International Guild of Knot Tyers Forum

General => Knotting Concepts & Explorations => Topic started by: agent_smith on April 27, 2020, 01:41:32 AM

Title: Scotts locked Bowline (failure mode)
Post by: agent_smith on April 27, 2020, 01:41:32 AM
I started this new topic in response to a post by KnotLikely.
Reference link: https://igkt.net/sm/index.php?topic=6689.msg44495#msg44495

Alleged failure mode:
Quote
Scott's Lock just scared the crap out of me.  I was playing around with snags on the wall and I caught the collar (try sticking your thumb through the returning leg side).  My knot was suddenly 3 feet away from me and out of reach, with a hoop of eye legs big enough to crawl through.  If my (imaginary, thanks covid) belayer had slack in the line, this would take it all in to expand the tie-in loop.  This seems to be an issue with all single nipping loop bowlines that I have tested.

and this:

Quote
I snagged the collar and fell.  The knot did not fall apart, but the standing end pulled through like it was made of ice.  The knot was slightly looser than when initially set.

and this:
Quote
The extra friction introduced by the lock is not much in even slightly slicker rope.  Even in ideal conditions, I was unable to recreate this issue with my red (fuzzy) rope.  But it certainly Did happen.

and...
Quote
I'm surprised that this comes as a surprise to you.  ...  The extra friction introduced by the lock is not much in even slightly slicker rope.  Even in ideal conditions, I was unable to recreate this issue with my red (fuzzy) rope.  But it certainly Did happen.

In reply to refute to this alleged failure mode.
1. Scotts locked Bowline is an inherently secure Bowline.
2. It is intended to be tied in EN892 climbing rope
3. As with all tie-in knots to a harness, it must be tied diligently and accurately - in a tight and compact dressing state.
4. The size of the 'eye' of the Bowline must be small - not larger than 100mm diameter.

The alleged failure mode is entirely dependent on "snagging the collar".
KnotLikely asserts that he was able to "snag the collar" - which sets in motion a cascading series of events.

My contention is the 'test' conducted by KnotLikely is flawed.
In order to "snag the collar" - a very specific set of circumstances must be achieved.
As a thought experiment - even if such a test was carefully designed and could successfully "snag the collar" - this by itself does not mean catastrophic core failure leading to ejection from the climbing harness.

Any test which could 'successfully' snag the collar would be counter-balanced by the body weight of the climber. There would be a force pulling upwards which is counter-balanced by the weight of the climber pulling downwards.
Such a test would require pinpoint accuracy - to target the single rope diameter of the collar and lift it upwards from the core.

There needs to be a downwards trajectory - ie the climber would need to be free-falling (ie an uncontrolled fall) or be lowered (which is conducted slowly and deliberately).

I am of the view that this alleged failure mode is being overstated - and is conditional on the following:
1. Pinpoint accuracy to target the collar
2. Relaxation of the counter-balancing force of the climbers body weight (which acts in a downward direction).
3. A loose initial dressing state - so as to improve the odds of successfully snagging the collar during a fall or while being lowered.
4. The climbers body would have to come into very close proximity to the cliff (ie rock face) - implying a slab rather than a vertical or overhanging section of rock. If a slab, this suggests the climbers waist is scraping down the slab - feet pulled back.

I do not believe that a test could be designed in which others could reproduce the same failure mode.

I'm therefore calling this a false positive.

EDIT NOTE: Image added
Title: Re: Scotts locked Bowline (failure mode)
Post by: Dan_Lehman on April 28, 2020, 01:01:41 AM
Mr. WordsWork, here,
and would like to see a sketch of the reported
failure / problem state.

I don't understand how snagging the collar
doesn't spill the knot but results in a large loop?!

... staying tuned ...

Meanwhile, I like the middle version  of A_S's trio
of versions, where the tail turns around 2dia (and
becomes TIB though that's irrelevant for tie-in).


--dl*
====
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on April 28, 2020, 06:12:15 AM
Quote
I don't understand how snagging the collar
doesn't spill the knot but results in a large loop?!
I think the first step is to design a test that can be reproduced by others.
See attached for a design proposal...

Note:
A problem will arise with the design of the protuberance.
The intent is to 'snag' and displace the collar 'upwards'.
There needs to be agreement of the shape of the protuberance - which will obviously have significant impact on the experimental results.
In the first instance, the 'snag' must successfully catch (ie 'snag') the collar.
Once snagged - it must remain in effective contact with the collar - so as to displace it.
While this is occurring, a continuous counterbalancing force must be maintained in the 'downward' direction (ie the climbers body weight).
I am of the view that 100kg would be a fair and reasonable weight (ie approx 1.0kN).

The tester would need to guide the collar to accurately snag the protuberance.
The intent is to simulate a climber who is free-falling or being lowered.
Free-fall is sudden shock loading to the collar.
A climber being lowered is a deliberate and slow process.
Title: Re: Scotts locked Bowline (failure mode)
Post by: SS369 on April 29, 2020, 02:36:51 PM
So, the conversation about the Scotts locked Bowline snagging and coming undone, failing, sounds like someone is trying very hard to discredit the simple lock. 

I have personally tried the tying of this in many different media and it has worked to lock the #1010 Bowline, and it hasn't failed.
This is my tie in and go to eye knot and I use it without a doubt multiple times during my week. It works and it is simple.

After reading the other post in the forum about the snagging and finding the knot some distance away from the particular climber it peaked my interest.

