EXTREME Winter Camping SLEEP SYSTEM // Good to -40°

👇 GEAR FROM THE VIDEO 👇
Reflective Mat: geni.us/ReflectiveMat
Nemo Switchback: geni.us/NemoSwitchback
Thermarest Xtherm: geni.us/xtherm
Hikenture Pillow: geni.us/HikenturePillow
Thermarest Polar Ranger: geni.us/PolarRanger
EE Revelation Apex Quilt: geni.us/revelationapex
Winter Camping Playlist: • Winter Camping & Backp...
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⭐ MY FAVORITE GEAR ⭐
Garmin InReach Mini: geni.us/inreach
Decathlon Down Jacket - geni.us/Trek100DownJacketM
REI Flash 55 Pack: geni.us/Flash55
Enlightened Equipment Enigma Quilt: geni.us/enigmadown
Garmin Fenix Watch: geni.us/FenixWatch
Lanshan 1 Pro Tent: geni.us/Lanshan1Pro
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CONNECT WITH ME!
Website: justinoutdoors.com
Facebook: / justinoutdoors
Instagram: / justinoutdoors
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This video description includes affiliate links. Affiliate links help support the channel at no extra cost to you!

[@link2299]

Hi Justin. One note about your reflective mat. The reflectiveness has nothing to do with convection. Convection is due to movement of fluids over the surface. Reflective materials would have improved performance for radiation. However, the reflective nature of that mat would have basically no impact as the heat transfer is almost entirely dominated by the conduction through the material. Regardless, it is a good loadout.

[@JustinOutdoors]

Yes, you are correct. I was getting my thermodynamics mixed up! Definitely radiative heat loss. My understanding is that the bottom would be experiencing mostly conduction while any area with air above the mat would be effective with radiative heat loss.

[@hitibikunu]

I put mine directly under the sleeping bag. Works fine

[@virtualtreadmillwalknature1488]

Amazing! Thanks for sharing! ❤️🇺🇸

[@royjohnson465]

@@JustinOutdoors Justin ~How do you take a PEE (urinate) with that set-up in the middle of the night.? ~In a sealed container 'or' out on the ground.?

[@joe5834]

@@royjohnson465 that is a great question

[@ScottBaker1]

That backdrop tho...

[@_Tree_of_Life_]

One day we will find out that Justin has been putting gear in front of a green screen all this time and has fooled us all... *shakes fist at sky* "Justiiiiin! Nooooo!"

[@PC-wh6oj]

Banff Alberta broski!

[@hesliterallyme.]

@@ethen2915 it's not fake u can see the water rippling

[@hesliterallyme.]

@@ethen2915wdm?

[@tankwfw]

$700 sleeping bag: Me: Guess I'll just die

[@belowdelancey1025]

My thought exactly - as insightful as it is, this is significantly out of my budget. 😂

[@craigf3624]

As a 50-year Alaska...............my go-to system is a good outer bag and a one-pound down inner sack.

[@tabithadebolt1708]

What a lovely winter bear sausage wrap !

[@ctbsancho2516]

Bears are usually hibernating in the winter. Just saying

[@Ambrose25]

Wow your knowledge of your entire sleep system is VERY impressive. I was locked in throughout your video. Great job. Look forward to watching more of your content.

[@JanJarvis]

It's a good choice of -40° in your title, as it's the same temperature in C and F so we all understand it...

[@gg3198]

2021 and still this only ppl from USA say that

[@cxsey8587]

⁠@@gg3198it’s almost like because Americans are the only major country who wouldn’t use Celsius….

[@edwardciaia3448]

Great gear man! Also many thanks to YT's AI/ML algorithms! Last night, after a long time in lockdown, I spent some quality time with my friends and found myself in a locked up situation. I had to camp outside and my door mat have a low insulating ratio and almost 0 heat reflective capacity. Obviously, in the morning I was in a near death situation at almost freezing temperatures. With all this gear I can now spend more quality time with my buddies, safely. Thanks man!

[@TheMrModders]

All I can think of is how warm my bed is in the morning that I don't want to get out of because my 70°f room feels like an ice box in comparison; I cant imagine how cold getting out of that sleeping bad feels.

[@Shane7492]

The discomfort of sleeping outdoors makes you appreciate your bed so much more. And the challenge is fun.

