Lateral tunnel tent?

[Roger Caffin]

I had not watched that video clip before, of the Warmlite. I have now. All I can say is ‘pathetic’ – and it was barely above 30 kph! Not fit for purpose.

Especially I did NOT like the way the pole was un-guyed and was bending around. Fast path to destrucution.

Cheers

[James Marco]

“I think James may have been focusing on the near vertical walls of a tunnel, regardless of the number of poles.”
Yes. The side walls with the wind impacting at close to a 90 degree vector on the side walls will need to be supported, even by a guy line which, as I said, are not considered.

The original spec was for a two person tent, not a solo. For a solo, the additional weight is simply too much to consider. Poles alone will come up to about 6-7oz each I believe. Poles will be about 11′ long at a even arc. This will give you about a 3’6″ or 42″ center height. Hmm in metric about 335cm long, with an arc weight of about 107cm. I would guess you need around a 3/8-1/2″(1.27cm) dia at that span. The 3/8″ pole at 132″ would be about 3.68oz per pole plus ferrules plus ends plus shock cord. Total around 6-7oz per pole, hard to get numbers from Easton on weights. Who uses grains anymore??? For fabric at 1.5oz/yd about 11oz of cloth. Floor would be about 10oz-20oz assuming you want a heavier PU or vinyl fabric for the floor. After loops, sleeves, guylines, stakes, etc about 3pounds 8oz. would do for a silnylon version. To me, anything over two pounds is getting a bit heavy for two people.

[Sam Farrington]

James,
For some time, carbon arrow shafts were by far the least expensive source for strong and flexible carbon tubes, because they are mass produced, bringing down the price. While many of the shafts are junk, a few from Victory and Gold Tip, are multi-layered, wound in different directions and very strong. One from Gold Tip break tests the same as Easton .344 alloy tubes, and is quite flexible. So those have been my ‘go to’ source.

Grains per inch of tube length (gpi) is the standard method of measuring the weight of carbon and other arrow shafts. On some shafts, gpi is noted right on the side of the tube, as is the case with shafts from Gold Tip, some of whose shafts are the strongest I’ve found for the weight. Since all of the better carbon shafts I’ve found have been fashioned from arrow shafts, that is the measure I use. For flexibility or rigidity, “spine” is the standard used; but one can just use the amount of deflection over the length of a two foot span with a 2 lb. weight applied at the center of the span. This is close, but not equal to “spine,” but is easier to use, and good if just comparing a few shafts.

Now that Easton is making carbon poles designed for tents, and making them available through Quest in small quantities at a reasonable cost, I want to test them to see if they are better than Gold Tip and Victory arrow shafts. (Note that the carbon shaft from Easton that were used on the MSR carbon version of the Hubba, was not as strong for the weight as the best arrow shafts.) Easton reps sometimes post on BPL that the arrow shafts are not as well suited as those designed for tent poles, but I want to see for myself. If they are better, and worth the weight penalty, I’ll use them.

In any event, on the model frame I just posted about, the length of each pole, excluding the elbow in the middle used to create a gothic arch, is 12 feet. Using the Gold Tip shafts, the weight of each pole comes to under 4 oz, or under 8 oz for both poles. This includes the ferrules, the shock cord and the end caps. That weight is a bit over 8 oz using slightly heavier Victory shafts, as I posted about in 2011 for a prototype dubbed ‘XX’. That pole set weighed 9 oz, but the poles were 13′ each, so heavier.

I think one needs to have weights of all materials, make precise diagrams to scale and use scale models to get the actual weights and dimensions before beginning construction. Problems with the design often show up with the scale models, and can be changed before wasting time and materials on construction. This works for me, and indeed, is the only thing that works for me. My Dad was a mechanical and chemical engineer, while I’m not; but he got me off to a great start for MYOG.