Using some BlueWaterII (7/16 inch), I tied the knot with a Sharpie (even tried it using a tapered spike) in the collar area between the SP and WE. I dressed and set it the same as I do normally whether climbing tie in or otherwise.

Putting my foot in the eye, then pulling up on the Sharpie/toggle using both hands, one on each side of the knot. Slow, hard pull - no untying.
Hard yanks, no untying.
Doing the same pulls with the SP in tension, no untying.

IMO, the reality of something inserting into a well dressed knot just boggles my mind. I can't visualize it and I am a climber.

Yes, the collar stretches open some, but no untying. The nip grips as it should.

I've repeated this "test" in accessory cord (6mm), paracord and twisted nylon rope, even slick poly throw cord, no untying.

I think if someone doesn't want to use it, doesn't like it for whatever reason, (real or not) then by all means don't. Please don't disparage it in a public forum as the truth according to you. Show some proof, not hypothetical imaginings..

SS
Title: Re: Scotts locked Bowline (failure mode)
Post by: Dan_Lehman on May 01, 2020, 02:57:08 AM
Quote
I don't understand how snagging the collar
doesn't spill the knot but results in a large loop?!
I think the first step is to design a test that can be reproduced by others.
See attached for a design proposal...
Okay, thanks for the good quick images.
And the assertion is that such a snag
rather than spilling the knot
drew in more & MORE SPart so to enlarge
the eye hugely?!  --a reverse-direction slippage
to what Brion Toss showed for a dbl.BWL tied
in HMPE cord, where the eye collapsed.

Well, my, this would be mighty disconcerting
to a tied-in climber!

Quote
So, the conversation about the Scott's locked Bowline snagging and coming undone,
failing, sounds like someone is trying very hard to discredit the simple lock.
But, rather, I think it's more general than any
particular BWL : it would apply to most any
that have a simple nipping-loop base (vs. two
such loops or the water bwl and so on).
It stayed Scott-locked, just had a growing spurt!
And in the "it's not a bug, it's a feature" spin of
it all, it showed a way of semi-soft-belaying
oneself, surpassing they infamous Tarbuck h.!


--dl*
====
Title: Re: Scotts locked Bowline (failure mode)
Post by: SS369 on May 01, 2020, 03:10:31 AM
Quote
I don't understand how snagging the collar
doesn't spill the knot but results in a large loop?!
I think the first step is to design a test that can be reproduced by others.
See attached for a design proposal...
Okay, thanks for the good quick images.
And the assertion is that such a snag
rather than spilling the knot
drew in more & MORE SPart so to enlarge
the eye hugely?!  --a reverse-direction slippage
to what Brion Toss showed for a dbl.BWL tied
in HMPE cord, where the eye collapsed.

Well, my, this would be mighty disconcerting
to a tied-in climber!

Quote
So, the conversation about the Scott's locked Bowline snagging and coming undone,
failing, sounds like someone is trying very hard to discredit the simple lock.
But, rather, I think it's more general than any
particular BWL : it would apply to most any
that have a simple nipping-loop base (vs. two
such loops or the water bwl and so on).
It stayed Scott-locked, just had a growing spurt!
And in the "it's not a bug, it's a feature" spin of
it all, it showed a way of semi-soft-belaying
oneself, surpassing they infamous Tarbuck h.!


--dl*
====

Hello Dan.
Why are you combining quotes from two different authors in the same post without differentiating who wrote them?
You've quoted Agent Smith first and then the first line of my post in your input.

And I don't follow what you've written about my sentence, please elaborate. Is there some tongue in cheek in there?

SS
Title: Re: Scotts locked Bowline (failure mode)
Post by: KnotLikely on May 03, 2020, 05:11:01 AM
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.
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 03, 2020, 06:03:38 AM
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.
While I've been a fan of the Scott's Lock general slack shaking 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)

I haven't been following this discussion closely, but I think I was able to reproduce what you are talking about in snagging so thank you for bringing it up.  When that large, wide upper collar gets snagged, the clamping forces let loose and allow sliding.  I think if it's something that happened in real life, it's worth considering.

Upon revisiting the knot, I also see that the shiftiness of the form can allow a snag of the tail to capsize the knot while pulling the standing part.  I believe it is the same capsized form I first saw by accident while doing cyclical strain tests many years ago on the specimen with different degrees of snugness.  I think the collar snagging vulnerability you found is the greater risk with a more hazardous outcome.  Good find.  I'm glad you were not harmed.

P.S.  This seems like a thread that should be moved out of the Concepts Forum and into the Practical Knots Forum.
Title: Re: Scotts locked Bowline (failure mode)
Post by: Dan_Lehman on May 03, 2020, 09:57:11 PM
Quote
Quote
But, rather, I think it's more general than any
particular BWL : it would apply to most any
that have a simple nipping-loop base (vs. two
such loops or the water bwl and so on).
It stayed Scott-locked, just had a growing spurt!
And in the "it's not a bug, it's a feature" spin of
it all, it showed a way of semi-soft-belaying
oneself, surpassing they infamous Tarbuck h.!


--dl*
====

Hello Dan.
Why are you combining quotes from two different authors in the same post without differentiating who wrote them?
You've quoted Agent Smith first and then the first line of my post in your input.
Because in this few-posts thread anyone considering
the points should have that clear enuff!
Quote
And I don't follow what you've written about my sentence, please elaborate. Is there some tongue in cheek in there?
Simply as I said, the slippage is of the SPart
and not any un"locking" of the knot --that the
hooked collar supposedly just arrested the knot
(nub) in place and then the loaded eye pulled
material through the knot on via the outgoing
eye leg (which leads to the SPart).

