how low (temperature) could you go with this?

[will sawyer]

just gathering opinions…
you are bedding down in a 3 walled lean-to with the following:
thin long underwear bottoms
100wt fleece jacket
1/8" full length pad
emergency blanket

how low could you go?

and this is in no way meant to be argumentative towards Scott's thread about sleep comfort, its something I am considering for a hike where I am willing to sacrifice comfort for weight.

Will

[Dale Wambaugh]

First impression? 50F without being really uncomfortable.

I assume you left out the other stuff you are wearing, in which case I would be wearing everything possible if it is dry, shoes included. Those extra layers of clothing, however thin, can add a lot of warmth. I would use my pack for my feet and lower legs too.

You could survive much colder. Add a fire and you could have a comfy night well below freezing.

I've thought about uber-minimal height of summer kits built around a poncho shelter and an AMK Thermal bivy. Then again, I have a Mont Bell down bag that is just 8 ounces more than the AMK bivy. I would go with the AMK Heat Sheet emergency bivy rather than a blanket style model if you must have the lightest and smallest options.

It is interesting to imagineer overnighter no-cook kits in a hydration pack. It isn't totally unreasonable to think about heading out in August with a 2-liter hydration pack, poncho, essentials, a few granola bars and snacks, a light pad and a bivy. A puffy vest and some long johns would get you though a summer night without chattering teeth.

My survival strategies have assumed that I would have forest debris or conifer branches for ground insulation, with leave no trace set aside for emergency situations, so the 1/8" pad is good for deliberate forays into minimalist kits. I have a Prolite small pad that would be my first choice, simply because I already own it.

I would go for heavier long johns if designing a system, and add socks, gloves and hat, add my windshirt and/or rain shell— anything to cut wind and retain heat. The trickiest part is moisture management and the non-breathable bivy could be a complication. A blanket would ventilate– possibly too well. Ain't no free lunch!

[will sawyer]

lots of interesting thoughts dale…
I was also thinking about 50F for myself.
A thought would be to trim down the pad to a mummy shape, and then get velco dots or something similar to put around the perimeter, and put around the edges of a trimmed emergency blanket to allow better control over ventilation. You'd also save weight over the full bivy and still have an almost sealed bivy if needed.

I didn't leave out much, i bring one pair of sock liners as my hiking socks, have a wind jacket and a hiking shirt/shorts, but those might all be wet. I did not think of shoes, but i guess if dry those would help. I would also be hesitant to add more clothing to the mix for two reasons. 1. It will definitely be at least damp in the morning and with a 'fast and light' mentality I wouldn't want to have to take breaks to dry things, or worry about them falling off my pack, etc. 2. insulating layers like gloves, hat, long johns would only be worn while sleeping, and the weight difference between my quilt and all these plus the emergency blanket isn't much.

I'm musing about a potential trip next summer, probably 6 days, many many miles. seeing how light I could go.

[Dale Wambaugh]

If the bivy isn't a sealed one, damp clothing (sweaty) would dry from body heat. For a trip like this, a light cloth bivy might be a better option than the blanket– like sleeping in a big windshirt. You have the lean-to for weather protection. I'm thinking of a big Pertex stuff sack kind of thing to sleep in. Or to take your velcro dot idea, make a Pertex "quilt" style cover to velcro to the pad. I'm liking that idea a lot. It would actually survive 6 days, where I doubt space blanket would make it through the first night. It wouldn't take much to make one and it could be very customized to your size. You could make a Tyvek one using the flexible kite-style Tyvek and even glue it to the pad, folding the whole works up for travel. Or glue one side and velcro the other

You could cut vents in a bag style emergency bivy or even go after with it with a hole punch, making screen-like vented areas.

*Any* extra dry layers will help. Power Stretch or 100w liner gloves and beanie would take up just a tiny bit of space and make you feel much warmer. I could get by without the gloves, but a beanie or balaclava would really help with the sleeping arrangement.