[Sam Farrington]

Roger,
In the interest of full disclosure, when Olivier posted links to the Warmlite video, a number of responders concluded that he did not pitch the tent correctly, and that was what caused the failure shown. But IMO the rear pole failed. I had bought a few of the prebent rear pole sections at Warmlite in Gilford NH to play with, and found them to be on the flimsy side, and easily rebent by hand. Still cut and use them as shims between different diameter tubes, though. The sections for the front hoop were stronger, but heavier than what I was looking for.

The original thread was started by Lynn Tramper, and you can check it out for yourself at: https://backpackinglight.com/forums/topic/34339/page/2/#comments

 

[Roger Caffin]

I would be willing to believe both versions.

That the tent should have been pitched with a much higher tension is certainly possible – but you cannot always do that. If, for instance, you are using rocks to hold the pegs down – difficult.

I agree that the rear pole is lighter, but it seemed to me that it was the big-diameter but very thin-walled front pole which was going oopsy.

And the sewing on the one I reviewed was NOT up to scratch.

Cheers

[James Marco]

Sam, even at three pounds the weight is still on the heavy side. But that IS light. 12′ is a reasonable number for length. I would have recommended 11’6″ even though the math says around 11′. Fabric has a way of stretching a but on the first five to ten uses.

Again, I am not enamored by the lengthwise tunnels. There is a lot of wasted space at the ends. Some is usable, some is just extra space for the claustrophobic. Even with two packs and paddling gear, it is hard to see a use for more vestibule space. Maybe by extending the floor into the rear vestibule, you might find a use for it. It sounds like a fun project.

Roger, yes the rear pole on the Warmlights can be a bit spongey. I seem to remember they offered a heavy duty pole set, and I think a third pole when I got mine. But that was a while ago.

[Roger Caffin]

Hi James

There is a lot of wasted space at the ends.
I cannot agree with this at all.

First of all, if you look at the typical tarp shelter, it is obvious that there is a huge amount of wasted space around the edges, where the fly is so close to the ground. In bad weather this wasted or lost space increases hugely, as the tarp is pushed downwards. The angles are too shallow. Examples and reports abound.

In a tunnel tent the walls and ends are all at much steeper angles, so this sort of loss is much reduced.

Next one needs to consider the front and rear vestibules separately, and one also needs to consider the weather outside and what one wants from the tent. Several combinations exist.

In my blue single-skin summer tent the rear vestibule has enough room for both packs to be stowed there, while allowing for access to any items left in the packs if needed later. We do not consider the option of leaving the packs outside overnight: both the weather and small rodents are a hazard. In severe weather the packs at the rear end act as a very good buffer against the weather as well.

In my red double-skin winter tent the groundsheet penetrates a bit further into the rear vestibule, so there is no longer room for the packs. This places width constrains on the rear vestibule (fit two air mats), but in practice this is not a problem. The wide end and some guy ropes help reinforce the windward end of the tent very nicely.

The front vestibule is used extensively for getting undressed in wet weather and for cooking. We place high importance on food, and I am not going to have my stove on the groundsheet. I have not tipped the stove itself over, but I have tipped the pot over once or twice. In the summer tent the front vestibule space is more limited, but it is adequate and essential.

On my winter tent the front vestibule is larger, very deliberately. There is room to store the packs, to get out of storm gear, to cook safely, and a few other things as well. This is emphatically NOT wasted space: it is vital LIVING space for a couple on extended walks in often bad weather.

I am not a fan of carrying excess weight, so every little extra on the tent had to justify itself. But looking at these two photos, is the vestibule space really all that much? I think not – and it is all usable space.

YMMV

Cheers

[Edward John M]

I’d go a bit further than Roger, to the point where vestibule space can be even more important [ although not bigger] than the sleeping space. I do not want to be bringing wet and snow covered packs and other gear into the same area that contains my sleeping bag and warm clothing. Weight is important but so is comfort and safety. It’s a balancing act we all partake in

[Sam Farrington]

James,
Not sure when you mention 3 lbs what that is in reference to. Please clarify. Thanks.

