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jliungman
Dec 19, 2012, 9:28 AM
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Hi!
I have received video material from some friends and experienced climbing instructors, showing some fairly alarming results concerning the use of knotted dyneema.
http://vimeo.com/41522053
I apologize for the fact that commentary is in Swedish. I´ve uploaded two doodles to try and explain whats going on. (EDIT: Note that this is NOT a static fall, the rope used is DYNAMIC. The rope is tied to the dummy, and to the carabiner shown at the bottom of each sketch.)
The results, in short, show that under heavy but entirely realistic loads (ff 2 with new rope and and test dummy), a new dyneema sling fails completely. This happens when the dyneema is shortened using two techniques which, at least in Scandinavia, are common and taught by instructors.
Any thoughts? To me the results imply that we should avoid knotting dyneema altogether, and use this fantastic material only in full length, stitched slings (like quick draws). At least until we know more about which nylon/dyneema/widths/knots combinations work and which don´t.
(This post was edited by jliungman on Dec 19, 2012, 8:29 PM)
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iknowfear
Dec 19, 2012, 10:44 AM
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jliungman wrote: Hi! I have received video material from some friends and experienced climbing instructors, showing some fairly alarming results concerning the use of knotted dyneema. http://vimeo.com/41522053 I apologize for the fact that commentary is in Swedish. I´ve uploaded two doodles to try and explain whats going on. The results, in short, show that under heavy but entirely realistic loads (ff 2 with new rope and and test dummy), a new dyneema sling fails completely. This happens when the dyneema is shortened using two techniques which, at least in Scandinavia, are common and taught by instructors. Any thoughts? To me the results imply that we should avoid knotting dyneema altogether, and use this fantastic material only in full length, stitched slings (like quick draws). At least until we know more about which nylon/dyneema/widths/knots combinations work and which don´t.
thanks.
http://dmmclimbing.com/...notting-dyneema-vid/
this can be summed up:
Don't fall on static stuff.
regarding this:
In reply to: ff 2 with new rope and and test dummy
I can't think of a situation in which a rope is relevant here... do you mean new sling?
(This post was edited by iknowfear on Dec 19, 2012, 10:45 AM)
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USnavy
Dec 19, 2012, 11:10 AM
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jliungman wrote: Hi! I have received video material from some friends and experienced climbing instructors, showing some fairly alarming results concerning the use of knotted dyneema. http://vimeo.com/41522053 I apologize for the fact that commentary is in Swedish. I´ve uploaded two doodles to try and explain whats going on. The results, in short, show that under heavy but entirely realistic loads (ff 2 with new rope and and test dummy), a new dyneema sling fails completely. This happens when the dyneema is shortened using two techniques which, at least in Scandinavia, are common and taught by instructors. Any thoughts? To me the results imply that we should avoid knotting dyneema altogether, and use this fantastic material only in full length, stitched slings (like quick draws). At least until we know more about which nylon/dyneema/widths/knots combinations work and which don´t.
(This post was edited by USnavy on Dec 19, 2012, 11:11 AM)
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njrox
Dec 19, 2012, 2:50 PM
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jliungman wrote: To me the results imply that we should avoid knotting dyneema altogether, and use this fantastic material only in full length, stitched slings (like quick draws).
Yep. I only use dyneema for sling-draws and never knot it.
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jliungman
Dec 19, 2012, 7:33 PM
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iknowfear wrote: this can be summed up: Don't fall on static stuff. regarding this: In reply to: ff 2 with new rope and and test dummy I can't think of a situation in which a rope is relevant here... do you mean new sling?
It´s highly relevant, since, as I said, it is a realistic factor two fall on a dynamic rope, NOT a static fall as in the DMM video. The rope is connected to the dummy, and runs through the bottom carabiner seen in the doodles I attached.
I do not agree that this is all well known stuff. There has been speculation and opinion, but I have yet to see anything but a half-hearted warning from the manufacturers. Most people I know, including quite a few highly skilled instructors and rope access people, use the dyneema just like they´d use the nylon sling.
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cracklover
Dec 19, 2012, 9:09 PM
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jliungman wrote: iknowfear wrote: this can be summed up: Don't fall on static stuff. regarding this: In reply to: ff 2 with new rope and and test dummy I can't think of a situation in which a rope is relevant here... do you mean new sling? It´s highly relevant, since, as I said, it is a realistic factor two fall on a dynamic rope, NOT a static fall as in the DMM video. The rope is connected to the dummy, and runs through the bottom carabiner seen in the doodles I attached. I do not agree that this is all well known stuff. There has been speculation and opinion, but I have yet to see anything but a half-hearted warning from the manufacturers. Most people I know, including quite a few highly skilled instructors and rope access people, use the dyneema just like they´d use the nylon sling.