[@rickmortyson4861]

And no one else can because Fahrenheit

[@rickmortyson4861]

@@Shane7492 try to sleep in the garden in your bed at winter. It's the best sleep you'll ever get. Camping is amazing

[@BigpapamoneymanMVPtypebeat]

@@rickmortyson4861 you’ve clearly bin camping wrong your entire life if you think sleeping in your garden is comparable lmao

[@richardjones2811]

People in Yakutsk use natural fur to keep warm. It gets down to -70c there.

[@frstesiste7670]

My challenge has not been while sleeping, but when getting started in the morning, packing up the tent etc. I've only been out down to around -20C. A Thermarest and a winter sleeping bag has worked well for that. Your system looks complicated, but also extremely flexible - don't envy you the -30-experience!

[@mpireoutdoors5274]

Something I use is caffeine tablets. They're very small and can really help to warm up and force movement in the mornings or at other difficult times. Along with ibuprofen for longer trips or late night tasks which one maybe isn't totally enthusiastic about. Also, multivitamins, especially if food is weight/volume prioritised - usually end up sacrificing nutritional content for availablity/weight consideration.

[@JohnDouqh]

I just got this new hot tent from seek outside. Start up the stove in the morning!

[@MikeY-nh2we]

@@jesusislord6545 if you have a moment I'd like to talk to you about you're lord and savior SATAN 😈

[@Shane7492]

No easy way to get out of the sleeping bag/quilt and deal with the cold mornings. Just have to suck it up, don't waste time, and start hiking asap.

[@JohnDouqh]

@@Shane7492 there is a way! Seek outside hot stove tent

[@Forbes123]

Wow, this stuff sure has changed since I used to do it back in my day. That is a lot of gear!

[@justsomeretardontheinterne6987]

Just a sheepskin and body fat will do

[@scottanderson3406]

Awesome video ! I like your system . It took me back to my army days . We slept in our bags in the snow . The temp was -35 F durning the day I'm not sure what the low was ,but the bags stayed dry and I used a small towel over the breather hole to catch condensation and keep the cold out. We were there for a couple of weeks. It was a great learning experience. That was in the early 80's. Thanks. for your video .

[@matthewmantee195]

Yeah army is very different from the old army. If it's too cold we go into shacks or we just have people on stove watch

[@scottanderson3406]

@@matthewmantee195 Hey wait a minute , what do you mean OLD Army ! Ha ha ha ! Thanks for the comment.

[@matthewmantee195]

@@scottanderson3406 there is the old army rough and tough. Our new army wont even let us sleep in the freezing cold. Even though we have 8 man tents with stoves. Well it is a different army in today's word.

[@scottanderson3406]

@@matthewmantee195 Are you serving currently ? Yeah, the old army is a relative term. Probably a natural evolution to a point . My first duty post was Ft Riley in the early 80's . My step dad was there at the beginning of WW2 and they were still pulling artillery around with horses. I guess that was old , old Army .🙂

[@MrTimGJ]

Again, good tips with context - you've just changed my mind about a couple of things that concerned me, and have saved me a fair bit of cash.

[@rezapanahi0_0]

Thanks for your advice and information,it’s too helpful for me🙏🙏 By the way wish you merry Christmas 🎄

[@10--50]

Such an absolutely beautiful location to film in.

[@kurtisf3366]

Peter Lougheed Provincial Park in Alberta, Canada.

[@lumiwilde1022]

Wow thinking about using components of this set up for winter vanlife here in the Colorado mountains! And the colors of that sleeping bag😍😍! Functional, minimal, light weight....AND CUTE! Thanks so much for this video!

[@raffaella150]

Great video. You confirmed me what am I preparing for my first winter holiday in tent. Going for first time in a -25 at the early age of 51, and you just made it awesome. (Little note, I will use a Cumulus because find the therm-a-rest in SHORT size is "mission impossible")

[@artysa.blackwood4261]

No need for short size my friend, you actually want a longer than your size sleepingbag in the cold to have room to put your boots, or boots liners in the bottom.

[@jonchase7752]

Wow been down to -40 and all the army gave me was a 4 piece sleeping system and a woobie

[@alquezada5910]

Nice video. Glad you're carrying all that gear in that cold of temperatures. Keep having fun.