[Sam Farrington]

Roger,
Yes you are right, it was the front pole in the video that distorted. Looks like one or two of the pole sections did a 180, making the pole concave rather than convex in the area affected. That should have been obvious to Olivier when pitching the tent and should have been corrected while pitching. With flexible (or elbowed) rather than precurved poles this kind of thing is less likely to happen as the pressure at the joints from flexing prevents the sections from rotating.

Surprised to hear James suggest your tunnels have TOO MUCH vestibule space. Maybe he was referring to the lateral tunnel I was suggesting, where the vestibules are larger because they are the width of the longer dimension of the tent. Do not see this as a problem for the reasons Edward J. mentions. I like to put everything (chair, pack, raingear etc) under separate cover as it may already be wet, or may get badly soaked in a rainstorm overnight. Either way, don’t want it in the sleeping area soaking the dry gear.

So with two vestibules, one can be used for storage and the other for cooking and eating in rainy weather. (But zero food is left anywhere in or near the tent-we have BIG and HUNGRY bears.) Hence no need to climb over or around gear to enter and exit the tent, especially during the night (will leave night activities to readers’ imaginations). And for me, tents that accommodate cooking and eating in rainstorms made backpacking much more of a pleasure. It is nice to be able to cook and enjoy dinner in a dry place while watching a raging downpour outside.

Please note that vestibule size may be academic, as with MYOG we can make them whatever size we want, or ‘decorate to suit’ as was mentioned earlier. However, I think your discussions of your modus operandi for tenting are helpful in making it safe and enjoyable.

[Roger Caffin]

Ah well, we all know I am biased and opinionated! :)

It is nice to be able to cook and enjoy dinner in a dry place while watching a raging downpour outside.
But that bit resonated!

Cheers

[James Marco]

Sorry, I was on a Lean2Rescue since 9/6 and just got back.

The 3 pound was a rough estimate based on rough numbers. It could be 30% off one way or another.

Tarp in snow? No, not unless there is a freak storm that has happened a few times. In colder weather (we can have snow anytime in the ADK’s Usually wet slushy stuff in September) and with a partner, we use the old Sirius Extreme, I repaired the floor after getting a somewhat lighter Big Sky from Will “Willi Wabbit” Rietveld. My tarp is mostly for solo hiking.

As far as using the larger vestibule space, sure. But a large vestibule usually means more stuff to carry. For an overnight kit my wife packs about 7 pounds. I pack about 9 pounds. Hers is mostly her cloths, she packs my fleece, though. I pack the whole rest of camp (food, fuel, and water included) for both of us with the Big Sky in summer.

Yes, it is certainly a pleasure to watch the pouring rain. And at night it is very nice to hear the sound of raindrops on the tent. The white noise puts my wife right out. After a little while, though, I need ear plugs.

[Roger Caffin]

But a large vestibule usually means more stuff to carry.
Will power! (as in ‘I will take that luxury’.)

One night we had corn snow the size of large rice grains at 50-60 kph all night. Just white noise … :)

Left: late afternoon: sunny but watch those clouds.
Right: early morning. See the corn snow on the tent. It did not stick.

Cheers

[James Marco]

Ha, ha….yup. I always have room for ONE luxury. Usually something good to eat or drink, though.

[Roger Caffin]

pouring rain …
What’s that?
Most National Parks in NSW now have a fire ban on all solid fuels until March 2019. No fires, no Esbit, and I don’t think they like alkies because they don’t have off switches.
This fire ban may be over-ridden by the Rural Fire Service towards summer, with a TOTAL fire ban.
Sigh.

Cheers

[James Marco]

Yeah, that is out west though. Those areas are like Grand Central Station on a Friday afternoon. In the ADK’s it is mostly snow, rain, and wind. Though we had a minor drought here this year…a LOT of canoe camping…

[Sam Farrington]

“It is nice to be able to cook and enjoy dinner in a dry place while watching a raging downpour outside. But that bit resonated!”

Roger, your comment resonated fully with me only on recalling the severe heat and drought in the NSW region reported here in the USA. Hope you got some snow this year.

