Forum Index » GEAR » Cuben Tent Question?


Display Avatars Sort By:
Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: flat felled seam on 12/26/2009 00:42:25 MST Print View

Hi Guys

OK, this is definitely off the top of my head.

> My concern about taping an elastic to an inelastic fabric, even if we had a common
> adhesive, is that there can be some locally high stresses (both peel and creep)
> in the adhesive layer trying to join an elastic to an inelastic fabric.
Speculation. If you had a strong (ie reinforced) seam on the Cuben, I think you could sew a silnylon sleeve to the outside and rely on the strength of the stitching. The silnylon sleeve would HAVE to be reinforced at the stitch line as well, but doubled-over layers might (??) be enough.

I have used an industrial thread (Rasant 75) to make the critical seam line on the pole arches on my summer and winter tents and that seems to have stood the test of time.

> a flat felled seam constructed using a PU coated material and seam stick is
> 2-3 times stronger then a seam without it.
Reasonable. The tape has two effects here: it reinforces the weave and helps distribute the load. It assumes the thread is strong enough - which seems to be the case.

> Does the water freezing make the material weaker or just more un-manageable?
Well, I worried about that too. It seems that at mild temperatures (say > -20C) the fabric itself is not damaged by the water embedded in the weave. I suspect that the high stress created locally when the frozen fabric is folded is enough to melt the ice at the fold line.
I don't think the absorbed water (ie 'inside' the nylon fibres) will be frozen - the chemistry would be all wrong for that.
But it sure makes the fabric/tent clumsy to fold up and heavy to carry!

Lawson - you do realise we will want photos and test reports! :-)

Cheers

Samuel C. Farrington
(scfhome) - M

Locale: Chocorua NH, USA
cuben tents? on 12/28/2009 00:43:26 MST Print View

After reading everyone's comments, I was not convinced that an all cuben dome or tunnel tent could not be made; thus eliminating the need for nylon panels. The GG One is mostly spinaker, which has very little stretch, but many satisfied users. But for a dome or tunnel, any pattern available would probably be intended for a nylon tent, as the bias stretch on the nylon should affect how one shapes the panels. I believe that working with no-stretch fabrics on geodesic or tunnel shapes will require a new technology or at least a very new approach, that, to borrow from T. Edison, will involve 1% inspiration and 99% perspiration. Go for it. But it won't be I, because the designs I'm working on depend on the diagonal stretch in nylon fabrics, on decent quality silnylon being quite sturdy for its weight, and on its affordability. I also worry about puncture resistance in the mylar that holds the cuben fibers together. So, will use cuben for door covers under an awning for a start. If they don't work out, they can be fairly easily replaced.

Jack Stephenson once told me that coated inner and outer walls on a double wall tent will be just as, if not more effective than a breathable inner to prevent condensation, and then provided his aerospace engineer's scientific explanation. He also mentioned that if the inner cannot get saturated with condensation, you don't have to carry the weight of the water in your pack. If this is all or mostly true, then the extremely light weight and vapor impermeability of cuben might be a workable double wall approach, especially for a tunnel, where you don't have to fool with crossing poles. That Early Winters tunnel tent I mentioned before was called the "Omnipotent," and although I never met one in person, and although it was a double wall, the photos nevertheless do suggest that there was a seam parallel to the pole hoops and halfway between them that created the catenary cut for a taut pitch. If this could be done with Cuben, maybe that's an answer.

Miguel; Thank you for the link to the Suolo pitch. It appeared that the whole tent went up without exposing the inner tent or floor to the elements. Although, at the risk of using the term, "Walmart," it was not clear to me how protected the very top of the roof was before the small Walmart type patch fly was affixed to the top. These little flies have been used on cheap domes for ages, but in a trekking tent, should have zip up panels with protective netting underneath, with the zips protected by flaps, to keep rain out during the pitch. The effect also allows top vents to be opened and closed from within the tent once the little fly is securely affixed over the top.

Roger, I don't want to get into politics here, and feel that each tent should be evaluated on its own individual merits, but agree that the Nippen tent is inferior, in the sense that the bathtub floor of a wedge dome of this type is going to fill up as soon as the door is opened for entry, if not during the pitch also. Will never forget my one nightmare experience with this when it was "raining buckets." It's a good thing that Shelties cannot file for divorce from their owners. The Suolo dome appears far superior in this department, and also has lots of vestibule storage space integral to the tent design, not some kind of add-on. But it's way too heavy for my target of 2#. In any event, the makers often advise to stake the corners of wedge domes first, before installing and clipping the fabric up to the poles. But no question, Roger; that is still not going to be anywhere near as effective in helping one get the tent up in a blow as with your double wall design with exterior pole sleeves.

