Cuben tent for mountaineering?

[Roger Caffin]

Hi John

If I am a bit cryptic at times, my apologies.

> I will reiterate my main concern: the lack of stretch
> what really matters is the length of the unsupported fabric span
The first is a concern about fabric properties; the second is a concern about tent design per se. Two quite different things. Sorry if that was not clear.

Cheers

[Franco Darioli]

There are a reason you only see four or five companies that dominate the mountaineering market

well yes, that is for the same reason why you can only have one market leader…

There are at least 3 companies that make mountaineering tents and have used Cuben but not in those shelters.
Terra Nova with a version of their UL Laser/Photon, Sierra Designs with the Mojo UFO and Crux with the vestibule of one of their alpine designs.
From the top of my head I can think of at least 20 International brands* that make alpine tents and most have some sort of proprietary/exotic fabric, however not Cuben.
Come to think of it, Brooks Range (make that 21…) had the Rocket (I owned their Propel) made with Cuben but that delaminated and was replaced by a silnylon version.
Mind you, I thought that it was daft to have a dark inside alpine tent anyway.
* I wrote them down as they came to mind…

[Rick M]

del

Any online trip reports/diary posts or hiking partners that can corroborate this?

giggle

rmjapan:

Any online trip reports/diary posts or hiking partners that can corroborate this?

Ok, I'll actually take the time to answer your question…

At least a couple dozen people here at BPL have seen it on the trail with me at least once or twice over the last three or four years. At the last last TWO GGG events at least 80+ people have seen it. A number of people within the cottage industry that work with CF have had access to the three whitepapers I have written on 0.34 cuben fiber over the last three years. Recently the tarp was sent around to a few cottage owners for them to look at it and see how it has held up.

End in the though your skepticism of me means nothing to me. Those that matter within the industry — know.

Now, lets get back to the topic at hand, shall we.

[Rick M]

del

[Billy Ray]

Somebody could email the various mountaineering tent makers and ask them why they don't or if they plan to make CF tents. And if not, why.

Billy

[Ryan Smith]

Edited

…

[Pierre Descoteaux]

To add to Franco's list…
Lightwave Artic has some cuben
Easton Mountain makes (or used to?) a Cuben Si2.

As for why do we always seem to see the same tent/makers in pictures from the big peaks? Let's face it, Some big brands simply lend their expedition tents because of the publicity it gives others have a contract with guiding companies.

Also, how about using 1.0 osy Cuben since it has a thicker membrane?
I got into the diy in order to make my own cuben tunnel tent but I have to learn too much still before I can be of any help. I only just made my 1st pack (TX07 and sil) and some CF stuff sacs as practice.
Cheers

Hey Pierre, yeah, I often wonder when we will see a company use some of the hybrid cuben fiber for a 4 season shelter. That stuff is super strong. Over 2 ounces heavier per square yard than what is normally used but it seems like it would make for one hell of a super strong shelter. At ~$10 more per square yard, those after a truly bombproof shelter should be willing to put out the extra money for this fabric.

[Ron Moak]

Just a few final thoughts before moving on.

>>
> There is the question of shock loading. One must wonder if the inherent stretch of
> silnylon is enough dissipate forces over twice it's static failure load.
Um – where do we get the figure of 'twice it's static failure load' from?
<<

Sorry brevity eliminated clarity. Assuming that my memory is still in tack and that tear strength of Silnylon and Cuben fiber are roughly 30 and 65 lb/in respectively, the stretch of the Silnylon would need dissipate roughly 30 pounds of force so that it would fail at the at approximately the 65 pound rate of the Cuben.

>> That is why I have some very special seam construction on my tunnels. <<

I'm sure you have, but "Any" seam in silnylon reduces it strength. While you can reduce the amount of strength reduction, you can't eliminate it all together. Properly designed Cuben seams are stronger than the underlying fabric.

