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flamer
Jun 3, 2007, 10:53 PM
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You answered "around" it. But whatever, you are right this is getting us no where.
Maybe you should look here.....
http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?post=1607567;page=unread#unread
Specifically the 3rd post down.
...nobody does that though!
josh
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rgold
Jun 4, 2007, 3:22 AM
Post #77 of 96
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I don't have any idea what "private" information Josh may be referring to, but there is some public information about tethers on canyoneering.net. The following post
http://www.canyoneering.net/forums/showthread.php?t=700
summarizes the results of some tests.
----------Begin Post----------
I recently attended the International Technical Rescue Symposium in Fort Collins Colorado. ITRS is a yearly event where rescue professionals from around the world meet to exchange ideas on advances in rescue equipment and techniques. There was an interesting paper presented this year that directly pertains to this thread.
Research was done by Mike Gibbs of Rigging for Rescue in Ouray Colorado on the results of shock loading daisy chains and other commonly used positioning lanyards. In addition to being the owner of one of the premier rescue training organizations in the country (R4R), Mike is an active climbing guide as well as a member of the Ouray Mountain Rescue team. Mike performed dynamic testing on daisy chains as well as a number of positioning lanyards commonly used in climbing and rope rescue. The results of this testing were informative, to say the least. After reading this post, many of you may want to reconsider your choice in positioning lanyards.
Mike designed a drop test representative of what could take place in the field that would provide some indications as to the capabilities and/or limitations of positioning lanyards. A common example in canyoneering would be slipping from a stance when starting a rappel with the anchor at your feet resulting in dynamically loading your safety lanyard. The purpose was to examine the magnitude of peak forces as well as the integrity of the connections on certain commercially and user-created lanyards in a dynamic event. The drops were conducted with 80 kg and 100 kg mass simulating the weight of a climber or climber with a heavy pack and fall factors from 0.5 – 2.0. The surprise was how easily daisy chains and some other lanyards resulted in catastrophic failure on relatively short drops.
Test results were sobering at best. Particularly considering how many canyoneers still insist on using the daisy chain (almost 30% of poll responders) as their primary positioning lanyard. Daisy chains failed in short falls (FF 0.5-1.0) and slings made of Spectra/Dyneema webbing exhibited alarmingly high impact forces (>12kN) and catastrophic failure at surprisingly low fall factors. In canyoneering this could easily happen at any rap anchor below chest level. One slip and bang, you’ve dynamically loaded the anchor.
Nylon slings (not nylon daisy chains) and the Purcell Prusik came out on top as a result of their shock absorbing abilities. Typically, nylon slings held falls with reasonable impact forces (<10kN). The Purcell Prusik did best holding up to factor 2 falls with impact forces of less than 12kN. (FYI acceptable impact forces: CE 6kN, CSA/OSHA 8kN and UIAA 12kN).
I would urge all of you using daisy chains as your primary positioning safety lanyard to stop immediately! And those of you using Spectra/Dyneema slings for this purpose do the same. I would recommend you switch to something like the Petzl Spelegyca, Imlay Clipster, Purcell Prusik or nylon accessory cord or tape sling that has at least some dynamic shock absorbing ability.
Charly
----------End Post----------
Unfortunately, the author uses the words "failure" and "catastrophic failure" in a way that makes one wonder whether there is an important distinction being made, and the piece is lacking in the kind of precise details that would help climbers make a sensible decision.
There has been some discussion about whether climbers can ever get into significant fall-factor situations while using tethers. Personally, I have found myself in two such situations.
1. In a few instances, I've found rap anchors placed in a position that has forced me to clip the anchors while standing above them and then climb down until below them.
2. I've often rapped from anchors that we backed up for all but the last person down, who removed the backup before rappelling themselves. In a few instances, the backup had to be placed fairly far above the anchor, requiring the the climber to climb up to the backup, remove it, and then climb back down to the rappel anchor.
