Scotts locked Bowline (failure mode)

[agent_smith]

in reply to roo:

Just to 100% crystal clear...
The topic of this thread is Scotts locked Bowline - which is intended to be used as a tie-in knot for climbing.

I am unclear if you have taken a wide detour from this basic fact?

When rock climbing, the alleged snagging and disruption of the collar of Scots locked Bowline could only occur:
1. While being lowered by the belay person; or
2. During a free-fall event - where the collar would have to precisely catch on a snag - at which point the climbers full body weight would bear down due to gravity.

Scenario #1 would be the more 'plausible' event.
Even so - in my testing yesterday, I reached my fatigue limit while attempting to induce the snag while being lowered (and my belay person grew impatient and bored).

One wonders how you test knot security if you assume that knots are only allowed to exist in taut line.

And one wonders if you really understand what is going on with this purported failure mode?
Your comment leads me to think that you might not understand the real-world conditions that prevail while rock climbing?
For example, while being lowered - by definition - the rope is under continuous tension!

Even in a free-fall event, the falling climber continues downwards as the collar 'snags' on some protuberance.
I believe this event to be 'remote' - meaning that the likelihood of successfully snagging the collar during a free-fall event is infinitely small.
And even if such a snag were possible, body weight would quickly counter-act any collar displacement.

Does this make sense roo?

[agent_smith]

per roo:

While I've been a fan of the Scott's Lock general slack security, I have been wary of recommending it as it can easily be dressed improperly and become prone to assuming an unstable form. (cf. https://igkt.net/sm/index.php?topic=5995.msg40270#msg40270)

In reply to the above post by roo:
roo's purported 'unstable form' is not shown in EN892 rope.
The purported condition does not occur in EN 892 rope.

It is a source of puzzlement to me that roo uses non EN 892 rope as a proposition to support his contention.

It is possible that roo fails to understand that Scotts locked Bowline is principally intended to be used a a tie-in knot for climbing - using EN 892 rope.

[KnotLikely]

Agent Smith, how is it that you can have no concept of lead climbing while insisting that the knot is intended as a climbing tie-in?!

If my belayer attempted to keep my body weight on the rope while I was trying to climb I'd fall off!  I have no idea what you are going on about, at this point.

I would like to repeat, one last time, that you are confused.  You tested while being lowered?  Well of course your snag couldn't pull in standing line, because it is tight with your body weight.

I think you need to take a step back and really look at what you are saying.  Watch a video of a belayer feeding slack so a lead climber can clip at head height.

Also, this discussion is not concerning only Scott's Lock.  This discussion encompasses all knots where the standing line and nipping loop is not secured enough through friction of other wraps, or complicated enough to lock itself, to prevent feeding of standing line slack back into the eye-loop.

Your contention that climbers have exactly zero slack and somehow keep their knot weighted at all times is simply absurd.  Take a step back and look at what you are saying.

2. During a free-fall event - where the collar would have to precisely catch on a snag - at which point the climbers full body weight would bear down due to gravity.

What exactly is the climber's body weight bearing down on when there is clipping slack?

Hmmm... Guess I wasn't done, here.

[Dan_Lehman]

per roo:

In real-world use, knots are sometimes slack.

Incorrect.
Tie-in knots to a climbing harness are life critical.
Climbers make sure that their tie-in knots are diligently dressed and cinched up tight (because their life depends on it).
For a tie-in knot to be 'sometimes slack' (implying loose) - indicates incompetence.

No, a "slack" or non-taut line (including the knot) indicates that it doesn't always follow your unrealistic assumption that:

"4. That the tie-in knot was maintained under continuous body weight at all times during the test."

...which you decided to snip out of the context of my reply.  It does not indicate that the knot is sloppily dressed. 

One wonders how you test knot security if you assume that knots are only allowed to exist in taut line.