Yes, that's right. Most folks have been saying something along the lines of "So long as the rope is in the system, that should limit the force and the dyneema will be fine". Now we know that, at least in some cases, that is not so.
Now a question for you - in the video you linked, it appears that there are two tests, and the sling fails in the first, but not in the second. I gather that the talking (in Swedish) after the second test, while pointing at points on the sling, is saying something like "here, here, and here, the sling is damaged." Is that what happened?
GO
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sittingduck
Dec 19, 2012, 9:58 PM
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cracklover wrote: I gather that the talking (in Swedish) after the second test, while pointing at points on the sling, is saying something like "here, here, and here, the sling is damaged." Is that what happened? GO
The sling was shortened by an overhand knot and both carabiners where clipped in the same loop.
He said that the overhand knot slid until it stopped at the sewing of the sling.
He could see no damage but said that the air was full of fibers floating around.
That is a super makeshift screamer :)
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cracklover
Dec 19, 2012, 10:13 PM
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Hmmm... so maybe the OP could explain what he (she?) means about both methods failing?
GO
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redlude97
Dec 19, 2012, 10:16 PM
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It seems like in the first test and your diagram, the slack in the leg without a knot causes the force to be put on only 1 strand of the sling with the knot in it, is that correct?
(This post was edited by redlude97 on Dec 19, 2012, 10:17 PM)
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sittingduck
Dec 19, 2012, 11:21 PM
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cracklover wrote: Hmmm... so maybe the OP could explain what he (she?) means about both methods failing? GO
At the end of the video the text says that drop nr. 2 also was performed with a nylon sling and then the overhand knot only walked 5 cm (2 inches). Maybe the criteria for success was for the overhand not to walk?
To me it looked like a success, will use it on ice :)
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bearbreeder
Dec 19, 2012, 11:50 PM
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interesting ... but where is the belay device?
for it to be a realistic you need a belay device ...
the other interesting thing is that the guy at the end goes totally hands free on a gri gri with no backups when inspecting the sling ... which is likely more dangerous over time than the very rare occurrence of a true FF2 fall on dyneema ...
which i think goes to show the "fear" people have of dyneema ... vs the everyday hands free use of a gri gri or other such which is much more likely IMO of killing you ...
theres a focus on the things that very likely wont kill you (dyneema is used my many many many climbers in their anchors including guides and professionals, not too many deaths from that) vs other things that very likely will kill you ...
(This post was edited by bearbreeder on Dec 19, 2012, 11:55 PM)
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markcarlson
Dec 20, 2012, 1:46 AM
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redlude97 wrote: It seems like in the first test and your diagram, the slack in the leg without a knot causes the force to be put on only 1 strand of the sling with the knot in it, is that correct?
I am surprised nobody pointed this out sooner. Is this something people do often?
I can not think of a time when I could have possibly weighted one side of a sling like that. That is, any time it looked possible (if a piece blew in a belay anchor,) I changed how the anchor was set up.
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jt512
Dec 20, 2012, 5:06 AM
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bearbreeder wrote: the other interesting thing is that the guy at the end goes totally hands free on a gri gri with no backups when inspecting the sling ... which is likely more dangerous over time than the very rare occurrence of a true FF2 fall on dyneema ... which i think goes to show the "fear" people have of dyneema ... vs the everyday hands free use of a gri gri or other such which is much more likely IMO of killing you ....
The fact that the guy went hands free on a(n already locked) grigri is irrelevant to the point of the video, which was the demonstration of a previously unknown (or little known) failure mode of a Dyneema sling. Secondly, there is no general "fear" (with or without quotes) of Dyneema slings, since they have mostly replaced nylon slings in practice. Third, if you ignore the results of the tests in this video, then you're an idiot.
Fourth, fuck Dyneema.
