Trekkertent Saor DCF / Djedi Dome DCF-eVent – Durability and Condenstation?

[Roger Caffin]

Hi Sam

Fwiiw – I use my single-skin tunnel most of the year, and it copes with most conditions very well.

The reason it works so well for us is, I am convinced, that I pay a lot of attention to getting a draft through the tent, from end to end. The draft sweeps the moisture away. Of course, if it sub-zero outside, some of that moisture may condense on the inside of the tent before it leaves. Oh well, it stays there until I strike the tent.

Yes, we use a double skin tent in winter – partly for the warmth, partly against spin-drift, and partly to help with the ventilation without freezing us.

So, bottom line for us: it’s ventilation, ventilation and ventilation that matters, not the fabric or how many skins the tent has.

Cheers

[Michael Harvey]

Hi, Sam, I haven’t had the tent out enough to know how much of my experience is due to the fabric breathing, how much to luck, and how much to other factors. What I can say is that I don’t have conclusive proof that the fabric *doesn’t* breathe well as in the condition that probably would have been most problematic (i.e., some ice scrim on the outside of the tent fabric) and cold temps, I didn’t have a condensation issue. Also of note, the little mesh vent at the top had also more or less crusted shut so any moisture transfer to the outside really had to be taking place through the fabric itself. I’m cautiously optimistic that I’ll continue to find condensation not to be problematic. Like you, I’ve been a double-wall tent person for my 40 plus years in the backcountry. (My other current go-to tent is the Slingfin Portal which I like a lot.) As I mention in my post, my biggest concern is actually with the durability of the fabric as it is very light. I’m definitely using the ground cloth and will endeavor to be kind to the tent.

[Stephen Seeber]

Breathable membranes rely on the difference in vapor pressure on both sides to force vapor through.  Vapor pressure difference is produced by the humidity and temperature conditions on both sides of the membrane.

In your tent, with little or no air movement, the humidity and temperature will stratify.  This means that the humidity and/or temperature at the interior of the tent walls  may be closer to the exterior conditions than the humidity and temperature around the occupant.  Thus, the vapor drive mechanism required to move moisture through an even highly breathable membrane may not be present.  When I do my MVTR testing,  the situation is somewhat similar.  I use a tiny fan inside the test enclosure to circulate air and even out the temperature and moisture distribution.  This produces a substantial increase in vapor transfer through a membrane compared with the absence of the little circulating fan.

So, in the words of the sage for your tent:  it’s ventilation, ventilation and ventilation that matters, not the fabric or how many skins the tent has

 

[Matt Dirksen]

Speaking of vapor transport through air infiltration vs. membrane diffusion…

Does anyone know approximately how much more vapor can be moved through air movement compared to a very “breathable” membrane?

Obviously it will depend on wet/dry bulb temps, air pressure, and cfm of air velocity.  But I’m simply looking for an rough approximation.

I ask because when experienced (and well informed) folks say that good ventilation is always better weather sleeping in a tent or wearing a rain jacket, I don’t get the sense that people really understand just how much increasing ventilation will help.

This article seems to think it’s “50 to 100 times” more, yet I think I’ve read it’s more like ten times more. Therefore, does anyone have a more authoritative source than an article written by a building product manufacturer?

[Stephen Seeber]

A while back, I purchased some breathable cuben from Rip Stop by the Roll. It is dyneema with an EPTFE membrane.  They don’t specify whose membrane is used.   I wondered if this could make a useful jacket fabric.    So, today, I placed it on my permeation kettle to measure the MVTR.  I did just one test and got an MVTR of 3040 g/m2/24hr.  This is equivalent to the breathability of an OR Ascentshell or a Neoshell.  Better than Gore Pro.  So, quite good.  However, whether it is good for a tent, for the reasons discussed above, is another matter.  Might well make a good jacket, but I guess that is a topic for the MYOG forum.

[J-L]

Locus Gear is working on a silnylon version of the Djedi (or at least they were last year):

https://www.instagram.com/p/BwOiTjBBJ0T/?utm_source=ig_embed

If it comes to market, it will be interesting to see how the non-breathable silnylon version compares to the breathable DCF fabric version, and how much mechanical ventilation Locus Gear will have added to account for the difference.