1) A_S, your red-bolded line is not true,
and an empirical examination of in-use-by-climbers
knots will show this.  I.P.,fig.8 eyeknots are both often
un-tight AND dressed, er, *naturally* (and there is seldom
any source to give a specification for (a) dressing & (b)
setting such a knot --at most, only those words w/o further
guidance (or something about strands "crossing")).
And the usual BWLs cannot be set so tight --the collar
e.g. (unless SS369'd!) cannot be drawn down hard.e
YMMV.

2) Note that e.g. the mirrored bowline is a knot designed
NOT to be (and to depend upon being) set tight-snug,
but to be of such abundance & interweaving of rope
so to not get TOO loose and spill.  (OTOH, I know of a way
to make #1010 tight-snug, too, and w/less rope than MBwls);
and the locktight eye knot is designed to be strangle-like
tight, with a bowlinesque *back door* for easy untying.

And yes the discussion has been about a non-tight rope
into the subject knot.
(To which KnotLikey's pictured wiggling & loosening
stages seem odd to the ones you earlier posted which
I think are agreed reasonable to the cited snagged-collar
issue?  That green rope'd final image looks more as
though THE TAIL WAS PULLED ?!

And I'll repeat a recommendation for the TIB
version of Scott's Lock'd BWL, for its 2-diameters
bending for final tucks, and thus better nipping.


--dl*
====

[agent_smith]

per KnotLikely:

Agent Smith, how is it that you can have no concept of lead climbing while insisting that the knot is intended as a climbing tie-in?!

?
Strange comment indeed (unless of course you are motivated by some other underlying purpose?).
I wonder if this is some sort of misplaced remark?
Your comment strongly suggests that I have no concept of lead climbing! Implying that I am inexperienced in such matters?
The heart of the matter is that I am providing counter argument to your assertion that there is a potential failure mode with Scotts locked Bowline - which there isn't. (in EN 892 rope).
It is obvious that you dislike my counter arguments - and so you are resorting to inappropriate behavior.

If my belayer attempted to keep my body weight on the rope while I was trying to climb I'd fall off!  I have no idea what you are going on about, at this point.

I have no idea what your attempted assertion is here.
A tie-in knot is not going to snag a protuberance to the extent that the collar will be displaced during the act of climbing up a rock face.
You might want to rethink your preposition as to which direction is required to induce the purported failure mode.
Scotts locked Bowline cannot suffer the purported failure mode during an (upward) ascent of a route.
For example, a lead climber - while in the act of climbing up a route, will immediately notice if his harness or something else has caught a 'snag' - since it would prevent further progress.
It might cause the climber to lose balance or lose momentum, and then suffer a fall (which is now in the downward direction).
The belay person would immediately respond by attempting to arrest the fall and the rope will rapidly come under tension (unless the climber continues to free-fall all the way to the ground).

I would like to repeat, one last time, that you are confused.

And I would like to repeat by stating that the foundational basis of your failure mode is not going to happen in real-world climbing.
I have personally tested Scotts locked Bowline over the past 10 years in both indoor and outdoor climbing environments including lead and top rope climbing.
I conducted yet another round of field testing last weekend and despite rigorous attempts to snag the collar - it simply wasn't possible.
I would add that i also tried to snag the collar while climbing up the route and while reaching up to clip a quick-draw - but this simply wasn't a plausible method of disrupting the collar.

Your contention that climbers have exactly zero slack and somehow keep their knot weighted at all times is simply absurd.  Take a step back and look at what you are saying.

That isn't my contention  - its simply your typed words.
I think you need to take a step back and look at your whole proposition including the underlying mechanism for inducing potential failure mode of Scotts locked Bowline.

What exactly is the climber's body weight bearing down on when there is clipping slack?