Still think that rain blowing at an angle into the gutters along those exterior pole sleeves is more likely to find its way in than if the poles were inside a clean canopy. Noted that your "When things go wrong" tent is a double wall (beautifully crafted BTW). If there is an inner tent with a DWR coating, minor leaks in the outer due to extreme conditions may well run off the inner to the ground. But if single wall design is the only way to get to really light weight, then the inegrity of the one wall becomes more critical. A pin hole in a deluge could spell disaster, which may explain some of the accounts along these lines on this web site in discussions of single walls.

Happy Holidays, everyone. Am finishing up some tests on carbon and carbon/FG shafts, as well as flammability and porosity of some different silnylons, will post some results on the MYOG forum and then begin another marathon tent project.
Sam Farrington

Edited by scfhome on 12/28/2009 00:48:39 MST.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: cuben tents? on 12/28/2009 03:01:56 MST Print View

Well.... I'm not convinced that it couldn't be done either. I could see problems - but they are what we are here to solve, aren't they? :-)

> coated inner and outer walls on a double wall tent will be just as, if not more
> effective than a breathable inner to prevent condensation,
Oh sure, but condensation is not the only reason for an inner tent. To my mind, the outer fly is meant to block 99% of the weather (and usually does), while the inner tent actually needs to let some air though for the occupants to breathe.

Yes, we do spend some effort adjusting the ventilation on both the inner and outer tents in order to get some fresh air through the tent - but not too much. Gently wafting the condensation (or ice) away is perfect. If the weather isn't all that bad I just use my single-wall tunnel. I know I will get enough ventilation with that one - it doesn't have a sod cloth!

> rain blowing at an angle into the gutters along those exterior pole sleeves
> is more likely to find its way in than if the poles were inside a clean canopy.
I understand the concern. I can only say that I have never had any leakage down the pole arch seams with my silnylon tents even in the worst storms. (Seam-sealed with silicone of course.) And we can get some 'weather' at times in our mountains - like when the bathtub groundsheet was floating in about 1" of water. Amusing, but it held. Yeah, I do have a slight sensitivity there for historical reasons. :-)

> A pin hole in a deluge could spell disaster,
Well, not really. While I haven't had a pinhole, let's imagine there was one and the weather outside was 'a trifle off'. So you get a few drips through (you did say 'pinhole') - what of it? Annoying, a blow to pride, but entirely survivable. Actually, you can get far worse than this from condensation on a rapidly cooling humid night. I have had water really running down the inside of the fly once or twice - but the design shunted the water away from the groundsheet.

> some tests on carbon and carbon/FG shafts
I tested some Carbon Express shafts which had a dress coat of CF over the pultruded FG. They looked fine - until I curved them. Then they split instantly full length, at what would normally be a quite reasonable curvature. I accept that they might be fine arrows, but they were not even remotely usable as tent poles. Testing is needed!

Cheers

David Olsen
(oware)

Locale: Steptoe Butte
Re: Cuben Tent on 12/28/2009 09:53:00 MST Print View

"I am a big fan of dome and tunnel tent's but I am still convinced that the best all around tent is one that is freestanding. If the wind changes direction or your guy lines break in a tunnel your up a creek without a paddle.

About 10-12 years ago my dad and myself weathered a storm in his two man single wall aluminum pole "popup". The storm produced 70 mph sustained winds and 105+ mph gusts. Of all the different type's tents at the site the two man dome's were the only one's that made it through the night."

I have had the opposite experiance, where a NF expedition
dome tent broke poles and collapsed from high winds
while a pyramid tarp stayed up. Also, stand alone tents
will blow away (even with someone in them) if not staked down well (and I mean miles away, if empty). Others styles
just tend to collapse.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Cuben Tent on 12/28/2009 12:57:21 MST Print View

Hi Dave

That's you and a friend with your cross-country skis in your avatar, right?
:-)

Cheers

David Olsen
(oware)

Locale: Steptoe Butte
Re: Re: Re: Cuben Tent on 12/28/2009 16:25:06 MST Print View

"That's you and a friend with your cross-country skis in your avatar, right?"