And you're a certified masochist for even thinking of such things ;)

[will sawyer]

While I would usually have a lean-to, It might be nice to have something waterproof as a just-in-case, I wouldn't have a rain jacket, and there is always a potential of injury and getting stuck out somewhere for the night. You are right about the durability though, thats something I'll have to look into. I would imagine that reflective mylar would be warmer than something like pretax, if not for the reflective coating, than for the VBL effect. Maybe do a half and half, to try to get both benefits….

for a bit more weight, I've also thought about making a similar attached quilt, but two open layers and you could stuff it with leaves or pine duff. This would work better in the fall when there are more leaves on the ground. And if you replace them all its LNT.
how about a sealed double layer attached quilt made out of space blanket that you can inflate. Convection would definitely be a heat-stealer, but it can't be colder than just a single layer, and having the air gap between you and the reflective coating is supposed to be beneficial.

I think I'll try to grab an emergency blanket in the next few days and check it out a bit. Open a window at night and get it down to the 50s in my dorm room and see how it feels.

Thanks for the thoughts Dale

[James holden]

Unless u wanna play bear gryllis i seriously recommend bring some kind of bag if temps are anywhere from 40-50f

even a superlight down/syn bag … Or at minimum a blizzard survival bag for 30 bucks

[Dale Wambaugh]

The AMK blankets are stretchy and more durable. Get the double.

You won't get much from reflection and VBL won't help you above freezing– just make you wetter. Pertex with DWR will give you some rain protection.

That being the case, you can sleep under a poncho. Many soldiers spent many a bad night doing just that. It will give you shelter, emergency rain gear and will work right out of the package. I was thinking you were going to use a tarp or poncho in a lean-to and then bivy under, which I would recommend.

The pitching technique shown in the photo is what I had in mind. You could get by with a found stick or a chunk of an old fishing pole to hold it up.

[will sawyer]

Eric,

I've checked out the blizzard bags, and i'm not sure i see the advantage of that. Its spec'ed at 12.6 oz, which is about 8 times as heavy as an emergency blanket. I don't doubt that it is warmer, but I can't see how it could be much warmer, and the clammy uncomfortable plastic feeling is still there. Also I bet its impossible to pack down to anything near its initial size, the website says to use a vacuum to repackage it!

I have a ~18oz nunatak quilt that I could use, buts I'm looking for something smaller, lighter, and cheaper.

Dale,

A tarp/poncho would be more than what I want to carry, unless it was very light, which would mean cuben and expensive. A large trash bag could serve as a bothy bag if needed.

You are right about VBL not working above freezing. I guess I was thinking more along the lines of blocking wind that could evaporate sweat…Which is also silly because there isn't much wind inside a shelter anyway.

[David Chenault]

Will, I've spent an unplanned night out in just such a setup, around a fire, at 8000', high 30s (F) in the rain and was able to sleep for about 45 minutes at a stretch (until the fire burned down and I woke up shivering). I slept a lot better than you'd think.

[Dale Wambaugh]

"Which is also silly because there isn't much wind inside a shelter anyway."

Depends on diet, I guess :)

A Golite poncho is 7oz. What are you planning on for the lean-to?

[will sawyer]

To clarify, by lean-to I didn't mean a tarp pitch, I meant a 3 sided wooden building with roof, so no need for water protection.

David, thats exactly the sort of thing I was hoping to hear. I imagine building a fire in a shelter is a bad idea, but high 30s is low…I would hope that it would stay above there in August.

[Brett Peugh]

I have been thinking of a similar setup for myself also using something similar to Cap 4 fleece tights, the Thermarest Solar Deluxe Pad, WindPro hat and gloves and an R2 jacket. It just seems to be easier and less bother and worry about getting anything wet or snagged. I have thought about the heatsheets also but am thinking on wearing the rain gear to help drop a few degrees lower.

[Dale Wambaugh]

Now I understand— you mean a classic trail shelter. 50F would be it for me. I would still go for the bag style heat sheet with some venting. The next step up would be a light puffy like a Thermawrap or a Nanopuff– just a couple ounces more than a 100w fleece. I would go up a notch on the bottoms too. Maybe Capeline 2?

[Richard Nisley]

Will,

An emergency blanket (reflective Mylar) blocks forced convection (wind), rain, and some percentage of your infrared heat losses (depends on the emissivity, air space, clothing worn, air temperature, and the surface orientation to your body). The theoretical best case situation is an R-Value of 2.3; this equates to an EN13537 Comfort Rating of ~63F. The EN 13537 rating assumes a base ensemble of .6 clo which is close to the clothing you described in your post.