(And that all this movement likely had some
decelerating effect on the suspended load.)

--as contrasted with something that might've
pulled apart the lock.

--dl*
====
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 05, 2020, 12:33:50 AM
Scotts locked Bowline (failure mode)

In reply to all posters who subscribe to, and support the notional concept that Scotts locked Bowline has a potential vulnerability in that the collar could be 'snagged' which leads to catastrophic failure.

Answer: No - there is no such vulnerability and no such failure mode in real-world climbing conditions.

Assumptions:
1. That EN 892 dynamic rope was used.
2. That testing was carried out on a real natural rock surface while climbing.
3. That the tie-in knot (ie Scotts locked Bowline) was diligently dressed and cinched tight with an eye not exceeding 100mm).
4. That the tie-in knot was maintained under continuous body weight at all times during the test.

On Monday 04 May 2020, I conducted a series of tests while climbing on a real natural rock surface.
I climbed using a 'top rope' climbing system - using Scotts locked Bowline as my tie-in knot to my harness.
I made vigorous efforts to snag and disrupt the collar on the rock surface - each attempt was unsuccessful.
I tried scraping the front of my body down the rock surface in an effort to catch a snag and disrupt the collar - again unsuccessful.
I deliberately positioned the collar on a 'snag' and then tried to vigorously bounce on the snag to disrupt the collar - again unsuccessful.

I gave up after 30 minutes because I was becoming fatigued from the effort - and my belay person was growing impatient and bored.

I would also comment that Scotts locked Bowline is oriented so that the collar faces either to the left or right...it never faces directly toward the rock surface. This is due to the design of all climbing harnesses. Given this orientation - it is even harder to snag the collar. Despite this orientation, I deliberately rotated the knot in an effort to forcibly direct the collar on to the 'snag'.
All unsuccessful.

I would also comment that while the knot is under continuous full body weight, the knot core is under compression - and so it is very tight.

I therefore conclude that KnotLikely is deliberately doing 'something' which introduces bias into his test results.
I would surmise that he has deliberately loosened the knot to improve the odds of achieving a snag or, removed his body weight from the knot.
Else, he has precisely targeted a snag at an acute angle with some deliberate earlier loosening of the knot in order to disrupt the collar (which would invalidate the test).

Another issue is the notional concept of reproducibility.
I am of the view that other testers would not be able to reproduce KnotLikely's test result in the field (ie on a real rock surface).
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 05, 2020, 12:44:28 AM
Scotts locked Bowline (failure mode)

In reply to all posters who subscribe to, and support the notional concept that Scotts locked Bowline has a potential vulnerability in that the collar could be 'snagged' which leads to catastrophic failure.

Answer: No - there is no such vulnerability and no such failure mode in real-world climbing conditions.

Assumptions:

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

That's not a very realistic assumption.  In real-world use, knots are sometimes slack.
Title: Re: Scotts locked Bowline (failure mode)
Post by: KnotLikely on May 05, 2020, 12:47:05 AM
Really, agent Smith?  All those words just to call me a liar?!

If you *conclude* that what happened to me didn't happen, then your conclusions are worthless.

Also, what is going on with you not just moving the goal posts, but creating new ones?  "Oh, he removed his body weight from the knot and it was deliberate!"  Yes, it is impossible to pull in standing line when the belayer is keeping you tight on top rope!  Imagine that.

I stated very clearly that belay slack is what will be pulled in to extend the eye-loop.  You can't keep your bodyweight on a knot that isn't weighted.  I have no idea what your issue is, but I'm done, here.  It happened.  I fell.  The eye-loop extended with slack.  Get over it.  I am.  Bye.
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 05, 2020, 12:59:39 AM
per KnotLikely:
Quote
Really, agent Smith?  All those words just to call me a liar?!
? Never called you a liar.
You should tender an apology for such a remark.

Quote
If you *conclude* that what happened to me didn't happen, then your conclusions are worthless.
Wrong.
Read more carefully before posting such comments.
Scotts locked Bowline is intended a climbing tie-in knot (right?).
Life critical applications is its scope of use.

Quote
Also, what is going on with you not just moving the goal posts, but creating new ones?
?  I report real world results under climbing conditions.
Scotts locked Bowline is intended as a tie-in knot for climbing (and can also be used to build anchors).
No goal posts have been shifted.
In the context of a tie-in knot - your test results cannot be duplicated in the field uder real-world conditions.

It is you who is skewing the goal posts with your test regime (not me).

Quote
Get over it.  I am.  Bye.
There is nothing to 'get over'.
I simply report the facts.
You appear to dislike the facts?

You might want to reconsider your attitude.
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 05, 2020, 02:24:30 AM
per roo:
Quote
That's not a very realistic assumption.  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.
Incompetence can be a contributing factor to climbing accidents - but then you would have to attack an entire cohort of skills that climbers must possess.

I think your comment; "real world use" is referring to situations other than rock climbing/mountaineering.

The context of this failure mode debate is tie-in knots for climbing - specifically; Scotts locked Bowline.

I think this point is getting lost in translation.