Yup, that is my wife and me at the longboard world championships a few years ago. Near Quincy California,
they have been racing these 13 foot long skis since
the gold rush days in the 1800's. No side cut,
only a block of wood for your arch and a strap of
leather over your toe. The miners would hit speeds
of 90 mph.

Nowadays the races are held on the bunny
slope.

We both managed to get into the finals, but
I drew some short (7 ft) skis which ended my progress.
My wife managed to place 2nd in the women's division.


Tough finding sperm whale oil these days to wax with tho.
The not-so-honest sometimes resort to fluorocarbon
ski wax.


http://sportsillustrated.cnn.com/vault/article/magazine/MAG1006338/1/index.htm

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: skis on 12/28/2009 19:55:44 MST Print View

Hi Dave

Blimey!

They used to race skis like that at Kiandra (goldfields) here in Oz at the 'Kiandra Snowshoe Club' - arguably the oldest ski club in the world (they have a certificate from the ski association in Norway or Finland to certify that!). I have read about the downhill races on planks just the same - a bit too frightening for my liking! The winner was sometimes the last one upright ... I'll pass on that one and watch with admiration from the sidelines I think.

Cheers


Cheers

Lawson Kline
(Mountainfitter) - M

Locale: LawsonEquipment.com
Cuben Tent on 12/29/2009 08:27:02 MST Print View

"I have had the opposite experiance, where a NF expedition
dome tent broke poles and collapsed from high winds
while a pyramid tarp stayed up. Also, stand alone tents
will blow away (even with someone in them) if not staked down well (and I mean miles away, if empty). Others styles
just tend to collapse."

I am a fan of domes, tunnels and mids but feel they all have there pros and cons. I think it what matters the most is a well built tent and smart placement in regards to the direction of the wind, natural sheltering features and the weather.

I too have seen a dome mid setup (unstaked with the door open) catch an updraft with no one in it and fly all the way to outer space.

David Olsen
(oware)

Locale: Steptoe Butte
Re: Re: skis on 12/29/2009 10:41:51 MST Print View

"They used to race skis like that at Kiandra (goldfields) here in Oz at the 'Kiandra Snowshoe Club' - arguably the oldest ski club in the world (they have a certificate from the ski association in Norway or Finland to certify that!). I have read about the downhill races on planks just the same - a bit too frightening for my liking! The winner was sometimes the last one upright ... I'll pass on that one and watch with admiration from the sidelines I think."

They called them snowshoes here too. The most famous one
was Snowshoe Thompson who delivered mail over the Sierra
Nevada Range in the winter.

Being miners at both areas, I wonder if someone was in both
areas looking for ore and passed on the idea or if there
were miners from Norway etc that brought along the idea?

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: skis on 12/30/2009 02:58:42 MST Print View

Hi Dave

It was some people from Norway and Finland, quite definitely. Books have been written ... :-)

I suspect after the Kiandra gold rush (it was quite short) some actually went to America chasing gold. No idea whether they contributed there though.

Cheers

George Geist
(geist) - M

Locale: Smoky Mountains
Re: cuben tent design on 12/30/2009 23:09:13 MST Print View

> After reading everyone's comments, I was not convinced that
> an all cuben dome or tunnel tent could not be made; thus
> eliminating the need for nylon panels.

An all Cuben dome or tunnel tent is certainly doable.
I think one of the ideas behind having nylon sleeves or small nylon panels was to reduce the precision required in the cutting and sewing of a non-elastic tent body (that can be pulled smooth and taut).

Getting the most from Cuben may require different design techniques. For example, typically the bells are sewn on each end of a tunnel tent. With a light Cuben it might be stronger to have the spectra fibers run unbroken from one end of the tent to the other rather than stopping at each sleeve. That would require figuring out the best way to sew the sleeves in the middle of a span of Cuben.

Another design technique that has been used with Cuben (for sails) and mylar (for aerospace) is to use heat to shape and tighten the fabric over a form. I wonder if this technique could be useful in building Cuben tunnel and dome tents?

