Warmth in tents vs. tarps & shelters

[Hendrik Morkel]

I'd like to hear your thoughts, comments and observations on the use of a tent vs. a tarp/ shelter in winter.

Somewhere I read that a double wall tent will be warmer in the winter, as the inner is trapping some of the heat. It also obviously protects you better from wind. On the negative side, they're more heavy, and that heat can result in condensation. Cooking inside is also not advisable.

A single wall shelter or a tarp have the advantage that they're a lot lighter, should be easier to keep condensation free, and given the right design they should shed snow as well as a tent. They don't have a floor, which might or might not be a problem.

I'm considering using a tarp or shelter for my winter tours. I'm considering a MLD DuoMid because it seems to be well made for the conditions, or a similar kind of shelter/ tarp. I usually camp in forests, so I can camp beneath trees and wind places which are less windy. Temperatures are between -20°C and -30°C, and snow can be from a few cm to 30 cm or more. I currently own the Scarp 1 with the crossing poles, but am wondering if I am able to get away with something lighter. A silnylon DuoMid + my bivy should be around 640 g, that's a kilo lighter than the Scarp 1. Anyhow.

I'd like to know if there's any truth in the argument that tents are warmer in winter, or if its just one of the many outdoor myths. I also would like to hear your comments and experiences with tarps and shelters in winter, and what you think about my idea for my conditions. Also, feel free to hi-jack the thread if you have related/ similar questions =)

[Jim MacDiarmid]

Roger Caffin has an excellent article about winter tents and the various pros and cons.

I believe though, that you have it backwards with regards to condensation. I think single wall tents are much more condensation prone, though any tent in the winter will have condensation issues if not ventilated properly.

Snow caves are the warmest if you have time to dig one out.

I'm not a huge fan of floorless winter shelters, but as the full-on, fully enclosed winter tents are out of my budget right now, this winter I'm going with a Duomid(camping in non-alpine conditions) after have a decent experience in a BD Megalight last winter.

[Travis Leanna]

Though I'm no expert on the subject, I have slept in both during winter. A fully enclosed double wall tent will keep you warmer ( possibly up to 10 degrees) and drier. Condensation will form in ANY shelter if the conditions are right, even open tarps. The purpose of the double wall is so that the condensation forms on the outside wall, keeping the inside wall dry which is important if you rub up against it. Wind is obviously much less a factor inside double walls, which is a major player in robbing you of heat. I myself am trying to find a 4 season shelter with a perfect balance between weight and protection. There are many options!

Tarps and shelters (I've used the Tarptent Squall 2 down to 11 degrees, no snow) may provide a little warmth benefit, but not much. There are ways to pitch tarps and shelters to minimize the breeze, but most of them are just not made specifically for winter. As long as your shelter can handle the wind and any possible snow loads, the main thing is your sleeping bag/sleeping system. Even if you use a breezy tarp, the proper sleeping system can help offset this and you can still stay warm.

And as Jim pointed out, there are people like Roger Caffin who have much more experience on these subjects and can offer more insight.

[Dondo .]

Just thinking aloud, Hendrik. If you were to get a foot or so of wet snow during the night, how would that affect the interior space of the Duomid? Would you still have enough room to stretch out? Would you have to stay up all night banging the snow off?

[Roger Caffin]

I think the biggest difference is how they handle wind – or even just gentle air movements. Tarps and single-wall tent don't block the wind very well – if at all. You really feel exposed sometimes. But a true double-skin winter tent (NOT some 3-season thing with a netting interior) will provide a really comfortable shelter despite a 100 kph wind outside.

The temperature difference people talk about is often more due to the wind-chill effect than a static air difference, although you do get a few degrees from the inner tent.

The idea that any tent or tarp will be condensation-free at -20 C has to be treated with great caution. I have woken up to a dry tent, but that was because there was a gentle wind blowing the whole night. I let it go through the outer tent while keeping the inner tent shut, and the dry air succeeded in removing all the condensation. It can happen, but don't count on it!

Cheers

[Paul McLaughlin]

I have used floorless shelters a lot for snow camping in the spring (like late april/early may) and they can be great for that, on a deep snowpack and with a few tricks. But for real winter, with real storms, I think a double wall tent – or a waterproof/breathable single wall (ID, Bibler) with a vestibule – is what you need. The only way I keep the wind out of my floorless shelters is with snow flaps that I pile snow on. This works great in spring conditions in the Sierra Nevada (settled, fairly wet snow that packs easily and weighs the flaps down nicely), but not so great in powdery snow or with a thin snow cover.
As to warmth, a tent keeps the wind off and that's its main contribution to warmth unless you have a heat source inside. But remember that it doesn't take much wind to rob you of a lot of heat. So while site selection can help your shelter stand up in a storm, even a light breeze will take heat away fast unless your shelter can be fully sealed up

[Hendrik Morkel]

Jim, thanks for the reminder, I had long planned to read it and finally managed to do so on the train last Friday.