One thing that helps this dome design avoid condensation in the first place is the lack of vestibules. In my experience, large pyramid tarps and large vestibules can trap a lot of moisture from the ground. But condensation is unavoidable under some conditions, no matter the fabric or how much ventilation you have. Where you pitch your tent is almost equally important.

[Roger Caffin]

Does anyone know approximately how much more vapor can be moved through air movement compared to a very “breathable” membrane?
“Insufficient information to give result”

In totally still air, the difference might be small. No air movement. Doors wide open would allow some diffusion outwards, which would still be larger that ‘breathing’.

In a howling gale, the difference could be a ‘little larger’ – maybe 100x? (or more?)

Which goes to show that pitching a tent for good results requires slightly more than dummies.

Cheers

[Sam Farrington]

Roger, et al,

Re:  “So, bottom line for us: it’s ventilation, ventilation and ventilation that matters, not the fabric or how many skins the tent has.”

Cannot disagree, because you said, “for us.”  And  I know there are plenty of poorly ventilated tents on the market, “dummies” do backpack, and conditions change.

Still and all, you can assume I am well ventilated.  But is this enough? (Note the yellow high DWR but breathable splash protector projecting up from the bathtub floor, and there is a larger one at the rear):

Or with the door open, is this enough?  Or enough if it is part way open?

Or is just this enough?  Assuming conditions that create high condensation, probably not, although the manufacturer might not agree:

These are all australian tents BTW.  So, in my stumbling and belated attempts to MYOT,  there would be large protected vents under the peaks at both the front and rear of the tent, and the vestibule door on the downwind side zipped up as far open as the weather would allow.

One way to do this is by opening vents at ends of a tunnel, as you suggest.  But one of my first attempts, as you might remember, was a solo tunnel, that bristled with condensation inside even with much venting at both ends. Another, is a tent like the above, with one-peg front and rear vestibules, allowing plenty of space for large vents on the non-door side of the vestibules at both the front and rear of the tent, and as said above, zipping open the door on the lee side as much as weather allows.

But I can tell you, with tents like those above, all of them were they single wall would be and have been loaded with interior condensation most places I hike.  It is just the nature of the weather in Colorado and northern New England.  If you want to stay dry, you must have a double wall; unless great advances have been made in tent fabric, as to which we both have expressed doubts.  I’m not one to build or buy a tent with doubts.  It’s enough work and/or $ already, and we should plan for the worst, or ‘be prepared’ as the scouts say.

[Roger Caffin]

Rather poor designs imho.
Australian? Asian copies of many standard Asian/American pop-ups.
Tiny vents well below the top: not enough.

Cheers
(Honest, I am not in a bad mood today!)

[Sam Farrington]

Oh Roger, the vent on the Goondie is up high and larger than most on the market, but they could have put one on a back also for cross ventilation; but following your principles, they kept the rear completely buttoned up.
BTW, I’ve never had a drop of condensation on the inner walls (or floors) of either of these tents; although there is one other Aussie on BPL who has expressed disbelief.

[Roger Caffin]

they could have put one on a back also for cross ventilation; but following your principles, they kept the rear completely buttoned up.
NO NO NO.
That would be in direct conflict with or opposition to my ‘principles’.
You need through-flow at the top for best control over condensation.

Given the design, it is likely that most users will pitch the tent with the short side into the wind. This too is contrary to my ‘principles’ (of not having huge fabric spreads direct into the wind). In other words, the vents should be at the top on the two short sides.

Cheers

[Sam Farrington]

Re:  “NO NO NO.”

Roger, wrote a wise-ass post that was annoying. Sorry about that. The devil just gets into me from time to time.

And think the point has been made, that good venting is essential to performance of tents, including single wall tents.  But so is fabric that better resists condensation.  Like mylar, a film used on DCF.  At least according to the late Jack Stephenson from his many trials.  But it could also be something else, like eVent or other WPB.