Jay
(This post was edited by jt512 on Dec 20, 2012, 5:07 AM)
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bearbreeder
Dec 20, 2012, 7:27 AM
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jt512 wrote: The fact that the guy went hands free on a(n already locked) grigri is irrelevant to the point of the video, which was the demonstration of a previously unknown (or little known) failure mode of a Dyneema sling. Secondly, there is no general "fear" (with or without quotes) of Dyneema slings, since they have mostly replaced nylon slings in practice. Third, if you ignore the results of the tests in this video, then you're an idiot. Fourth, fuck Dyneema. Jay
blah blah blah blah 
like i said i find it quite odd when people go off about things while going against petzl's recommendation of a hands free device ...
no one is ignoring anything here mistah jay ... but there have been a few questions asked as to the test ...
theres plenty of "fear" going around about PASes, dyneema, ATC guides, etc ... on the intrawebs ... but as evidenced by the video, they dont take the basic safety precaution of tying off a device ...
if theres a test with a proper anchor (as others have pointed out) and a belay device in the system ... and dyneema consistently fails ... thats definately something to consider ...
until then ... ill focus on the stuff that will likely kill you
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patto
Dec 20, 2012, 8:17 AM
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bearbreeder wrote: until then ... ill focus on the stuff that will likely kill you
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jt512
Dec 20, 2012, 8:38 AM
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bearbreeder wrote: theres plenty of "fear" going around about PASes, dyneema, ATC guides, etc ... on the intrawebs ... but as evidenced by the video, they dont take the basic safety precaution of tying off a device ...
What you think is "fear" is actually people making intelligent inquiries. And those inquiries are independent of whether they hang off a fully cammed grigri or not without a backup.
In reply to: if theres a test with a proper anchor (as others have pointed out) and a belay device in the system ... and dyneema consistently fails ... thats definately something to consider ...
What's that called, the incautionary principle: "If anything can go right, it will"?
In reply to: until then ... ill focus on the stuff that will likely kill you
Assuming everything in climbing is safe until absolutely proved otherwise is pretty stupid, although it is true that you will probably be ok.
Jay
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bearbreeder
Dec 20, 2012, 8:52 AM
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jt512 wrote: What you think is "fear" is actually people making intelligent inquiries. And those inquiries are independent of whether they hang off a fully cammed grigri or not without a backup. What's that called, the incautionary principle: "If anything can go right, it will"? Assuming everything in climbing is safe until absolutely proved otherwise is pretty stupid, although it is true that you will probably be ok. Jay
no its simply focusing on things that are most likely to go wrong and kill you ... dont assume EVERYTHING is safe ... ANYTHING can kill you, but you cant worry about everything can ya now
the fear about "the deadly dyneema" occupies many intraweb threads ...
how about more basic stuff like wearing a helmet, which of course you ALWAYS do when leading dontcha mistah JAY
what we have is an incomplete test IMO ... people have pointed out the funny anchor setup ... and we DO belay with a device or other such dont we ...
how many dyneema anchor FF2 failures have we had in real life ... i suspect there many be at least one or two since its a very common material ... and in fact i expect that there are at least a few nylon or cordellette failures in history as well ... but compare that to the much more common ways to die ... worry about the things that matter
tying off a proper anchor with dyneema, nylon, cord isnt whats going to kill you tmr (well it might if you are on such sketchy anchors that you cant clip the belay bolt or a piece, but are YOU doing such a climb mistah jay )
i once remember someone who yakked all about only climbing with partners who knew how to built zpulleys, using only lockers at anchors, unsafe PAS/dyneema ... what did he do? ... rapped off the ends of his rope ...
bottom line ... i want to see more info, a proper anchor setup and a belay device in the system ...
and if you are worried about being "safe" ... dont use a device that aint hands free according to the manufacturer ... well hands free
(This post was edited by bearbreeder on Dec 20, 2012, 9:00 AM)
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jt512
Dec 20, 2012, 9:05 AM
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bearbreeder wrote: jt512 wrote: What you think is "fear" is actually people making intelligent inquiries. And those inquiries are independent of whether they hang off a fully cammed grigri or not without a backup. What's that called, the incautionary principle: "If anything can go right, it will"? Assuming everything in climbing is safe until absolutely proved otherwise is pretty stupid, although it is true that you will probably be ok. Jay no its simply focusing on things that are most likely to go wrong and kill you ... dont assume EVERYTHING is safe ... ANYTHING can kill you, but you cant worry about everything can ya now the fear about "the deadly dyneema" occupies many intraweb threads ... how about more basic stuff like wearing a helmet, which of course you ALWAYS do when leading dontcha mistah JAY what we have is an incomplete test IMO ... people have pointed out the funny anchor setup ... and we DO belay with a device or other such dont we ... how many dyneema anchor FF2 failures have we had in real life ... i suspect there many be at least one or two since its a very common material ... and in fact i expect that there are at least a few nylon or cordellette failures in history as well ... but compare that to the much more common ways to die ... worry about the things that matter tying off a proper anchor with dyneema, nylon, cord isnt whats going to kill you tmr (well it might if you are on such sketchy anchors that you cant clip the belay bolt or a piece, but are YOU doing such a climb mistah jay ) i once remember someone who yakked all about only climbing with partners who knew how to built zpulleys, using only lockers at anchors, unsafe PAS/dyneema ... what did he do? ... rapped off the ends of his rope ... bottom line ... i want to see more info, a proper anchor setup and a belay device in the system ... and if you are worried about being "safe" ... dont use a device that aint hands free according to the manufacturer ... well hands free
Do you ever write any sentences that aren't logical fallacies?