First as a qualification let me say that I've never owned, made or used a 4 season mountaineering tent in my lifetime. So I claim absolutely no expertise in either their design nor usage. While I did a bunch of mountaineering earlier in my lifetime, I never felt the need for a true 4 season tent.

As to the question of force loading on a tent (4 season or otherwise). From my limited perspective, a mountaineering tent has basically two types of forces to content with. Static, derived from snow loading. Dynamic, derived from wind loading.

Lets take dynamic first. I'd posture that all tents/tarps both summer or winter need to equally handle dynamic loading. I don't know of any statistics that state that Winter winds are significantly stronger than Summer winds. Nor are Winter storms more fierce than Summer ones. While a Winter snow storm can be pretty nasty. I don't recall any that can dent a car roof like a summer hail storm. I do know that we've had our tents survive Category 1 hurricane conditions with no damage.

Dynamic loading is also where stretch is at its best. It allows the tent to flex and respond to rapid changes in pressure as wind flows over the tent in a series of pulses of varying pressure. Currently 90% or more Cuben tents are functioning quite adequately under these conditions. It would appear that Cuben is still well suited for this environment despite its inability to stretch.

Now to static loading. This is really where 3 and 4 season tents really differentiate.
Mountaineering tents are designed to handle snow loads. They do so by incorporating 2 to 3 times the internal structure in order to prevent collapse under the weight. Again this is potentially an area where Cuben can also shine. With it's significantly higher weight to strength ration, Cuben should excel in this area. Again it does require a lot more engineering and labor to produce tents that can handle the stresses, but it certainly is possible.

Due to the high cost of material, labor and engineering, I don't expect to see Cuben used in mountaineering tents coming from major manufactures anytime soon. At this point it's probably cost prohibitive with respect to the rewards. Still that doesn't prevent a small upstart to enter the market. Market voids are where start-ups survive.

[Roger Caffin]

Hi Ron

In general I agree with you.

The fact that Cuben (of a certain weight) is twice as strong as brand X silnylon is interesting, but I have never seen silnylon ever get loaded anywhere near failure, so I suspect that fabric strength is not an issue anyhow.

Static and dynamic loadings, tent flexing, and summer vs winter – yep. The mountains have their own weather.

Someone else raised a concern that snow sticks to Cuban much better than to silnylon. I have no knowledge of this, and it could be a concern, but I have seen plenty of snow-covered tunnels in my time. Domes and tunnels have flattish tops, so snow does accumulate. Maybe it knocks off silnylon more easily?

I have thought about making a Cuban tunnel one day. An interesting thought. Would be 'not cheap' of course.

Cheers

[Ron Bell / MLD]

My answer to the Original Post question:

The reason you don’t see much cuben fiber in full-on winter mountaineering tents is because it is very expensive and costly to build shelters properly in cuben using traditional cut and sew manufacturing techniques. I am absolutely sure if you used the correct styles and weights of cuben fiber in these tents and modern cuben fiber construction techniques they would be stronger and lighter. They would be very expensive and maybe that expense could not be justified by any sales model outside a few very special custom shops receiving a custom order with a very high initial commission cost.

Frankly, until you have built a few hundred cuben shelters you really don’t know what it can do. After almost ten years of daily cuben shelter/gear building I still learn new cuben tricks every few months.

---

Now my apologies to the OP as I am now going beyond the OP question, and god I really hate to do this and I’ll no doubt get crucified, but after literally hundreds and hundreds of these type of cuben naysaying sessions by Roger or Richard over the years I finally want to put in my 2cents. Normally it’s usually best for a manufacturer to stay out of these type things on BPL, as there is never a winner or even a truce and the post usually goes downhill into a rabbit hole rapidly. I’ve kept mostly silent on BPL on this for a long long time.

Note: I would never be this pointed in commenting about any regular BPL forum poster, so before anyone jumps on me specifically about critiquing Richard or Roger: Remember that Roger is long time BPL senior staff and Richard has worked/collaborated on stories/info/research with Roger many times- he is a defacto BPL contributor/staffer. They should be able to handle any critique.