And there are the devilish details, like the tautness of a tent wall that keeps it from rubbing and soaking you in the night.  Or the tautness or lack of it with DCF in a single wall.  There are many accounts here of DCF Fiddle-Factor with regular reports of difficulty getting tent walls taut.  The photos look good, but the desperation of one current poster was so great he has set out to make a tent with zero pegs.  Maybe a large dog will stay in it the whole time it is up.

And the Djedi’s 34+ oz less pegs is hardly revolutionary.  Plead guilty to going for a SnowPeak Largo, same design as the Djedji in 1P, and it was worse than going head first into an MRI.  But it provides an idea of why people go for “pop-ups,” the conventional hubbed or hubless flexed pole domes with the structural part being the floor and pole supported fabric/net inner, that  in turn supports a fly that includes the vestibule(s), and gets thrown over it (Possible big Fiddle-Factor there also).

Despite all the mental energy gone into a hybrid that is the best of all worlds and leaves out the worst, would go for a truly WPB single wall tent fabric, because dream tents would be so easy to make.  But they’ve been working on WPB rain jackets for decades, and lots of people find they fall short.  So it is a big stretch to believe magical success has arrived with tent fabrics.  Certainly won’t bet money on it.

[Roger Caffin]

Hi Sam

I was not annoyed, really.
My replies are often aimed at other readers, especially novices.

Cheers

[Michael Harvey]

Hello, all, this thread has been quiet for a while but I wanted to return to it with an update on my experience with the Locus Gear Djedi Dome. I own the tent and posted about it above a year ago. I felt quite positive about the tent at the time and specifically felt that its promises of breathability, beautiful design, and livability were largely met. I had used it in my backyard during freezing rain here in Norfolk, and on a very hot and humid trip (but with no precipitation) in the Blue Ridge Mountains. Since then, I’ve had it out on the trail several times and it is fantastic one person shelter that can still accommodate two people if no bulky gear needs to be stowed inside. But none of these trips featured precipitation of any consequence.

HOWEVER, I just put the tent to a real test and, unfortunately, have to report that it did not do well at all. Based on this, I have come to feel that the tent is very much a specialty piece of gear but not a good option as an all-around multi-season tent. More on my thoughts below…

I just came back from a trek of the entire 105-mile Uinta Highline Trail with my two adult daughters. We took three tents: a Nemo Hornet 2P, a Nemo Hornet Elite 2P, and the Djedi Dome. (We also took a Hyperlite flat tarp to create a group cooking and lounging space as we knew there would be precipitation.)

Our weather prep work for the trip included talking to others who had hiked the trail including Benny Braden from the “Highline” movie, lots of online research, talking to the rangers in the Ashley Nat’l Forest, and studying up on historical average temps and precipitation. We anticipated daytime temps in the low 70s to mid-60s, colder in the passes and on the peaks, and nighttime temps in the low 40s to mid 30s. We expected typical mountain weather with afternoon thunder activity including potentially severe and dangerous thunderstorms up high or in exposed areas. All good.

As we got within days and then hours of the trip, it was clear from Meteoblue that there was going to be a lot more precipitation than we anticipated, and that temperatures would be at least 10 degrees colder all around. This wasn’t a big deal to us as we had brought the gear and clothing to Utah to handle a range of conditions with final decisions as to what to actually take to be made at the trailhead.

On our second night out, heavy rain set in and continued all night. I had brought along the rain “beak” for the Djedi Dome (the Djedi VT) which allowed me to leave the front door partially unzipped. Significant condensation built on the tent walls throughout the night to the point where anything in contact with the walls became quite wet. So much for breathing. More problematic still, water was pushing through the floor. I was careful with my tent site—we were camped on meadow grass with generally soft but not squishy soil—but the ground  became so saturated that pockets of standing water formed, some of which managed to get between the very thin Locus Gear groundcloth and tent floor. I had brought my gear into the tent with me and anything that exerted any pressure on the floor at all generated a puddle within the tent.

