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guying out mountain hardwear direkt 2?


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Viewing 17 posts - 1 through 17 (of 17 total)
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  • #3459495
    Justin Baker
    BPL Member

    @justin_baker

    Locale: Santa Rosa, CA

    I own a mountain hardwear direkt 2 tent. I am a bit confused on how to use all of the guy out points. They have guy out points on the x-pac pole sleeves as well as the side panels.

    On the mountain hardwear website, they have a setup video where the person setting it up only guys out the the points on the xpac pole sleeves. I don’t understand how guying out those points adds stability to the tent as that material is already taught from the poles. I also don’t understand why it’s guyed out in a v-shaped configuration. Wouldn’t only guying out the xpac sleeve poles and not the side panels make it unstable?

    On the website the main product photo shows the tent guyed out one of the pole sleeve sections but not the other. In what situation would you want to guy out only one of the pole sleeves? Also in this photo it shows the side panel guy out is one piece of cord threaded through both loops and staked in 2 places, is this the correct way to do it? What’s the advantage over have 2 separate lines? Should both of the stakes be staked near each other or separated:

     

    I’m confused about what situations I would want to only guy out the side panels, only guy out the pole sleeves, or guy out both the side panels and the pole sleeves. Also is it necessary to stake out all of the stake loops or will just the 4 corners be sufficient?

    #3459516
    ThatCatChat
    BPL Member

    @rmeurant

    Locale: Laniakea

    I hazard a guess that the v-shaped configuration on the pole-sleeve attachments is to attempt to constrain those points in space, which the tension in the tent fabric won’t do – under strong and variable wind, the rectangular section the four points make could rotate a bit, oscillate, like a spring, as the tent shell develops torsion about the vertical axis.

    The attachment points on each surface would I presume be more concerned with stopping the skin of each section flapping, so in effect damping the tendency of each skin section to move in and out, like a drum surface (even though the tent skin is a curved surface). The two points asymmetrically located on the side sections might be to dampen higher frequency oscillations of those two panels. You could imagine the base frequency as the center of the panel oscillating, but a 2f harmonic would likely involve the center being static, but one half of the panel ocillating out while the other half oscillates in, and vice versa. So it would make sense to attempt to damp both possible modes of vibration. But I am only speculating, and there might be a more prosaic reason, like attachment for a vestibule.

    You pose a very interesting question.

    #3459517
    ThatCatChat
    BPL Member

    @rmeurant

    Locale: Laniakea

    And on further thought, the unguyed rectangular tensile dome itself must have 3D oscillatory patterns that hopefully the tent designer has studied, and the attachment points together with the likely directions of guy lines ought to be optimized to inhibit such oscillation in extreme conditions. In much the same way as the vibration modes of very large suspension bridges and flyovers need to be modeled in the design process to prevent unwanted resonance from wind (and from earthquake) that can become catastrophic.

    [Later:But of course the comparison is weakened by bridges and flyovers being massive systems, and the tent having very little mass. And I am neglecting the critical overturning tendency.]

    #3459592
    Art …
    BPL Member

    @asandh

    maybe just take your tent out for a spin in a windy winter storm and see what actually works …

    #3459593
    Jeff Jeff
    BPL Member

    @jeffjeff

    Both poles and fabric deflect so both need to be guyed out. Guy out each pole (4 points). The side has a large area that is not supported and will deflect in wind. I use one line on each panel. You can use two separate lines if it’s really heavy wind. I have no doubt you could burn 20 lines if you wanted to, but that is a ton of snow stakes that I don’t want to carry.

     

    I don’t understand using one line on two points (like on the side panel). This is a climbers tent and every climber knows the american death triangle adds unnecessary load on an anchor point (guy out point).

    #3459604
    Brad Rogers
    BPL Member

    @mocs123

    Locale: Southeast Tennessee

    I would guy it out on all the available spots in extreme conditions.

    #3459647
    Mario Caceres
    BPL Member

    @mariocaceres

    Locale: San Francisco

    I use the Black Diamond “El Dorado” tent (previously Bibler) which has similar shape than the Direkt 2.