Falling in either of these situations would have been an incredibly bad idea, and I didn't do it. But I recall at least one accident that occured many years ago in exactly situation number 2. A factor-2 fall on a tether extracted the bolt everyone else had rappelled from and killed the last person down. (But the tether in this situation was nylon, so this tragedy cannot be counted as evidence for nylon over spectra.)
Frankly, I find myself in sympathy with both sides of the argument. However, it makes sense to me that one's gear have the smallest possible range of "improper use." I retired my PAS (which I also found to be about a link too short) in favor of a Purcell prussik, but I don't think it is an ideal solution for climbing. The Sterling Chain Reactor looks like a better mousetrap.
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tradmanclimbs
Jun 4, 2007, 2:42 PM
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Jim from sterling rope did some tests last year on slings and daisies. i am not suer if he broke any PAS in those tests but he did pretty conclusivly prove that spectry/dynema while stronger than nylon in slow pulls was drasticly weaker than nylon in drop tests. He broke a bunch of spectra slings in short drops designed to simulate slipping on to an anchor. One of his quotes from that session was " Nylon, the new miracle fabric" The results were posted on neclimbs.com
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flamer
Jun 4, 2007, 4:07 PM
Post #79 of 96
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Rgold.
Thankyou. That is exactly the information to which I was refering.
My reason for not wanting to say anything before is that I was gvien that info from a freind who is one of the head riggers and instructors for Rigging for rescue. He participated in the test's mentioned. I did not want to post it publicly because #1 I wasn't aware they had already made the results public #2 I didn't want to post their hard work, which is a part of their livelyhood.
The one qeustion I have concerning the post made by "charly"...I'm wondering if he was aware of the difference's in spectre vs. nylon daisy chains? He doesn't seem to make the distinction between the 2, which was apparently a big difference in the study mentioned.
Again thank you for your good post.
josh
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papounet
Jun 4, 2007, 4:20 PM
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I have been in the situation described by rgold: having to move around above the anchor.
not so perfect solution: autoblocking knot on the rappel rope, extended by using a spare 7mm cordalette
One of the very few tether setup that provides safety from ff2 (apart from tying with the rope)
take 1m50 of 8,5 climbing rope
at one hand make a bight (doubleoverhand on a bight aka barrel knot for example)
put a locking biner in it
at the other end attach to your harness leg and belt
take 40cm of 6 cord
position an kleimheist knot on the rope
attach the cord to the belay loop
slide the knot to adjust tether
in case of fall, both the dynamic properties and the setting of the autoblocking knot would limit the maximum fall factor.
or use a modified Purcell setup (where the Prusik is made on a shorter strand to allow fthe full length of the cordelette to be used
or us the Kong Slyde
http://www.kong.it/doc408.htm
Although I used to like very much the combination dynamic rope + Ropeman, this report made me change my mind
http://www.hse.gov.uk/...df/2001/crr01364.pdf
This report "Industrial rope access - Investigation
into items of personal protective
equipment" tested:
Ropes
• Back-up devices
• Ascenders
• Descenders
• Lanyards: fall arrest and cow’s tails
• Knots: termination and prusik
• Anchorage loadings
• Rope protectors
(This post was edited by papounet on Jun 4, 2007, 4:26 PM)
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healyje
Jun 4, 2007, 6:50 PM
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The R4R testing cited twice now is appears to not be available. I have just emailed them asking for the testing documentation or a link to it.
Again, I have no doubt their their results are as claimed. The issue is still whether they are relevant. With regard to the testing one has to know at exactly what forces did a PAS break and would those forces in fact be generated with a dynamic human being versus a dead static weight? And did the PAS break at forces far above what the human body can tolerate.
As for the scenarios Rgold cites, both would represent a gross misuse of any such device, daisy or PAS. It's simple - never fall from above an anchor onto a lanyard. The material of the lanyard is immaterial as it will generate forces which can seriously damage a human body and cause death if the lanyard doesn't break. In both the situations RGold cites an end of the rope itself is basically always available and that is what should be used instead. Again, the logic is entirely flawed - in any fall likely to break any lanyard dying will likely be the least of your worries and you should never have been using a lanyard for that purpose to begin with.
