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DCF Shelter failure during a hailstorm in Alaska – Skurka video


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Home Forums Gear Forums Gear (General) DCF Shelter failure during a hailstorm in Alaska – Skurka video

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  • #3757624
    Murali C
    BPL Member

    @mchinnak

    I know even the 0.67 camo suffered from hail damage in other reports.

    Could a silnylon canopy also fail if the hail was sufficiently large? I mean hail that damages roofs and breaks windows can defnitely kill a silpoly tent as well I would assume. Maybe a better question to ask is what should one do when it starts hailing.

    Maybe immediately loosen the guy lines and let the tent just rest on you? Will that help as the tent is not taut anymore. Or just remove the tent completely and let your rain gear take care of you?

     

    #3757625
    d k
    BPL Member

    @dkramalc

    It makes sense to me that loosening the tension on the canopy might help reduce the chances of severe damage.  But just how much it would need to be loosened, and how bad a hailstorm would it need to be for the potential of damage, I have no idea.

    #3757632
    Jerry Adams
    BPL Member

    @retiredjerry

    Locale: Oregon and Washington

    camp under trees?  and hope a branch doesn’t fall on you : )

    #3757633
    Jon Fong
    BPL Member

    @jonfong

    Locale: FLAT CAT GEAR

    loosening the tension should help.  This appears to be an impact/momentum issue.  Given that the hail mass and velocity are pre-determined, the maximum force is determined by the time duration of the impact.  The shorter the time (hard surfaces) the higher the force, the longer the time (softer surface) the lower teh force.  My 2 cents.

     

     

    From teh web…

    The impulse experienced by the object equals the change in momentum of the object. In equation form, F • t = m • Δ v. In a collision, objects experience an impulse; the impulse causes and is equal to the change in momentum.

    #3757637
    Eric K
    BPL Member

    @fairtheoir

    This is a very interesting thread, and in particular I do wonder the age/usage/fabric weight involved. Regarding tension, that is of course a compelling argument as it relates to impulse. However, a low-tension shelter is a huge liability when it comes to wind. I don’t have the physics to describe it, but from experience, when the shelter is low-tension, the panels and guy-outs get whipped around mercilessly by the wind. That leads to stakes getting pulled out, extreme “dynamic” spikes in tension on the seams, and so forth. Overall, you want to do everything you can to keep the load paths “static”. Personally, I would always advise someone to set up a very taught shelter for these reasons.

    So with that, this type of weather situation has competing principles. The need to survive the whipping wind gusts, but also the puncturing hail. Perhaps in this situation, fully exposed, with large hail that would probably be denting cars, Dyneema isn’t the solution. But again, that is without knowing the age/usage of the shelter. It’s just that Dyneema is specifically not known for puncture resistance.

    All the more reason to favor protected campsite selection whenever possible. But we’ve all been there in situations where it’s not possible. That storm looks more like Hilleberg territory!

    #3757641
    Jon Fong
    BPL Member

    @jonfong

    Locale: FLAT CAT GEAR

    Interesting. Dyneema primary use is as a sail cloth and I would imagine that dynamic spikes in tension are very common in sailing. while impact, less so.

    an interesting note on DCF on Wikipedia.   “The material is reportedly more durable than laminated sails of comparable strength while being lighter in weight. UHMWPE has excellent resistance to ultraviolet light and is less prone to disintegrate from repeated flexing than either Kevlar or carbon fiber”.

    It seems that exposure to UV exposure may not be a significant factor.  In fact, as a sail cloth, I would imagine that it would be a pretty good outdoor material.  That and sail cloths are subjected to salt crystals, if it durable for sails, it’s probably a pretty tough fabric (for wind anyway).  My 2 cents.

    #3757645
    Murali C
    BPL Member

    @mchinnak

    You definitely want to keep it taut – but just during the 10 or 15 minute hail event, loosen it so that there is flex rather than a taut sheet.