---

To Roger Caffin:
It’s clear in your many posts over the years you do not like cuben fiber much for anything – especially shelters. If that was only your personal opinion, that would be fine except that your are BPL senior staff and most of your posts on cuben state your opinion as absolute fact or are at a minimum perceived that way by many. Look at your first response to the OP: “not trusted” “leaks quite easily” “can fail catastrophically” “ stitch holes have a very bad habit” “adds weight” … geeezzzz – sure you did not miss anything?… The primary way to build cube fiber seams in 2014 is bonding- not by sewing. I can only guess your info on cuben seam construction is from quite a long time ago when the material was still new. (FYI: Contrary to hundreds of BPL forum posts- 3M tape is NOT the way to bond cuben) I’ve never seen any shelters you built from cuben fiber using any modern bonding techniques detailed here on BPL. It seems most of your info on cuben fiber mainly comes from an old and limited exposure to it or from info old BPL posts by a very few others claiming this or that – most all that only conjecture or just plain not correct. Most of the repeated info on cuben fiber strength or waterproofness in shelters that get repeated by you is so outdated it is useless and misleading.

That Old BPL Post:
There is one early 2011 BPL post by Richard Nisley that Roger and others here quote often and it seems to be the main reference material used to poop on cuben. I will address it for that reason. That one post seems to be patient zero for all the wrong info repeated over and over. At that time I did not add my thoughts to the posts (I was trying to work behind the scenes to achieve clarity vs lots of he said she said posts) and just let it roll on and on past 100 posts and now four years later it’s maybe past 1,000 posts through references in many other posts here on BPL and many other websites.

Here is my synoposis of that one post and info I know about it: Richard bought a cuben tarp from us, set it up in the yard and it rained very hard for three days/nights straight. When he saw a lot of moisture on the underside he thought it was leaking. (I guessed it was condensation as it was out for three continuous days/nights over wet ground.) He used a hydrostatic tester that he had just bought used and tested areas of the tarp to destruction (any HH test blows out the fabric in the are tested.) He found the hydrostatic head ( waterproofness) at a very very low number and published his results and the reply posts started about how bad cuben was- his posts clearly intimated it I (and anyone else) selling customers shelters from it was keeping a “dirty little secret” and in effect misleading customers for profit.

Most people would contact the mfgr at that point for a refund. He did not. After seeing that info we contacted him and were understandably concerned that maybe he got a bad cuben batch. We immediately offered complete refund and only then he sent it back and was fully refunded. (Talk about customer service! You buy it, never actually use it as intended, destroy it, post wrong info about it and still get your money back. It took almost five months of our polite emails with him to get him to at least edit the OP to point our he got a refund and to sort out at least a few of the the other inaccuracies.)

We tested it ourselves in the undamaged areas and could not find any where near his low numbers. We also tested many other samples from that same batch of fabric in the shop and could not find those low numbers thier either. His numbers were so low that if cuben was really that bad we would have seen a large number of shelters being returned. Anyway – flash ahead to 2014 and folks, including Roger, still reference that post like it is the absolute truth.

HERE IT COMES:
My one and only clear piece of info needed to positively refute any notion that cuben fiber is not waterproof or strong in any normal backpacking rain/weather/wind condition over any reasonable user/shelter service life is this: If it were as bad as that one single viral 2011 post claims, why would any manufacturer still be able to sell any cuben shelter at any price?

If cuben were that bad every cuben shelter would be returned to the mfgr after only one hard rain trip. At only MLD over the years we have sold many many cuben shelters over many years – How many have ever been returned for fabric leakage? That’s Right- Only One, that one from Richard he tested to destruction.

