Combination Heat Sheet/Sleeping Bag:

[Duzzy]

Has anyone ever tried improving a sleeping bags insulation by using a heat sheet/emergency blanket either on top, or inside, of the sleeping bag? If so, how well does it work?

I'm doing a Winter Bivouac SAR training exercise and I'm looking for quick, and expedient, ways to stay warm with things I would normally have in my SAR pack. I've been searching but most of what I've found are the neat "super shelters" that use reflective blankets and plastic. However, I don't know whether or not there will be an artificial time constraint for training purposes. (The last time I did this in the fall we were given 30 minutes to build a shelter in the dark.) And as I wouldn't normally carry my 0 degree bag on a search task I'm hoping to do without; and instead take a much smaller, lighter, 50 degree bag. Ideally I want to to be able to go without using a sleeping bag at all, but I don't think that's a realistic goal at this point in time.

I'll have:

Tent Foot Print
Cordage
5 Contractor bags
Foam Pad
AMK Heat Sheet
Clothes
50 degree Sleeping Bag

So I was thinking of stuffing the bags full of leaves, putting the foam on top of that, then the sleeping bag, then the heat sheet, and covering it all with the foot print. The temperature looks like it will be around 20 degrees F though it could potentially get colder.

Any thoughts? Am I being an idiot through sheer force of ignorance? Winter camping without the creature comforts of a tent, sleeping bag, and pad isn't my normal thing so any advice would be greatly appreciated. Thanks.


Note: I also know about the emergency bivy sacks, but I'm worried that I'll wake up soaked in sweat--and I while I don't mind being a little cold I do mind being wet.

 

[rnpollard]

Adventure Medical has a couple of Bivy Sacks that are really good. One is about $30 and worth every penny. I own one and it is really well made. Check it out.

 

[kgd]

Duzzy,

This is a really tough call and I feel there is no perfect solution. First, combining a heat sheet with a sleeping bag really won't do much good. As much as folks talk about the magic of reflective surfaces bouncing back IR, the simple fact of the matter is that your body doesn't radiate all that much heat. Most of the benefit of an emergency blanket as a blanket is that it is an effective wind breaker and the reflective coating helps a little bit given that it has zero insulation value, but not that much. Here is why - if you have any clothing with colour e.g. lets say a pair of jeans on under the blanket, the jeans will absorb most of the IR your body radiates so there really isn't that much for the blanket to reflect back to you. The myth of the emergency blanket as an emergency blanket has been well sold to the survival community. So adding a heat sheet inside your sleeping bag or on top, won't contribute that much actual heat and it probably will contribute to collecting condensation.

That said, using an emergency blanket in combination with fire, having the heat sheet as a reflector in back of you and fire in front is incredibly effective. The heat sheet can serve the duel purpose of reflector and as a water proofer for your shelter as well. The casualty blankets (thicker heat sheets) are strong enough to act as a tarp in addition to being a reflector. This is the best use of an emergency blanket - see super shelters or other common reflector blanket posts. The problem with your set up comes with the fact that your 50 degree bag, like most sleeping bags, isn't likely very compatible with fires, so using a fire in front of your shelter will cause your bag to receive numerous spark holes. I would suggest getting yourself a wool blanket and practice setting up your shelter in conjunction with fire and a reflector surface. This is very effective and you can easily keep yourself comfortable with a long fire + reflector shelter + wool blanket down to 30 degrees. Some people go further than that, but it requires more elaborate shelter designs.

Check out Abo4ster's Blanket Tech thread for some guidance, search Youtube for iawoodsman's channel as he has some of the best info out there. Here is one of my older videos...

[youtube]gZxdea1ycDQ[/youtube].

BTW - I have the thermolite bivy 2.0 - its okay but I think they promise more than it can actually deliver. I've used it twice to try and supplement my bag when I was cold. In both cases I was disappointed with the results (but I lived - so I can't claim it didn't work)...

 

[foxx]

Have you considered a Kifaru Woobie or Doobie? Inside a Bivy sac, works even better than a tent, shelter, or just in the open. I've only used it once with my bivy, and I was almost too warm, but it was summer. I have a Woobie, and I just love it, as a blankey I'm not so mummified. It has 14 paracord loops so that you can tie them together, making a sleeping bag. Or you can just use it like a blanket, single layer or double it up, in some places.
They are pricy, but my Woobie, a 65lbs dog, and a winter tent was comfortable down to 29 degrees.
They are no good for sleeping next to a fire, IMO, being synthetic, but that's when you need a wool blanket.

 

[Duzzy]

Hey kgd,

Thanks for the insight. Unfortunately, wool blankets aren't something I would realistically carry--so if I can avoid using them in a safe situation I think it would be better off in an emergency. (Of course, at the end of the day maybe I just need to reevaluate what I carry.)

I've seen the super shelters and they look neat, I just don't know if we'll have the time. If we do, I certainly would like to try one; but right now I'm planning for the worst case scenario. And, if I need too I'll just haul around my 0 degree bag this time and figure out something better for the next.

Thanks for sharing your thoughts.