?
Collar displacement via a snag (a protuberance) and subsequent loss of knot core integrity is the key issue.
Something has to snag the collar - and then displace it.
This isn't going to happen while a climber is in the act of climbing up the rock face.
It isn't going to happen while a lead climber grasps slack rope and then reaches up to clip into a quick-draw.
If a lead climber clips a quick-draw and then falls off - this is a loading profile that is now identical to top rope climbing (ie the tie-in knot is now pulled upwards).
As the lead climber falls down, the rope is coming under tension (rapidly). If the rope never came under tension, it implies the lead climber entered a free-fall state and continued to fall down...until ultimately striking the ground. This implies belay error or protection pulled out (popped out), and if enough protection pulled/ripped out, this might result in a ground strike.

Hmmm... Guess I wasn't done, here.

I can confirm that I will continue to counter your assertions that Scotts locked Bowline has a failure mode which casts it into doubt for life critical applications (eg climbing is a 'life critical' application). So I presume that you will continue to counter my countering!

[agent_smith]

per Dan Lehman:

1) A_S, your red-bolded line is not true,
and an empirical examination of in-use-by-climbers
knots will show this.

?
Your comment is only true for cases of incompetence.
That is, a climber who does not diligently dress and cinch his/her tie-in knot is either:
1. Reckless
2. Incompetent

The issue of recklessness or incompetence should not be the basis of an experiment to induce a failure mode on Scotts locked Bowline.
This would add too many variables.
In all knot testing, it is nominal to tie the specimen knot diligently and accurately - otherwise the results may not be valid (unless you are specifically testing for some other stated variable).
In the specific case of Scotts locked Bowline (for climbing) - the tester must ensure that the knot is accurately dressed and cinched tight.
The reason for this is that the aim of the test is to snag and disrupt the collar - to induce a failure mode.
Obviously, if the tester deliberately tied the knot in a loose dressing state - that would skew the results - because obviously, the tester has created conditions that favor a successful snag.

There is a growing movement amongst climbers to undertake a 'partner check'.
The idea behind this check is to detect errors and correct them before commencing the activity.
Checking the tie-in knot is a mission critical action.
A wrongly tied knot could have catastrophic consequences.

Dan - are you suggesting that a test regime to induce the purported failure mode requires the specimen knot to be tied loosely?
Or are you suggesting that the loosely tied knot would serve as the experimental control?
If you do suggest a control that uses a loosely tied knot - that would be valid as it would provide a comparison against the knot that was properly dressed and cinched up tight.

And yes the discussion has been about a non-tight rope
into the subject knot.

From who's point of view?
I'll repeat that a loosely tied knot isn't valid to base an argument from.
Any loosely tied knot can snag on a protuberance - thats like stating that a shoe lace is not valid because if its tied loose, it will fail.
Obviously a shoe lace will fail to hold if its tied too loose to begin with.
Another example of invalid testing: I declare Tesla electric cars to be unsafe because they cant stop quickly enough on greased road surfaces. That is, I'll apply grease to the road surface and then test the Tesla vehicle to see if it can stop quickly from 100kph (60 mph). If it cant stop within a certain distance, I'll declare that vehicle to be unsafe.

I also understand that if I tie any eye knot into my climbing harness too loosely - it will likely fail and I could die.
Thats stating the obvious.

Dan - the real issue here is that the OP made an announcement on an open public forum about a failure mode of Scotts locked Bowline in climbing applications.
Why make such an announcement to the world if the knot was in a loose initial dressing state?
What does that prove?
And more to the point, why continue to defend such a failure mode as the OP has done?
Do you see my point? The OP is now determined to tender argument to support his claim that there is a serious failure mode with Scotts locked Bowline.
If this were simply a case of "Heh, lets loosen Scotts locked Bowline and then see if we can induce structural failure" - I think the OP would have stopped trying to defend his proposition.
But he isn't. He is intent on pointing out the failure mode.

Extraordinary claims require extraordinary evidence.

Because Scotts locked Bowline is used in life critical applications - the burden of proof lies with the tester to create valid test conditions to prove the failure mode.
It might be valid to use a loosely tied Scotts locked Bowline as the experimental control.
But, you must also test properly dressed and cinched Scotts locked Bowlines to compare against - otherwise your test results are invalid.