Also, if a person was to call into question the reliability of Scotts locked Bowline - that person has the burden of proof.
That is, the onus of proof lies with the person making a claim that Scotts locked Bowline is not fit for purpose on account of a vulnerability triggered by snagging the collar.
And this is the heart of KnotLikely's proposition - he announced to the world via a public forum that Scotts locked Bowline has a vulnerability. Such an announcement would raise alarm in the minds of some climbers. Casual readers of IGKT forum posts (such as from KnotLikely) might develop concerns based on unrealistic test conditions to induce failure.

There are no liars in this debate.
The issue is lack of understanding of key fundamental factors to induce the purported failure mode under real-world climbing conditions.
Scotts locked Bowline's principal application is as a tie-in knot for climbing (it can also be used to build anchor systems).

Extraordinary claims require extraordinary evidence.
Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3114207/
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 05, 2020, 03:10:32 AM
per roo:
Quote
That's not a very realistic assumption.  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.
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 05, 2020, 03:38:40 AM
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).

Quote
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?
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 05, 2020, 04:15:46 AM
per roo:
Quote
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.
Title: Re: Scotts locked Bowline (failure mode)
Post by: KnotLikely on May 05, 2020, 06:47:46 PM
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.

Quote
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.
Title: Re: Scotts locked Bowline (failure mode)
Post by: Dan_Lehman on May 05, 2020, 10:51:48 PM
per roo:
Quote
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*
====
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 06, 2020, 12:32:20 AM
per KnotLikely:
Quote
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.

Quote
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).

Quote
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.

Quote
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.

Quote
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.

Quote
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!
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 06, 2020, 01:11:42 AM
per Dan Lehman:
Quote
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.

Quote
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.
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 06, 2020, 10:39:27 PM
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.
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 06, 2020, 10:54:39 PM
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.
Title: Re: Scotts locked Bowline (failure mode)
Post by: SS369 on May 07, 2020, 01:03:48 AM
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
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 07, 2020, 01:27:00 AM
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.
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 07, 2020, 11:46:10 PM
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:

Title: Re: Scotts locked Bowline (failure mode)
Post by: SS369 on May 08, 2020, 12:18:37 AM
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.  :D :( ::)

SS
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 08, 2020, 12:26:00 AM
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.  :D :( ::)

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.
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 08, 2020, 12:55:24 AM
per roo:
Quote
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?

Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 08, 2020, 01:08:31 AM
per roo:
Quote
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.
Title: Re: Scotts locked Bowline (failure mode)
Post by: SS369 on May 08, 2020, 01:22:36 AM
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.  :D :( ::)

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.

Your are correct, I don't understand and you have not explained anything very well.
Just how have you loaded it and performed the failure. Are you tied in? Is the eye/loop loaded? Any tension on the standing part? Are you loading the tail instead? How do you push under the knot?
 Is this in any way a real world scenario??
The Eureka X signifies nada at this point.
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 08, 2020, 01:42:29 AM
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.  :D :( ::)

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.

Your are correct, I don't understand and you have not explained anything very well.
Just how have you loaded it and performed the failure. Are you tied in? Is the eye/loop loaded? Any tension on the standing part? Are you loading the tail instead? How do you push under the knot?
 Is this in any way a real world scenario??
The Eureka X signifies nada at this point.
I assumed it was clear, but I'm happy to explain any details in relation to the photo.  The harness pulls at the bottom of the loop.  The protrusion (at X) provides the reaction upward against the knot and the standing part starts sliding.  The knot body is allowed to sit on the shelf as the standing part slides, so it's not really comparable to simple free air ring loading.

I'm kicking myself that I didn't see it earlier.   I'm always snagging loops inside the crotch of the two legs.
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 08, 2020, 03:25:30 AM
per roo
Quote
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.
?
What a strange and odd comment.
It is even more odd when you consider that I have already tested this type of loading profile - which is essentially circumferential in scope.
I am curious if you were in close proximity to your keyboard while contemplating your underlying motive for these strange and odd comments?

In the first instance, KnotLikely pointed toward snagging the collar. One presumes that you are now ignoring his original proposition and morphing his purported failure mode into something of an entirely different character.

While you are contemplating notional concepts of apology, - I guess this means you owe me an apology?
Also with such apologies, it implies some form of misbehavior or misdeed that one person did to another - to which an apology is owed?
This in turn leaves me wondering where the act of the misdeed lies?

While you are entertaining matters of 'apology' - I am curious if your Eureka test had the following parameters:
1. That you used EN892 rope?
2. That you correctly dressed and cinched Scotts locked Bowline tightly?
3. That you created an eye not larger than 100mm?
4. That you lowered yourself in a climbing harness and intercepted a protuberance on a rock surface?
5. That the interception of the protuberance occurred within the eye at a point on the outgoing eye leg proximal to the knot core?
6. That you managed to cause structural disruption to the knot core - leading to a situation where the eye of the knot significantly expanded ?

Extraordinary claims require extraordinary evidence. :)

EDIT NOTE: I'll post some photos of Scotts locked Bowline under various loading profiles...
Title: Re: Scotts locked Bowline (failure mode)
Post by: SS369 on May 08, 2020, 03:50:48 AM
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.  :D :( ::)

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.

Your are correct, I don't understand and you have not explained anything very well.
Just how have you loaded it and performed the failure. Are you tied in? Is the eye/loop loaded? Any tension on the standing part? Are you loading the tail instead? How do you push under the knot?
 Is this in any way a real world scenario??
The Eureka X signifies nada at this point.
I assumed it was clear, but I'm happy to explain any details in relation to the photo.  The harness pulls at the bottom of the loop.  The protrusion (at X) provides the reaction upward against the knot and the standing part starts sliding.  The knot body is allowed to sit on the shelf as the standing part slides, so it's not really comparable to simple free air ring loading.