    Also if you have a Zpacks or Tarptent, maybe you want to reverse the tent – that is drape the 1 oz floor fabric on your head – maybe that will fare better:-)

    #3757650
    Ryan Jordan
    Admin

    @ryan

    Locale: Central Rockies

    If you carry a groundsheet or footprint (as some DCF tent owners might, to protect their floors), draping it over the shelter during a hail event might be a good option. Having guylines from the corners of the groundsheet to the stakeout points would keep it in place.

    #3757673
    MJ H
    BPL Member

    @mjh

    In fact, as a sail cloth, I would imagine that it would be a pretty good outdoor material. That and sail cloths are subjected to salt crystals, if it durable for sails, it’s probably a pretty tough fabric (for wind anyway).

    I think they just burn money so fast on so many things that they don’t really care about how often they have to replace the sails.

     

    #3757674
    Jon Fong
    BPL Member

    @jonfong

    Locale: FLAT CAT GEAR

    A friend of mine use to yacht race and he told me the funniest line.

    Do you know how to simulate yacht racing?  Stand in a cold shower and shred $100 dollar bills!

    #3757675
    MJ H
    BPL Member

    @mjh

    That’s the nice thing about backpacking.  You only need to shred singles.  Maybe fives, if you’re fancy.

    #3757677
    jscott
    BPL Member

    @book

    Locale: Northern California

    Ryan’s suggestion about using a ground cloth seems pretty good. I use very thin polycryo, but it might be enough. Of course, the problem is realizing there’s a potential problem in time! Maybe this is a good reason not to cut down the ground cloth to size, but leave a bit extra polycryo.

    #3757697
    lisa r
    BPL Member

    @lisina10

    Locale: Western OR

    I was in a different Skurka group in AK at the same time this storm hit, but we were 20 miles south and only got rain. My sources tell me the hail was about marble size. There were apparently two DCF tents that were “shredded”, including the one in the video. The other DCF tents all suffered damage, none of the nylon tents did. This was a group of 9, but I don’t know how many had DCF tents. You’re supremely exposed up there and many many difficult miles from anywhere. It’s a good thing they had nine tents among them and only two nights left in the trip. It definitely sealed the deal for me on DCF. Storms seem increasingly unpredictable anymore and marble size hail is not extremely large. I’d rather save a few bucks and carry a few more ounces and have a bit more peace of mind.

    #3757707
    Jerry Adams
    BPL Member

    @retiredjerry

    Locale: Oregon and Washington

    maybe DCF is stiffer, so the impulse happens in a short period of time

    nylon stretches so it stretches out the impact over a longer period of time, so the force per time is less

    along the lines of what Jon was saying

    #3757741
    DWR D
    BPL Member

    @dwr-2

    “Ryan’s suggestion about using a ground cloth seems pretty good. I use very thin polycryo, but it might be enough.”

    Er… in my experience polycryo tears WAY easier than DCF… and just how do you get the guy lines to not rip through the polycryo corners??

    As for a tight pitch for wind vs. a lose pitch for hail… I have seen wind so bad that I just dropped the fly to the ground and slept under that. That should also help with hail. Problem would be if there was also rain and your sleeping bag was spread out could get wet. Recently, I was in a hail storm in the Sierra at 11,800 feet. Sierra storms typically in the afternoon and over by evening. So I just retreated into my Tarptent Notch Li but kept everything packed in their waterproof sacks and my rain gear handy just in case the fly failed. So, maybe pitch the DCF tent for rain, get inside with your rain gear handy or on and sleeping bag and other puffy items in their water proof sacks or in the backpack until the storm is over (assuming just an afternoon storm). Then if hail starts, drop the fly to the ground and just huddle under that. Not comfy and not great, but ya gotta do what ya gotta do.

    #3757788
    Devin Z
    BPL Member

    @drz_pnw

    Fascinating discussion and very interesting to see all the perspectives, here is mine: I would contend that this is a perfect example of stupid light. Ryan- I agree that in a vacuum, labeling something with that moniker is unhelpful but I actually believe it’s warranted here.