    I normally don’t bother with the corners at the bottom and only guy-out the tabs along the poles.  It’s amazing how much rigidity they add to the whole shelter.  On the side panels the “El dorado” only has one tab which I normally guy-out to avoid flapping when is windy and to gain a bit of extra interior space when there is two of us.  Looks like the guyouts system on side panels on the direkt2 is more cumbersome.

    Here a picture of a trip I did a couple of weeks ago to Hoover Wilderness in Eastern Sierras.

     

    #3459666
    ThatCatChat
    BPL Member

    @rmeurant

    Locale: Laniakea

    This tent shape is so archetypal in form that surely its deflection has already been studied in wind tunnels and on site, and there ought to be research available on it. If there is not, it would be a useful research topic for someone somewhere. Data could include anecdotal accounts of both failure and near-failure, as well as wind-tunnel tests and simulation. Variables would include ridge detailing. The research should explore the effect of different attachment points and guying patterns in stabilizing deflection. One problem would likely be in modeling the microclimate wind phenomena, specifically blustery changes in direction and pressure in a mountain environment.

    #3459921
    Paul McLaughlin
    BPL Member

    @paul-1

    Used to have a BD lighthouse; same basic shape, it has guy points only on the corners where the poles live, not in mid-panel. I always took just two guylines with me, and used them on the upwind side. That handled plenty of wind. I would expect that if you used guylines on all four corners of the Direkt2 you could handle some serious wind. That tent is marketed as a high-altitude mountaineering “assault” tent and I would guess that sort of usage, high on an exposed ridge, is why they have all those guy points. Unless your goal is to camp in the most exposed location you can find, I’d go with the 4 corners.

    #3459932
    Justin Baker
    BPL Member

    @justin_baker

    Locale: Santa Rosa, CA

    Thanks for the input everyone! It sounds like guying out the pole corners prevents the wind from deforming the structure. Sounds like I should guy out the poles first and the side panels second if I feel the need.

    “I normally don’t bother with the corners at the bottom and only guy-out the tabs along the poles.” Do you mean that you don’t stake the tent at ground (snow) level and instead rely on the pole corner guy lines to secure it in place? That makes a lot of sense and would require fewer stakes.

    #3459934
    ThatCatChat
    BPL Member

    @rmeurant

    Locale: Laniakea

    Not staking the tent at the corners at ground level doesn’t make sense at all to me, unless you are in guaranteed mild conditions – but that is never a certainty.

    Staking the base corners of the tent gives more or less (given that there are probably very short straps from the corners to the stakes) fixed corner points that are stabilized by planet Earth. Given that the aim of staking is to retain tent stability, providing four fixed corners in space (on the planetary surface) has to be preferable to allowing them to potentially wander, either in the more or less horizontal plane, or even in the vertical direction under over-turning moment.

    #3459949
    Mario Caceres
    BPL Member

    @mariocaceres

    Locale: San Francisco

    Justin, that’s right I don’t use the tabs on the corners located at ground level/floor.  I only use this tent for winter and early spring snow camping.  I never use stakes on snow.  I always use “dead-mans”.  My “dead-mans” are twigs I find on site or pick up along the way if I know I will be spending the night above treeline.  The twigs remain buried when I leave camp.  In the past when I used stakes or other kind of commercial anchors I always struggled to get them out as the ground(snow) had frozen solid overnight.  With my new system I undo one of the knots and pull the guyline, leaving the deadman buried.  Here is a diagram of my system:

    Robert, because I use “deadmans” as anchors is kind of hard to put good tension when using the bottom / floor tabs.  Using solely the “elevated” tabs and getting good tension on the guylines allow me to achieve two things 1) to pin down the shelter good to the ground and 2) to reinforce the shape of the tent which is provided by the poles inside.  I heard stories of poles breaking when subject to strong winds.  Using the elevated tabs help reinforce the whole thing and minimize deflection.  I have use this system under very strong winds without any issue.