I'm kicking myself that I didn't see it earlier.   I'm always snagging loops inside the crotch of the two legs.

I call misinformation.

I just tried multiple attempts to induce a failure or duplicate your claim.

BlueWater II rope, 1/2 inch diameter. Tied, weighted, inserted various "protuberances" of varied diameters. Pulled steady with all my strength, Approx. 300#'s, jerked, jumped, twisted and repeated this 10 separate times. Even untied and retied for a few of these "tests".
Not only did I not experience a failure, the knot tightened further than the original setting of it.
Easily untied though.
In my opinion, there is nothing you can say or prove, to me, that will convince me that your claim is factual, nor will anything you add dissuade me from its use. And I will continue to teach it to anyone who cares to learn it.

If you find that you do not agree, then fine, don't use it for anything.

Stay away from snagging your crotch and don't kick too hard...   ;)
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 08, 2020, 06:58:05 AM
In my opinion, there is nothing you can say or prove, to me, that will convince me that your claim is factual, nor will anything you add dissuade me from its use. And I will continue to teach it to anyone who cares to learn it.

If you find that you do not agree, then fine, don't use it for anything.

I'm sorry there is nothing I can "say or prove".  Maybe I'll have to break down and get a YouTube channel to upload video of the event.  It took only about 50 or 60 pounds at the bottom of the loop with a suspended 1.25" wooden dowel under the knot in the "x" location in the attached photo just now to make it slide in BlueWater II rope.
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 08, 2020, 07:59:51 AM
TEST REPORT
Note: This test configuration is not designed to snag the collar.
It is something of a completely different character...as per roos' 'Eureka moment'.

Image is attached of load test configuration using EN892 rope.
As I had already known through previous testing and real-world experience, there is no such failure mode.

I reached a force of 5.2kN - which is over 500kg (metric).
Note also that the knot is carefully dressed and cinched up tight - as would occur in real world climbing conditions.
The eye was set at 100mm.

The fact that I can't repeat other peoples alleged experimental test results indicates something is fundamentally wrong with their reported failure mode.
It must be due to non EN892 rope or, the knot isn't properly cinched tight (ie the tester deliberately ties the knot in a loose dressing state).

EN892 rope is correct for climbing applications.
However, EN1891 rope can also be used for anchoring situations (eg around a sturdy tree).
I had previously tested this knot using EN1891 - and can confirm there is no alleged failure mode in this rope either.

EDIT NOTE: It appears that roo has ignored the #1034 1/2 variant when making his Eureka moment declaration.
There are in fact 4 different variants of Scotts locked Bowline...and I am also unclear if 'KnotLikely' has also overlooked this fact?
Title: Re: Scotts locked Bowline (failure mode)
Post by: SS369 on May 08, 2020, 03:24:26 PM
In my opinion, there is nothing you can say or prove, to me, that will convince me that your claim is factual, nor will anything you add dissuade me from its use. And I will continue to teach it to anyone who cares to learn it.

If you find that you do not agree, then fine, don't use it for anything.

I'm sorry there is nothing I can "say or prove".  Maybe I'll have to break down and get a YouTube channel to upload video of the event.  It took only about 50 or 60 pounds at the bottom of the loop with a suspended 1.25" wooden dowel under the knot in the "x" location in the attached photo just now to make it slide in BlueWater II rope.

Pictures or it didn't happen. Proof is on you.
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 08, 2020, 09:08:55 PM
In my opinion, there is nothing you can say or prove, to me, that will convince me that your claim is factual, nor will anything you add dissuade me from its use. And I will continue to teach it to anyone who cares to learn it.

If you find that you do not agree, then fine, don't use it for anything.

I'm sorry there is nothing I can "say or prove".  Maybe I'll have to break down and get a YouTube channel to upload video of the event.  It took only about 50 or 60 pounds at the bottom of the loop with a suspended 1.25" wooden dowel under the knot in the "x" location in the attached photo just now to make it slide in BlueWater II rope.

I noticed that once slipping starts, it is really easy to keep sawing away even if you pause and resume.  The protrusion must be affecting the knot body in some way.

P.S. Thank you, moderators, for not censoring/deleting the incident report per agent_smith's request.
Title: Re: Scotts locked Bowline (failure mode)
Post by: Dan_Lehman on May 08, 2020, 11:13:35 PM
Btw, did you try the snagged-collar situation,
which I believe IS what KnotLikely cited (I don't
see him denying it, and is more likely to leave
the knot *nub* up high as SPart flows through
it, than your ring-loading case which could bring
the knot down from the upper apex) ?!

Ring-loading, btw, is something that in my somewhat
casual playing around with doesn't always produce
the feared slippage in the common/#1010 BWL that
it CAN do --a YMMV case.  So, different results shown
here (Roo's vs. A_S's) although contradictory still can
be the "YMMV"'d cases proving that "may vary" point.
(And can tickle the how-to-properly-SET-a-knot issue.)

And, I will reiterate to Scott, that we see not the SLock
failing to keep intact, but ... slippage of the SPart through
the knot, which should be findable in other BWLs.