    To whit- when your shelter fails during a less common but certainly not unheard of event, and that shelter was chosen to cut 5 to 20 oz from your pack, I believe that qualifies as stupid light. To be put into a potentially life threatening situation for the marginal gain of that weight loss feels like the height of a back-country own-goal. I personally feel like life safety equipment (and I’d damn well include your shelter in the alaskan wilderness in that category,) is not the place to shave weight unless you’re pushing an objective that truly awards speed (think fkt) and you’re prepared for the ramifications of equipment failure. If your equipment (and more importantly, your body- remember that almost all of us are not optimized in terms of weight….) isn’t fully optimized for speed then there’s no point in shaving weight and gaining unreliability in your shelter.

    The fact that shelters made from .55 dcf would require you to add a protective layer over top, or move them during a storm or adjust your pitch during a storm should make this a non-starter if you’re actually placing storm worthiness at the top of the requirements for your shelter. And if you’re not doing that, and you’re choosing to hike in locations/conditions that can produce these kind of events- well, I guess we just put a different priority on survival. Because after all, if someone goes into a situation eyes wide open, intentionally chose a shelter for weight and then dies because of that choice- that has to be stupid light, no?

    I fully understand the allure of the lightest pack, but…at what cost?

    #3757794
    Murali C
    BPL Member

    @mchinnak

    Here are couple of folks who have encountered hail on their CDT thru (from reddit):

    level 1Yeah-BUDDY
    ·3 mo. ago
    PCT 2016, GR20 2018, CDT 2019
    Had pretty huge hail on the CDT up near lehmi pass in Wyoming, while camping in a stock DCF plexamid. Just dropped the central pole and lay under a loosened tent during the hail storm to mitigate some of the damage and got through with no issues.
    27

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    level 2BobTheTaco21
    ·3 mo. ago
    CDT ’19 | AT ’18 | PCT ’16
    Oh whaddup RS ;)

    I was with him on that ridge in a .51 Hexamid. Same thing — drop the pole to loosen the DCF and wait for the storm to pass

    Worst exposed storm I’ve been in for sure.

    #3757801
    unnamedpeaks
    BPL Member

    @unnamedpeaks

    <p style=”text-align: left;”>@DevinZ, yeah I like the stupid light term, and I think it’s quite useful. I went 5 summers of 15-30 days out in the Sierra alpine without getting rained on. All shelters are awesome in those conditions…they are almost as awesome as no shelter when there’s no inclement weather.</p>
    The funny thing is I have my first ever dyneema shelter in the mail, an X-Mid 2 pro, and if I had read this first I probably wouldn’t have bought it. I switched to xmids from a Tarptent Notch, which wasn’t storm worthy enough for me (couldn’t get the fly to the ground which caused significant splash into shelter from the ground when pitched on decomposed granite, and head close enough to fly to feel this on skin. Also storm doors on either side did not close taught….these issues might have been addressed in later version but I find X-Mid superior in every way I can think of).

    I’m now considering selling the pro and just getting the regular version. I’d like my shelter to protect me from hail, personally.

    Surprised this wasn’t on my radar!

     

    #3757803
    W I S N E R !
    BPL Member

    @xnomanx

    A lot going on here. I think “stupid light” is perfectly useful term. I believe I first heard it used by Andrew Skurka here:

    https://andrewskurka.com/stupid-light-not-always-right-or-better/

    And I’ve been there many, many times and I’m happy to own it. Most notably I once ruined a potentially great solo trip in the Sierra…on my well-earned vacation time, no less…because I was so focused on spreadsheet weight that I carried what I now consider to be a tarp that was way too small. Within two days my sleeping bag was wetting out, there was too much rain to get a chance to dry it, and I started to become precariously close to getting too cold to sleep…so I bailed. The sad part is, if I had carried nearly ANY shelter of what I now consider reasonable size/weight…we’re talking a meager difference of a half pound to a pound here…and I would’ve been fine! And I guarantee the weight would’ve had no appreciable effect on my hiking performance! This is the epitome of stupid light.