 

[Duzzy]

Have you considered a Kifaru Woobie or Doobie? Inside a Bivy sac, works even better than a tent, shelter, or just in the open. I've only used it once with my bivy, and I was almost too warm, but it was summer. I have a Woobie, and I just love it, as a blankey I'm not so mummified. It has 14 paracord loops so that you can tie them together, making a sleeping bag. Or you can just use it like a blanket, single layer or double it up, in some places.
They are pricy, but my Woobie, a 65lbs dog, and a winter tent was comfortable down to 29 degrees.
They are no good for sleeping next to a fire, IMO, being synthetic, but that's when you need a wool blanket.

Thanks, but I'm in cash conservation mode at the moment, so buying just about anything from Kifaru is out at the moment. I might just pack my 0 degree bag this time and figure out something better for next time. Thanks for the thoughts though.

 

[CellerDrummer]

I've always had the "better safe than sorry" train of thought...Your going to be out in below freezing temps I'd take the best bag I had...Then add a little something to that..

 

[OwenM]

So who comes to get the unprepared SAR people?

So I was thinking of stuffing the bags full of leaves, putting the foam on top of that, then the sleeping bag, then the heat sheet, and covering it all with the foot print. The temperature looks like it will be around 20 degrees F though it could potentially get colder.

Any thoughts?

I doubt that will make a noticeable difference. In leiu of fire and reflector, the only way you're adding 30F of warmth is with a lot more loft, and/or multiple layers, and that will weigh more than just carrying a warmer bag would have. I started that route with my 40F bag after spending a night in it where temps fell into the teens. I intended to buy a quilt to supplement it, but the only reason that really got any thought was liking the idea of having something for my girlfriend or her son to use in warmer temps. It ended up being simpler to just buy what is basically the same bag with almost an extra pound of 800 fill down, and ~30 degree lower EN rating.
When you start thinking about adding insulation separately to stretch a bag's limits, consider this: My Marmot Arete is a 40F bag, EN rated to 42.6F with 8.4oz of fill. My Marmot Pinnacle is basically the 15F version of the same bag, EN rated to 10F. They are both 800 fill down. To achieve that 32.6 degree difference, the Pinnacle almost triples the fill weight of the Arete, using 22.5oz.

 

[Duzzy]

So who comes to get the unprepared SAR people?

Well, I was thinking that was the purpose of training... But if that doesn't work then hopefully, all of the people with the snappy comebacks will come to the rescue.

In all honesty weight is not why I chose to leave my 0 degree bag at home, size was. My 45 degree bag is smaller than a football, and my 0 degree bag is roughly the size of a five gallon bucket. I don't have money for a really nice bag right now, and I don't want to haul a huge pack. If someone is actually in trouble during a winter rescue then I believe speed, and ease of motion, should take primary consideration. I don't need to be comfortable, or happy, I just need to not become a liability if an emergency happens. So I'm trying to find a happy minimum of what I can carry while still remaining effective. This is all new to me, so more experienced people might know better but...

Anyways, I survived. My feet were cold, but I had long underwear on, two sweaters, a jacket, and fleece bottoms under my pants so the rest of me stayed warm. The only downside is that my sleeping bag and pad kept sliding downhill on the trash bags so I would wake up every few hours with my head planted into the tree. Here's my shelter the following morning:

I started to put it up near dusk so most of it was completed while it was dark out. It's not fancy, but I don't think it's too bad for my first time.

 

[OwenM]

Well, I was thinking that was the purpose of training... But if that doesn't work then hopefully, all of the people with the snappy comebacks will come to the rescue.

If someone is actually in trouble during a winter rescue then I believe speed, and ease of motion, should take primary consideration. I don't need to be comfortable, or happy, I just need to not become a liability if an emergency happens. So I'm trying to find a happy minimum of what I can carry while still remaining effective. This is all new to me, so more experienced people might know better but...

Anyways, I survived. My feet were cold, but I had long underwear on, two sweaters, a jacket, and fleece bottoms under my pants so the rest of me stayed warm. The only downside is that my sleeping bag and pad kept sliding downhill on the trash bags so I would wake up every few hours with my head planted into the tree.

Yeah, I understand your needs are going to be different from that of someone backpacking, but don't have an easy solution to minimizing all your gear if you want to be prepared to deal with the elements overnight in cold temps. I guess if you're just doing a rescue, that's one thing, while a search that takes longer and keeps you out, or getting stuck somewhere where you have to stay out would be something else.
Hey, have you looked into getting pro deals for being involved with SAR? You might be able to get gear at a much lower cost. Just a thought.

"I survived"...the night it dropped in the teens, I was stuck. It had taken me 5.5 hours to get where I got in 1hr 33min(took a picture of my watch, even) on the same trail in more normal conditions later, and the temps dropped ~20 degrees below forecast. I ended up with all my clothes except rain gear on in the bag, and was still chilly. Good thing I threw an extra layer in at the last minute before leaving the trailhead, since I was hiking into a storm. I'm now more likely to err on the side of caution than intentionally push the limits. Was just thinking you wouldn't want to be just surviving, but fully functional. I wouldn't have been much help to someone else when I was exhausted and cold, and just happy to be able to get back out, myself.