--dl*
====
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 08, 2020, 11:45:48 PM
Btw, did you try the snagged-collar situation,
which I believe IS what KnotLikely cited (I don't
see him denying it, and is more likely to leave
the knot *nub* up high as SPart flows through
it, than your ring-loading case which could bring
the knot down from the upper apex) ?!
Yes, I tried it in many different forms, but it was much more difficult, required special shapes that didn't seem to match his blockish-corner description, and would stretch the collar.  It was that last factor that made me try something else, and on the first or second try of that something else, I noticed the slide that did not affect the collar.

I think a blockish shape could make it easier to keep the knot body on the shelf, but even in my tests, as you'll notice in the video, sometimes sliding really takes off after the knot wobbles off the shelf.

P.S.  I think KnotLikely is gone for good from this forum.  He did not like the treatment he got from agent_smith.
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 09, 2020, 12:09:57 AM
per roo:
Quote
P.S. Thank you, moderators, for not censoring/deleting the incident report per agent_smith's request.
?

Thank you roo for posting a test video that bares no resemblance to a real-world climbing situation.

Testers have a duty to properly declare the application of their test to the context in which it applies.
Casual readers of your post will likely be misled into believing that Scotts locked Bowline is not fit for purpose in climbing applications.

I note that you didn't use EN892 dynamic rope in your test - this makes the test invalid.

I note that the knot wasn't properly cinched up tight - as it would be in real climbing activities.

I note that the eye of the knot was incredibly large (ie oversize). This is also incorrect.

I note that a climber would have to stop climbing, ask a gremlin to grasp the tip of the eye of the tie-in knot who would then pull down.
The climber would have to remain stationary and wait while the gremlin imitates some see-saw hack to eye legs of the knot - and then pulls the outgoing eye leg down.

I note that there cant be any load on the Standing Part (SPart) - this cant be replicated on a real cliff in a real climbing situation.

...

As the tester, you should type a conclusion as follows:

Conclusion:
The conditions to induce slippage of the SPart through the core of knot require an initial set of parameters that don't exist in real climbing conditions.
There must be zero load on the SPart and something has to initiate a downward pull on the outgoing eye leg. Furthermore, the eye of the knot must be tied oversize (normally it would be approximately 100mm). The test video did not employ EN892 rope and the knot was loosely dressed - both of these parameters depict conditions that don't exist in real climbing.
The effect produced in this video cannot occur in real climbing conditions - it is for academic purposes only.
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 09, 2020, 12:22:02 AM
per roo:
Quote
P.S. Thank you, moderators, for not censoring/deleting the incident report per agent_smith's request.
?
Thank you roo for posting a test video that bares no resemblance to a real-world climbing situation.
You really need to stop in every conceivable sense of the word.  I'm not taking any testing advice from someone who assumes that knots are only allowed to exist in taut line:


Answer: No - there is no such vulnerability and no such failure mode in real-world climbing conditions.

Assumptions:

4. That the tie-in knot was maintained under continuous body weight at all times during the test.
Title: Re: Scotts locked Bowline (failure mode)
Post by: enhaut on May 09, 2020, 12:29:16 AM
@ Roo
I don?t want to piss on your parade but it seem obvious to me that you test bowline is not cinched properly.
Looking at the frames between 13-14 seconds a neophyte like me can see the bad state of dressing in a place that can render the slipping behaviour possible.

image from Youtube = bad dressing
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 09, 2020, 12:38:28 AM
@ Roo
I don?t want to piss on your parade but it seem obvious to me that you test bowline is not cinched properly.
Looking at the frames between 13-14 seconds a neophyte like me can see the bad state of dressing in a place that can render the slipping behaviour possible.

image from Youtube = bad dressing
Thick BlueWater II is stiff line.  It's hard to get it to cinch tighter, and even if you managed it, it doesn't take much motion at all to spring to where it wants to go.

Also, your image shows the knot after failure.
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 09, 2020, 12:49:25 AM
per roo:
Quote
Thick BlueWater II is stiff line.  It's hard to get it to cinch tighter, and even if you managed it, it doesn't take much motion at all to spring to where it wants to go.
EN892 dynamic rope is the correct material for a tie-in knot to a climbers harness.

Tying-in with stiff EN1891 rope would be reckless and incompetent.

roos test to assess a failure mode in Scotts locked Bowline is fundamentally flawed because:
1. He used incorrect rope material; and
2. He failed to cinch the knot tight (because he used the wrong rope).

I think roo needs to look in the mirror.
This will provide him with an opportunity to reflect on the invalidity of his test conditions.
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 09, 2020, 02:24:21 AM
While I was pondering roo's reflection in a mirror, it occurred to me that he could also run a second test.

It would be a reflection of his first test - where everything is 'reversed'.

That is, he could use EN892 rope instead of incorrect EN1891 rope.
He could dress and cinch the knot tightly - as opposed to loosely.
He could ensure the eye is no larger than 100mm - instead of half the size of mainland USA.

This would create a fair and accurate representation of the parameters in a real climbing situation.

If roo chooses not to run this second test - it would indicate that he is unwilling to report in a fair and balanced manner - choosing only to report biased tested results.
Furthermore, knowing that his original test is being propagated through the internet and likely being misreported/overstated, he has a duty to correct this situation.
Title: Re: Scotts locked Bowline (failure mode)
Post by: SS369 on May 09, 2020, 05:23:18 PM
Quote
Thick BlueWater II is stiff line.  It's hard to get it to cinch tighter, and even if you managed it, it doesn't take much motion at all to spring to where it wants to go.

