Author Topic: Rope joining knot failure - death  (Read 5439 times)

agent_smith

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Re: Rope joining knot failure - death
« Reply #15 on: June 03, 2016, 01:29:52 AM »
Quote
I would be particularly interested to see where you are at as far as developing a Quality Function Deployment (QFD) matrix, testing (and perhaps what kinda test standards are being used and if they are related to UIAA/EN or similar) and data collection as well as statistical analysis of the results. Then maybe I can find somewhere to jump in.

Link: https://en.wikipedia.org/wiki/Quality_function_deployment

A noble aim - maybe you could do this yourself? The question is..would you actually do it?

For me personally, over the past few years I have a developed a clear and well defined understanding of the content and object of my paper. An analogy would be a university thesis...I set out the scope, clearly describe the aims and go from there. The issue boils down to demonstrating (proving) that the instability thresholds of certain offset rope joining knots are well above the nominal loads expected. One has to keep in mind that we are only talking about the mass of 1 person (eg 100kg). In an extreme case - as might happen in a emergency - the mass of 2 persons (200 kg).

And we already have a well understood knot to begin with... #1410.
Virtually all 'testing' done to date has been simplistic MBS yield point tests. This proves nothing in my view.
As far as I know, nobody has written papers  that have examined instability thresholds and jamming thresholds.

...

As for UIAA / EN test standards - I am unclear why you think there might be any such standards for (offset) knot testing? Or more generally, testing of rope joining knots... I am aware of ASTM D3217 / D3217M - 15 and also the Cordage institute but, this again is too general and not specific enough for my purposes. Most have specifications to test the MBS, abrasion resistance, UV resistance, stretch, diameter, etc...but nothing specific to an actual rope joining knot.

One could equally ask,"Are the people (ie committees) who develop technical standards really expert in knots - or in particular, rope joining knots?  There are no technical standards in existence on knots and knot testing... eg there is no EN or ANSI standard for offfset joining knots (and I doubt there ever will be). There are standards for general testing guidelines - but these are not intended for knots, and these are aspects about knots which are difficult to quantify (eg MBS yield, the precise location where failure propagates from). I also doubt that EN/ANSI technical committees have the requisite theoretical expertise on knots - which is one of the reasons why I originally came to the IGKT.

As for statistical analysis, this is something that is more important to me... eg aiming for a minimum sample of 5 tests to probe each area of interest (eg instability thresholds).
Link: https://www.khanacademy.org/math/probability/descriptive-statistics/variance-std-deviation/a/calculating-standard-deviation-step-by-step

...

I am somewhat curious about your whole premise - there are ways to assist with a project in an informal way - eg by simply tying some of the offset knots and documenting what you tested (eg by conducting 5 consecutive tests to probe the jamming threshold using low stretch or dynamic rope in a certain diameter class...although you would need access to a load cell).

All this is drifting away from my original post asking for accident reports and info on recent accidents. This is now moving into the realm of knotting concepts...

Mark G
« Last Edit: June 03, 2016, 11:15:48 PM by agent_smith »

agent_smith

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Re: Rope joining knot failure - death
« Reply #16 on: June 07, 2016, 09:00:21 AM »
Found this report:  http://www.rockandice.com/climbing-accidents/euro-death-knot-mysteriously-fails
Original source: Published in Rock and Ice issue #233 (April 2016)
Date: Jan 2016
Route: Raggeds Wilderness of Western Colorado
Victim: Colorado ice climber (wishes to remain anonomous)
Knot used: Offset F8 bend (offset form of #1411)
Outcome: Survived fall

Mark G

alpineer

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Re: Rope joining knot failure - death
« Reply #17 on: June 07, 2016, 02:32:45 PM »
Anonymous climbers! Hah! Something stinks here. How does this stuff get published??!! Thanks R&I. :o
« Last Edit: June 07, 2016, 06:29:04 PM by SS369 »

Dan_Lehman

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Re: Rope joining knot failure - death
« Reply #18 on: June 07, 2016, 10:05:17 PM »
Anonymous climbers! Hah! Something stinks here.
How does this stuff get published??!! Thanks R&I. :o
?!  I see nothing terribly troublesome with their
anonymity, but as the comments strongly note
--praise be for that (the point, the predominance!)--,
the knot at issue was NOT the knot named "EDK"
in the title.  (But say something wrong often and
loudly enough, and it becomes the rule.)

Alpineer, Agent_Smith, Mobius, et al.,
did you follow the URLink(s) given by some
French gal commenting on the above, showing
some testing done with (much uses ...) "PURE
Dyneema? !!!  --slow-pull slippage in many of
our commonly used knots : fisherman's,
triple fish.(!), water knot (weak form),...
.
And some purely not-hymod, regular ropes,
with offset knots.

https://www.youtube.com/watch?v=N-jE-Da4P1U

I'm troubled by the last procedure, where the
thin, pure HMPE cord is joined w/offset knot
but the single-line climbing rope is abseiled on,
relying on the ARJ knot to work qua stopper
in the ... <well, maybe a pretty narrow quicklink?>?!
Should that stopper pull through, GOOD BYE
CRUEL WORLD!  (Whereas rapping with it, which
is the supposed No-No of penultimate sketch in
this multi-sketch/-test video, would give one a
fighting chance.  (In penultimate, the ARJ knot
wasn't stopped but the thin line ran through the
anchor and showed movement via its much lesser
resistance coming up through the abseil device.)

