Cuben tent for mountaineering?
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Ron Moak
(rmoak) - F
Re: Re: Cuben usage in mountaineering tents. on 04/05/2014 15:21:43 MDT Print View

>> I will reiterate my main concern: the lack of stretch. <<

It is true that Cuben doesn't have the stretch of Nylon. But then again polyester doesn't either and unless my memory fails me, it's been used in mountaineering tents.

>> That makes getting the seams dead right really critical, and it means the fabric cannot absorb shock loads in a storm. These may not matter in a tarp of course, so the fabric can be great for that. But I have reservations about its use in a tunnel tent in a storm. <<

With standard 1.1 silicone coated nylon the tear strength is roughly 30 lb/inch. . All though my memory maybe a bit off on this one. Plus its strength varies wildly depending upon coating etc. With .74 cuben it's about 65 lb/inch. Or roughly twice as much.

With silicone nylon the weakest point is where the panels are sewn together, ie the seams. With a properly designed CF tent, the weakest point is fabric panel, ie. the seams are stronger than the material itself.

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.

While you can do lab test to mimic that kind of load, it only tells a partial story. The configuration of your pole structure can greatly affect how a tent will respond to wind loading and it's ability to dissipate forces.

In the end, the suitability of a fabric for a task depends upon a myriad of factors. Not simply a direct comparison of replacing one fabric with another.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Cuben usage in mountaineering tents. on 04/05/2014 18:13:57 MDT Print View

Hi Ron

No, polyester fibre does not have as much stretch as nylon fibre, but polyester FABRIC does (usually) have enough stretch in practice - in my experience. Often the stretch you need is on the bias rather than square on anyhow, and most any woven fabric has stretch there.

> With silicone nylon the weakest point is where the panels are sewn together, ie the seams.
I agree.
That is why I have some very special seam construction on my tunnels. I put a lot of design work into that too: both seam design, stitch length and thread gauge. Field testing shows that the seam construction works very well, even When Things Go Wrong. The tent took a fair old hammering that night, and the seams, fabric and CF poles all came through without any damage at all. Pity about the Spectra guy ropes which died, but they were fretting against sharp Ti all night.

So it is possible to have really strong seams in silnylon, even if most Chinese manufacturing never bothers.

> 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? I am not aware of any real test reports showing that sort of load on a real tent under real conditions. Yes, I have seen photos of shredded tents on the South Col of Everest, but those tents took the weather just fine when first pitched. It was many months later after lots and lots of UV degradation that they failed.

I have tested my snow stakes in the snow to see what sorts of forces they can withstand. The forces are not astronomical, far below anything that could cause damage to the fabric, but even so I have never seen any of my stakes show any sign of moving under load in the field. (Except for one time when the sun heated the stakes so much that the snow around them melted ...) I normally use Ti wire stakes in the summer, and I have never had one of them pull out either. So I am not convinced that the tent fabric on a well designed tent is ever loaded near its limits.

To my mind, what really matters is the length of the unsupported fabric span. But, always happy to learn.

Cheers

John Abela
(JohnAbela) - MLife
Re: Re: Re: Re: Cuben usage in mountaineering tents. on 04/06/2014 01:19:37 MDT Print View

You are losing my ability to follow you with all of this Roger...

I will reiterate my main concern: the lack of stretch


and then you say:

what really matters is the length of the unsupported fabric span


So, which is it?

What really is it that you think IS the issue that is the "main issue" or "what really matters".

Or, perhaps there is just a long laundry list of things you have against CF ;) Stop being a hater :-p

Edited by JohnAbela on 04/07/2014 15:59:22 MDT.

Justin Baker
(justin_baker) - F

Locale: Santa Rosa, CA
Re: Cuben tent for mountaineering? on 04/06/2014 01:46:29 MDT Print View

I have an idea, someone should take a cuben fiber tarp, pitch it super taught off some rocks on some remote ridge in the high sierras during summer, then come back next summer after the tarp has survived a winter on an exposed ridge. Then we will know.

Mole J
(MoleJ) - F

Locale: UK
CF on 04/06/2014 02:52:47 MDT Print View

nm

Edited by MoleJ on 04/06/2014 21:08:27 MDT.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Re: Re: Cuben usage in mountaineering tents. on 04/06/2014 04:02:11 MDT Print View

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
(Franco) - M

Locale: Melbourne
Cuben tent for mountaineering? on 04/06/2014 05:52:31 MDT Print View

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...

Edited by Franco on 04/06/2014 16:44:31 MDT.

Rick M
(rmjapan) - F

Locale: London, UK
Re: Re: Cuben tent for mountaineering? on 04/06/2014 06:11:54 MDT Print View

John sez, "I have 3,000+ miles (~5000km) of hiking with a 0.34 CF tarp."

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

John Abela
(JohnAbela) - MLife
Re: Re: Re: Cuben tent for mountaineering? on 04/06/2014 06:36:11 MDT Print View

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


giggle

John Abela
(JohnAbela) - MLife
Re: Re: Re: Cuben tent for mountaineering? on 04/06/2014 07:03:52 MDT Print View

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
(rmjapan) - F

Locale: London, UK
Re: Re: Re: Re: Cuben tent for mountaineering? on 04/06/2014 07:19:57 MDT Print View

John, I was more curious about the 5km distance part of your statement than the CF tarp. Because when I clicked on the "Hiking Journal" link of your blog I only found 5 somewhat strange posts going back to 2012. A lot of gear talk and philosophy, not much on trail life, pics or video. Your body of online published work just seems to stand in stark opposition to the blogs of other "long distance" hikers that expound more on SPECIFIC DETAILS of their adventures.

http://hikelighter.com/category/hiking-journal/

Edited by rmjapan on 04/06/2014 07:25:43 MDT.

Billy Ray
(rosyfinch) - M

Locale: the mountains
Re: Re: Re: Re: Re: Cuben tent for mountaineering? on 04/06/2014 08:29:04 MDT Print View

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
(ViolentGreen) - F

Locale: Southeast
Re: Re: Re: Re: Re: Cuben tent for mountaineering? on 04/06/2014 08:57:09 MDT Print View

Edited

Edited by ViolentGreen on 05/30/2014 10:36:16 MDT.

John Abela
(JohnAbela) - MLife
Re: Re: Re: Re: Re: Re: Cuben tent for mountaineering? on 04/06/2014 09:03:29 MDT Print View

...

Edited by JohnAbela on 04/07/2014 16:00:34 MDT.

Pierre Descoteaux
(Pierre) - MLife
Re: Cuben tent for mountaineering? on 04/06/2014 09:19:00 MDT Print View

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

John Abela
(JohnAbela) - MLife
Re: Re: Cuben tent for mountaineering? on 04/06/2014 09:24:56 MDT Print View

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
(rmoak) - F
Re: Re: Re: Re: Cuben usage in mountaineering tents. on 04/06/2014 10:59:55 MDT Print View

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
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Re: Re: Cuben usage in mountaineering tents. on 04/06/2014 15:58:51 MDT Print View

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
(mountainlaureldesigns) - F - M

Locale: USA
Cuben Fiber on 04/06/2014 18:10:15 MDT Print View

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.

Edited by mountainlaureldesigns on 05/05/2014 09:30:10 MDT.

Richard Nisley
(richard295) - M

Locale: San Francisco Bay Area
Cuben Fiber on 04/06/2014 22:54:10 MDT Print View

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.

Edited by richard295 on 04/08/2014 17:26:06 MDT.