[Rod Lawlor]

Hi Will,

I think you'll need to have another think. Your plan is okay for one or possibly two nights but I think once you get out past that the weight of food required to stay thermally neutral will start to overtake the weight of something like a one pound WM Highlight. Push that idea a bit further, and you could cut it in half with no zip, and get down around 7 oz.

Disregarding comfort, and your need to end up at a shelter, I really don't think that you can save this much food weight over 5 nights. 1.4oz of olive oil will give about 325cal. Someone will be able to tell you how warm this will keep you.

If you're talking about one night, my plan is normally to sleep in all my clothes, wet or dry, in a bin liner bag. The really thin, crinkly ones. If your clothes are wet, they'll still keep you warmish, as there's no evaporative heat loss. They'll still be warmish in the morning, since you're wearing them. Don't sleep in the shelter, but crawl under a bush to reduce radiant heat loss, and pile up some leaves under your garbage bag to reduce conductive heat loss. Use your pack as a pillow.

I've done this maybe 8-10 times in 24hr races. At 40 I can sleep for about 45 minutes at a time. At 50 I can sleep until my alarm goes off at an hour, but figure I could go 3-4 hrs no problem. It's pretty sweaty though.

In a Summerlite I can cowboy camp and sleep all night, wake up refreshed, and go again for another 16 hours.

YMMV

[James holden]

will … the blizzard bag has been tested to 8 togs … thats about a 40F comfort rated bag … the advantage is that its a bivy and bag all in one … while one can say a down quilt is just as light … the blizzard will still work in moist environments

i havent opened mine yet as i havent had an emergency yet … so there is a bit of bulk to it when used i guess, but hey thats life

i would much rather bring a bag than a pad … you can usually improvise a sleeping bad from branches and leaves, much harder to do for proper insulation …

40F-50F temps are no laughing matter … im not sure exactly what activity you are doing … but for any high exertion activity i recommend having either a warm insulated jacket or a light bag … the reason why you see so runners and other high intensity atheletes with blankets or other such is so that they dont catch hypothermia after high exertion … remember that activities produce sweat, and the flash off of that sweat can be dangerous …

consider as well the possibility of soaking rain or a dump on a cold creek … in those situations a sleeping bag can save your life

like i said i recommend at minimum a blizzard bag or UL single season quilt for anything in that temp range … it pays not to waste your energy shivering at night, or being dependant on making a fire

as a homeless vancouver bum ive got plenty of experiences from living in cardboard boxes and shivering =P

a testimonial about blizzard bags and racing …

n 2009 I made the first ever attempt to run the length of the UK off-road, I succeeded. 1,254miles across trails mountains, moorland and highlands. An average of 30miles a day for six weeks, the run took 45 days and 17 hours, including 3 rest days.

Two weeks before the start of the event, plans for a support crew fell through, I had to run solo and unsupported. I almost dropped out of the challenge, two weeks before the off, I was already having butterflies and losing sleep over the enormity of the route, which includes enough ascent to climb Everest several times over. Having no support crew, would be tough psychologically, but the glaring problem it created was weight – I had to carry all my kit, running 'mountain-marathon' style. I didn't know if it cold be done, I hadn't trained to take the extra strain of a pack for that length of time. i'd already made a commitment to go through with the run, so I only had one choice – slash weight as much as possible, 'trimming the fat' of any piece of kit and the kit list it self.

One of the biggest weight savings I made was in my sleeping system. In adventure races you carry either a very light tent or if crazy just a sleeping bag and a waterproof cover 'bivi bag' I had both options available to me – but looking at the numbers both options were too heavy. I'd already gone to extremes- cutting the handle of my toothbrush (yes a few grams saved here and there really does add up especially when your running over two million steps!)

To have confidence in finishing the run i knew I had to go as light as possible – while remaining safe. I began looking at ways to ditch the sleeping bag, perhaps using foil blankets inside a bivi bag would be enough to keep me alive at night yet light enough to carry through the day.

i knew I was being desperate now – there was no way that system would work, as soon as I moved the foil sheets would move away from the body losing all insulation properties instantly.