It would be invalid to publish test results based only on the control group (ie loosely tied knots) - and declare all Scotts locked Bowlines as potentially insecure.

[agent_smith]

AND THIS IS HOW DISINFORMATION STARTS AND THEN PROPAGATES:

Scott - please take an urgent look at this post in Saferclimbing.org website:
http://www.saferclimbing.org/en/comment/2402#comment-2402
Link was submitted by ND (not verified) on Tue, 2020-05-05 19:29 (one wonders who this 'ND' is!).

We will need to move quickly and shut this one down.
The guy that runs that website has a personal issue against the use of 'Bowlines' in life critical applications (eg rock climbing).

He has seized upon this opportunity to propagate an alleged failure mode of Scotts locked Bowline - knowing that his website has a substantial readership.
Once these things get loose into the wild - they are hard to stop.

The underlying parameters created for the alleged failure mode are (at best) - a possible control group to compare against.
That is, you could devise an experiment where the control group is a deliberately loosened collar and a deliberately induced snag on a protuberance.
BUT, you also need to compare the results of that control group to where a Scotts locked Bowline has been properly dressed and cinched tight.

Partner checks are gaining momentum in the climbing community - because checking your tie-in knot is a mission critical action (ie your life depends on it).
Only a reckless or incompetent person would commence climbing with a tie-in knot that is loose.

Recklessness and/or incompetence are variables that exist across the entire spectrum of human existence.
In a properly devised experiment, the tester needs to carefully establish what the variables are.

[roo]

Only a reckless or incompetent person would commence climbing with a tie-in knot that is loose.

After some motion and bumps on the side, even an initially tight knot can gain some daylight.  The sharper the protrusion, the less it takes.

In the separate case of tail snagging, all it takes is an acute angle opening to wedge the tail even if the knot stayed relatively tight.  But there are other ways to get a tail caught.

I would like to see the protrusion that caused NotLikely's incident (which I do believe occurred).  A path with branches would have been an easier way to get a snag.

[SS369]

AND THIS IS HOW DISINFORMATION STARTS AND THEN PROPAGATES:

Scott - please take an urgent look at this post in Saferclimbing.org website:
http://www.saferclimbing.org/en/comment/2402#comment-2402

We will need to move quickly and shut this one down.
The guy that runs that website has a personal issue against the use of 'Bowlines' in life critical applications (eg rock climbing).

He has seized upon this opportunity to propagate an alleged failure mode of Scotts locked Bowline - knowing that his website has a substantial readership.
Once these things get loose into the wild - they are hard to stop.

The underlying parameters created for the alleged failure mode are (at best) - a possible control group to compare against.
That is, you could devise an experiment where the control group is a deliberately loosened collar and a deliberately induced snag on a protuberance.
BUT, you also need to compare the results of that control group to where a Scotts locked Bowline has been properly dressed and cinched tight.

Partner checks are gaining momentum in the climbing community - because checking your tie-in knot is a mission critical action (ie your life depends on it).
Only a reckless or incompetent person would commence climbing with a tie-in knot that is loose.

Recklessness and/or incompetence are variables that exist across the entire spectrum of human existence.
In a properly devised experiment, the tester needs to carefully establish what the variables are.

Hello Mark.

I?ve read the article and feel it would be a waste of life to argue any points further than the ones that you offered. I believe that a mind is made up and there?ll be no changing it. How often have you heard or read, ? I was wrong.?

I?ll stick to using the bowline that I offered for any and all purposes. It works for me, and probably for others as well. I don?t need to sing its praises.
Btw, I diligently check my equipment, rope and knots (they are SS369?d tightly) all the while throughout my use, as well as my partner(s). It is life critical and only fools do reckless things.

Any knot can fail given the right circumstances. I bet I could contrive a failure scenario for the Gordion knot. ;0

SS

[agent_smith]

Hi Scott,

I provided an incorrect link (apologies).
The link to the saferclimbing.org website is here:
http://www.saferclimbing.org/en/comment/2402#comment-2402
Link was submitted by ND on Tue, 2020-05-05 19:29 (one wonders who this 'ND' is!).

