Furthest below your bag's rating?

In the spirit of all this "best and worst" posting, and the fact that it's been so hot, I though I'd start a thread about the coldest we've all been. I know that being 5 degrees below your bags temp rating can be slightly chilly and being 15 degrees below can be darn cold. I'll start by mentioning the time this last winter when 3 friends and I were doing an overnighter and bagging a peak. It never got above zero the whole weekend. 3 of us had zero degree bags and one of us had a -20. It got down to about -15 at night and the three of us were very cold but managed to sleep most of the night. The guy in the -20 bag was fine (he sleeps hot anyway). After this I'm looking for a -20 bag to use on those very cold trips and I realize that 15 degrees below a bags rating is not too fun. Would anyone else like to share about their coldest (feeling) nights and what they learned? I also learned how to "exercise" in the bag at night by flutter kicking my feet and rubbing my arms up and down across my chest. That usually warms me up enough to fall back asleep.

My brother and I went up to the Nauman tent site 2 years ago in March heading to Washington. I had my +20 which should have been fine but that night a rain/snow storm rolled in with high winds, when the rain stopped the temp dropped, about 1:30 AM we woke up with cold noses and the temp in the tents had dropped to 10 degrees. The wind was still howling and the rest of the night was restless. When we got up in the morning the tents (3 season)were frozen over like Eskimoe pies. We cancelled the rest of the hike up because of 70+MPH winds and -5 wind chill at the top. It wasn't unbearable, but definately uncomfortable. When we got back to the parking lot is was 70 degrees and sunny.

Capoken said:

In the spirit of all this "best and worst" posting, and the fact that it's been so hot, I though I'd start a thread about the coldest we've all been. I know that being 5 degrees below your bags temp rating can be slightly chilly and being 15 degrees below can be darn cold. I'll start by mentioning the time this last winter when 3 friends and I were doing an overnighter and bagging a peak. It never got above zero the whole weekend. 3 of us had zero degree bags and one of us had a -20. It got down to about -15 at night and the three of us were very cold but managed to sleep most of the night. The guy in the -20 bag was fine (he sleeps hot anyway). After this I'm looking for a -20 bag to use on those very cold trips and I realize that 15 degrees below a bags rating is not too fun. Would anyone else like to share about their coldest (feeling) nights and what they learned? I also learned how to "exercise" in the bag at night by flutter kicking my feet and rubbing my arms up and down across my chest. That usually warms me up enough to fall back asleep.

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There are a variety of factors such as an individual's metabolism, how much/what he had to eat, how much insulation is under the bag, wind, etc. Manufacturer's also have different standards for rating a bag. In other words, the effective limits are pretty variable--one just has to learn by experience what the temp limits of a bag are. The rating is just a starting point. (Loft is probably a better means of comparison than temp rating. The insulation value of a sleeping bag is primarily determined by the loft.)

US Army Quartermaster insulation table
temp ... sleeping ....... light work ..... heavy work
40F .........1.5" ................. .8"................. .20"
20F .........2.0" .............. 1.0" ................. .27"
. 0F .........2.5" .............. 1.3" ................. .35"
-20F ....... 3.0" .............. 1.6" .................. .40"
-40F ....... 3.5" .............. 1.9" .................. .48"
-60F ....... 4.0" .............. 2.1" .................. .52"

For a sleeping bag, the loft above you should be at least the number from the table. Remember you also lose heat through the ground below as well as air pumping in and out of the bag (from breathing or movement) and through the zipper. Some total (top+bottom) lofts from real bags:
20F ... 5"
.. 0F ... 6"
-20F ... 9"
-40F .. 12"
If your bag doesn't have a draft collar, you can use a fleece or down jacket as one by draping it around your shoulders.

Women tend to sleep colder than men, so women's bags tend to have a little more insulation for the same rating.

Rather than moving around in your bag (which will pump air in and out and make noise), you might try isometrics if you need to generate heat. Also a small snack, bit of candy, or chocolate will create a surprising amount of heat. (Was cold once, ate a piece of hard candy, warmed right up but got tired of waiting for the candy to finish dissolving so I could go back to sleep...)

Doug

Different Brands Different Ratings! I agree....

I had an old Peak 1 sleeping bag that was sapposably rated at -40. It was really heavy, but I would have said more like 0 or -5 at most. I now have a Campmor Brand 0d bag. I use a thin bag liner inside.

Well I was up in Jim Liberty Cabin this past winter. I hike up on Saturday, Febrauary 12. I was the only one that slept at the cabin that night and only saw 6 other people Saturday (4 of them hiking down and 2 other day hikers at the cabin). Below is the weather reports on top of Mt. Washington Saturday and Sunday. I know that the temps probably where not quite as cold on Chocorua. I'am not sure exactly how cold it was, but
-14 on Washington sounds like it it must have been pretty cold on any high peak (even Chocorua). I did have the added help of the cabin to protect me from the wind, but I can't amagine any kind of body heat would collect with just me there. I have to say that the bag kept me very warm through-out the night. My big nose sticking out of my mummy hole was freezing friggin cold though to go along with freezing boogers!



