Rethinking the Double-Walled Tent

If cost isn't a concern, which I assume is the case if the fly is going to be Cuben, Momentum90 may be an option for the breathable inner. Its about as light and breathable as anything I can think of.

Adam

The answer is always: it depends on the circumstances.

I am perfectly happy to use my single-skin silnylon tent in the winter if I know that I won't be camping on high windy cols and won't be camping in the snow. Mind you, I have also used it in the snow, but that was by accident rather than design.

But if I am deliberately going on a snow trip, I take a (real) double-skin winter tent with a full fabric inner – no netting. Why? If you have to ask this then you haven't camped out on the high plains with spindrift flowing along the top of the snow at high speed. There is nothing quite like finding spindrift blowing through your tent, all over your sleeping bag and dry clothing. Adding a few ounces of down to your sleeping bag does NOT help in this case!

The inner tent needs to be 'air permeable' for two reasons. The first is so that you have some air to breathe. The second is so that the humidity in the air inside the inner tent has some chance to slowly escape to the outer tent. I have spent still cold nights where the morning has seen lots of hoar frost on the inside of the inner tent from our breathe, but I have also woken up to a completely dry tent when there was a 'gentle breeze' all night, clearing the excess humidity out of the tent.

Couldn't you have doorways or vents in silnylon for the air flow? Yes, but the condensation levels would be awful. And any gap on the upwind side will let the spindrift pour in.

What material is suitable for the inner tent? most any of the good light down-proof fabrics – with a good DWR of course. I normally use classic silnylon for the fly and a 30 gsm fabric for the inner. Carrington N1050 or Bainbridge AirX500 would do, as would Quantum, Momentum, or some of the 15 denier Toray fabrics. But skip the idea of netting completely.

Cheers

For winter use, a double wall tent with a fabric inner that can keep out winds and snowdrifts is still the most versatile.

For most all three-season use, a double wall tent with a mesh inner provides the most comfort — and versatility. My practically-all-mesh BA Seedhouse 2 SL blocks almost all winds (there have been many times when it was just howling out there — but nice and calm inside) — but lets slow-moving night air permeate through — making for a delightfully comfortable tent.

I see single wall tents as filling in particular niches — and not for all-around use. A breathable single wall tent can be great for use in cold/dry climes. And a vented single wall tent is great for use in temperate climes with low to moderate humidity.

Personally, I think a double wall design with a mesh inner tent is better for 3 season use – "IF" the bottom 12-15 inches is fabric. This lower fabric wall pretty much eliminates the "wind-in-your-face" problem that I think causes many people to say tarp tents ar "too-breezy", and it prevents wind-blown dust/sand getting all over everything inside. However, the upper mesh part still eliminates heat better than a fabric inner tent, and any condensation on the underside of the outer tent that gets shaken loose in the rain won't penetrate the "no-see-um" type mesh.

I'd like to see 3 main improvements in a double wall tent:
1) Make the outer tent be about 12-15 inches away from the inner tent at the bottom (like a tarp)for enough ventilation even in humid conditions.
2) Use a lighter weight fabric (like the heavier silnylon in the Hex 3, or something else that won't mist in heavy rain even in year 5) – but not something so sturdy that even Scouts don't have to be careful.
3) Make the poles attach to the outer tent (attach the inner & outer with cordage) so it can be pitched in 1 step – and easier in the rain.

ps: If camping on snow in open areas, then I agree with Roger. Although, my 1/2 mesh inner tents do OK in a snowstorm – as long as I'm in a dense enough forest that windspeeds near the tent are "light" (15 mph or less).

Adam: Yes, I think it makes sense to assume that the cost of manufacturing or the cost of fabrics isn't an issue.

Roger: Interesting analysis. It seems as though most tent makers would agree with your approach when it comes to making a winter (or expedition) tent. What I find interesting is that most of them seem to have a mix of mesh and fabric in their "three season" tents. For example, MSR has "Expedition" tents and "Fast and Light Tents" (seen here: http://www.msrgear.com/tents/). The "Expedition" tents are all fabric underneath while the "Fast and Light Tents" have a mix. I wonder if the folks who make such tents feel that the added mesh is needed to allow the tents to breath enough in milder conditions (say, 40 degrees and raining)?

I also find it interesting because I think the closest thing to what I imagine is a combination bug net and tarp, such as the MLD serenity shelter and tarp (about 14 ounces for the one person combo). This is certainly on the light end of the scale. I'm not sure if such a design would act like Reitveld described in his article (adding 17 degrees of warmth) under several conditions (blowing snow like you described, cold and dry, 40 degrees and raining, 50 degrees and raining).

I should add that the bug bivy/tarp combo is also a bit cramped (but again, that is price for having it be so light). It would be nice to have larger, more integrated options (the tarp tents are quite roomy even though they could shave ounces by making them tight).