I spoke to a mountain leader friend of mine who always carried a vacuum packed 'blizzard bag' made of foil – asking if they were just glorified foil blankets- aparantly not, he informed me they were actual sleeping bags made out of several layers of foil-and importantly they were designed to be re-usable, i.e. they didn't tear after one use.

Looking through the blizzard survival website and after phoning the info line i decided to go with just a foil bag – one piece of kit instead of two that did the job of both 'bivi' bag – it's fully waterproof, and sleeping bag – it's insulated – having three layers of foil I could see how it would work like a down jacket – trapping pockets of air.

I figured the bag would last one week maybe two at most – planning to ask family or friends to post replacements ahead of me along the route. I was happy – with half a sleeping mat and a tarpaulin to cover my head, I knew I had the lightest practical sleeping system to tackle a mountain marathon challenge. The whole system came in at under 700g.

It might seem excessive to just save 300g but the run was approx 2.4million steps, that 300g had to be lifted on every step 2.4Million x 0.3kg = 720,000kg's! 720 tonnes of extra lifting! It's that extra strain that could see an athlete fail short of the mark. It cold well have been the difference between sore feet and stress fractures. Imagine running a marathon Everyday over mountainous terrain – then at the end of each week having to lift over a hundred cars before repeating the same the following week, over these distances saving weight – whilst keeping equipment sable and safe is paramount.

To my surprise the bag lasted over a thousand miles before it started to show signs of abuse, the bag is designed to be used in emergencies – and be reusable for the next emergency you encounter. used nearly every night for 6 weeks – packed a way wet, sat on like a cushion during food stops, this thing was abused – and it lasted.

In my opinion, any athlete looking for the lightest possible sleeping system on the market today, that is actually still practical to use should look no further than a Blizzard Survival bag. I won't lie, its far from comfortable, it doesn't breathe well (but in my opinion no gore tex bivi can deal with the amount of sweat coming of an athletes body after running a marathon over mountains) you will get wet with condensation – but you will be warm no mater the weather outside. The weight saving is too much of an advantage for any athlete to look-over, when wanting to travel fast and light nothing compares.

Kevin Carr.

http://www.facebook.com/notes/blizzard-survival/testimonial-on-blizzard-bags-on-solo-expedition-in-uk-of-1254-miles-in-45-days-1/163514820346210

[Erik Danielsen]

You might want to consider something like this instead:

http://www.seatosummit.com/products/display/91

It probably insulates at least as well as a mylar blanket, is a whole lot more comfortable, and doesn't trap moisture. I know that I'd consider the extra 7 oz. worth it, because my experience relying on space blankets has been that I feel warm when I go to sleep, and wake up less than an hour later absolutely freezing and damp from condensation. A piece of insulation that's actually, well, insulation as opposed to just a reflective barrier, is a lot more likely to maintain comfort through the night. Last time I was out in the cold with just a space blanket (it got down to the 40s) I didn't even use it; I had a nice big fire, then used the old trick of digging a trench and burying burning coals in it, then sleeping on top. Kept me nice and toasty all night long. Had it been windy I possibly would have rigged up the space blanket as a wind barrier, but there was no way I was going to enjoy waking up wet and cold on a night in the 40s.

[Brett Peugh]

I actually have one of the Blizzard Survival Blankets and have found the material to be less than advertised. It is going to be noisy if you move at all in it and the material is somewhat thin so you could rip one of the outer layers pretty easily if you do not baby it. I know I have ripped it when it has come in contact with just the securing tape on the item. It also does not compact back down very small again and tends to take up a bit of volume. It will keep you pretty warm though.

[will sawyer]

Another thing to note is on the AMK website they mention using their emergency bags as summer sleeping bags down to 50F.

Thanks for chiming in Richard. your rating of 63F is quite a bit higher than AMK's, I guess theirs is just more optimistic, i don't think it said 'comfort' anywhere on the page.

Rod, You have a very good point about needing more food to stay warm, and that adding up. I definitely will not be buying a new sleeping bag to cut in half, but I see your point. Thanks for relating your emergency sack experiences.

I'll keep my mind open to some more technical things like a blizzard bag or the thermolite liner. I've seen both of them and they both seem like they could work.