I don't agree with this. I can easily pinch a bight to close it smaller than one diameter.
I also don't believe that an eye that large is a real world use that will get snagged in the way you've contrived.
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 09, 2020, 07:48:27 PM
I don't agree with this. I can easily pinch a bight to close it smaller than one diameter.
I'm not disagreeing with the proposition that it is possible to get a tighter knot, especially if you are in the upper percentiles for strength.  I part ways with the idea that testing should give preference to the easiest conditions for a knot and ignore the rest of the bell curve.
Title: Re: Scotts locked Bowline (failure mode)
Post by: SS369 on May 09, 2020, 08:00:22 PM
I don't agree with this. I can easily pinch a bight to close it smaller than one diameter.
I'm not disagreeing that it is possible to get a tighter knot, especially if you are in the upper percentiles for strength.  I part ways with the idea that testing should give preference to the easiest conditions for a knot and ignore the rest of the bell curve.

With any testing of knots, there should be a benchmark to adhere to. A fully tightened knot, such as minimal spaces within the structure would qualify for such adhoc tests.
Many knots will fail when left loose.
If you can't reach that benchmark, then I'd say the test doesn't qualify.
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 09, 2020, 08:09:59 PM
I don't agree with this. I can easily pinch a bight to close it smaller than one diameter.
I'm not disagreeing that it is possible to get a tighter knot, especially if you are in the upper percentiles for strength.  I part ways with the idea that testing should give preference to the easiest conditions for a knot and ignore the rest of the bell curve.

With any testing of knots, there should be a benchmark to adhere to. A fully tightened knot, such as minimal spaces within the structure would qualify for such adhoc tests.
Many knots will fail when left loose.
If you can't reach that benchmark, then I'd say the test doesn't qualify.
The pictured knot is hardly "left loose".  After some motion and bumps, even a tighter Scott's Locked Bowline knot could easily get looser than the one shown.  The tight hairpin change of direction at the lower edge of the knot doesn't lend itself to easy closing.  During failure in the video with the standing part sliding through the knot, it's not surprising that this ends up springing back more.

Nor does the two parts of rope going through the upper collar lend itself to a compact upper region.

One nice thing about the Figure of Eight loop, by contrast,  is that the gradual curvatures make for easier tightening and less tendency for spring-back.
Title: Re: Scotts locked Bowline (failure mode)
Post by: SS369 on May 09, 2020, 08:44:37 PM
I don't agree with this. I can easily pinch a bight to close it smaller than one diameter.
I'm not disagreeing that it is possible to get a tighter knot, especially if you are in the upper percentiles for strength.  I part ways with the idea that testing should give preference to the easiest conditions for a knot and ignore the rest of the bell curve.

With any testing of knots, there should be a benchmark to adhere to. A fully tightened knot, such as minimal spaces within the structure would qualify for such adhoc tests.
Many knots will fail when left loose.
If you can't reach that benchmark, then I'd say the test doesn't qualify.
The pictured knot is hardly "left loose".  After some motion and bumps, even a tighter Scott's Locked Bowline knot could easily get looser than the one shown.  The tight hairpin change of direction at the lower edge of the knot doesn't lend itself to easy closing.  During failure in the video with the standing part sliding through the knot, it's not surprising that this ends up springing back more.

Nor does the two parts of rope going through the upper collar lend itself to a compact upper region.

One nice thing about the Figure of Eight loop, by contrast,  is that the gradual curvatures make for easier tightening and less tendency for spring-back.

Well it is certainly well tightened. I wouldn't leave it like that for my use, especially in a life critical situation.
And I certainly don't believe that I will ever be in a scenario where the eye is that large and a "protuberance" will engage this knot as in the way you're forcing a failure.
If you accept the dressing and tightness of the video'd knot then please don't volunteer to be my climbing partner. ;-)
As for loosening up; it is the user who is responsible for diligence of their own safety.

Please lets not bring other knots into this thread. They have there own foibles.
Title: Re: Scotts locked Bowline (failure mode)
Post by: agent_smith on May 10, 2020, 02:37:45 AM
What continuously amazes me is the fact that there is no tester willing to step up to the plate and run the same test using EN892 rope in a properly dressed and cinched Scotts locked Bowline.

Furthermore, it also amazes me that none of the current crop of hobbyist/enthusiast testers test the other versions of Scotts locked Bowline.
They seem to fixate only on one of the 4 possible versions and also fixate on an eye half the size of mainland USA.

When pondering these facts - it strikes me as highly unusual and hints of experimental bias.

A potential problem with hobbyist/enthusiast testers is that they are not held to account for the design and structure of their testing regime.
They are free to undertake and publish whatever 'results' and 'conclusions' that fit their personal narrative. Human bias can also be driven my emotional desire to vindicate a personal opinion.

Here's a challenge for a hobbyist/enthusiast knot tester:
1. I challenge you to use EN892 rope
2. I challenge you to dress and cinch the knot tightly with an eye not exceeding 100mm
3. I challenge you to test all 4 versions of Scotts locked Bowline

And finally, I challenge you to publish your test results (with strict adherence to the above points) and write a conclusion.
Title: Re: Scotts locked Bowline (failure mode)
Post by: KnotLikely on May 14, 2020, 11:36:32 PM
This is the mode of failure that happened in real life. (Second video without me also holding the tail in place with the collar).