There is this video which follows (for me):
www.youtube.com/watch?v=l_5z6A5Z1h0
and LOOK FAST AT THE VERY STARTING IMAGERY
you'll see (a) not only an offset fig.8 used vice the
recommended EDK, but (b) DRESSED SLOPPILY!!!
Holy smokes, THIS is what is advising people?

Agent_Smith, you have some researching in these
videos to dig into!

OH, do note that the French video shows obvious
remaining knots (parts) where tails weren't equal.


--dl*
====
« Last Edit: June 07, 2016, 10:09:34 PM by Dan_Lehman »

agent_smith

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Re: Rope joining knot failure - death
« Reply #19 on: June 08, 2016, 05:37:42 AM »
Finally found this accident report:  http://publications.americanalpineclub.org/articles/13199507102/Fall-on-Rock-Failure-of-RappelKnot-Came-Undone-No-Hard-Hat-West-Virginia-Seneca-Rocks

Date: October 12 1994
Route: Candy Corner to Skyline Traverse: Seneca Rocks, West Virginia USA
Victim: Imtiaz Lalvi
Outcome: Died
Abseil rope joining knot: Speculation only - no hard evidence

Mark G
« Last Edit: June 08, 2016, 07:53:29 AM by agent_smith »

Mobius

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Re: Rope joining knot failure - death
« Reply #20 on: June 09, 2016, 12:33:25 PM »

Alpineer, Agent_Smith, Mobius, et al.,
did you follow the URLink(s) given by some
French gal commenting on the above, showing
some testing done with (much uses ...) "PURE
Dyneema? !!!  --slow-pull slippage in many of
our commonly used knots : fisherman's,
triple fish.(!), water knot (weak form),...
.
And some purely not-hymod, regular ropes,
with offset knots.
...

https://www.youtube.com/watch?v=N-jE-Da4P1U
...

.... the recommended EDK, but (b) DRESSED SLOPPILY!!!
Holy smokes, THIS is what is advising people?

--dl*
====

Thank you Dan, I have spent some time trying to work out out the video and 'results' (French is not my native language).

Dan and I are mostly at odds with how good the EDK is (or so I feel we are ;) ). I do not like the knot for what I consider good reasons, check some of my recent posts, and I have not changed my mind. However, the video result (above) is nothing I want to use to support my case.

The image I show below is the best I could get from the start of the EDK video trial. As somebody who tries to trial knots with serious intent, I would not present to a discerning readership a dyneema vs dyneema EDK trial, with a skull and X-bones fail, passing that off as relevant. The EDK is quite possibly poorly tied in the trial, just to add insult to injury!

I have not had much direct experience with dyneema. I have trialed 3mm dyneema exactly once (with a bowline). That said, I do not expect it to 'work' with any reasonably footprint-sized offset knot, including the ones I have worked with lately. That does not mean that offset knots should be ignored in this application, unfortunately the video gives the counter impression from what I gather from it. Dyneema is a very harsh mistress when it comes to knot integrity from what I know about it.

The second image I show is a knot I did not recognize (what is it?). The fact that it sits against the the D-clip under load annoys me greatly. I wanted to see the knot perform in a bit of space.

Cheers,

Ian.

[Edit: it is suppposed to jam that way apparently]
« Last Edit: June 11, 2016, 02:12:31 AM by mobius »

agent_smith

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Re: Rope joining knot failure - death
« Reply #21 on: June 10, 2016, 02:11:27 AM »
I have attached 2 photos from my upcoming paper on 'analysis of abseil rope joining knots'.
They are reduced resolution/quality due to the size restrictions imposed on this forum.

The second (lower) image illustrates the concept of using a thinner 'pull' cord to retrieve the abseil ropes.

The 'white' rope would be the thinner/lighter 'pull' cord.

The blue rope is deadheaded (jammed) up against the anchorage.

Obviously, this is not a nominal loading profile for #1410 - since it is reliant upon jamming up against a small orifice - with that orifice being of a such dimensions that the mass of the knot cannot pull through.

The principal concept behind this technique is weight savings. Full length abseil descents are still possible...however many of the advantages of a double rope climbing system are sacrificed. The lead climber can only lead with a single dynamic rope (instead of 2 dynamic ropes).

The thinner pull cord is simply to allow retrieval of the rope after a full length abseil descent.