[@devinbrita8557]

That sleeping bag is so cool!

[@BackcountryExposure]

Justin, your gear videos are so well presented. This is a sweet system!

[@JaredandTasha]

Love the shots in the sun by the lake

[@lloydlifestone7045]

Apparently, staying cozy in the cold can be a costly affair. Great upload, Justin. Great channel. Thank you & GOD bless

[@TheKro16]

How much is your life worth to you?

[@shycabs]

The pillow is cute,the view is beautiful.

[@togeika]

I am looking forward to using my Big Agnes Echo Park -20*F bag with my R9 self inflating pad for winter camping. The pad is bulky, but I motorcycle camp with my dog and sidecar, so I have the space. If I want to go colder, I can always put my down bag in the Big Agnes for more insulation. Probably zipped open as a quilt.

[@WEF2030SLAVE]

What a background! Amazing

[@kevinfarias7065]

Super useful video. Thanks!

[@perandersson4528]

So beautiful nature!

[@Sparker408]

MY GOD THAT VIEW IS BREATH TAKING!

[@azclaimjumper]

Yes, I just "Subscribed", rang the notification bell, & "Like" this video. Gotta LOVE that 70D ground side material on your XTherm. It's R6.9 & 2.5" thickness has been improved the newest model, introduced earlier in 2023, the NXT R.7.3 & 3" thickness is, of course, more expensive than the one you have. However, in cold, cold temperatures or even year round in warmer temperatures the XTherm NXT is THE air mattress for anyone wanting the best air mattress in every conceivable way/measure. Warm Regards from Reno, Nevada

[@wisenber]

Down is fine for a few days, but if you're spending several days and a lot of time in a moisture laden tent, it really starts to drop in efficiency by the third or fourth night. Your daytime clothing is wet. If you're cooking , your stove and your pot are giving off a ton of moisture vapor. Then there's the respiration from everyone in the tent. Combine that with stuffing your damp bag into a sack for transport each day, and it gets worse. It's not unusual for a 4 lb down bag to weight 10 lbs within a week. That being said, there are lots of ways to find oneself in minus 30 C. Altitude and/or severe weather tend to require performing more chores inside a tent which produce inherent moisture. A few brief hours at those temps around dawn followed by a 10-20 increase during the day is quite different than a steady minus 30.

[@patrickhowell2502]

Throw a moisture absorber in your bag during the day? Or tent as well

[@wisenber]

@@patrickhowell2502 What size of moisture absorber did you have in mind to keep a tent dry?

[@patrickhowell2502]

@@wisenber ive never had much moisture build up, so probably a handwarmer sized one maybe

[@wisenber]

@@patrickhowell2502 I think you're dreaming. Well funded expeditions have endured failing down bags for decades from condensation and frost. If it were as simple as adding a handwarmer sized decadent to resolve a bag doubling in weight over the course of a week, I imagine that would have been done.

[@patrickhowell2502]

@@wisenber besides being condescending id say your wrong. New ideas that seem obvious after the fact happen all the time. So maybe its been tried, but then again maybe not.

[@JourneyontheTrail]

Excellent list and info. Thanks for sharing.

[@MsBizzyGurl]

I would like to see this sleep system packed up. Looks massive.

[@garier6652]

What a beautiful place!

[@robertjackson1407]

Thank you 😊

[@tshandy1]

Fantastic review. Thanks.

[@peterjohnson6273]

Good video Justin, thanks. Something I use as a vapour barrier over my bag or quilt, is a piece of tyvek. Big enough to tuck in all around, light enough so as to not be noticeable, and multi-function during the day. It adds close to 5 deg Celsius to whatever sleep layout I'm using.

[@c.vonsohn9566]

shouldnt you be using the vapor barrier inside your bag or quilt?

[@nateearle844]

Yeah, never want to trap moisture outside the bag. You will end up covered in frost which could weigh down your bag reducing loft. Vapor barriers are generally used next to skin to protect insulating layers on multi day sub freezing cold trips where drying out your gear is not an option.

[@azclaimjumper]

The outer fabric of my Western Mountineering Antelope (5ºF) is Gore-Windstopper. Warm Regards from Reno, Nevada U.S.A.