Jay
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bearbreeder
Dec 20, 2012, 9:10 AM
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jt512 wrote: Do you ever write any sentences that aren't logical fallacies? Jay
yadda yadda yaddaa ... did ya say something mistah jay ;)
i suggest writing to all those manufacturers who make dyneema and tell them how "unsafe" you consider it to be for anchor usage ... as a recognized expert and knowing fully well that they did not test their materials in common usage setups ... theyll be shocked that you didnt come forward to them sooner ... this will insure positive change
or are you more interested in telling people they are "idiots"
(This post was edited by bearbreeder on Dec 20, 2012, 9:11 AM)
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healyje
Dec 20, 2012, 9:25 AM
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It's not new and it's not particularly alarming - people have been warned for some time that knotting dyneema is a bad idea. More of an issue with skinny dyneema slings is keeping and using them to long. They are designed as a ultralite, short-lifespan, alpine consumable and were never intended for long term use on trad racks or sport draws.
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Syd
Dec 20, 2012, 10:26 AM
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healyje wrote: More of an issue with skinny dyneema slings is keeping and using them to long. They are designed as a ultralite, short-lifespan, alpine consumable and were never intended for long term use on trad racks or sport draws.
It's not just dyneema that's short lived. I was surprised reading this recently:
" Testing by Todd Vogel at Blue Water Ropes showed consistent strength losses for most cords and tapes, after one or two years use the strength dropped to 60% even when there was no obvious wear. I’d be replacing critical slings such as cordellettes every year or two."
Also:
http://www.efclimbers.net/resources/Knot-and-cord-strength.pdf
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jt512
Dec 20, 2012, 11:11 AM
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bearbreeder wrote: jt512 wrote: Do you ever write any sentences that aren't logical fallacies? Jay yadda yadda yaddaa ... did ya say something mistah jay ;) i suggest writing to all those manufacturers who make dyneema and tell them how "unsafe" you consider it to be for anchor usage ... as a recognized expert and knowing fully well that they did not test their materials in common usage setups ... theyll be shocked that you didnt come forward to them sooner ... this will insure positive change or are you more interested in telling people they are "idiots"
I don't know how you escaped my killfile on this laptop, but back you go.
*plonk*
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patto
Dec 20, 2012, 11:48 AM
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bearbreeder wrote: patto wrote: Which is NOT sitting on a tightly cammed gri-gri! if you really wanted to be "safe" according to petzl
bearbreeder wrote: of course if the new RC stance is that the gri gri is now suddenly a hands free device ... now thats something ...
A loaded grigri is 100% safe to go hands free provided the cam isn't forced open.
Forcing a cam open takes a fair bit of force that is very unlikely to occur when loaded. Like many such situations if you want to make it super safe tying off helps.
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bearbreeder
Dec 20, 2012, 12:05 PM
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patto wrote: bearbreeder wrote: patto wrote: Which is NOT sitting on a tightly cammed gri-gri! if you really wanted to be "safe" according to petzl This does not help your argument at all. bearbreeder wrote: of course if the new RC stance is that the gri gri is now suddenly a hands free device ... now thats something ... You are confusing belaying hands free with having a loaded locked off gri-gri hands free. They are NOT the same!
A loaded grigri is 100% safe to go hands free provided the cam isn't forced open. Forcing a cam open takes a fair bit of force that is very unlikely to occur when loaded. Like many such situations if you want to make it super safe tying off helps.
ummmm ... that petzl diagram was very specific for descending (rappelling) on a gri gri ...
so you are saying that its 100% safe for one to go "hands free" on a gri gri if the cam is engaged ...
so for example is my climber is resting on the rope, the cam is fully engaged, i can let go of the brake hand ?????????
of course if you are swinging around theres absolutely no chance anything will happen at all will there now
im gonna go ask petzl about it ... i suspect theyll know if its "100% safe"
(This post was edited by bearbreeder on Dec 20, 2012, 12:10 PM)
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