Rethinking the Double-Walled Tent
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Ross Bleakney
(rossbleakney) - MLife

Locale: Cascades
Rethinking the Double-Walled Tent on 07/24/2008 17:13:50 MDT Print View

Conventional ultralight wisdom is that while a double-walled tent does provide some warmth (along with some other advantages) you are better off getting a single-walled tent and applying the weight savings towards a warmer sleeping bag. So, for example, if a double-walled tent weighs a pound more than a similarly designed single-walled tent, you can add eight ounces of insulation to your sleeping bag and have a warmer, lighter experience. I wonder, though, if advances in material have now changed so much that this general approach is no longer valid. If the difference between a double-walled tent and a single-walled tent is, for example, eight ounces, then it isn't hard to imagine that for the same weight, you might be warmer with a double-walled tent, especially when you add the possibility of two people sleeping under the same tent. Even if it is a close tie, the other advantages (better moisture control and no drafts) suggest that is it reasonable to consider ultralight double-walled tents.

I am curious what people think and specifically what materials might make sense for such a tent. In Will Rietveld's excellent article he mentions using "an air-permeable inner wall" and that "Double wall tents work best if the inner wall is fabric and not mesh" (scroll down to "Single-walled versus Double-walled"). I've read many posts confirming that opinion. This is where my mental design of an ultralight double-walled tent stalls. I can imagine the bottom being silnylon (bathtub perhaps) followed by a combination of mesh and this permeable fabric above it. The rain fly could be Cuben. What makes sense for the permeable fabric? How does nano-seeum compare to other permeable fabrics (in terms of weight)? I believe Ron Bell mentioned that spinnaker fabric is treated to get it to be waterproof. Is untreated spinnaker breathable at all? Obviously, it can't be too breathable, or it wouldn't work well for a sail.

Edited by rossbleakney on 07/24/2008 17:15:07 MDT.

Adam Rothermich
(aroth87) - F

Locale: Missouri Ozarks
Re: Rethinking the Double-Walled Tent on 07/24/2008 17:48:47 MDT Print View

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

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Rethinking the Double-Walled Tent on 07/24/2008 18:05:19 MDT Print View

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

Ben 2 World
(ben2world) - MLife

Locale: So Cal
Re: Rethinking the Double-Walled Tent on 07/24/2008 18:22:39 MDT Print View

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.

Edited by ben2world on 07/24/2008 18:26:56 MDT.

John Gilbert
(JohnG10) - F

Locale: Mid-Atlantic
Ultimate double wall on 07/24/2008 18:23:35 MDT Print View

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).

Edited by JohnG10 on 07/24/2008 18:31:05 MDT.

Ross Bleakney
(rossbleakney) - MLife

Locale: Cascades
Re: Rethinking the Double-Walled Tent on 07/24/2008 18:33:57 MDT Print View

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).

Ross Bleakney
(rossbleakney) - MLife

Locale: Cascades
Rethinking the Double-Walled Tent on 07/24/2008 19:02:04 MDT Print View

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...

Ben 2 World
(ben2world) - MLife

Locale: So Cal
Re: Rethinking the Double-Walled Tent on 07/24/2008 19:10:56 MDT Print View

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.

Edited by ben2world on 07/24/2008 19:15:15 MDT.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
re Netting inner tents on 07/24/2008 19:20:23 MDT Print View

> 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

Ben 2 World
(ben2world) - MLife

Locale: So Cal
Re: re Netting inner tents on 07/24/2008 19:55:32 MDT Print View

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.

Edited by ben2world on 07/24/2008 20:01:12 MDT.

Lynn Tramper
(retropump) - F

Locale: The Antipodes of La Coruna
Re: Rethinking the Double-Walled Tent on 07/24/2008 20:02:14 MDT Print View

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...

Adam Behr
(justsomeguy) - MLife
Re: re Netting inner tents on 07/24/2008 20:25:17 MDT Print View

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.

Edited by justsomeguy on 07/24/2008 20:28:20 MDT.

Ben 2 World
(ben2world) - MLife

Locale: So Cal
Re: Netting inner tents on 07/24/2008 21:01:58 MDT Print View

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

Adam Behr
(justsomeguy) - MLife
Re: Re: Netting inner tents on 07/24/2008 21:12:04 MDT Print View

I've always meant to visit New Zealand...

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: re Netting inner tents on 07/24/2008 22:21:51 MDT Print View

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.

Outside view

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.

Inside view of tent

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

Scott Jones
(Ultimate2) - F
Rethinking the Double Wall Tent on 07/24/2008 22:49:15 MDT Print View

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.

Edited by Ultimate2 on 07/24/2008 22:50:26 MDT.

Ben 2 World
(ben2world) - MLife

Locale: So Cal
Re Netting inner tents on 07/24/2008 23:14:48 MDT Print View

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.

Devin Montgomery
(dsmontgomery) - MLife

Locale: one snowball away from big trouble
Re: Re Netting inner tents on 07/25/2008 04:21:14 MDT Print View

Caffin Designs Ltd.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re Netting inner tents on 07/25/2008 04:32:23 MDT Print View

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:

Cooking Inside

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

David Lewis
(davidlewis) - MLife

Locale: Nova Scotia, Canada
Re: Rethinking the Double Wall Tent on 07/25/2008 04:34:42 MDT Print View

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?