John: I posted my note while you were posting yours. I agree with what you said, especially the first paragraph.

What I find a bit frustrating is that there are very few ultralight options for fans of the double walled tent. Folks seem to settle for a tent from someone like Big Agnes or MSR. These are good tents (and most of them have the added benefit of being free-standing) but they are quite a bit heavier than a typical tarp tent. Part of that is design (you pay in weight for not using trekking poles to support your tent) but a lot of that is in material. Not only are the big tent makers not using cuben fiber, they aren't even using silnylon.

Likewise, the little tent makers (Six Moons, Tarp Tent, MLD, GG, etc.) aren't making double walled tents. It's too bad, because I think there is a big market out there.

One last thing about price: Many folks expressed concern when Ron said his Refuge X would sell for $400. It turns out that Big Agnes is selling their 2 man Copper Spur UL2 tent for the same price. The Refuge X has sold so well that they are out of stock. Build a better mouse trap…

Ross:

There is an important reason why mainstream tent makers as well as retailers DON'T make or stock double-wall tents made with silnylon or spinnaker or cuben fabric.

Have you read the thread titled "misting silnylon"? Even within our own little UL community where folks are much, much more aware about the characteristics and limitations of UL materials — some posters still suggest "returning the tarptent to Henry"! Imagine how "mainstream" consumers would react when they find out that their UL gear aren't 100% bombproof!

As for why UL gear makers don't make UL double wall tents… I think these makers tend to focus on the UL niche where every ounce that can be sacrificed will be sacrificed — and the type of users are mainly those who would rather "manage" condensation as they occur — in exchange for lighter weight.

Alas, I think you might be part of the "semi UL" segment that isn't being served. I find myself there too sometimes.

> a double wall design with a mesh inner tent is better for 3 season use
While I do agree that you don't need a real double-skin winter tent for summer use, I will also argue that you don't need a full netting inner tent in summer either. My single-skin summer tent is fully bug-proof because there is an inner netting wall between the groundsheet and the roof at the sides and there are full netting doors at the ends. Needs to be so in Australia!

The point here is you can eliminate the netting *roof* at no penalty: the design is fully bug-proof as it stands. There are extra benefits of doing it this way: you don't have all that extra weight of the unnecessary/useless netting roof, and you get more headroom as well.

– "IF" the bottom 12-15 inches is fabric.
Agree. I only go as far as 6" (150 mm), but that is groundsheet silnylon. Bathtub floor: very useful.

Cheers

Roger:

Can you post a pic of your tent? I wonder how closely it resembles a tarptent (or not)?

For me, I like a full mesh inner tent as it allows me to use it without the fly — in good but buggy weather — to enjoy the full view of the night sky. Since most of the weight of an inner tent is in the coated flooring, the additional bits of mesh to completely enclose an inner tent is probably not more than 2 ounces.

But when the winds are howling, I feel very little of it inside my tent. The mesh itself blocks winds very effectively. The combination of a rising floor and downward reaching fly gives that much more protection. But unlike a solid fabric, the mesh inner allows slow-moving night air to permeate through much more readily — thus making for a more comfortable warm-weather tent.

Ross, there are a few tentmakers that have ventured into the UL double wall UL field. Stephenson's and Hilleberg come to mind. If either Stephenson's or Hileberg were to offer a "convertible" tent that you could swap the inners of, it would be a real winner in my mind. I have a MYOG mesh/silnylon inner I've made for our Nallo2 which turns a very nice 4-season tent into a very friendly 3-season lighter tent just by choosing which inner you take along.

A cuben plus mesh (for 3-season) or momentum for winter tent along the lines of the Warmlite/Hilleberg would also be an intriguing concept. If I had the time and the money I wouldn't hesitate to knock off a few demo models along those lines (with convertible inners).

The other thing I really REALLY like in a double skin tent is the ability to pitch either the fly OR inner on it's own. On hot, calm days there's nothing as nice as leaving the fly off and watching the stars…

For me, the netting "roof" is worth carrying for the times that the bugs are biting but there's no rain.

I don't get nearly as many nights under the stars as I'd like to and want to spend them with as few things between me and those stars as practical. Unless there's a pretty good chance of rain, I won't be putting up any rain protection.

That's actually what kept me in an MSR Hubba until pretty recently when SMD came out with their Serenity Net Tent, which I pair with their Gatewood cape.

I get more utility out of them than any combination of tarp with attached netting so the few extra ounces over the SMD Oasis (for example) are worth it to me. They both stay in my backpack whenever possible.

EDIT: While I was typing Ben and Allison both managed to say pretty much what I said, but with fewer words. I think that means they win.