I understand your position on this matter... all good.

However, please consider deleting this entire thread that I created - that will shut down propagation of disinformation and misinformation into the internet.
By deleting this thread - it will make the link on Saferclimbing.org dead and buried.

[roo]

Okay, I deleted those posts as agent_smith was right.  It was way off topic.  As for everyone demanding proof, I'm sorry that I don't have video of me falling.  I'm sure it would be amusing.

Scott, I was not disparaging the knot.  I was simply reporting what happened to me and that I thought it presented a possible danger that I had not considered until it happened.  Yes, it is probably a fringe case, but most accidents are.

The why:

I have a friend who is worried about knot size and stability on hard slab.  He explained that a tie-in that I had discussed with him was large enough to push him off a route that he had been trying (I think in Zion, but don't quote me) and he was looking for something almost as small as a bowline backed up with a double overhand on the returning eye-leg (what he said he switched to when his retraced 8 pushed him off the wall).  Scott's lock is one of the smallest knots and was the third I "tested" his scenario on (I was just messing around).

I simply posted my experience.  I'm extremely surprised that no one is able to reproduce it when trying to reproduce it, considering that it happened to me when I was just feeling what different knots felt like on slab when my foot slipped.  I've never climbed anything where a retraced figure 8 could push me away from the wall or even bother me.  That is all that I was doing.  I was not attempting to bring any knot to failure.

The how:  https://imgur.com/a/O4ZSFC6

This imgur album is as close as I can come to explaining what probably happened to me.

I was tied into the left pictured knot in agent_smith's picture.  I can not reproduce it on the middle pictured cowboy bowline version that also grabs the returning eye-leg.  I've never tied the cowboy bowline with the lock outside of the eye-legs until just now, to add it to my naming system text document.

The protuberance pictured in agent_smith's photo caught the opposite side of the collar as presented in his failure mode test picture.  The snag was limestone and was not nearly as pointy as presented.  It was basically the corner of a cube.  I may have fallen to the opposite side, allowing a better snag.  I don't know, as it took a total of maybe 0.5 seconds and was completely unexpected.

The snag would only pull in slack left by the belayer, though this is often enough to pull the knot out of reach, especially when clipping.  The collar was not significantly elongated by the time I landed (a few feet, and no injury).

I had already run my hips into the wall a couple of times and the collar was not as tight as when initially set.  Nothing had been done to it, intentionally, other than climbing a slab where my knot hit the wall a couple of times.

The first picture is the knot set as tightly as possible.  Even fully set, the simple bouncing of walking 10 feet allows some of the returning eye-leg to feed into the collar and give it the collar hole in the pictures.  The knot does not lock down into an immovable locked knot in my rope, though the tail stays put nicely, despite that.  The next picture is a little jiggle.  I'd guess that tiny hole or simply the width of the rope of the collar is all that could have been snagged.  I do not believe the knot would have opened further than the zoomed in picture by the time that I fell.

This is used rope with no core or sheath issues.  I do not know the brand or model, but it was originally purchased by a climbing gym before being given to me to practice tying with so I didn't have to pull out 60m or use the small nylon I had laying around.

My theory is that my position and the orientation of the knot to my harness allowed the ongoing eye-leg to receive a small tug before the returning eye-leg was set and added friction to the standing/nipping parts.  From how I usually feed my harness loops, this would mean that my leg loops pulled first, as I usually feed my harness bottom to top.  Once the standing end, the nipping loop and the ongoing eye-leg overcome the initial friction, there isn't much to stop it from feeding through, at least in this rope.

I do have trouble reproducing this in my stiffer, fuzzier rope.

Anyway, that's all I've got to say on the matter.  I just thought that since it happened, I should tell someone.

EUREKA!

It was bothering me that NotLikely's collar did not expand during his snag.  I think the collar never snagged.  I think it was the inner crotch of the loop near the intersection of the initial bowline coil.  Once I snagged there, it was much easier to reproduce the reported incident.

update:

[SS369]

EUREKA!