    But no, I loved the look of a stupid light shelter system on my gearlist and the feel of it in my pack. This is THE definition of stupid light in my book; failing to reconcile spreadsheet “utility” with the reality of conditions, i.e. intentionally erring on the side of reduced weight in return for reduced function…and it coming back to bite you. I think a lot of us SUL/UL backpackers cheat and get away with it through no skill of our own. I’m reminded of a trip over a decade ago during which a friend proclaimed the Gossamer Gear SpinTwin the best shelter he had ever carried. Never mind we saw no storms…

    It’s really hard to not read this thread as a cautionary treatise on certain dyneema shelters and wonder if this same spreadsheet vs. reality mentality is not creeping into the decision making process here.  Dyneema shelters getting wrecked by hail while others weren’t? Success with dyneema shelters requiring advanced weather notice via satellite device from home or ample time to head for the treeline to stay safe? Not to mention the inherent fussiness that I have witnessed firsthand among many users and designs in getting a perfect dyneema pitch…when, by contrast, most non-freestanding silnylon models are far more user-friendly in that they can be really cranked down drum-tight and rock solid with a less than perfect pitch and are thus less dependent on site selection.

    I understand site selection should always be part of the equation. But this thread seems to gently nudge me towards wondering if certain shelters…whose primary benefit seems to be only weight…might be dependent upon site selection in certain weather conditions. Just as we have 3 and four season shelters, I wonder if many of the dyneema offerings out there are not in fact “2+”, i.e. you might be in trouble in slightly more extreme, but not unheard of, 3 season weather?

     

    #3757804
    Dan Durston
    BPL Member

    @dandydan

    Locale: Canadian Rockies

    It’s not clear to me whether 0.75oz DCF would fully resolve this. Certainly it is more difficult to puncture, but it still has the same low stretch properties that are great for some things (e.g. wind performance) but worse for others (e.g. hail tolerance). It sounds like quite a few DCF shelters were damaged here but I haven’t seen info on whether the rest of the shelters were 0.5 or 0.75oz (only that the shelter in the video is 0.5oz). Given that there were lots of DCF shelters damaged and we don’t know what material the rest of them used, it seems premature to think 0.75oz is a full solution.

    With that said, DCF has been hugely popular in tents for close to a decade now yet the number of reports of hail damage are quite sparse. I can only recall 3-4 accounts over the last decade. So it is a consideration but should be kept in perspective.

    “I have my first ever dyneema shelter in the mail, an X-Mid 2 pro, and if I had read this first I probably wouldn’t have bought it”

    “I rode out a 10 minute long hail storm (part of a longer thunderstorm), with hail getting to the size of small marbles, in the Durston X Mid Pro (o.55 oz DCF) earlier this summer…..I didn’t notice any damage.”
    A major variable that hasn’t been discussed yet is the slope of the roof panels. Most tents have relatively flat roof panels which results in lessened snow shedding and more direct blows by hail. Conversely, the X-Mid has relatively steep roof panels (about 55 degrees) which mean that hail is going to deliver a lower impact/glancing blow rather than a direct hit. I’m not saying the X-Mid Pro is 100% not doing to be damaged by hail, but since the roof panels are substantially steeper than the tents that were damaged here, it seems quite a bit less likely.

    #3757806
    DWR D
    BPL Member

    @dwr-2

    Well, a cautionary tale for sure! But before we start throwing the baby out with the bathwater, it would be good to see some hard facts. Hopefully, we could get a detailed report from the guides of this trip that tell us, for instance:

    * Brand and Models of the DCF tents affected.

    * Brands and Models of the tents that were NOT affected.

    * Age of those DCF tents affected.

    * Estimated days left in the sun all day

    * A definitive confirmation that none of the other tents were affected.

    * size of the hail?

    * frequency of maintenance and inspection of the tents affected.

    * were the tents typically set up by the clients? any wear from allowing them to drag on the ground while setting up?

    * etc, etc…

    I would think that both the outfitter and the tent manufacturer(s) would want to look at this in detail. But will they ever make their findings public?