Commentary:
1. All of the benefits of the offset knot profile are lost (if a larger knot mass is used instead of an offset geometry)....if the knot must translate around a 90 degree edge, it may become stuck.
2. In this particular loading profile, it would be preferable to tie #516 (double overhand stopper knot) in the blue rope - and then 'strangle' the white pull cord around the blue rope (in effect #1415 Double Fishermans).   #516 would create a larger and more secure mass to jam up against the anchorage (however in doing so, you lose the benefit of an offset knot profile as stated in #1 above).
3. The context in which this type of system would be employed is 'sport climbing'. This is a type of climbing where the route is fully equipped with existing permanent bolts to 'protect' the route plus a well defined existing 'rap station' (or belay station) where a descent can be initiated or the climbing route continues up to the next 'rap/belay station' (ie a multi-pitch sport route). This also assumes that that route is vertical - so the presence of ledges and protuberances may not be a factor - and so the abseil ropes will retrieve easily. 'Rap/belay stations' can often be strategically sited so as to permit a clear and unobstructed path for the rope retrieval process.

EDIT: I have finally found the accident link related to this type of jammed knot loading profile:
Link: http://www.rockandice.com/climbing-accidents/rappel-knot-fails-climber-falls-300-feet-to-death
[ ] Victim: Brian Ellis
[ ] Route: Linkup of Serenity Crack (5.10d) to Sons of Yesterday (5.10a)  Yosemite, California USA
[ ] Outcome: Fell to his death

Commentary: http://www.traditionalmountaineering.org/FAQ_ReepschnurRappels.htm
Reepschnur translation = accessory cord

The art of double rope climbing is in slow decline...with the majority of modern climbers opting to use a single rope system. I did say 'majority'...there are still some very active climbers (like me) who continue to use 'double rope' lead climbing techniques. The big trad routes - and in particular, new routes (ie first ascents) still see double rope techniques employed. I personally enjoy the added safety benefits provided by double ropes (including self-rescue options). You need a competent belay partner who is proficient in belaying with double ropes...

Mark G

EDIT NOTE: Clarification on loss of benefits afforded by offset knot profile... If you use a thin pull cord to retrieve your abseil rope, you have to assess the risk of the knot pulling through the anchorage link. It may turn out that you need a larger knot mass and therefore you will have a larger footprint - and it most likely may not be an offset geometry.
« Last Edit: June 11, 2016, 09:40:06 AM by agent_smith »

agent_smith

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Re: Rope joining knot failure - death
« Reply #22 on: June 10, 2016, 02:57:39 AM »
Here is another accident link I have found... this one is closer to home.

Link: http://www.theage.com.au/victoria/melbourne-university-climbing-club-culture-branded-dangerous-after-twin-accidents-20150708-gi7eu3.html

It appears that the club responsible in both abseiling accidents has a 'culture' of silence.
Because of this culture - we may never know the facts which caused the accidents...
NOTE: There were no fatalities, however both were serious injuries requiring hospital treatment.

Another link to the Mt Buffalo accident: http://www.abc.net.au/news/2015-04-26/man-falls-15m-while-abseiling-at-mt-buffalo-after-rope-snaps/6423018
(news reports are usual unreliable or manifestly wrong...so its hard to determine fact from fiction).
And another link: http://www.bordermail.com.au/story/3040981/mountain-miracle-abseiler-survives-fall-after-landing-in-worst-possible-spot/
There is a clue given that it may be the 'inadvertent' release of the abseil ropes from above by an unknown person or persons in the party.

Mark G
« Last Edit: June 10, 2016, 03:06:43 AM by agent_smith »

Dan_Lehman

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Re: Rope joining knot failure - death
« Reply #23 on: June 10, 2016, 09:50:22 PM »
Commentary:
1. All of the benefits of the offset knot profile are lost....if the knot must translate around a 90 degree edge, it may become stuck.

I don't see this --one still has an offset end-2-end
knot (if that was indeed what was tied).  Although
there might need to be some test-inspection of how
various offset knots when loaded qua stopper in
the various (largely thick+thin) materials and expected
forces (NOT at Mobious forces!) react / distort.


--dl*
====

Dan_Lehman

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Re: Rope joining knot failure - death
« Reply #24 on: June 11, 2016, 03:40:22 PM »
Here is another accident link I have found... this one is closer to home.

Link: http://www.theage.com.au/victoria/melbourne-university-climbing-club-culture-branded-dangerous-after-twin-accidents-20150708-gi7eu3.html

It appears that the club responsible in both abseiling accidents has a 'culture' of silence.

Wow, I'll quote a bit of that article:
Quote
It followed another accident on April 26
in which a male member fell about 20 metres
while abseiling on the north wall of Buffalo Gorge,
in the state's north-east.
The 24-year-old was lucky enough to fall into a pool of water,
but suffered back injuries and was trapped at the bottom of the cliff
in sub-zero temperatures overnight.
Search and rescue police, paramedics, and State Emergency Service crews
hiked in to the gorge and winched the club member out the next morning
and he was taken to the Royal Melbourne Hospital,
the ambulance spokeswoman said.

The club did not report the severity of the Buffalo Gorge accident
and told the university the injured club member was in a "good"
condition, therefore not triggering a "critical incident response"

by Melbourne University Sport, a university spokesman said.
Ahhhh, yes, right : all's *well* that ends well (the frightening
in-betweens be darned) !!

Where falling XX meters (okay, even 2) and being trapped
and isolated overnight (and at freezing temps, no less)
is not a critical incident in need of accounting,
I'm ... not joining THAT group!


--dl*
====