The Cuben Crisis – MLD Duomid Pole Mk2

Camped on top of Whernside

Camped on top of Whernside

A month or so ago I posted about a new pole set up my MLD Duomid. This used a length of carbon fibre pole to join a new pair of trekking poles I’d bought (Fizan Broad Peak). It was a neat solution and very light.

After a couple of nights recently in extremely high winds, I’ve been forced to go back to the drawing board and look again for a solution. And it’s forced me to think about one of the major short-comings of Cuben fibre as a tent material. It just doesn’t ‘give’.

At the beginning of May my brother and I camped on top of Whernside in the Dales, on what turned out to be an extremely stormy night. Even sheltered behind a wall over a meter high, my cuben Duomid took a severe battering with winds gusting at over 60mph (95 kmh).

The tent stood it’s ground, but at 3am I was woken by that familiar crack that cuben fibre makes in wind, with the whole structure thrashing about violently. Turning my torch on I noticed that my pole had shortened by at least 10cm, the carbon fibre joint disappearing inside the trekking poles. So the Duomid had of course then completely slackened off all around and the pole was now being thrashed back and forth in the wind.

If you’ve ever tried to extend a pole in a Mid in high wind you know what I’m talking about when I say it was an almost hopeless task. Grasping the pole with both hands I was barely able to lift it off the ground with the force of the wind bearing down on the tent. Letting go with one hand in order to re-lengthen the pole with the other hand was impossible. I propped the shortened pole up on the toe of my boot to try and take the slack out of the Duomid, but by 5am I was fearing for the tent itself, so we struck camp and bailed out in the teeth of some pretty ferocious gusts and beat a retreat down off the top.

The lack of stretch in Cuben fibre is well known, and for some people it’s one of it’s attractions along with the obvious  low weight of the material. But I’m beginning to think that in Mids, that lack of stretch could be a serious downside. Because cuben fibre doesn’t stretch, it absorbs very little if any of the energy that hits the panels of a tent in high winds, and a great deal of that energy is simply transferred up the tent panels and down the pole. And in a mid, all that energy gets transferred to one single pole. That’s an awful lot of force being applied downwards, and at some point something has to give. That’s either going to be the pole, the joint or one of the pegging points. If you loose a pegging point in a four sided Mid, you loose an awful lot of what’s keeping the tent up, and if you loose the pole then it’s good bye Vienna.

All this downwards force also raises the question about how sensible it is in a cuben mid to offset (slant) the pole, since that downwards force would then tend to buckle or bend the pole if it’s not vertical.

Cuben fibre was after all developed for use in boat sails, and in that use you actually want all that wind energy to be transferred through the sail into forward motion, and not absorbed by the sail. Giving a tent forward motion into the ground will eventually break something.

The more I think about it, the more I begin to wonder whether cuben fibre really is the material we’ve all been waiting for. Add in dyneema anchoring and you have a very unforgiving strucrure. There’s something comforting in the ability of silnylon to be pulled and stretched into a taught shape, and still absorb and dissipate whatever the winds throws at it. It’s not perfect either of course, but it’s proven itself to me.

So what’s the solution ?

If my trekking poles had ‘shock absorbers’ I’d be inclined to activate this in at least one pole section in high wind so that the pole can absorb gusts. But the Fizan Broad Peak do not have this, so I’ve had to seek some other way of putting an energy absorber into the pole joint.

What I’ve come up with is still very simple, but may just work. I’ve taken a short (75mm) section of braided hydraulic hose, which just happens to have the same internal diameter as the external diameter of my carbon fibre joint, and bonded a rubber washer to each end.

Slid tightly onto the carbon pole this then sits between my trekking poles when they are joined. Pressing down on the whole set up shows it has a satisfying amount of give, but doesn’t depress too easily. Hopefully just enough to absorb gusts of wind and protect the poles themselves.

DSC_0419

I’ve yet to try it for real in the field, but I’m hopeful it may work.

However one final observation. With all this tinkering about with my trekking poles to try different ways of joining them, I’ve begun to notice some slight wear on the plastic ends of the bottom trekking pole sections where these slide inside the adjacent pole. It makes me wonder about the long term impact of continually taking your poles apart, on a daily basis. Poles surely weren’t designed for this and at some point they may themselves fail.

Bottom line is that my experience so far with the Cuben Duomid hasn’t lent it to being my ‘go to’ shelter. Long term confidence and experience says I would probably still prefer a shelter in silnylon, and one which doesn’t require trekking poles to be extended in order to maximise the useable area of floor pan. Perhaps the Cuben Duomid is just not the tent for me.

16 thoughts on “The Cuben Crisis – MLD Duomid Pole Mk2

  1. Interesting that cuben is now coming under more scrutiny. In Mids, it certainly puts a lot of strain on poles and pegs. Shock absorbing poles is an interesting thought. I need to test my Tramplite properly. I suspect a lower shelter using just one pole might be less problematic. Trouble is you don’t know until you are in a critical situation. I do think that the advantages of silnylon have been overlooked in the rush to have the lightest possible shelter.

    • I’m hoping a shock absorbing pole will work in gusts, and perhaps save the pole, but it probably has it’s limits in persistent high wind. Also wouldn’t do much to stop pegs being flicked out.