James, am going to guess maybe you were estimating the likely weight of a version of a lateral tunnel I was posting about. I’ve spent a lot of time doing estimates much like yours. If and when I get it to the point of making a reliable list of each item going into a design with its weight, much like one would do for a pack, then I’ll put it up here.

Also, am discovering that the design is much more complex than originally thought. The Macpac Celeste, the only one of this design that appears to be a ‘lateral’ tunnel, has been discontinued. But it can be viewed here: https://www.youtube.com/watch?v=VQ0DW0xrby4

Of course this and many other tunnel designs all seem to top out around 5-6 lbs, which is hardly a backpacking LIGHT tent.  Nevertheless, there is no reason why it could not be a light tent with the light fabrics and poles that have become available in recent years.  And I think that for a lateral tunnel, as opposed to a conventional one, the clamshell pole arrangement will provide more resistance to winds striking the front and back vestibules.

So back to the drawing boards.
Kudos for the Lean2 work.

[James Marco]

Sam, yeah, you guys got a bad drought. Not good in the forest with a lot of scrub/duff around… I think there used to be an old fire starter kit that used a plunger and super dry tinder(charred cloth, etc) to use to start a fire. I sometimes wonder if a heavy footfall on duff couldn’t do the same.

Yes, I did material take-offs all the time. So, it was easy to do a tent. I think I came up with 2#8 as the minimum weight, but this is usually off by about 30% (seams, length of loops, thread, doubled cloth at the poles, etc) after figuring the surface area for the cloth. So I just added a pound as a rough estimate rather than go any further with it. As I remember (I just used a piece of scrap paper that was tossed,) Easton gave me fits with their grains. This is likely an estimate and multiplying by 264″ put in a LOT of slop. And I didn’t find the grains on the various ends, cord, etc. All that suff comes up to about 75% or so of the pole weight, so I just added that in. Real sloppy, but within magnitude. Cloth was a big variable, cuben/DCF vs Silnylon vs Silpoly and the various weights makes a real challenge. I just used about 1.6oz/sqyd, took me all of 2 seconds to choose. Again, within magnitude. Loops, reinforcements, sleeves, thread, zippers, velcro are guestimates. But yes, I believe you can get it down to 2.5pounds to 6.5pounds depending on how many/much and your choices. Conics can be figured as one cone split, so I just looked it up on the web and got a number for area of the cone and the two floor pieces. Overall, a trivial take-off with nothing really exact. What the hell, I ain’t building one;-) It is nice to have some sort of number to target, anyway.

Lean2Rescue is just something I go to play with. I am really too old to do much real work lifting the 2000 pound logs. But, I spent many years as a builder in my younger days…till my disks decided to move/break. I worked at that about thirty years(from the time I was 12 with my grandfather/father/uncle) and it is real nice to go play with lean-too’s. I still miss making stuff…Not a lot of people make stuff for themselves anymore. At least here(BPL,) people still do.

[Sam Farrington]

James. Yes, used to work for the Cohos Trail (TCTA), which runs north from the White Mtn Nat Forest to the Canadian border, where it connects to a trail maintained by a club in Quebec. TCTA also welcomes volunteers of all shapes and abilities helping out. There is always something to do that is not too stressful on the bod; and then they have inside work, like secretary, treasurer or website (stressful on the brain), and even if one becomes pretty useless, they are always glad to see you for old times sake (hope so, because there is a cook-out on Sep 22d).

Your estimate process sounds pretty rough. Have some surgery coming up, but when there is time, I could be helpful by making a scale cardboard model of a very light solo version of the Macpac Celeste (linked earlier on this thread page) that would show all the dimensions. Will also get to break testing the two sizes of carbon pole tubes from Easton, and measuring the flex (spine), which should show whether they are better or worse for the weight than the Gold Tip and Victory arrow shafts, especially in terms of their ability to maintain shape of the longer lateral arcs in high winds. Do not want the initial stability, or rigidity, to depend entirely on guylines, as it can easily get to the point where the weight of a lot of guys and stakes make an ultralight into a heavy tent, defeating the whole purpose.