    I would also say that much, if not most, of the gear we discuss here on BPL is ‘stupid light’ if not used under appropriate conditions… er… even 4 season nylon tents will fail under extreme conditions…

    my 2 cents…

    #3757807
    DWR D
    BPL Member

    @dwr-2

    Also… I seem to remember some talk a few years ago about some runs of defective DCF fabric… could these tents in question be made with defective fabric???

    #3757812
    jscott
    BPL Member

    @book

    Locale: Northern California

    Skurka makes a report and we all listen. but, agreed…how often has this been mentioned/reported in the past? DCF has been around for quite a while. This is the first I’ve heard of hail damage here, as far as I recall. I may be wrong. Have others experienced, heard or read of this much before, if at all?

    You would think that consensus would have formed by now: DCF sucks in hail. I’ve not heard that.

    #3757823
    Murali C
    BPL Member

    @mchinnak

    Hail is still relatively infrequent event in my opinion.  And it typically happens during the afternoon. It also happens in the night – but, I think in the high mountains temperature drops in the night time and hence the likelihood of hail should be lower (I am not a weather expert:-))

    In the past 6 years of using DCF tents/tarps, I have encountered hail only twice – once on the JMT around 2 PMish and once on the CT around 4 PMish I would say. I always hike when it rains, hails etc. I don’t stop and setup my tent like some do. So, for me, hail can be managed. Just don’t set up your DCF tent once it starts raining. Keep hiking. And if it happens in the night, as has been said, just loosen the guy lines.

    I think you can go multiple seasons without encountering hail when camped and that is why you don’t see a big blowback against using DCF tents. And not many folks know about this. I have definitely heard about camo Duplexes developing holes in hail – but, I continued using my DCF shelters like Duplex, Altaplex’s etc as it had slipped from my consciousness. As I said, I have not encountered hail when camped with my DCF shelters in 6 seasons.

    But knowing now what can happen – I wonder how many will stop using their DCF shelters – at least the ones who are reading this thread. I am on the fence as I typically like hiking in the rain and usually set up camp 1 to 1.5 hours before darkness. So, I feel I should be fine. I will probably keep using my Altaplex in 0.51 till something catastrophic happens:-)

    Again, risk is relative and everybody has different tolerance to risk.

    #3757827
    Sam Farrington
    BPL Member

    @scfhome

    Locale: Chocorua NH, USA

    This tent was not just punctured by hailstones.  It was ripped to shreds in a number of places, while other shelters of nylon, and even polyester for heaven’s sake, did not suffer the same fate.  Thank goodness the occupants had something else to cover the ripped tent.

    There may be some denial going on here in some of the posts; but more to the point, agree with those who mention more likely causes for such a disaster; such as an overused and abused tent, or defects in fabric manufacture.  As a former trip leader, found it necessary to replace an entire collection of shelters that were just plumb worn out.  And it struck me that this was also for a group excursion, which rang bells.  Safety is the  obligation of a trip leader, period.

    Maybe some of the engineers here can posit other reasons to explain such a drastic failure.  But am not persuaded it was a routine event, especially in the absence of similar events having been reported on this site over many years.

    As stated above, I remain unsure of the reliability of DCF for this application, due to the variance in user reports.  So the devastation of this tent, without explanation, does not change things.  I am testing both polyester and nylon fabrics which are rated 20D, but lighter than 1.1 oz/sq/yd when finished.  These have been discussed on other threads, so will not repeat them here.  But the bottom line is that if they test well, they will be incorporated into an MYOG solo tent that is heavier than most DCF solos, but lighter than non-DCF solos on the market.  However, if the lighter 20D fabrics do not test well, either heavier silpoly will have to be used, or to insure safety, a replacement DCF tent will have to be built every year, which is hardly likely.

    Spectra and Dyneema fibers, or UHMWPE, can be woven into fabrics under 3 oz/sq/yd, such as ECOPAC Ultra100, so plan to make a pack of it and see how it performs.  Wouldn’t it be great if fabric makers could do this with such fibers for a coated woven tent fabric with a bias stretch.  But would there be enough other applications to make it worthwhile?

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