[@MG-bp8kj]

Justin, At 5:12 you demonstrate the over-quilt and It reminded me of the setup I recently used. It was an extreme cold weather sleeping bag inside an two person generic sleeping bag. It was 18 degrees Fahrenheit and I was toasty warm, even when I had the inner sleeping bag half way unzipped. It was nowhere close to the temperature you are describing but this type of secondary blanket or sleeping bag will increase the temperature rating of your gear. With that said, kudos to a very instructive video with excellent attention to detail.

[@Thomk121]

Scouts taught me everything i need to know about wjnter camping. Im so grateful for the time i spent in scouting

[@dojocho1894]

Nice video...I use a Marmot cwm -40 bag with a exped down pad and have been warm at -28c in the Alps.

[@squadcast7456]

Really good vid mate very well explained

[@thomasf.5768]

Wow !! Great info & presentation

[@jeffreycarman2185]

Pretty extreme. It is worth noting that inside a good shelter it will be warmer than the outside air temperatures. Great system!

[@ricardoherrera7252]

great info, thank you

[@francoismorin8721]

Cool. Needed a better system as a newbie in winter camping.

[@GauravYadav-mh8jk]

I love your work. I am going to visit coldest regions in India. Thank you.

[@secnbc]

Looks cozy. My problem would be getting out of it!

[@GoodkatNW]

"..some really cool, awesome vents..." This is all we need to know Great video, always appreciate your info!

[@nateearle844]

Excellent dialed-in kit. Way warmer than what I would bring in similar conditions. Glad you mentioned the EE over quilt, pro move. One thing I never forget is a little bit of suffer. Weighs nothing.

[@NatureHeadSupreme]

The world is a beautiful place. ❤

[@sailme2day]

well gezz . I have sent a bunch of folks to your channel . Great layer / winter camping gear video BUT , one critical element missing !!! I used it while living in michigan for 3 years in my non heated solar motor home. That is a vapor barrier. The vapor barrier goes inside the sleeping bag ( yes sleep inside of it ) .Reduces body moisture loss ( dehydration) , zero moisture gets into the sleeping bag , adds easily 10-20 degrees of comfort , to the whole system. Ultra lite weight . I made mine out of 2- 50 gal leaf bags . Cut the bottom out of one and tape the inside and outside over lap together . Mine never wore out with years of winter night use. The same works for footwear , VB socks , they last years . Keep the socks and boots dry forever. The boot VB goes between the inner nylon sock and the outer wool sock . 25 years of building homes year round, it works. Time tested :) Please go research on this important tool missing from your kit .

[@eternal7083]

check out the 'western mountaineering vbl hot sack'. its a bit pricey but works like a charm.has a reflective golden coating on the inside.

[@alan4sure]

@@felixnicsergulden9786 plastic

[@JoATTech]

Great video. Now I want this sleeping bag ;)

[@alexheinonen3388]

What a well explained video, straight to the point and informative! Very neat sleeping system, albeit a tad pricey, haha. Then again, if you're going to do winter camping you probably don't want to cheap out. Liked and subbed man!

[@JustinOutdoors]

Thanks Alex! Welcome!

[@michaeldbhawker3556]

Try a mylar vapor barrier mummy bag inside the sleeping bag. If you use it right it will change your setup dramatically.

[@philochristos]

That's an awesome sleeping bag.

[@SeekingSnow]

Solid advice🤙

[@sapiophile545]

Great stuff! Had a humorous thought. I'd hate for a Sasquatch to happen upon someone in that sleeping bag. Takes home a bag of goodies. 😋

[@Fjall-Anders]

I really understand that you have gained so many followers. Really good video, very good tips. I myself am Swedish and love hard winter trips. on my latest I was trapped in an extreme storm for nine days. Really thank you for sharing 🙂👍

[@RagnarLothbrok2222]

Great info!

[@rickmortyson4861]

Thanks for using Celsius.

[@Fjall-Anders]

You have a new subscriber😀Thanks for a great video😉 I have Exped downmat tt 9 on my wintertrip. The safest inflatable in my opinion. It has six separate tubes, for punk you can replace the broken tube.

[@christianborgwar666]

My biggest concern with winter backpacking is keeping my beer from freezing. Nice video, a cheap alternative to the reflective mat is reflective Tyvek reflective house warp, you can usually can find scraps big enough for your sleeping bag. Made a pad big enough to go inside my tent. I have used that for years and creates a nice layer against the snow.