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tradmanclimbs
Jun 4, 2007, 8:35 PM
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Healy, Sometimes you come accross as doing everything perfect all the time. Real life is not that perfect. On any given day I witness folks clipping in to raps with slings daisys etc in situations that could shockload the dynema pretty good. i even do it myself on rare ocasions. I do seriously doubt that the human body would break spectra in most if any of those situations but Nylon seems to be a no brainer as a sling material for anchoring. Nylon is stronger than spectra/dynema in a climbing aplication and it offers a slight dynamic efect. The weight saveings is negligable when compared to the excessive price and use restrictions of spectra/ dynema INMOP.
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healyje
Jun 4, 2007, 8:49 PM
Post #83 of 96
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Again, slipping of a ledge at an anchor (at or below the anchor) might likely hurt, but the force will not break a PAS. The only situation that could ever possibly break a PAS would be a gross misuse of it (i.e. a fully extended daisy-like fall) and will severally damage or kill you. The no-brainer is don't ever put yourself in that situation; or if, by some rare happenstance, you do - then use the end of the rope for a moment and don't use a lanyard made of any material as nylon will likely just result in you hanging there dead or wishing you were.
Also, I asked Metolius about the materail in the PAS and it isn't straight spectre - it's a special run of material the Metolius crew engineered specifically for the PAS. And given the R4R testing is apparently out in the open I've suggested Metolius contact them directly and also post up their own response here.
Edited to respond to the following
tradmanclimbs wrote: Healy, Sometimes you come accross as doing everything perfect all the time. Real life is not that perfect. On any given day I witness folks clipping in to raps with slings daisys etc in situations that could shockload the dynema pretty good. i even do it myself on rare ocasions.
I'm by no means perfect and my climbing has always reflected playing at the edge of protection in that I've always free climbed on what most folks consider aid-only gear. To do that I have to understand the design utility of gear, it's limitations, and how I can best utilize what it offers for my own purposes. I also still rope- and free-solo and and apply the same understanding of limits there as well. And I've taken enough bad and hard falls over three decades on a variety of funky ropes to know I don't ever want to take a daisy fall on any material, ever. I use a PAS, but the first thing I tie into an anchor is the rope, I use the PAS as a second, longer point something like 75% of the time. Any situation where I am facing a daisy-like fall I use the end of the rope instead.
(This post was edited by healyje on Jun 4, 2007, 10:06 PM)
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kixx
Jun 4, 2007, 10:38 PM
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To the OP:
If your Screamer only tore a little bit and you want to get some of it's original energy absorbing power back you could put a few wraps of duct tape around it. This is untested of course and too many wraps of tape could actually make it too strong.
For the daisy ; PAS debate:
I've switched to a prussic type of teather with 7mm cord this season and it's great. It's lighter, cheaper, and more adjustable than a daisy, although will need to be replaced more often (at little cost). In my mind the argument should not be daisy or PAS but why not a Purcell Prussic? If any body can dig up some dirt on this DIY device I'd like to see it. There are some good threads on the "lab" forum for this I believe.
To Flamer and Healy and the crew from VT:
Josh went about this all wrong.. if he didn't want to tell the whole story he should never have brought it up in a Public forum. I'm sure he's gloating now about how right he was despite how wrong he looked. From now on he should take a different approach to addressing a topic which he has some knowledge about so that everyone else will be more open to listening to him... and everyone else should just ignore posts like his designed to insight useless babble so we can get down to the business of actually discussing these things. 50% of this post is very useful.. but the other 50% was a waste of precious time. This is much more fun and informative if we keep the teenage quabbling to the general and community pages.