Almost ten years since the first cuben fiber shelters were made, major science or lab testing is not needed to have good faith about the waterproofness or strength of cuben fiber. Using only a small amount of common sense I think about the many thousands of cuben fiber shelter owners around the world over the years and how many night they have used those shelters. My very conservative guess is maybe 10,000+ cuben shelter users (bought from all the many manufacturers) and all the nights used by each owner- That’s a heck of a lot of field use with next to zero online reports of major issues in waterproofness or strength.

Given that overwhelming and self evident info – It baffles the hell out of me how anyone can reference a couple of single source old BPL posts and that anyone could take that info and think it means anything at all.

[Richard Nisley]

Ron Bell,

Your were right when you said, ”They should be able to handle any critique.” I will handle your attempt at character assignation veiled as critique. The original post Here stands on its findings. In summary it concluded that in the Q1 2011 time frame some, but not all, samples of .07 Mylar Cuben had pin holes in it before it was made into a product.

Character assassination is an attempt to tarnish a person's reputation. It may involve exaggeration, misleading half-truths, or manipulation of facts to present an untrue picture of the targeted person.-Wikipedia

Exaggeration – You said, “He used a hydrostatic tester that he had just bought used and tested areas of the tarp to destruction (any HH test blows out the fabric in the are tested.)” Low pressure hydrostatic head testing (3,500 mm max) does not blow out the fabric. Your implied logic being you can’t say that a sample has low hydrostatic head by testing it because testing it causes to have low hydrostatic head.

Misleading half-truths – You said, “Most people would contact the mfgr at that point for a refund. He did not”. The following day, after I made the forum post, I sent Ron an email not asking for a refund but, a replacement. He was the one that made the decision to refund rather than replace the tarp.

From: Richard Nisley >
To: ron bell
Sent: Fri, March 18, 2011 9:00:28 PM
Subject: RE: A MLD Cuben Test Thread You Need to be Aware of
…The material is defective, in my opinion, and I would like to return it. Please provide an RMA # and shipping address or alternate return procedure.
Thank you,
Richard Nisley

Manipulation of facts to present an untrue picture of the targeted person – You said, “It took almost five months of our polite emails with him to get him to at least edit the OP to point our he got a refund and to sort out at least a few of the the other inaccuracies.) There was ONE email from you (Ron Bell) requesting testing clarification and I updated my original post the following day. The time line was a mid-March ‘11 initial thread creation, followed by Protocol B testing of other samples ending late April ’11, a SINGLE request for clarification from Ron that I received July 29, '11, and my post addressing his concerns Aug 1, ’11.

[Franco Darioli]

Going back to the why not Cuben…
A very popular design for alpine tents is the freestanding two pole wedge type ,like this :

(I used that shot before to illustrate why front entry sometimes works better…)
Anyway these kind of tents are small and have by necessity poor air flow so condensation is a problem.
Most makes claim that their fabric "breathes" and up to a point they might, but in the end most drip or have ice /frost build up and maybe Cuben could be more expensive and not better in this regard .

[David Ure]

I also can't see how the popular weights of. Cuben currently used for shelters could take the abrasion that would occur at points where the fabric would rub against the poles, at least with the proven wedge design for mountaineering. But I am probably wrong.

[Roger Caffin]

Hi Ron (Bell)

First of all, can I reassure you that I will not take offence. I have a hide like a warthog, and just keep smiling.

Second, it's about time some of you guys (Henry, Ron M, Ron B, etc) did contribute a bit more to some of the discussions here! You have a depth of experience most everyone else lacks. We welcome your contributions.

Now, to the issues about Cuban.

First of all, just because Richard's testing was done a few years ago does not mean it is no longer valid. Richard is a professional, using professional testing gear. And 2011 is not THAT long ago!

Yes, Richard is a respected BPL contributor. He has earned that respect by his work on fabrics. No, Richard is not a BPL staffer.

Second, I have to say that your claim that 'There is one early 2011 BPL post by Richard Nisley' is a bit off the mark. There was a thread on fabric testing which went on for a long time. Richard tested a very wide range of fabrics both new and after a moderately standardised amount of 'wear' – done following known fabric testing Standards. Both Richard and I are fairly familiar with professional fabric testing Standards, for professional reasons.