[@nerdy1701]

If you have a little more space for gear coolers work great for winter camping/ice fishing as well. If I'm outside I'll just stick a water bottle filled with warm water in the corner every couple of hours. Stuff then stays at refrigerator temperature. You do have to dial it in a bit though.

[@johnjenkins8782]

Beer for summer. Liquor for winter.

[@colwem]

You just bring nearly everything into your bag with you. Everything you want to keep warm or dry out you need to sleep with.

[@andrewweninger1059]

That’s why you bring whiskey with you instead of beer, as the whiskey will never freeze LOL. Ask me how I know LOL

[@todd4480]

Good to know this can be done. But I don't plan on ever sleeping outside in below freezing temps. Although, I am starting to prepare for some winter camping.

[@climbingsnowboarder]

Great video! I use mountain hardwears synthetic -30f bag and exped down mat size XL. The down mat is a game changer with 7.8r value and its sooo comfy and worth the extra weight.

[@JustinOutdoors]

I wish I could love the downmat, but it doesn't have insulation in the side baffles!

[@climbingsnowboarder]

@@JustinOutdoors that’s not right, maybe you have/saw a defective one.. ? mine has down insulation in all the baffles. I just double checked cause I thought that was weird. I have the exped downmat UL 7. Or did they start making them differently?

[@cherokeefit4248]

My sleeping kit is my army gortex bivy, recon gen 2 -10 bag, my army thermal blanket liner, and two snugpak fleece liners with the pull cord to zip it closed. Got my army air mattress and thermarest foam pad too.

[@thegroove2000]

Nice set up man.

[@christopherandreou8002]

Excellent video

[@rmiddlehouse]

Love it.

[@Wild-Camping-Geordie]

Synthetic top quilt is a great idea 👍

[@thegroove2000]

Im here in the UK and up in scotland there are places similar to where you are with that amazing backdrop. I aim to get up there for next spring on an adventure.

[@mafa5289]

Hey what’s up! I am a german backpacker and mountain sportsman :) I would like travel in the middle of march to the Scottish highlands for backpacking with tent and be self supportet. Do you have insider/local tips where is the best spot ?! Sorry for my rosty english…best regards from Germany

[@thegroove2000]

@@mafa5289 No sorry but google. I need to also do my research.

[@hawaiidogs9277]

Ty sir

[@toml.8210]

We learned all that stuff in Boy Scouts, for the annual February weekend camp. The important thing to remember for winter sleeping is to have the same amount of insulation BELOW you, as you have above you, after you dig out the snow, so you aren't sleeping on an ice block! I sleep in the open, not in a tent! A tent is basically a pretty refrigerator.

[@CraigBaughan-mg3hf]

Yes, two bags are warmer than one. Use roomy, wider, taller bags to trap more dead air and allow movement within the bags. The best sleep system on snow is a small grain scoop to fashion a snow shelter. Insulation loses its R-value when compressed, down is highly compressible and loses its loft quickly under the weight of the sleeper.

[@paulknoer1259]

i was wih you until the 700$ sleeping bag came up. then again id rather survive than freeze to death with money in my pocket. great information, great video

[@vitcermak7737]

Its all about what you love and what can you spend on it. Obviously, its not for anyone to buy just like that, but so isn’t winter camping. But if you find yourself having such hobby, you probably will invest the money in it no matter your financial situation. Also, I believe you might do okay in cheaper sleeping bag, it just won’t be so convenient, light, with so wide range of temperature.

[@parbindersinghshahi2512]

Wow what a view .... Awesome blossom From india

[@hernandezwalter8308]

Reflective nature of your first layer helps because of radiation, not convection. Convective heat transfer occurs as the flow occurs around a body, radiative heat transfer occurs between two bodies (in this case, your reflective mat and the sun)

[@ImDembe]

Good foam is king, so many days ive been out icefishing and it's the only thing you need to not freeze or getting wet also weighs very little.

[@tomnoyb8301]

Flip the Nemo reflective-side up. Two metal-barriers touching are wasted. Best stack is insulator, metalyzed, insulator, metalyzed, insulator... There are three mechanisms of heat transfer: A) Conduction (transfer through solids), B) Convection (gas thermal transport, wind, etc.), C) Radiant (heat or cold). Thin metalyzed layers are utilizer to block radiant heat, but they do little good in contact (conduction) with the ground or body. Well done putting the metalyzed side of the Mat up. Notice how Thermarest hangs the metalyzed layer between the top and bottom of the pad? That's smart too. Baffles block convection. Flip the Nemo and the system will perform slightly better.