It seems like space blanket/bags work for short naps and the condensation is the downfall, which happens after a longer time. I wonder if a sleep schedule could be made up that would play off of this….especially having lots of shelters on the trail. maybe, get to shelter A at 6:00, eat, sleep for an hour, then hike on to shelter B, 3-7 miles away. sleep for another hour or so and repeat. you could travel like this for 12 hours and get 6 hours of sleep, and 6 of hiking (numbers just guesses). I've been thinking about polyphasic sleep, it might work….

[Erik Danielsen]

I've also given polyphasic sleep some contemplation (for a variety of reasons) and the main problem that I see with it for backpacking is that while it (in theory) satisfies the brain's sleep needs, it doesn't address the body's need for physical recovery time. For someone who needs more time to study as a student or more time to work at some sort of non-strenuous job, that's fine, as they're resting much of the time that they're awake. If you're covering 20+ miles per day on foot, I suspect the lack of recovery time could catch up with you pretty quickly, unless you spend some of that waking time resting, in which state your body will cool down, requiring some sort of insulation to keep you warm, which starts the whole dilemma over again.

Perhaps a 2-phase sleep schedule could work. Sleeping several hours early in the day while it's warm, then sleeping a few more in the evening just after dark, during the warmest part of the night. That way you're hiking and warm during the coldest parts of the night, and still get plenty of daylight hiking, and sleep during relatively warmer parts of each day, requiring less insulation.

[Steven Paris]

I am not advocating doing anything from the show (or even watching) but the one "Dual Survival" show on Discovery Channel I have seen had Cody Lundin creating a shelter from a large piece of plastic (not sure of thickness) and a space blanket/heatsheet (not sure which one).

He made a simple A frame structure from branches, covered the "back" with the space blanket, and the sides and "front" wall with the plastic sheeting. He then made a fire a few feet away on the front side. The heat from the fire was trapped in the "greenhouse" shelter and reflected downward to the ground by the space blanket. Interesting concept, and according to the two "survivalists" it was very warm inside. I imagine this shelter took — at minimum — an hour to construct and so wouldn't be great for a hiker who rolled into camp late and wasn't in survival mode. Also, don't know about embers and the plastic sheeting.

HOWEVER, with an existing structure, it could work. Thoughts?

[will sawyer]

Steven, I remember watching that show as well. You could make a fairly simple and cheap tube tent with 2/3 reflective mylar and 1/3 clear plastic, pitch it with a trekking pole at either end, and have the clear side facing a fire…
I can foresee a ventilation problem, since the concept works by trapping air, which would become moist and wet out insulation(if you still needed it…). A very interesting concept. definitely something cool to think about. Maybe something fun to play with on a low milage trip this winter.

[Mike M]

I've experimented a bit w/ emergency blankets in the past- and for your "normal" thin mylar blanket, I think Richard's assessment of 60-ish degrees is pretty darn close

my current day hike shelter bits consist of a AMK 2 person heatsheet, a AMK Thermolite bivy and some cordage- if caught out I plan on building a debris shelter, using the heatsheet stretched over the frame to help keep moisture out (rain or snow)and the bivy to crawl into

obviously not something you'd be doing on a multi day trip where your trying to cover the miles- for that scenario why not just go to a full SUL setup- a 5 lb base weight feels like nothing on your back and lets you operate quite comfortably) in a pretty wide range of temps

[Barry P]

“…how low could you go?”

That’s some amazing technical advice Richard. When I’ve lived the OP’s set up I’m comfortable to 62F; so I’m impressed with your deductions.

I would never use a clammy thermal blanket again. A silk sheet does much much much better.

-Barry

[will sawyer]

I've done a bit of testing the past few nights, and I'm forced to agree with what most of you are saying. Last night I went to sleep at around 60*(according to wall thermostat) after doing some push-ups and jumping jacks. I was actually too hot at first, but didn't want to vent/expose myself more because I was clammy and it felt so cold outside of the blanket. I was just sleeping in a pair of boxers, and I woke up three hours later, and the temp was 57* then. I had planned to try to go back to sleep after warming up, but took the easy way out and just got into my real bed.

A three hour nap ain't bad, do that twice and you've got a full night's sleep. maybe bring some coffee….

[Author]

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