 

[Duzzy]

Yeah, I understand your needs are going to be different from that of someone backpacking, but don't have an easy solution to minimizing all your gear if you want to be prepared to deal with the elements overnight in cold temps. I guess if you're just doing a rescue, that's one thing, while a search that takes longer and keeps you out, or getting stuck somewhere where you have to stay out would be something else.
Hey, have you looked into getting pro deals for being involved with SAR? You might be able to get gear at a much lower cost. Just a thought.

"I survived"...the night it dropped in the teens, I was stuck. It had taken me 5.5 hours to get where I got in 1hr 33min(took a picture of my watch, even) on the same trail in more normal conditions later, and the temps dropped ~20 degrees below forecast. I ended up with all my clothes except rain gear on in the bag, and was still chilly. Good thing I threw an extra layer in at the last minute before leaving the trailhead, since I was hiking into a storm. I'm now more likely to err on the side of caution than intentionally push the limits. Was just thinking you wouldn't want to be just surviving, but fully functional. I wouldn't have been much help to someone else when I was exhausted and cold, and just happy to be able to get back out, myself.

The last team I was on did not get pro deals, but the current team I'm joining has some deals in place (I'm not privy to them yet). As I said, I don't know the best solution yet, and I'm sure that more experienced people would know better than I. So for now we'll do what we do and see how it goes.

 

[kgd]

Glad to know things went okay. Do you know what the temps went down to during your time out with minimal kit?

How was the foam pad on its own for insulation? Looks thin in your pics. Might be worth the effort to try and pile leaves to aid the insulation value of the foamy in the future....Or make a raised platform with logs/sticks or twigs and add your foam on that. Wood is usually a better insulation than a foamy directly on the ground....Just some friendly advice - but advice that also takes more time to implement than just throwing gear down and setting up.

Nothing sucks more than sleeping on a hill with your head in the downward direction. That usually gives me a headache....I can tolerate feet pointed down more than head pointed down.

 

[Duzzy]

Glad to know things went okay. Do you know what the temps went down to during your time out with minimal kit?

How was the foam pad on its own for insulation? Looks thin in your pics. Might be worth the effort to try and pile leaves to aid the insulation value of the foamy in the future....Or make a raised platform with logs/sticks or twigs and add your foam on that. Wood is usually a better insulation than a foamy directly on the ground....Just some friendly advice - but advice that also takes more time to implement than just throwing gear down and setting up.

Nothing sucks more than sleeping on a hill with your head in the downward direction. That usually gives me a headache....I can tolerate feet pointed down more than head pointed down.

I believe that the temperature was down around 20 degrees, but I couldn't tell you for sure. The low hit 25 in a town about 10 miles away, but I would imagine we were at least a few degrees below that.

Those are actually bags of leaves that have been compressed down, I had my foam pad and sleeping pad on top of those. I honestly did even think about having my head downhill when I set it up--the wind was swirling so I set it up so that the opening would have the least exposure to the elements. I didn't have a headache, but as I mentioned I did wake up several times with my head butted into the tree.

The sticks off to one side were a hasty attempt at weighing down that side to keep the wind from lifting that side up too much.

 

[Bo T]

You might have been able to substitute a Heat Sheet for your tarp and gain a little heat. You'll loose more IR through a 50 degree bag so the Heat Sheet will be more helpful. Did you sweat laying against the plastic bags?

 

[kgd]

I believe that the temperature was down around 20 degrees, but I couldn't tell you for sure. The low hit 25 in a town about 10 miles away, but I would imagine we were at least a few degrees below that.

Those are actually bags of leaves that have been compressed down, I had my foam pad and sleeping pad on top of those. I honestly did even think about having my head downhill when I set it up--the wind was swirling so I set it up so that the opening would have the least exposure to the elements. I didn't have a headache, but as I mentioned I did wake up several times with my head butted into the tree.

The sticks off to one side were a hasty attempt at weighing down that side to keep the wind from lifting that side up too much.

Thanks - good stuff on packing the leaves in the bag! Understood about setting up quick and perhaps in the dark. Stuff like that happens.

You might have been able to substitute a Heat Sheet for your tarp and gain a little heat. You'll loose more IR through a 50 degree bag so the Heat Sheet will be more helpful. Did you sweat laying against the plastic bags?

I still disagree with this. It would be negligible and he would have a poorer quality tarp then the one he was using. Again, using a heat sheet with fire to bounce back heat = awesome. Using a heat sheet to bounce back a trivial amount of body heat escaping the bag isn't likely worth the effort.

 

[Bo T]

"I still disagree with this. It would be negligible and he would have a poorer quality tarp then the one he was using. Again, using a heat sheet with fire to bounce back heat = awesome. Using a heat sheet to bounce back a trivial amount of body heat escaping the bag isn't likely worth the effort."

This is something that I have never considered. It seems apparent that someone who is lightly attired using a Heat Sheet as a cocoon will get much more dramatic effects than someone who is heavily attired and using it as a roof. Any idea about the amount of heat lost through respiration versus radiant heat?