The heavy precipitation stayed with us for the next five days ranging from sustained heavy rain, to wind-driven hail, some of it marble-sized that quickly created an inch or more of ice on the ground, and full-on snow. Despite several different approaches to pitching the Djedi Dome including without a groundcloth and on various surfaces, we ultimately started using it as a gear garage and my daughters doubled up in one of the Hornets and I took the other one.

Fortunately, for the 2nd half of the trip traversing the actual high wilderness itself, we had a fantastic weather window and were able to enjoy truly magnificent hiking. Water levels were extremely high, however, and the footing in the parks was essentially a bog, and creeks and rivers were all at flood stage.

With no more precipitation and with gusty wind, the Djedi Dome performed extremely well and I slept in it for the remainder of the trip.

From my perspective, the Djedi Dome failed me in the conditions we encountered despite my efforts over the prior year to shake it down and use it in a variety of conditions. Specifically:

– Condensation was as problematic in sustained downpours as with any single-walled tent. The Djedi Dome has a very small triangular mesh vent at the apex of the front door held open by a little kickstand, in addition to venting through the large front door mesh. While the rain beak permitted me to keep the door approximately 50% unzipped, airflow into the tent and across its “breathable” membrane did not dispel heavy condensation;

– The floor failed. Any water beneath the floor at all took only very light pressure to seep through. Additionally, the floor is very fragile. I had already patched two small tears accumulated over the past year and had to make another patch on this trip. That is not where the water was coming in, however, it was truly pushing through the fabric of the floor itself. Even with very careful tent positioning, the conditions made it impossible to site a tent such that there would be no possibility of some amount of ground saturation

– While the large front-door entry is dramatic and fantastic for star-gazing, it also proved less than functional in the rain and mud. the front door flaps (fabric and mesh) get rolled into a cylinder at the base of the entry. Because of the rain beak, to enter the tent or deal with any of its contents, I had to kneel in the mud and sort of scootch my way in. As a result, the fabric was prone to getting dirty and wet. Fortunately, it held up and did not tear although I did manage to put a small hole in the mesh.

So where would this tent do well? In dry conditions with good airflow, it would be hard to imagine a better tent. It pitches quickly and with its six guy-outs, is very stable even in very high winds. It would be a great tent for clear, cold nights in the desert, or at high altitudes with bug pressure. It would probably also do very well in winter where any precipitation would materialize as snow. (Certainly, my first test of it in freezing rain was positive.)

Reluctantly, I am going to part ways with the tent. I will sell it but make sure that any buyer knows all of the caveats above. There may well be people who like to have a range of shelters and with whom the Djedi Dome could have a place. (For example, true winter-camping short of actual alpine expeditions.)

It’s worth calling out that both Nemo tents performed extremely well. I’m not sure why but Nemo seems to have discontinued the Hornets. I have a few quibbles with them but at 2 lbs apiece, they are great 3-season tents and I’m glad we had two of them.

Despite my tent troubles, we had a terrific hike and are already looking forward to returning next year and exploring the wilderness further than just following the trail corridor permitted this time around.

[Michael Harvey]

–

[Christopher S]

If you like the Djedi eVent dome you may want to consider Samaya:

https://www.samaya-equipment.com/collections/tous-les-produits

Personally I find the Djedi takes low weight too far with the tiny zippers. I also prefer aluminum poles vs CF

Rab has also redesigned its whole line of single skin mountaineering tents using the new Pertex Shield “Air” which just sounds like Pertex licensed the Neoshell membrane from Polartec and paired it with their very light nylon face fabrics. While a bit heavier I would suspect they will be more durable and not to mention the fabric will actually be air permeable and likely deal with condensation much better.

The single skin stuff from Big Agnes is also definitely worth checking out – their stuff is air permeable as well – I am using their 4 season Three Wire Bivy and it blows away any other bivy I have used. I have not used their Shield 2 or 3 tents but they use a similar fabric and also look like they have better physical vents than most other domes.

Finally a japanese company called Heritage also makes some interesting mountaineering domes that all have double tunnel vents which is a very nice feature indeed!

[Author]

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