[@JustinOutdoors]

Great overview! I think the grey part of the switchback is actually not the metalized film and that the reflective film is one layer in and facing towards the orange foam. It then operates by reducing radiative heat loss through the air pockets in the foam.

[@chasee1563]

another great video. Thanks Justin!

[@SsgtHolland]

Would have loved to see all items stowed. Thanks, Justin!

[@JustinOutdoors]

kzbin.info/www/bejne/n3m5e2h7h5qJq5Y

[@Mp57navy]

Apart from the sleeping bag, good choice. I use my trusty Marmot Never Summer, rated to -18 comfort zone. If it dips below -20 I add a silk liner and It's cozy again down to Siberia. Beware of icicles forming in your face at night.

[@josh1804josh]

Great video

[@ronstoner1823]

The best “system” I have found for elk season is my sheep herders tent, and A WOOD STOVE!

[@ecopsych101]

Would be interesting to see a thermometer on every layer

[@grininventor]

Hey Justin, I think that the Rab Mythic 600 could be an interesting sleeping bag because it’s lightweight (900g) and it have a -6 Celsius comfort temp and -12 Celsius limit temperature.

[@johanneswe]

cant wait for you buying new gloves :). System seems very solid

[@JustinOutdoors]

They are getting worse... haha. I think I'll need a new pair before my next trip.

[@ralphsmith8682]

The sleeping bag I was issued in the military was ratted to -65. That was 40 years ago. I woke up covered in snow once.

[@brushbum7508]

Were you issued the extreme cold weather bag ? TAKE CARE..

[@zyezues2387]

Man amazing smart dude

[@ericb.4358]

My system: LL Bean 750 fill -20 F. down bag (DWR treated down), REI ALL Season insulated mattress, "polar weight" polyester long johns and fleece balaclava. For below .20 F.-> add down pants and light down jacket, Thermarest Ridge Rest pad. That's it, well except for my Tarptent Moment DW (Double Wall) one person tent with Crossing Pole for snow load.

[@LuckyTown77]

Almost fell asleep watching this...

[@unos10]

Is this a sleeping bag ad? ;) Good and experienced explanation like it

[@youreaphagatron]

You can approximate the effective temperature rating of two stacked quilts by adding their ratings (in Fahrenheit) together and subtracting 70 degrees. So if you're stacking a 50 degree F quilt on top of a -20 degree F sleeping bag, the effective rating should be approximately (-20) + 50 - 70 = -40. This is the formula Enlightened Equipment uses in the table they have showing the effective ratings of stacked quilts, though they cap it at -40 degrees Fahrenheit. You can also just consider the effect of the second quilt on it's own. The temperature rating of the second quilt minus 70 degrees Fahrenheit gives you the effect of the second quilt. So, adding a 50 degree Fahrenheit quilt will always increase the temperature rating of the system by approximately 20 degrees Fahrenheit, as you stated in your video. Adding a 40 degree quilt will add 30 degrees, a 20 degree quilt would add 40, and so on.

[@SheriffofYouTube]

great video new sub

[@redensign9975]

I use a thermarest and a decent rectangular sleeping bag that's good to at least 0 or a little colder. Then I put a mummy bag good to minus 10 to 15 Celsius inside the rectangular bag and I've been toasty warm down to -30 and I know I'd be comfortable below that.

[@kensantiago8729]

All this works great once you are inside the toasty warm bag but all that is thrown out the window the minute you have to get out. At -40 unless you are in a warm tent you are going to endure some major cold discomfort just getting out of the bag and into your gear...especially your boots! Every little thing is a major chore!

[@DannyBoyOutdoorsTravel]

Absolutely technical system and gear. I use the same system to sleep in a cold tent under normally -10C to -20C, sometimes I put wool blanket instead of foam pad. The difference is that I use all cheap stuff on Amazon, and put a hot bottle of water inside the bag, that gives me at least 4hours of solid warm sleep, sometimes 5hours. I also tried -30C once, without a heater, I couldn't sleep AT ALL. I'm in MB, believe me, -30C or lower is absolutely no joke. Maybe your gear would work, not sure😅

[@climbingsnowboarder]

@@cardiogirl798 get a -20, -30 or -40 bag. I've been using Mountain hardwears -30 synthetic bags for years and am super skinny and never gotten cold. they're reasonably priced too.

