View the most recent posts on the forum.


Author Topic: Pushing my -20 F. down bag to lower temps  (Read 767 times)

Offline 300winmag

  • Stoking the Woodstove
  • ***
  • Posts: 221
    • View Profile
Pushing my -20 F. down bag to lower temps
« on: December 12, 2018, 04:17:13 pm »
This question has been likely asked and discussed before but I have a specific question.

BAG-> "LL Bean -20 F. 750 fill" (that's its name) goose down bag.

MATTRESSES->
Top- REI FLASH Insulated 3 season air mattress - R-3.7 insulating value
Bottom- Thermarest Ridgerest closed cell mat - R 2.6 insulating value

SO... in a one person Tarptent Moment DW tent with Polar weight polyester long johns, Norwegian wool sweater, Eddie Bauer down "sweater" (jacket) and Montbell "Superior" light down pants, quilted synthetic booties over heavy socks and a fleece balaclava

what temperature do you think I could comfortably go? -30 F.? -40 F.?

I will usually be between 9,000 and 11,000 feet altitude. (approx. 3,000 to 4,000 meters)

Eric B.



 
« Last Edit: December 12, 2018, 04:23:00 pm by 300winmag »

Offline yardsale

  • Hauling Sled
  • ****
  • Posts: 300
    • View Profile
Re: Pushing my -20 F. down bag to lower temps
« Reply #1 on: December 12, 2018, 05:05:20 pm »
I worry that the down sweater will actually compress the bag and reduce it's effectiveness.  Is that enough r value underneath you?  We use Expid 9 pads. An overbag is the next option.  Also, think about nutrition and hydration. Lots of fat for dinner and a high calorie snack at 3 am.

Offline Forse07

  • Supporter
  • Coming in From the Cold
  • *
  • Posts: 44
    • View Profile
Re: Pushing my -20 F. down bag to lower temps
« Reply #2 on: December 12, 2018, 05:05:48 pm »
I have an REI bag rated to 10 above and I sleep with wool socks, sweat pants and a sweatshirt on a exped downmat 7 (R5.9 I believe). Last year we spent nights in temps that reached -42 and I slept fine. I don't typically wear my balaclava to sleep but I am pretty sure I did those nights.

Offline Bothwell Voyageur

  • Vendor - Supporter
  • Living Large At -40
  • *****
  • Posts: 1406
    • View Profile
    • CanoePaddler
Re: Pushing my -20 F. down bag to lower temps
« Reply #3 on: December 12, 2018, 06:42:01 pm »
Insulated clothing inside a bag is the go to option in high altitude mountaineering. Bags are cut big and with a differential cut to maintain loft.

Haven't a clue how low you can go, certainly -30, just depends on how warm your thinnest layer is.
www.canoepaddler.net for custom made gear and fireboxes

Offline 300winmag

  • Stoking the Woodstove
  • ***
  • Posts: 221
    • View Profile
Re: Pushing my -20 F. down bag to lower temps
« Reply #4 on: December 12, 2018, 08:57:37 pm »
Thanks gents for the replies. I think I'll be OK, at least at -30 F. which is as cold as it ever gets here at 11,000 ft. and even that is rare.

-> I tested the bag with all those extra clothes on and it's generous 65" chest girth does not compress the bag or down jacket.
-> R-6 is "supposedly" the mattress insulating value for coldest temps. My 2 mattresses add up to R 6.3 which should be OK.

I have actually skied in -40 F. (Like skiing on sand) so I do understand how dangerous those temps are.

My years as a Nordic and Alpine Ski Patroller and US Army ROTC winter survival instructor put me in a good place for knowing how to "do" winter safely, including avalanche safety. But you guys in "The Great White North" have a lot of valuable tribal knowledge too.

Eric B.

Offline Moondog55

  • Supporter
  • Living Large At -40
  • *****
  • Posts: 1541
    • View Profile
Re: Pushing my -20 F. down bag to lower temps
« Reply #5 on: December 12, 2018, 11:41:21 pm »
Well Eric if you freeze to death you'll certainly know it wasn't enough insulation.
It all depends on how warm that LLBean down jumper is. But you know that at your age the bags has to be down-rated by 10 to 15 degrees at least; just like me. In these circumstances I would want to have a Thermos of hot chockolate on hand in case I woke up due to feeling cool and I'd make sure that the Thermos bag also had some high calorie snacks with it. Unlike Forse07 I doubt very much I could push a bag 55 degrees below its rating and not wake up dead unless somebody kept a stove burning all night.
My new sleeping bag is so tight that all I can wear inside it is a set of winter base layers [ socks/gloves/balaclava too naturally] but I am hoping a -55C rating will be enough. My solution in my old system was that extra large overbag/quilt combination from Nunatak and if you could afford it I would say that was a better solution in case it did bottom out in a record low

Offline Bothwell Voyageur

  • Vendor - Supporter
  • Living Large At -40
  • *****
  • Posts: 1406
    • View Profile
    • CanoePaddler
Re: Pushing my -20 F. down bag to lower temps
« Reply #6 on: December 13, 2018, 11:57:09 am »
One of the big advantages of using insulated clothing as opposed to an overbag as part of your sleep system is that it is dual use, you can wear it during the day at rest stops or can change in to it once camp is set.

Plus if you do have to head out for a pee you stay a lot warmer than if just wearing a thin baselayer.

You could always swap out that down sweater for something a bit thicker, lots of deals out their right now!.

www.canoepaddler.net for custom made gear and fireboxes

Offline 300winmag

  • Stoking the Woodstove
  • ***
  • Posts: 221
    • View Profile
Re: Pushing my -20 F. down bag to lower temps
« Reply #7 on: December 13, 2018, 02:03:09 pm »
Bothwell,

Yeah, regarding thicker clothing, I've been looking at LL Bean'w lightest baffled down parka. It is a good deal at the regular price ($309. for Large, Tall). I'll wait until January to see if the price comes down.

Though I'm 5' 10" I'll get a Tall size B/C I want my butt covered! literally.

And yes, I'm a geezer so my metabolism ain't what it was but last year using the bag in +5 F. I was so warm I had to vent the foot a bit. (Plus I've got a layer of fat i didn't used to have in my XC ski racing/bike racing days. ;o)

Eric B.
UPDATE: As posted in the CLOTHING forum I did get the LL Bean "Big Baffle" down parka. It was NOT baffled but sewn thru. Well made with many nice features but not baffled so I sent it back. Bean's Product Specialist, after looking at one of them, parka, said it was an "...ad copy mistake." INDEED!

SO... I promptly ordered an Eddie Bauer PEAK XV parka which comes tomorrow. I'll take some photos and post. I am certain that it IS baffled.
« Last Edit: January 10, 2019, 10:19:45 pm by 300winmag »