And will post the weights of materials chosen, which will be at or below one oz per square yard. Roughly, the main canopy will be a ~0.7 oz inner from Extrem Textil, with a 7D outer of ~ weight. The outer, or fly, will be ‘thrown over’ the inner, as Roger says; but do not see any other way to have a taut inner that is concentric to the shape of the outer, in order to limit the inner from detracting from the internal space. Roger would not like the throwing over; but since the fly will be limited to the occupied space, not including the vestibules, I think that attaching it will be doable in high winds. The vestibules will be single wall, as with most tents, and will be 1.05 oz 15D taken from a StoS Escapist tarp and tested by Richard on BPL. Ditto the floor. I expect Roger would like the use of pole sleeves, but they will be a bit wider to maintain separation between the inner and outer. Note that the high DWR of the solid inner will block water for the brief time it takes to pitch the tent and attach the fly. More details to come.

[Edward John M]

I’m just now remembering a tent made by Bergans that was being sold about 40 years ago. Transverse hoops, what I assume you mean by a lateral tunnel. I remember being in it one night when it was hit by a gust of wind that clapped both sides of the tent together despite being well guyed. Fibreglass wands not alloy

[Sam Farrington]

Edward J: “lateral” tunnel was taken from the OP’s choice of the thread’s title. To avoid confusion, I referenced Matt D’s photo of a blue tunnel on page 1, and posted a link on this page to the Macpac Celeste. The pole hoops spread at the apexes, and the pole tips unite at the ground, as shown in those photos. That is also why I also mentioned the term “clamshell.”

If we are on the same page, conceptually, then your experience does give me some pause. If the wind can overcome the vestibule pegs, AND the additional guylines, thus forcing the apexes together, then there is a problem. That Macpac discontinued this type of design also raises some concern. Thank you for your comment. Will think more about this design before proceeding.

[Edward John M]

Looking back on the experience I think that the very flexible fibreglass wands were part of the problem. If this is the case then I agree with the previous conjecture that this type of structure needs more substantial poles. There must have been downwards flex at the same time as a sideways force

[Sam Farrington]

Edward,
I’ve used carbon poles for a long time, and they are more rigid than FG of similar weight, an example of the latter being the small diameter FG poles made by Early Winters for its Omnipotent tunnel tent. They flex too much for a stable tent, IMO. There are a lot of stiffer FG poles around, but they generally come with low cost tents, and are quite heavy. They are good for other MYOG uses, though.
After pondering your ‘clapped together’ experience, I think carbon poles would do well on a solo ‘clamshell’ type of tent, albeit with use of side guylines that angle a little forward and backward to add some stability to the front and rear vestibule stakes also. I don’t think they would be needed often, except above timberline. I’m still bullish about this type of solo tent. If you recall the model of the Bergans tent, I’d love to know that, in order to look it up online.

[Edward John M]

Sam it was over 40 years ago and my memory isn’t that good unfortunately. I have tried googling but to no avail and I have long lost contact with the person who owned that tent but I did find an old catalogue picture

https://www.google.com/imgres?imgurl=http%3A%2F%2Fwww.outdoorinov8.com%2Fpictures%2Fimage821.jpg&imgrefurl=http%3A%2F%2Fwww.outdoorinov8.com%2Fbergansimages.html&docid=Q43BOwX6zK9K4M&tbnid=Mxpuw_mr1V5wLM%3A&vet=10ahUKEwin-bzo69ndAhWDbN4KHasdBdUQMwh_KD8wPw..i&w=770&h=480&client=firefox-b&bih=887&biw=1511&q=1970%20tunnel%20tent%20by%20Bergans%20tents&ved=0ahUKEwin-bzo69ndAhWDbN4KHasdBdUQMwh_KD8wPw&iact=mrc&uact=8

[Franco Darioli]

There are many tunnel tents designed more or less like that Bergans

but this thread I understood to be about getting into the tent directly  from the side , not into the vestibule and then turn left or right.

Like this for example :

 

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