Today's Weather
atop Mount Washington
Saturday, February 19, 2005
Conditions at 6:00 a.m.

Weather: Clear skies with brief periods of freezing fog.
Temperature: -14° Visibility: 80 miles
Wind Chill Index: -45°F Relative Humidity: 78%
Wind: Northwest at 30 MPH Station Pressure: 23.34" and rising
Ground Conditions: 15 inches of snow, with higher drifts


Today's Weather
atop Mount Washington
Sunday, February 20, 2005
Conditions at 5:00 a.m.

Weather: Freezing fog with blowing snow.
Temperature: -14° Visibility: 300 feet
Wind Chill Index: -51°F Relative Humidity: 100%
Wind: Northwest at 66 gusting to 76 MPH Station Pressure: 23.47"
and rising
Ground Conditions: 14 inches of snow



I remember the day here in Massachusetts this past winter (not sure of the date) when temps dropped to at 6am here in Marlborough. School was cancelled, businesses didn't open, it didn't snow, but the City was like a goast town. My friends and me had a really late night drinking and we all had to go home that morning at about 6:30am. I said to one of my friends that the temps of -14 are the kind of temps that us hikers sometimes encounter when up in the White Mountains. He said to me "you crazy, why would you do that to yourself"? - Good question?!?!

Slept in minus 40 temps the Boundary Waters of MN.
We all had double bags, one down and one synthetic. We slept with all our fleece, polypro, etc but not our down jackets or gortex pants. We all wore hats and had to run around and get nice and warm before getting into our bags. We were told , and I proved them right, that if you get into your bag cold you will have a very difficult time warming up. Your changes of freezing are excellent in those frigid temps.
The hardest thing when you are exhausted is to get up to relieve yourself and then have to run and jump to warm up when all you really want to do is go back to sleep.
I could not believe how fast you can get severly hypothermic in those temps by just making one small mistake.
There is an excellent book " The Outward Bound staying warm in the outdoors handbook", written by Glenn Randall and published by Lyons press. Cost approx. $14.95 and well worth the money. It covers everything you need to know on this topic and very well written.
I regard it as a "life saving investment"!

I've used my zero bag in minus-20 temps but slept with my down jacket on for an extra layer of insulation. It seemed to work fine.

This post is sort of off topic but would-be winter campers might find it interesting....

It has been a while now since my severe cold weather camping days but when I was a university student in Winnipeg (North of Minnesota) my buddy and I got into winter camping. During the Christmas break it was always neg 40 overnight so that's what we cut our teeth on. Obviously we purchased the best down bags available and they have massive hoods that when drawn tight leave only a small blow hole around one's mouth. We slept in a tent which must have helped to keep us warm except for the incredible hoar frost on the walls that showered down at the slightest motion. The bag's blow-hole was pretty gross too, all surrounded by frost that fell onto our cheeks waking us up. An alarming amount of frozen condensation built up on the outside of the bag around the crotch and feet. After a few nights you lost a lot of loft. I eventually wised up and got a vapour barrier liner which made a huge difference. We also finally ditched the tent and made rough lean-tos.

We read that protein digestion was an exothermic reaction so just before turning in we would roast over the fire and eat one pound of meat each. Believe me, this really works. You can really feel the heat.

Double the warmth

Doubling up bags also works very well. I've put my 0 degree inside my 20 degree bag and slept very comfortably in -19 weather before. Obviously, lugging two bags out into the wilderness isn't very feasible unless you have a gear sled.

Artex said:

Doubling up bags also works very well. I've put my 0 degree inside my 20 degree bag and slept very comfortably in -19 weather before.

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I used a double bag system for a number of years--down inner and polarguard outer. Worked quite well--the down inner fills up the interior space of the outer bag (prevents air pumping) and the polarguard resists the effects of frost collecting in it. Disadvantages: heavy (6-7lb) and takes up a lot of space in one's pack.

Doug

Neil said:

This post is sort of off topic but would-be winter campers might find it interesting....
We read that protein digestion was an exothermic reaction so just before turning in we would roast over the fire and eat one pound of meat each. Believe me, this really works. You can really feel the heat.

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Thanx so much for sharing this. I'm going to try it. I tend to get cold easily.

I don't know what the number was, but it happened on a winter camping trip many years ago with the Boy Scouts. We spent a February night in NH at a Scout camp in a shelter with wood floor. I slept in a summer Boy Scout bag with a wool Army blanket for extra insulation, no pads. It was so cold the muscles in my legs were cramping during the night. I learned a lot about insulation that night and it wasn't long before I bought my first down bag and down parka.

Maddy said:

Thanx so much for sharing this. I'm going to try it. I tend to get cold easily.

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Try a snack just before you hit the sack. (Pretty much anything--digesting carbs and fat will generate heat too.) As long as the bears are hibernating, you can keep a snack nearby in case the cold creeps in at night.