Maybe the three of us should do a hike and enjoy the night sky together! :)

I've always meant to visit New Zealand…

Hi Ben

> Can you post a pic of your tent? I wonder how closely it resembles a tarptent (or not)?
I don't think it bears much resemblance to a tarptent really. It is very much a classical tunnel, and has taken wind and rain to severe levels. It is what I took to France for 3 months, and we had some *bad* weather there.

Key features:
* 3 carbon fibre poles, with corners. You can't get CF tubing to bend like Al tubing so corners are needed, and the use of the corners gives you a lot more headroom.
* Bathtub groundsheet: this has literally floated a few times when we were caught by flash storms.
* Netting side walls: keeps out the bugs and holds the bathtub walls up
* Vestibules both ends: packs at the rear end, wet clothes and cooking at the front end
* Poles sleeved into the roof and guyed: this has taken a lot of wind over the years.

This gives an inside view of the space and headroom. Yes, maybe the tent is a trifle generous in interior space, but the extra weight involved is pathetically small. We LIVED in this tent in France for 3 months: you need the space for that.

Cheers
Roger

Terra Nova has rethought the double wall tent and they claim to make the lightest two man double wall tent in the world. It is sold at Prolite Gear for a very dear price and it weighs only 1 pound 14 ounces. Here is the link.

http://www.prolitegear.com/terra_nova_laser_photon.html

You can copy that into your browser and take a look.

P.S. Your tent looks cool Roger.

Roger:

Very nice, especially the 'model' in your photo! :)

What brand/model is it? What's the weight?

You are right that it looks nothing like a tarptent, although it shares some features with tarptents — such as peripheral mesh venting. Curious, with the nylon/poly fabric coming down so low to the ground, did that compromise venting? Any issue with condensation? I really like the double doors, which give you both convenience and added venting.

Caffin Designs Ltd.

Hi Ben

> Very nice, especially the 'model' in your photo! :)
> What brand/model is it? What's the weight?
The model is my wife, and her weight is not available … :-)

Otherwise, it is a Wombat 3-pole summer tent (V7) made exclusively by and for Roger Caffin.

Weight: with the three carbon fibre poles, 1.28 kg or 45.1 oz. Ti wire pegs extra.

Venting: the bottom edge of the fly comes down to 60 mm above the ground all around. But in addition there is a roof-level vent at the rear end, similar to that at the front end.

I have had bad condensation inside it once, but that night there was as much condensation on the outside of the tent as on the inside. I sometimes get a thin film of condensation on the inside on very still humid nights, but it is very rarely a worry at all. Any wind and there is no condensation to speak of.

Doors at each end: yes. Packs are stored in the rear end, even in serious storms but the contents are still accessible of course. Cooking inside the front end in anything other than hot summer conditions, thus:

Sue arranges the air mats and gets into her SB. I make myself comfy on the foam mats and cook. As you can see, it was dark by the time I started cooking. We often go fairly late – as long as I can get the tent pitched before it is dark.

Cheers

Umm… that webpage says that the Laser uses Titanium skewers that weight 1 gram. 1 gram?! How is that possible? Surely that's a typo and they meant to say 10 grams?

Nope, no typo. BPL sells 1 gram tent stakes.

Adam

You ground dwellers are so cute when you talk tents.

Seriously, Roger, that tent has huge commercial potential. Lighter and roomier than a 2R. Possibly copy Stephenson models' wardrobe though.

Those 1 gram stakes are not for regular use and would probably not take much of a pounding (before bending that hooked portion) to get them in the ground.

Roger, that is one great tent and I'm sure many customers would line up for one, but I would suggest that you keep your current wardrobe, even though it does add a few ounces :-)

My view is that there are double wall tents and then there are double wall tents and the two are not the same beast and don't serve the same function, huh?

In other words, there is a double walled summer bug tent and there is a double walled winter bomb shelter. They simply aren't the same, despite the similar name.

My wife & I have a Big Agnes Seedhouse SL3 which is simply a 100% noseeum inner, with a fly that sits just above the ground for ventilation. I camp with it in Florida and don't even use the fly, I just have it ready in case of rain. Keep in mind that bugs live here year round and if one stands still for 5 minutes you will mildew!

That is not the double wall tent that I would take to Everest!

Of the tent makers mentioned

Tent Specs: http://tinyurl.com/6yj4by
Tent Review: http://tinyurl.com/34wrfw

I think the Terra Nova Photon seems closer to the design I had in mind (a mix of mesh and netting for the inner tent). Their claims to be the "lightest tent" are a bit exaggerated, though. The Refuge X is much lighter (1 pound) and sleeps 2. It isn't clear what materials Terra Nova uses. None of the three makers I mentioned use trekking poles for support (a standard approach for tarp tent and six moon). None of them use cuben fiber. It isn't clear to me whether any of them use silnylon (or anything close to that weight fabric). By the way, here is another great home made double walled tent (weighing in at 20 ounces including stakes and poles): http://tinyurl.com/5ast55