    #3459955
    ThatCatChat
    BPL Member

    @rmeurant

    Locale: Laniakea

    Fair enough, but you are increasing the stress on the guyed attachment points, part of which stress would ordinarily be taken by tthe corner stakes. I agree the deadman is a super strong anchor (in a past incarnation, I anchored a four-parachute festival structure I designed with deadmen, and they performed superbly – that was a lot of windage, and the wind it did blow). As long as the guys or attachment point dont fail, or the tension in the tent skin becomes too much, then ok. I’d be a little concerned about the tent hopping or walking around a bit in bad conditions, e.g. sudden suction lifting the tent ( when you’re not in it, or heavy gear), then flattening it while pushing it sideways. The problem I saw with it initially was that if a stake to the tieouts failed, a corner might lift, and the wind get under it, but the deadman ought to be a dependable solution.

    #3459974
    Matt Dirksen
    BPL Member

    @namelessway

    Locale: Mid Atlantic

     

    “Justin, that’s right I don’t use the tabs on the corners located at ground level/floor.”

    Mario, based on personal experience, I HIGHLY RECOMMEND pinning your tent to the ground, at the ground level. I don’t know that I can do the math on it right now, but, I’d suspect those ground points might be more important to the tent’s structural integrity than the upper guylines on the poles.

    If one has ever been in serious wind, there is a strong probability that if the bottom of the tent is not pinned, only a modest amount of wind can likely lift you, your gear and the tent right off the ground. Or perhaps tumble you & your gear around a lot. The upper guy lines might help a little to keep your tent (and you) from flying away, but the upper guy points are primarily designed for lateral stress, not uplift. Wind, like water, has a nasty habit of getting into small spaces. And once it gets a corner of a tent, it can become airborne.

    I forgot to pin a very sturdy freestanding four season tent once, and had only guyed the upper points out. When a derecho-like cold front greeted us at midnight with a sustained 60+ mile/hr wind, two out of the four of us in the tent were thrown straight up in the air with our gear. We were fortunate that three of us could stay inside the tent, while I went outside to pin it the floor down. If there were any fewer occupants inside, I’m certain we would have tumbled away. Three out of the five guy lines had popped right out in the first 30 seconds.

    I won’t forget that lesson again, especially on a “free standing” tent… ;>D

    #3460071
    Mario Caceres
    BPL Member

    @mariocaceres

    Locale: San Francisco

    Thanks Matt, scary situation you were on.  I definitely will keep it in mind.  I agree, more staking points add redundancy to the system.  Just out of curiosity, were you using dead-mans as anchors when that happened? and if so, how deep into the ground?

    #3460099
    ThatCatChat
    BPL Member

    @rmeurant

    Locale: Laniakea

    Sorry, even with Mario’s deadmen, I still agree with Matt’s warning. Tents such as these domes are specifically designed to be fixed to the ground at the corners, and not doing so transfers that stress to add it to that already taken up by the rib attachment points, so overloading them and the guys beyond their design strength. So in extreme conditions, I would expect the tent or the guys to fail earlier, even though the deadmen hold, if the bottom corners are not secured. Corner ground staking not only holds the tent tight to the ground, it provides triangulation of the ground plane, the floor, while fixing the four corner points in space, which has to increase the strength of the entire system. By contrast, rib attachment points (and mid-panel tieouts more so), have considerably more freedom to move in space, which means the entire tent can more readily assume configurations that could lead to failure. You could argue that the tent can more dynamically respond to the wind stress, and therefore handle it better. But I think that would only be true up to a point, beyond which failure could quite quickly occur. Just my structural opinion of the tensile structure, but my structural intuition is quite well honed through explorations and experience.

    #3460269
    Mario Caceres
    BPL Member

    @mariocaceres

    Locale: San Francisco

    I’m not an expert by any means and what I say needs to be taken with a grain of salt. What I said earlier is based on my personal experience and conditions that may not be the same than everyone else. I have used this tent and this set up for over 7 years, some times under very strong winds. I have used this tent as a base camp for alpine climbs in several trips to the Cordillera Blanca in Peru and at least 40 times in California’s Sierra. That being said, if all manufacturers of this kind of tents have those corner bottom tabs there must be a reason for it so you probably should use them.

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