Samuel C. Farrington
(scfhome) - M

Locale: Chocorua NH, USA
cuben tent on 12/31/2009 00:02:36 MST Print View

Al,
Do not see how one can avoid need for catenary cuts in dome or hoop tents, whether they are made from stretchable or non-stretchable fabric. That means that seams will be necessary at some points on the canopy. So I guess the suggestion to experiment with Mylar in determining the shape of the panels before cutting the Cuben was a good one.
But here's a thought: Have noted that a yard of the lighter cuben that I bought from Quest to experiment with does have some diagonal stretch, tho not as much as with nylon fabrics. So a dome pattern designed for ripstop nylon might work OK. Also, if the lighter cuben is cut on the bias, or diagonally to the direction of the fibers, then your idea to just sew or weld the sleeves, also on the bias, onto the cuben might work. As with most fabrics, the bias stretch would then create its own catenary slopes between the hoops; hopefully not so much as to overly restrict tent space.
As for the sleeves, I do think you would want as much stretch as possible, to lower noise, as well allow the sleeves to conform to the arc of the hoops. Rockywoods sells a silnylon available in red, gray or white, that they call Ultrasil (not to be confused with Westmark's offerings with the same name)that is quite soft and flexible, and less flammable than other silnylons. I have found it to also be less water resistant than other coated silnylons, but if you were using it for pole sleeves, maybe that would not be a problem.
What would be a problem is poles, as you would have a tight radius arc on a one person hoop tent that puts too much stress on most light weight material tubing. Early winters used a smaller diameter, external ferruled, wrapped fiberglass tubing on the Omnipotent that was very flexible, and not much heavier than carbon, but don't know where you would find this material today. Or you might be able to buy some prebent aluminum poles from Warmlite. Or you could try Roger's different uses of elbows shown on this site and his own.
The design of the end panels (is that what you meant by "bells")would be the key to the whole design, as they would have to uniformly pull the hooped cuben tunnel taut, and also function as doors, at least at one end. Looking at Henry's designs as well as Warmlite's might be helpful in approaching this issue.
Love your idea for the heat formed canopy - almost something like shrink-wrapping your tent. Perhaps someone will try it.
Happy New Year!
Sam F.

Franco Darioli
(Franco) - M

Locale: Melbourne
Cuben Tent Question? on 12/31/2009 01:35:59 MST Print View

We , here Downunder, just had the annual Sydney to Hobart yacht race . One of the favourites broke the mast (80k AU) a few days before the start. So they had another one flown in from France. That broke too going out of Sydney harbour.
Bad luck old chap and all of that.

Why do I mention that ? Because THOSE are the kind of people that buy the "shaped" cuben sails.

A spinnaker in Cuben is 60K plus. That may or may not last a race.
Cuben is a manufacturing process not a particular fabric or laminate. So many variations are possible, however they all have some "creep" , that is with pressure they go out of shape. Like say Gladwrap, once expanded it does not go back to the original size. Hence the problem with having to work with fine tollarences first only to end up with flapping panels once expanded.
Franco

Diplomatic Mike
(MikefaeDundee)

Locale: Under a bush in Scotland
Cuben tents and 'airbeams' on 12/31/2009 01:37:01 MST Print View

I wonder if Cuben might be a suitable fabric for using 'airbeams' like some of the Nemo tents, and doing away with poles all together?
The stress would then be placed on the whole of the sleeve, and not contentrated on the point where the pole is in contact with the fabric.

Franco Darioli
(Franco) - M

Locale: Melbourne
Cuben Tent Question? on 12/31/2009 02:24:05 MST Print View

Now, that is an idea...
Maybe that and the much maligned but functional BD/Bibler hook and loop fastening of the internal poles. As an added bonus they would not cause condensation to form as the aluminium poles do.
Franco
I will provably wake up in the middle of the night thinking about this. Thanks Mike and Happy New Year to you too...

Diplomatic Mike
(MikefaeDundee)

Locale: Under a bush in Scotland
Cuben tents on 12/31/2009 02:43:13 MST Print View

Don't mention it Franco.
Sweet dreams, and a happy new year to you too mate! :)