I too am thinking about a DuoMid/ SpinnShelter/ Laufbursche Shelter for the trip, as that together with a bivy should save a kilogramm or more. Tempting.

Dondo, I would not have a problem to bang snow off the Tarp/ shelter during the night. I'm not super tall at 175 cm so the DuoMid / SpinnShelter/ Laufbursche Shelter should be spacious enough.

Roger, thank you for your insights. We will be camping in forests all the time so it should be no problem to find a wind sheltered spot and prepare it for the night, like you wrote in your excellent article. Condensation will need to be thought about.

I do not expect storms or high winds. We're going to be hiking in Southern Finland, not Lapland. Of course we should expect the worst, but I believe that it should be possible to camp in a tarp/ shelter + bivy and save a kg of weight in comparison to the Scarp 1 and still be save. Best would be to test it for a night or two close to home, and then go out for a week.

Any opinions/ experiences on how the GG SpinnShelter, Laufbursche Shelter or MLD DuoMid fare in winter conditions?

[Roger Caffin]

Hi Hendrik

> We will be camping in forests all the time so it should be no problem to find a wind sheltered spot

Hum … we want to hear how it goes!

Cheers

[Hendrik Morkel]

Hi Roger,

you will! Lots of photos and insights as well.

Cheers =)

[Jim Colten]

I'll stand with Hendrik on this one …

It's no accident that there's a town named "Finland" in MN. When visiting Hendrik's homeland 4 years ago I was advised "You'll love Suomi … it's just like northern MN." That advice was correct (on both counts).

So here's one winter tarp/bivy data point from northern WI (just like MN except for the football teams they follow).

Weather forecast was an inch or two of snow and temps about 15F (-9C), nearly calm winds.

Started out that way but ended up -13F (-25C), 20-25MPH winds (32-40kph) and 6 inches (15cm) snow. Exposed conditions (on a lake 100 yards away) were pretty ugly.

Shelter: 5×8 tarp pitched REALLY low and MYOG bivy zipped closed except around my face, 30*F sleeping bag (Marmot Arroyo) under synthetic quilts (8oz/yd^2 insulation), ridgerest and another 1/2 inch CCF pad. Clothing was vapor barrier socks under wool socks and SD Down booties, light weight synthetic base layer top&bottom, nylon pants and shirt, 3oz/yd^2 PL1 insulated pants, 200wt fleece jacket and hooded nylon windshell, smartwool balaclava, light wt gloves.

Sleeping site was in low area with a small clump of Balsam Fir trees in a mostly hardwood forest. I didn't notice the wind at all when in bed. I did need to thump the tarp periodically to keep the snow from accumulating but I wake hourly to roll over when on CCF pads anyway so that was mainly just an inconvenience. D*mn cold emerging from that cocoon in the morning but I was warm (not just OK) all night. My only regret is not insisting that the trip photographer take my picture while still in it.

Granted, that's not a lot of snow and not very extreme winds, mine is just one data point and there are many many places where that'd be a dangerously inadequate shelter. But I suspect it's very much like what Hendrik is likely to encounter.

Site selection was a key to success that night … I smiled and nodded agreement when Fritz Handel named "a large spruce tree" as his favorite shelter in the interview Hendrik recently posted … indeed, the night previous to the one above was spent under just such a tree without the tarp.

[Roger Caffin]

> Site selection was a key to success that night
In the shelter of some trees. Right on Jim.

Cheers

[s k]

Good morning, Jim,

As I read through your post the 8 ozsq/ quilt caught my eye and had me thinking about gradient dew points. Many overbags are relatively thin and I wonder if they accomplish the goal of moving condensation into the synthetic. Obviously a large number of variables, but I can imagine that your Marmot was dry in the morning that you describe.

Rereading I realize that you had two? quilts. Is one slit for camp use?

Not very extreme conditions? Maybe not… but only if they're well managed.

[Jim Colten]

@Roger … and having visited the region Hendrik said he'd be camping I felt confident that he'll have plenty of sheltered sites to chose from.

@skots
About those two quilts. One is just adequately wide enough for me, and with a little less than 6oz of PL1 insulation is OK for me somewhere below 30*F (0*C). Yes, it has a head slit and can be worn when I'm standing around camp … similar to the JRB NoSniveler quilt. The other is sized to be layered outside the first. It uses 2.5oz XP and has been OK for me at 40*F (4.5C). Used together I've woken up slightly chilled at about 0*F (-18C).