What we found was that both light 'crackly' spinnaker fabric and light Cuban Fibre fabric could eventually develop pin holes at the corners of creases, and these pin holes could leak under pressure. This is not to be wondered at: it is in the nature of the materials involved. Testing the fabrics like this did not destroy the fabrics either. If it could then the fabrics would be useless in the field.

However, I am quite happy to agree that for many users, the pin holes will not matter as the pressure from rain will not be that high. My own opinion is that this latter is why so many Cuban tarp users remain happy with their tarps. Fair enough: carry on tarping!

In addition, there were one or two other threads which covered the problems with stitch holes expanding under load (eg guy ropes). There were even photos of the expanded holes. I think we all understood back at that stage that sewing Cuban Fiber fabric is not the solution.

> flash ahead to 2014 and folks, including Roger, still reference that post like it
> is the absolute truth.
Um, well, the measurements and observations and photos were made by several of us. That is indeed absolute truth. The validity of the test results does not decay with age. That is another scientific truth.

> The primary way to build cuban fiber seams in 2014 is bonding- not by sewing.
I do not think anyone is arguing with you here. Not even me! Bonding is the way to go.

Are we wrong to pay attention to lab testing using acknowledged industry Standards and professional lab testing gear? I think not. Should we ignore the (tens of) thousands of hours of field use? I think not. Both are valid; both have lots of meaning.

Cheers
Roger Caffin (PhD)
(In my own right, not as a BPL Staffer)

[rmeurant]

With regard to your statement that "That’s a heck of a lot of field use with next to zero online reports of major issues in waterproofness or strength", the problem may be that not all failures are reported.

While I am an enthusiast for cuben, having my brand new cuben pyramid shelter disintegrate under brisk winds and rather hot weather, at the start of a one month camping sojourn in Japan, provided me with direct evidence that failures do occur with cuben, and can be catastrophic.

I emphasize that the manufacturer, although American, was NOT MLD (nor HMG). The tape near the apex started coming off, and in addition, tear marks like a perforated strip near to and parallel to the top of the zipper became evident – possibly where a line had been sewn erroneously, then removed (?). The apex was beginning to disintegrate, and it became necessary to strike the tent and protect my gear, before the failure became complete.

The workmanship in general was pretty shoddy; some seams looked as though they had been sown by a drunkard, in the dark. It made me angry to look at it. The manufacturer, when phoned, tried to assure me that the cuben pyramid should be treated gently, and not be used in too rough a conditions (God forbid!) He refused to refund the purchase price, as the one month's grace period had expired (I'd had heavy monsoon rains and an excessive workload, and so had only been able to test pitch it once or twice prior to starting the trip).

To be fair, he did agree to fix it and return it for free, and I eventually received it with a new door, of slightly different but noticeably yellow color. But in the meantime, I had to purchase a second tent while in Japan, to continue my trip.

This happened 2 or 3 years ago, and I have refrained from making it public, and embarrassing the manufacturer. But it certainly did happen. While I am at it, the bug inner I had ordered with the tent arrived with a hole near the apex that any self-respecting mozzie would have had no problem in flying through, which I had to fix. The tent pole I ordered had been assembled wrongly, so that when folded, it was much longer than it needed to be, which meant I had to remove the elastic, and reassemble it correctly. One end of the pole had been sawn at an angle…

---

Since then, I have had a much better experience with a Locus Gear cuben Khufu, with excellent workmanship, and with which I am much content; they are currently making me a ripstop 2/3 inner.

I note also that reinforced cuben Khufu and I think Khafra 'mids are being used by alpinists, and in the Himalayas.

---

I have the highest respect for MLD products and the DuoMid – I regard the LG Khufu and the Duomid as classic designs – but I do think that cuben shelters can cause problems, particularly when there is shoddy workmanship. Just to reiterate, the problems I had were most emphatically NOT with MLD, HMG, or for that matter Locus Gear, all of whom, as far as I am aware, make first rate gear.