[@trevorhill1577]

Hi Justin. I'm a theoretical physicist and wild camper, but not down to these chilly temps. Around -12C is the lowest here on Dartmoor. It's that challenging low temperature where it can be wet too. Guess that's why they train our marines here? I've found that the Thermarest 'transverse' tubed sleeping mats 'exhaust' warm air out the sides as convective heat rises from the depression caused by say a hip, to the sides of the mat. The testing procedure doesn't account for this depression and halving the thickness of mat can halve its R-value. The Exped 'longitudinal' mats avoid this though. Snow traps air and it tends to be a much poorer conductor than damp ground or slush ground'. These expensive mats seem to perform well on snow but not so well on slush ground at or just below freezing. I have no problem with sleeping bag. I find if it's too thick, the outside bag temperature is only just above air temperature in the tent and moisture from the body can form frost on and even in the bag, making the bag wet when packed away. It's rarely cold enough here for a VBL though. I've solved this problem by adding a shiny but breathable layer on the outside of the bag. Around 60% of heat lost from the top of a bag is radiative and the shiny layer virtually eliminates this. This means the bag operates with a higher surface temperature preventing any frost from forming. Overall, it reduces heat loss from the bag permitting a thinner bag. Both theory and experience suggest this shiny outer layer is adding around an extra 7DegC to the performance of the bag, but it must be breathable otherwise condensation forms on the inside, as it does in the non-breathable emergency space blankets. Getting to the main point, I'm finding theory and experience suggest the majority of heat loss from the wild camper is to the ground. The weight of the camper crushes any down to a thin layer and combined with the depression caused by the hip, it all acts as a short circuit for heat to the ground. Synthetic bags crush less and perform well in the damp but are heavier. I've solved this problem by taking an extra layer of foam, placing it under the bag and on the sleeping mat, but once more, it's adding weight and bulk. I'd be interested to hear if you've experienced heat loss and chilling due to ground effects.

[@beetooex]

Well go on spill the beans then. What breathable radiant reflector did you find for a top layer? There's only one commercial product I know of.

[@trevorhill1577]

@@beetooex Lame fabric, with acute over the e.

[@beetooex]

@@trevorhill1577 Awesome. That's exactly what I was considering as a DIY solution. Is it as breathable as the loose weave suggests it should be? I'm surprised you can't find anyone talking about this online.

[@trevorhill1577]

@@beetooex Thanks beetooex. You're the first to show any interest after 8 years! I've published on this result, tested to -8DegC, and contacted RAB, seatosummit, Snugpak and a few others but nobody is interested as I don't think they fully understand the Physics. RAB have this very expensive sleeping bag with the reflecting material on the inside which doesn't work as claimed since the heat will simply choose to conduct through. The reflecting side must face outwards on the outside of the sleeping bag. It's why they originally used to make kettles shiny on the outside. It's the principle of the space blanket. Space blankets don't just reflect the heat back, they stop heat being radiated away from the outside. The blanket must not touch your body or clothes though as heat will just conduct through, the space blanket being metallic. It doesn't breathe either. However, yes, I can confirm that the material lame breathes. They also do a version of lame with elastane. They use it for making skin tight costumes for dancing and theatre etc and it's essential that it breathes and stretches. My Vango Cobra 200 has a lame layer sewn in to the outside. Extra 100g but the improvement in performance is genuine.

[@beetooex]

@@trevorhill1577Thanks so much for your explanation. I can't believe no one is interested in peer reviewed empirical data! I hadn't considered how shiny surfaces are low emitters- only their reflective properties. Is there really significant conduction between a metallised surface and high lofting insulation though? All the modern European military bags have a reflective sandwiched between two layers of climashield apex (or a close copy of). How could we apply your method and remain camouflaged? I would, for instance, always want a matt green bivvy bag as my outer most layer...

[@MikeHacker]

Crazy

[@thierrysf]

You look like a robot from a dystopian future in this sleeping bag, hilarious.