      There’s probably quite a lot that’s either been overlooked or neglected in the race to go ever lighter. I feel the same with packs sometimes where durability and features sometimes suffer from light weighting (e.e. lack of a useful lid pocket). I wonder whether light-weighting has currently raced a little too far ahead of comfort and durability. After all, I think my set-up is light enough as it is.

  2. Silnylon Mid and 12in pole jack on then end of a trekking pole. Done. Cuben: over priced, over rated and over here 😦 Stick with Silnylon which is forgiving, cheaper and lasts longer.

  3. Have you considered doubling up your support poles? Andy Walker doubles his up in his SilHexPeak to good effect. As Cuben has no stretch, had you thought about using a very tough bungy section in the guys? This will provide the ‘give’ you require to take the stress from the poles.
    In all my backpacking, I’ve never had pegs “flick out.” It’s just a question of using appropriate pegs for the job – I take a selection to cover all expected ground conditions.
    I hope this helps, John.

    • Thanks Alan, using some thick bungee at the corner tie outs would certainly help to provide some ‘give’. robin also suggested that so I’ll give that a try.
      I’ve tried lashing two poles together in the way Colin Ibbotson suggests, with a length of cord from tip to tip and then using two velcro straps to lash the poles against each other. Works OK; cord would certainly provide a damper and lashing two poles together would get around having to constantly take pole sections apart. I guess I didn’t persue that one as I’m a lazy sod at heart and it takes a bit more fiddling & setting up than just joining two poles together. Perhaps I should revisit that idea.
      As a complete asside I’m sort of coming to the conclusion though that mids, however much I want to like them, need to be excessively high in order to use the available footprint (steepen the sides) hence need a long pole. But even though they have plenty of height, they don’t always have good usable head room. It’s all concentrated in the pointy bit in the middle. A twin pole tent 20-30 cm lower has much more headroom.
      I think the appeal of a mid has a lot to do with harking back to a bygone era, like Scott of the Antarctic holed up on the Beardmore Glacier. Their shape oozes nostalgic adventure. That’s why I want to like them.

  4. I like your thinking John on the suspension system. I hope it works. I also hope it isn’t the hose that has a wire braid inside. I need to improve my pole arrangement so I will bear your troubles in mind. I have another tent in mind at the moment. (More on that later).

      • Can’t divulge on the net at this time. It’s a unique tent of very small batch quantities and I hope to be lucky enough to get one. Hence keeping it close to my chest. When I am in a position of success I will tell all. I doubt that it would be of any interest to you though as its a 2 person tent replacing my Scarp 2.

  5. Pingback: The Howgills spits out my tent pegs |
  6. I have the MLD Duomid and was considering getting the Leki carbon Photosystem single hiking pole or staff as it is plenty long enough. At 340 grams, it may be a bit much but also very strong.

    • Hi Michael, I must admit I’ve never used a single trekking pole (with or without the MLD extender) with the Duomid as I always carry a pair of trekking poles anyway. I figured I’d rather not use the lower small diameter sections of poles which would be the weakest, so joining them has always been my preference. I think that with a Sil Duomid most of the pole options are fine as there’s plenty of give in the fabric to absorb stresses, but with Cuben I still find that a heck of a lot of force is transmitted down the pole in high winds, and your pole and pegging need to be really bomber to absorb it. The weakest point has always been the pole joint slipping, not the strength of the pole itself.

      Hope your Leki solution works well, I’ll be interested to find out if you try it.

  7. My TN laser comp has finally died and I’m thinking of getting a Locus Gear Khufu in Sil which is a mid with the same footprint as the duomid but pitches shorter at 130cm so can use one pole. I’ve always used one pole, the same one actually, for the last 30 years and don’t want to change .. Have you seen it on your trails and have any opinion on it for UK conditions? Thanks

    • Hi Colin, quite spooky that you’d ask about the Khufu. That was a shelter I started looking into as an alternative to the cuben Duomid, something that would have a bit more give in the fabric and potentially dissipate wind better. I wasn’t too worried about use of a single pole however.

      As it happens I did actually buy a sil Khufu with the additional tie-outs. But whilst waiting for delivery I started playing around with the duomid and different pole set ups, and decided all I needed to do was make some sort of damper for the pole. Something that would take strain off the pole joints during wind gusts. What I came up with worked a treat and I’ve not suffered a problem since (I did a seperate post on that pole modification).

      So upshot was that the Khufu arrived, and I had to make a decision which to keep, and as I’d need to order a different inner for the Khufu (the Oookworks inner I have for the Duomid wasn’t an ideal fit in the Khufu), I sold the Khufu without actually using it.

      The quality of the workmanship on the Khufu was exceptional, very well made. I did set it up once, and if I was picky I would say that the the fine denier of the sil nylon meant you really needed to tighten it down to get a neat pitch. I would have been glad of the extra tie outs too as fine denier nylon still has some give even when pegged taught.

      So in short, I’m afraid that I can’t comment on how the Khufu behaved in use, but I certainly can’t knock the quality. I used the cuben duomid on this years TGO challenge with quite a high level route, and I grew to love it.

  8. Thanks,
    I may take a punt on the Khufu then with the extra tie outs as you suggest and with a 1/2 inner. I’m thinking about the TGO for 2019 – I haven’t done it before but know the Cairngorms pretty well from various climbing trips etc. I like the high route you took and fancy doing something similar if my old knees can take it – they are also 1967 vintage like yours ..

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