[William Chilton]

Robert, it seems that the problem with your tent wasn't "… major issues in waterproofness or strength" but indeed, as you said, due to shoddy workmanship. The problems with sewing cuben may have exacerbated things, but it seems the workmanship was the real problem.
Personally, I think you should name the manufacturer. Otherwise, you are casting a doubt over a number of good manufacturers, with the exception of MLD, HMG and Locus Gear.

[David Chenault]

This thread is overdue in at least four or five ways. I appreciate everyones candor.

[matt brisbin]

Who knew that post would come this far.

Seems like I missed a few updates since the first few posts. Perhaps somethings up with the BPL notification system? In any case, I appreciate all the info even though it appears to have gotten a bit dicy at times :-) I think I'll still carry on and prototype out a cuben fiber mountaineering tent in my spare time.

[Sam Farrington]

"I think I'll still carry on and prototype out a cuben fiber mountaineering tent in my spare time."

Good. At least we are both on the MYOG track, which is the purpose of this forum.

This thread and the long nights spent studying many similar threads remind me a bit of the long threads formerly read on Thru-Hiker about insulation for sleeping gear. Very interesting, but not enough help in making a decision.

What we hear from the small business folk is that the Cuben is superior if the seams are done with their expertise, expertise that is not shared. So that's no help.

What we hear from Roger and Richard is that some of the Cuben fails sooner or later, but maybe not so badly in practice, or if maybe it's a tarp. That's not much help either.

What we know from Richard's tests is that some of the Cuben leaks and some does not, and ditto with the silnylons; but to a lesser extent with the latter, because we know with reasonable certainty the few silnylons that are consistently good, and where we can buy them.

With the above in mind, we face the core MYOG dilemma; that is, the design and construction (done by us) are a BIG hurdle, fraught with lots of BIG risks of failure. If we can successfully cope with all that, how much sense can it make to use materials that we are unsure of, or that we might be sure of if we could find out more about bonding and such, but can't.

It is not only mountaineers that want a tent that will provide the best protection "when things go wrong," as Roger says. For an ordinary old backpacker like me, there are plenty of situations, on the Continental Divide for example, where the best protection is essential. I would love to make the Cuben tent already designed in my noggin; but without the materials, adhesives and techniques I can rely on, it makes no sense. Silnylon exists that I can rely on, that is obtainable, and that works with known techniques. So I'll carry the additional couple of ounces.
(1.1 [oz/sq/yd] minus .75 [oz/sq/yd] = .35 x 6 [sq yds] = 2.1 [ounces]).

Seems like a no-brainer, but maybe I'm missing something.

[Lawson Kline]

The reason you don't see more cuben mountaineering tents is because of the construction techniques that would have to be used.. The shelter would have to be both bonded and sewn as bonding alone doesn't work in cold weather. The adhesive looses all its strength and the shelter will just fall apart.

I had a problem with my drybags in cold weather. People were stuffing their down bags in them and then going out in cold weather mountaineering, snow shoeing, skiing, hunting, etc and the seams were failing. The down bag would literately push the seam apart… So I paid 3M to test the problem. Well they found that ALL roll adhesives loose about 50%- 90% of their bond strength under 0F. Put it this way. 9485PC which is the adhesive that Cubic Tech use to recommend before selling their own, and most likely the adhesive most companies are still using has a T-Peel bond strength of 90.4oz/in at room temp and 12.5oz/in at 0F..

So the problem can be fixed by sewing the seams after bonding, BUT then your sewing through a non-woven material which creates a whole set of new problems…..

[Greg Mihalik]

"So I paid 3M to test the problem. Well they found that ALL roll adhesives loose about 50%- 90% of their bond strength under 0F. "

Tip of the hat to you, Lawson. Thanks.

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