Thanks to those who had something to say here and weren't trying to win RC.com popularity aka "MR. Right" contest. Good info. (Flamer and Healy both had good things to say a few pages ago)
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healyje
Jun 4, 2007, 11:25 PM
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kixx wrote: In my mind the argument should not be daisy or PAS but why not a Purcell Prussic?
I would agree, in part, that it isn't about daisy vs. PAS - but the essential point is don't daisy fall on lanyards of any kind. It isn't a casual the - 'oh well, shit sometimes happens' sort of deal - several folks here keep making it out to be.
In reply to: I'm sure he's gloating now about how right he was despite how wrong he looked.
Nothing could be further from the truth. Nothing in RGold's comments or his second reference to R4R's study change a wit about the facts of the matter at hand, the fact that it's a discussion about the wrong issue, or the the fact that the interpretation of R4R's results, whatever they may be, is completely misguided relative to using them to suggest a Nylon Daisy is in any way preferrable to a PAS.
It's actually a bit stunning that some simply aren't getting the basic concepts of 'gross misuse', that a nylon daisy is going to tear you up just as bad as a PAS, and any fall with a force that would break either with a real human body is probably not an event you'd want to live.
(This post was edited by healyje on Jun 4, 2007, 11:29 PM)
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flamer
Jun 4, 2007, 11:35 PM
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flamer wrote: My reason for not wanting to say anything before is that I was gvien that info from a freind who is one of the head riggers and instructors for Rigging for rescue. He participated in the test's mentioned. I did not want to post it publicly because #1 I wasn't aware they had already made the results public #2 I didn't want to post their hard work, which is a part of their livelyhood.
hey kixx,
Did you read this?
As far as I'm concerned I went about it perfectly.
I'd rather put something out there, no matter how vague, that will get someone thinking than say nothing.
Now there's no way i was going to post someone else's research, which is part of their livelyhood, without knowing it was already out there. Especially when i was only privy to that information due to a friendship.
As an "Entrepreneur" I expect you wouldn't like it if you discussed your business/ money making idea's with a friend, and they turned around and told the world before you could use it.
Now if you'll look back I didn't start being a jerk until I was "jumped" by other's. But I assure you and everyone, when attacked I will come out swinging. I have no apologies.
I did however PM several different individual's, who asked appropriately, with the information I had.
And I want to thank you for continuing the thing that you found bad about this thread. Even after the rest of use had clearly put it behind us.
sincerely,
Captain Gloating
aka josh
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healyje
Jun 4, 2007, 11:40 PM
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Josh, again, you were 'jumped on by others' because your whole approach to this was just flat out wrong and inept as well. Even if you were to miraculously go away still thinking nylon daisies are in any way preferrable to a PAS, I would hope you at least figured out this isn't how such a topic should be broached or approached in an on-line forum.
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flamer
Jun 4, 2007, 11:48 PM
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healyje wrote: Josh, again, you were 'jumped on by others' because your whole approach to this was just flat out wrong and inept as well. Even if you were to miraculously go away still thinking nylon daisies are in any way preferrable to a PAS, I would hope you at least figured out this isn't how such a topic should be broached or approached in an on-line forum.
Healy,
You are wrong.
You were wrong to post the information I gave to you in private.
You are wrong about the PAS.
Your opinion means nothing to me.
I will "broach or approach" any subject in anyway I
choose. I do not care what a backstabber like you thinks.
josh
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kixx
Jun 5, 2007, 12:01 AM
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Sheeesh - go climb
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healyje
Jun 5, 2007, 12:07 AM
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flamer wrote: healyje wrote: Josh, again, you were 'jumped on by others' because your whole approach to this was just flat out wrong and inept as well. Even if you were to miraculously go away still thinking nylon daisies are in any way preferrable to a PAS, I would hope you at least figured out this isn't how such a topic should be broached or approached in an on-line forum. Healy, You are wrong. You were wrong to post the information I gave to you in private. You are wrong about the PAS. Your opinion means nothing to me. I will "broach or approach" any subject in anyway I choose. I do not care what a backstabber like you thinks. josh
There you go, now we certainly know a great deal more about each other than we did before. I explained my actions completely - if you can't back up a statement about a product, then don't make one.
