't afford to get a new bag, throwing on a ton of layers will work, if you have the extra space in your pack. I have been there and done that, but the temperature distance you are suggesting is massive. It would be very hard to tell how much you need and underestimating could be very painful.

I have the lamina 35 and it's definitley a little optimistic. I need long underwear, thick wool socks, a good warm hat, and a a couple light wool sweaters to be comfortable at freezing. If I am going to push it, I will usually blast a fire all night. It is very effective but probably too much work for most.

thanks for all the input. i still have a couple months to decide my winter setup. i'll be check out the gear swap.

"As far as I know all tests are done with the mannequin wearing long underwear and a balaclava/face mask or hat."

And as well, a pad with an R-value of over 5.

Another important variable is the type of shelter and the weather conditions. If you're in a small, solid wall tent that can be buttoned up tight you will be much warmer than under a tarp with less effective protection from drafts. Do you expect precipitation, wind, etc?

Seems like a lot of variables when you're already trying to push near the edge.

However, I have NO experience in actually trying this so, take my free advice for what it's worth.

Jim

More on the widely misunderstood EN rating...
You (that is "one") are not necessarily the standard , that being a fit ,well fed, clean and rested 25 year old man. having a constant 34c surface temp.
The mannequin is all of that , because as a starting point it cannot really simulate tired,dirty,not all that well fed and with a somewhat less than ideal metabolism individual .
So you need to adjust the rating for your particular situation.

AND out of the wind (still air temp, no wind chill)

Edited by Franco on 09/25/2012 17:25:35 MDT.

Just go to REI and rent a warmer bag, problem solved. It would be incredibly uncomfortable not to mention dangerous to willingly go into a environment under-prepared IMO.

Edited by king2005ify on 09/25/2012 17:15:53 MDT.

You'd probably live.
Not guaranteed.

I pushed a 45 degree bag into 5-10 degree temps with a LOT of layers, and it was hugely uncomfortable. I slept, but in very short stints while quite cold. I don't suggest doing it at all. You'll live, but it will not be pleasant. Rent a bag or find another to doublebag.

I wouldnt use that bag in subzero temps. I wouldnt use the Ultralamina 15 in subzero temps. I think the 32 is a 37F EN limit rated bag. My son uses the 15 for car camping and its about 28F rated. The bags are lightweight for synthetic, that means something , like doesnt have that much insulation, or something like that.

Looks like plenty of folks have chimed in.

I have slept hundred of nights outside in Ireland, UK and France and on the odd occasion it has been far colder than expected I have suffered because I brought kit for the expected conditions, nowadays I make sure I pack a bag and pad that's more than sufficent.

You can uprate a bag with down clothing once it has sufficent room to allow the clothing and bag to loft properly and you have sufficent ground insulation.

Short answer? Yes.

Long answer? It depends on what type of base layers you have on. Are you using minus-33 wool thermals and down booties? Are you willing to sleep fully clothed?

Best answer? Seriously, get a winter bag. A 32 Degree bag is not a winter bag.