Regarding moving the dew/frost point outside of a down bag by using a synthetic overbag … I was only out two nights so I didn't get a good feel for how much moisture was retained and where. But my own feelings are that while the theory might seem sound, in practice there may be too many variables to rely for that to work in the long haul. I'm pretty sure that vapor barriers are the only sound solution for that. Also, in addition to insensible perspiration there is respiration and while I worked at breathing to the outside there was still a LOT of frost condensed on the outside of the bag ear my head in spite of the bivy being wide open above my shoulders.

And one cautionary note. Had I packed for the weather forecast I would have left the sleeping bag at home … the quilts would have been adequate for the forecast low temps. THAT would have been a looooong cold night! But I was attending our scout council's "winter camping school" (something I have to do every three years to maintain a "certification" that allows us to go winter camping without a council provided guide). The instructors are decidedly not UL and that was not a venue to have the UL/HW debate (although they did not challenge my tarp … did kinda smirk at it though).

[Steven McAllister]

Hi Hendrik,

Regarding:
"I too am thinking about a DuoMid/ SpinnShelter/ Laufbursche Shelter for the trip, as that together with a bivy should save a kilogramm or more."

I don't do a lot of winter backpacking. It would seem to me that what you are proposing is basically a double wall shelter. It could even outperform a double wall when it comes to warmth and condensation. It would be much lighter than a double wall shelter and would be more flexible.

So what is the advantage of the popular and heavier double wall shelters?

[BlackHatGuy]

N/A

[Eric Blumensaadt]

Roger Caffin feels there's only a few degrees of warmth (in still air) to be gained with a double wall tent.

Well, I dunno about that. From my own experience I've found when unzipping that door and fly to crawl out first thing in the morning is that there must be at least 10 F. temp difference. I sure notice how d@mn cold it is outside on a -5 F. morning compared to my nice "warm" tent.

[Paul McLaughlin]

I think that here we have a situation where "Warmth" and "Comfort" may be two different things. A tarp and bivy combination with a slightly warmer sleeping bag may offer the most sleeping warmth for the weight. But with any breeze blowing, you will be less comfortable when doing anything other than lying snug in the bag. A shelter that can keep out the wind effectively will be more comfortable for those times when you are not lying snug in the bag. Whether this is a single or double wall shelter is far less important than the ability to keep wind out. A single-wall shelter can keep wind out just fine if it is either a waterproof/breathable single wall tent (Bibler, ID or similar)with sewn-in floor, or if the snow conditions are right, a shaped tarp with snow flaps that can have snow piled on them to seal the bottom to the snow. This last system does not work well in cold, dry conditions, as the snow often will not consolidate enough the hold the flaps down, but does work well in climates where the daytime temperature is often above freezing , so that the snow is wet in the afternoon and then freezes in the evening, locking things in nicely.
So for the climate you are describing, I doubt you can effectively keep the wind out with any kind of tarp or tarpish shelter, and unless you can keep the wind out the weight savings will not likely be worth the reduced comfort.

[Roger Caffin]

Hi Eric

When I talk about a 'few degrees' I mean something of the order of 3 Celsius. That would be a bit over 5 F.

If two very thin layers of fabric could support more temperature gradient than that, why would we bother with fleece and so on? But, there may be (a lot) more to this.

I suspect that the inside of your tent might be a bit warmer than my 3 C if it is all sealed up. Sure, you would be losing heat through the tent walls – but maybe it is being replenished from your breathing. And that inside air is still: the air around your head may be slightly warmer than the air against the wall of the tent. It all adds up.

When you stick your head outside into the morning air, maybe it has a slight movement which whisks away the boundary layer around your head – making it feel a lot colder. That is effectively the 'wind chill' effect.

On the other hand, if you leave your double-wall tent slightly open, to minimise any condensation, it may prove slightly cooler inside. And when you are sleeping there for many hours, things do cool down after a while.

I think the key thing here is to not *rely* on the tent making a huge difference – because sometimes it won't. But, sometimes you can be lucky.

Ah, the complications of living well below freezing! Every night is different.

Cheers

[Eric Blumensaadt]

Roger,

It's true that when I leave 6" of netting showing at the top of the door for ventilation to reduce frosting, even on the inner tent body, I DO find the temperature difference between the tent and the outside not that great. I guess it's when we're all zipped up tight in a storm that I notice the difference more. But it could also be the insulating effect of fallen snow around the lower tent walls that helps in insulation.

I wonder if there would be much benefit in a fly with an aluminized inner face to reflect infrared heat radiated from inside. (?) :) Probably been tried already by Jack Stephenson.

Eric

[Roger Caffin]

Hi Eric

> I wonder if there would be much benefit in a fly with an aluminized inner face
> to reflect infrared heat radiated from inside.
Well, in theory this should help, but the amount of IR lost by a body is not great. Granted, the night sky temperature is about -70 C so there is a significant differential, but even so.

It is a thought that an aluminised Cuben shelter might have greater value just for privacy! That's my 2c.

Cheers

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