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greenketch
Jun 5, 2007, 12:13 AM
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I would tend towards agreeing with Healy on this one. In Largos new book he repeatedly emphasizes that sometimes you just need good enough. Now I could easily break just about any piece of gear that is out there. Would I survive the force involved if I was on the device that did it probably not.
Healy's point is well taken. Climbing is a heads up sport. You need to constantly be thinking about stuff which makes it easier to prevent failures like we are discussing.
Now in the rescue world rigging is done to a differant standard than we climb to. What is perfectly normal when I am climbing is just plain not good enough for hauling a litter and rescuers up a cliff.
I am all for advanceing the craft with better gear. I am not for throwing out a perfectly good piece of gear just because I can't accidently hang my truck from it.
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flamer
Jun 5, 2007, 12:14 AM
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healyje wrote: if you can't back up a statement about a product, then don't make one.
I encourage you to look at the last page, closely.
Fully backed up...
josh
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majid_sabet
Jun 5, 2007, 12:45 AM
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This is one of the most advanced troll I have seen in RC .
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rgold
Jun 5, 2007, 2:07 AM
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healyje wrote: Also, I asked Metolius about the materail in the PAS and it isn't straight spectre - it's a special run of material the Metolius crew engineered specifically for the PAS. And given the R4R testing is apparently out in the open I've suggested Metolius contact them directly and also post up their own response here.
As I said before, I'm not trying to argue with either side here, I think both positions have merit. The real issue is understanding the limitations of the gear you choose to use, and having a clear idea of possible onsequences so that your judgements are informed.
With respect to the "specifically engineered" material in the PAS, Jim Ewing broke two new PAS's with a factor 2 drop test, so different material or not, lumping them with spectra slings is appropriate---they seem to break the same way.
By the way, Jim's test of other spectra and nylon slings seems to confirm the factor 2 R4R tests. Spectra broke, nylon didn't. But the canyoneering.net post also refers to problems with slings at much less than fall factor 2 drops. Unfortunately, one can't tell from the post whether the poster is describing "just" high impact loads or actual breakage for these less severe falls.
Dropping weights is a more severe test than dropping humans, because the human body doesn't arrive at the bottom all at the same time. (People speak of the body's ability to "absorb" fall energy, but I think there is relatively little such ability. Compressing soft tissue just isn't going to do that much.) How much less severe the numbers and results would be for a human subject is, I think, unknown. But many aid climbers have fallen on their daisy's, and I don't think the daisy's totally rupture that often, so the actual impact loads are probably significantly less than the results obtained with weights. We need some realistically weighted test dummies.
In any case, perhaps a more interesting question is what happens if one takes a factor 1 fall on various materials. This is a reasonable test level for tethers used "properly." The standard mathematical models and the scanty test data available predict something like 13.7 kN for nylon and 15 kN for spectra, both above the UIAA upper limit for damage to the human body.
Bottom line(s):
1. Don't you dare fall from above an anchor when connected with a tether.
2. Even if below the anchor, tethers ideally should have no slack. They're for weighting, not for falling on.
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papounet
Jun 5, 2007, 5:37 PM
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rgold wrote: The standard mathematical models and the scanty test data available predict something like 13.7 kN for nylon and 15 kN for spectra, both above the UIAA upper limit for damage to the human body.
Please note that the those values were computed some long time ago from the maximum deceleration (12G) the army "felt" safe for parachute opening.
Harsher values would have meant more than 5% of broken soldiers arriving on the ground.
Which means that 12kn is not a magical threshold (below never an injury, above always an injury) , it is just an actionnable measurement.
One may think that a climber sustaining a 12G decelleration in a seat harness may have a higher risk of injury than a soldier using a full harness and having trained and prepared for this.
For more, read http://www.hse.gov.uk/...df/2003/hsl03-09.pdf
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