Samuel C. Farrington
(scfhome) - M

Locale: Chocorua NH, USA
cuben tent on 12/31/2009 10:55:25 MST Print View

Al,
Mea culpa for my suggestion about cutting cuben on the bias to make panels for a hoop tent. Because the Cubic Technology rolls are only a maximum of 54" wide, even if the panels were only two feet wide in a four hoop design (similar to Roger's), the panels would only extend about halfway down each side of the hoop.
But I think your idea to somehow fashion the main canopy of a tent from one or two pieces of cuben is still worth pursuing, and have spent much thought toward coming up with a silnylon design pursuing the same goal, and will start a post when something concrete materializes.
Also failed to mention that the tunnell ends have to serve a third function in addition to access/egress and support, and that is ventilation. Years ago I put hoops on each end of a tarp made by Gerry that also had insect netting sewn front and back. The front and rear of the tent were supported by guylines with some cover from fabric extensions that cinched tight over the guylines with a drawcord. But even though the front and back were mostly open, there was still a lot of condensation on the lower sides of the tunnel. Hence, I understand the function of Henry's designs that place some netting between the floor and canopy wall on the sides of the tunnel, and leave some space between the canopy wall and the ground for airflow to the netting.
So, sorry for the impractical suggestion.
Sam F.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: cuben tent on 12/31/2009 13:29:51 MST Print View

Hi Sam

> Do not see how one can avoid need for catenary cuts in dome or hoop tents,
> whether they are made from stretchable or non-stretchable fabric. That means
> that seams will be necessary at some points on the canopy.

So far I haven't bothered using deliberate catenary cuts on any of my tents. But the tunnel design tends to exercise the stretch in the fabric to get maybe 10 mm of catenary curve at the roof anyhow, aided (maybe) by the external pole sleeves.

> heat formed canopy
It might be possible to heat form the Mylar, although I have some doubts. But you could not heat form the internal threads! I think that idea has to be abandoned.

> As for the sleeves, I do think you would want as much stretch as possible,
> to lower noise, as well allow the sleeves to conform to the arc of the hoops.
Dunno about the noise, but the conformability would be fairly essential imho. Also, I don't think the Cuben fabric would handle the sliding of the poles all that well over the long term - the Mylar would abrade.

Prebent poles should be available from TentPole Technologies (used to be TA Enterprises). But you can pre-bend Easton poles with a rolling jig yourself. Been there, done that.

> The design of the end panels would be the key to the whole design, as they
> would have to uniformly pull the hooped cuben tunnel taut, and also function
> as doors, at least at one end.
Dead right. It's those two end stakes at the windward end which hold the entire tent up, and down! The way the load is distributed across the first pole through the end-bell fabric is crucial. That said, the zipper lines up the doors and two end guys are important as well. And one extra stake in the middle of the bottom of the windward door is also important - 'middle anchor'.
.
5668SEndGuys
This shows the fully kitted out windward end bell on my latest winter tent.

Note that in the absence of a howling gale I can open the top of the flat door panel under the hood to let air through the tent, both for fresh air and to clear away condensation. But the top edge of the door can also be shut completely with Velcro, to keep out the spindrift.

Cheers

Edited by rcaffin on 12/31/2009 13:33:07 MST.

Bill Fornshell
(bfornshell) - MLife

Locale: Southern Texas
Re: Cuben tents and 'airbeams' on 12/31/2009 18:48:27 MST Print View

Hi mike,

"I wonder if Cuben might be a suitable fabric for using 'airbeams' like some of the Nemo tents, and doing away with poles all together?
The stress would then be placed on the whole of the sleeve, and not contentrated on the point where the pole is in contact with the fabric."

I bought two of the Nemo "Airbeams" to play with a couple of years ago. They work great. The problem with them was they weighed to much for a really light weight tent.

Roger:

How much does your Red Tent weigh?

Cuben makes a lot of different weight material. My heaviest Cuben weighs 6 ounces per square yard and is super strong. I use small amounts of it for stress areas and might work well for the sleeves used for the poles. I have some 0.98 ounce per square 4 directional material that might be strong enough for the rest of a tent. After you sent me the data on your tent I wanted to make one out of Cuben but then medical problems stopped all that effort.

George Geist
(geist) - M

Locale: Smoky Mountains
Re: : Cuben tents on 12/31/2009 19:26:19 MST Print View

> How much does your Red Tent weigh?

Hi Bill,

Roger's 4 pole winter tent (red) weighs 1650 grams.
The outer silnylon is about 500 grams of that.
The ground sheet is about 200 grams and
the inner tent is about 340 grams but these
two items are less suitable for being replaced
with Cuben. The rest of the weight is everything else
that makes a tent.

Bill I know you looked into the issue of the transparency of Cuben. Not a good property for tent bodies! (Little double meaning there.) What did you try? Did anything work?

Edited by geist on 12/31/2009 19:27:53 MST.