Fat digests slowly (typ times are carb: 1 hr, protein 4hrs, fat 7hrs) so if you have a good supply of fat in your dinner (up to a stick of butter per person if it is really cold and you can stomach it...) it will help keep you warm in the wee hours.

Doug

jfb said:

I slept in a summer Boy Scout bag with a wool Army blanket for extra insulation, no pads. It was so cold the muscles in my legs were cramping during the night. I learned a lot about insulation that night and it wasn't long before I bought my first down bag and down parka.

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I hope you bought a pad too...

For winter use:
1/2 in minimum closed cell foam
or
3/8 (or 1/2) in closed cell foam plus a self-inflating pad

(A 1.5 in self-inflating pad is inadequate in winter plus a leak could be dangerous. The combo is safe and comfortable.)

As a data point, I was cool one night at 5F with a -20F bag and a Prolite 4 full length self-inflating pad in a shelter. Needed a better pad...

Doug

Don’t overlook the need for a good sleeping pad. Your bag can be rated for -20 but the loft will be useless under you. I always add a RidgeRest under my Thermorest in the winter months.

The lowest below my bag rating was probably on my Northville Placid Trail thru hike. I stated Labor Day weekend and was carrying a 40F bag. I didn’t have a thermometer with me, so I’m not sure of the temperatures, but I woke up to it snowing on one of the warmer mornings. I slept in all of my cloths most nights.

DougPaul said:

I hope you bought a pad too...

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Yes, I did buy a pad afterwards, but for comfort in summer not for insulation in winter. It was about 1 1/2 inch thick open foam pad with no cover. First time I used it on snow was in a tent. The frost inside the tent fell on the floor where my body heat turned it into water and the pad soaked it up like a sponge. Bought a Volarafoam pad on the way home that weekend. Now I prefer a 2 in. Camp Rest over a 15 mm. Evazote.

Many years ago, I spent a -25 F night @ Liberty Springs campsite in a tent with a bag rated to +5. Wore all my fleece and had a rather uncomfortable night but was able to sleep much of the night.

These days I bring a -25 F rated bag and generally sleep indoors if it's much colder than -10 F! Getting soft!

DougPaul said:

I used a double bag system for a number of years--down inner and polarguard outer. Worked quite well--the down inner fills up the interior space of the outer bag (prevents air pumping) and the polarguard resists the effects of frost collecting in it. Disadvantages: heavy (6-7lb) and takes up a lot of space in one's pack.

Doug

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Doug- were you using a vapor barrier with this system as well? I've tossed around this idea as I have a 25 deg. bag with lots of room inside for one of those UL 35-45 deg. down bags. I was wondering how well moisture will pass through the down with the frost point being somewhere at or near the shell of the sythetic bag. Could I forgo a liner on 2-3 night winter trips with such a combo?

Ken999 said:

Doug- were you using a vapor barrier with this system as well? I've tossed around this idea as I have a 25 deg. bag with lots of room inside for one of those UL 35-45 deg. down bags. I was wondering how well moisture will pass through the down with the frost point being somewhere at or near the shell of the sythetic bag. Could I forgo a liner on 2-3 night winter trips with such a combo?

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Wasn't using a VBL in the synthetic/down double system.

I have spent -30F -- -40F night out, but it was in a single -40F bag, no VBL. Just a single night, so no issues of frost build-up. (And yes, I was comfortable.)

Of course, the point in using a synthetic outer was to put the frost point in it rather than the down. I have also briefly used a down outer (0F) with a down inner (20F), but the temp was so warm (28F) that I only really needed the outer (the inner stayed stuffed the second night).

If you use the insulation tables that I posted earlier in the thread, it looks to me like your double system should be good to somewhere around -20F. (Remember the double system probably won't have a draft collar, but probably won't suffer from too much pumping or heat leakage out the (doubled) zipper.) And unlike the down-synthetic double, the frost point may move into the inner bag as the outer loses loft.

A VBL will keep you somewhat warmer, but more important for a long trip, will keep the down dry. (VBLs are somewhat inconvient to use. A consensus seems to be that they are only worth using below about 0F.) Dave.M has a nice write-up on his experiences using a VBL: http://home.comcast.net/~pinnah/DirtbagPinner/vb.txt

You could probably get by without a VBL on 2-3 night trips. May depend on the temp--the colder it is, the more benefit from the VBL. (You should also air and sun the bag as much as possible to dry it out.)

You can easily improvise a VBL with two garbage bags taped end-to-end (plus a cut) so it would be easy enough and light-weight enough to bring one along just-in-case. In fact, just a single garbage bag pulled up over your legs is likely to be of some help.

Doug

DougPaul said:

And unlike the down-synthetic double, the frost point may move into the inner bag as the outer loses loft.



Doug

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DougPaul, can you explain more about this "frost point" and how it's affected by the different types of bags. My winter bag is a huge old down bag, weighs 5+ pound, from Eddie Bauer. Tons of down, about 25 years old.