It was bothering me why NotLikely's collar did not expand during his snag.  I think the collar never snagged.  I think it was the inner crotch of the loop near the intersection of the initial bowline coil.  Once I snagged there, it was much easier to reproduce the reported incident.

So you tied into your harness with it, climbed some, fell and snagged the knot and duplicated the failure ?

I think you are misleading the readers here. If the knot was dressed as it should be, easy enough, there will be nothing or nowhere for a "protuberance" to find entry. One would have to manufacture the conditions perfectly (every time) to even get close to this happening, or aim just right.
All the people that are using it have had no problem with it. It certainly hasn't caused them to be pushed away from a face nor has it come undone during ascent or descent.

I think your Eureka moment is a poof. 

SS

[roo]

EUREKA!

It was bothering me why NotLikely's collar did not expand during his snag.  I think the collar never snagged.  I think it was the inner crotch of the loop near the intersection of the initial bowline coil.  Once I snagged there, it was much easier to reproduce the reported incident.

So you tied into your harness with it, climbed some, fell and snagged the knot and duplicated the failure ?

I think you are misleading the readers here. If the knot was dressed as it should be, easy enough, there will be nothing or nowhere for a "protuberance" to find entry. One would have to manufacture the conditions perfectly (every time) to even get close to this happening, or aim just right.
All the people that are using it have had no problem with it. It certainly hasn't caused them to be pushed away from a face nor has it come undone during ascent or descent.

I think your Eureka moment is a poof. 

SS

You don't understand;  the protrusion never enters the knot.  It's under the knot.  I'll attach a photo marked with a red X.

[agent_smith]

per roo:

You don't understand;  the protrusion never enters the knot.  It's under the knot.  I'll attach a photo marked with a red X.

I think Scott understands perfectly well.

I think your so called Eureka moment is gone in a "poof" of smoke

roo - what you have described induces circumferential loading profile - aka 'ring loading'.... because you are snagging the eye (not the collar).

Scotts locked Bowline is resistant to circumferential loading.

When this knot is correctly dressed and cinched tight in EN892 rope - with an eye not larger than 100mm - the likelihood of snagging the eye is remote (infinitely small).
As stated, even IF you managed to snag the eye - nothing happens because Scotts locked Bowline is resistant to ring loading.

I presume that you will reply and counter by stating that Scotts locked Bowline is vulnerable to circumferential loading?
If yes - and you are determined to announce Scotts locked Bowline's vulnerability to circumferential loading - you would need to provide evidence of the dressing state for your test.
I would assume that the dressing state for your 'Eureka test' was loose and with an eye larger than 100mm?

[roo]

per roo:

You don't understand;  the protrusion never enters the knot.  It's under the knot.  I'll attach a photo marked with a red X.

I think Scott understands perfectly well.

I think your so called Eureka moment is gone in a "poof" of smoke

roo - what you have described induces circumferential loading profile - aka 'ring loading'.... because you are snagging the eye (not the collar).

Scotts locked Bowline is resistant to circumferential loading.

When this knot is correctly dressed and cinched tight in EN892 rope - with an eye not larger than 100mm - the likelihood of snagging the eye is remote (infinitely small).
As stated, even IF you managed to snag the eye - nothing happens because Scotts locked Bowline is resistant to ring loading.

I presume that you will reply and counter by stating that Scotts locked Bowline is vulnerable to circumferential loading?
If yes - and you are determined to announce Scotts locked Bowline's vulnerability to circumferential loading - you would need to provide evidence of the dressing state for your test.
I would assume that the dressing state for your 'Eureka test' was loose and with an eye larger than 100mm?

This is a little different than simple ring loading.  There are more forces involved with the protrusion pushing under the knot and the legs at a much different angle.    I would invite you to step away from the keyboard for a few hours and do some testing.  You may owe an apology to NotLikely.