Make the knot tighter and you'll get more resistance.  At some point, you won't be able to overcome the initial friction with bodyweight.  Standard Scott's bowline (as opposed to the left hand / cowboy version) does not stay tight enough to prevent body weight from pulling standing line slack through.  Test all you want.  Decide that it is impossible all you want.  It happened in real life.  The slack all pulled into the eye-loops.

https://vimeo.com/418599010

The knot is not built to stay rock solid tight.  The nipping loop and collar are not structures that are made to prevent the ongoing eye-leg from feeding back through the 1mm necessary to allow the returning eye-leg the ability to give an extra couple mm to the collar.

https://vimeo.com/418599156

I was holding the tail in this video.  Yes, I'm only pulling on the ongoing eye-leg.  The returning leg is directly stuck on a snag.  Yes, there should be extra friction from the harness loops sliding down the rope, but there should also be much more weight than me just quickly tugging.  I can't currently get video of this on the wall (without endangering my skull).

Somehow the tail stayed almost perfectly in place when this happened in real life.  I assume that it was pinned by the snag, somehow.  I slid a few feet down a vertical face.  I assume the knot was pointed down (gravity, and all) and turned up when it hit what it snagged on.  The knot, as pictured in this video, is not immediately post setting.  I held the standing end and banged it on the ground two times then immediately took this video.  I would guess this is equivalent to having climbed a little bit.  Scott's lock (non left hand / cowboy version, at least) knot does not stay perfectly set.  This is rope that I have personally climbed on at, and was purchased by, my gym before it was cut into sections for discarding.  I was given this piece to practice tying with.  It is most certainly a rope built and rated for climbing.  I trust that my gym and insurance company are not messing around.  I'll be happy to get the brand and model when they open back up.
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 14, 2020, 11:51:36 PM
Somehow the tail stayed almost perfectly in place when this happened in real life.
My guess (as stated in the other thread (https://igkt.net/sm/index.php?topic=6781.msg44706#msg44706)) is that this might be consistent with a failure mode as shown in the video at the beginning of that same spinoff thread:



Title: Re: Scotts locked Bowline (failure mode)
Post by: SS369 on May 15, 2020, 07:18:43 PM
I don't agree with this. I can easily pinch a bight to close it smaller than one diameter.
I'm not disagreeing with the proposition that it is possible to get a tighter knot, especially if you are in the upper percentiles for strength.  I part ways with the idea that testing should give preference to the easiest conditions for a knot To Fail (As it should read)and ignore the rest of the bell curve.
I'm sorry that you seem to not have the determination or ?strength? to snug this knot as it should be, although it takes very little effort. Please don't use it.

If I use any knot, your gnathitch loose for example, it too will fail. Push or pull enough and Eureka! Please don't use it loose!

I have tested, with my own existence, this eye knot and used it exclusively for my eye knot needs and have never had a failure of any kind. I don't use it loose. And I tie in with it, using it with confidence born from my own tests and evaluated usage.
Other users have given positive feedback.

To anyone concerned: If you feel uncomfortable using it - don't.

SS
Title: Re: Scotts locked Bowline (failure mode)
Post by: roo on May 15, 2020, 07:52:19 PM
I don't agree with this. I can easily pinch a bight to close it smaller than one diameter.
I'm not disagreeing with the proposition that it is possible to get a tighter knot, especially if you are in the upper percentiles for strength.  I part ways with the idea that testing should give preference to the easiest conditions for a knot To Fail (As it should read)and ignore the rest of the bell curve.
I'm sorry that you seem to not have the determination or ?strength? to snug this knot as it should be, although it takes very little effort. Please don't use it.

I would request that when you quote my posts, you do not insert your own verbiage to make it look like I said something I did not say.
Title: Re: Scotts locked Bowline (failure mode)
Post by: SS369 on May 15, 2020, 08:55:53 PM
Your request is under consideration.
It did look as though you forgot to write it though. I thought I was being helpful.
Next time I'll try to be more thoughtful.
Title: Re: Scotts locked Bowline (failure mode)
Post by: KnotLikely on May 17, 2020, 09:09:15 PM
Scott, do you set and dress this knot by tugging on the returning eye-leg until the collar folds the knot in half?

I've never once seen a picture of it that way, but that would explain why you think we have it set so loosely.  I generally tighten extremely hard without deforming the shape pictured in agent_smith's photos.

If I push the tail's hard turn around the nipping loop at the same time as I tug the returning eye-leg as hard as I can, the knot folds in half and the S-Part makes a hard bend.  I never really set it like that because I expect the S-Part to straighten on a fall until it forms the nipping loops.

I don't think of the collar of a bowline as something required to stay tight.  Am I wrong about that?
Title: Re: Scotts locked Bowline (failure mode)
Post by: SS369 on May 17, 2020, 09:39:22 PM
Scott, do you set and dress this knot by tugging on the returning eye-leg until the collar folds the knot in half?

I've never once seen a picture of it, that way, but that would explain why you think we have it set so loosely.  I generally tighten extremely hard without deforming the shape pictured in agent_smith's photos.

If I push the tail's hard turn around the nipping loop at the same time as I tug the returning eye-leg as hard as I can, the knot folds in half and the S-Part makes a hard bend.  I never really set it like that because I expect the S-Part to straighten on a fall until it forms the nipping loops.

I don't think of the collar of a bowline as something required to stay tight.  Am I wrong about that?

Hello Knotlikely.

I dress my and set all my knots tightly. I believe that a loose or slightly loose knot promotes failure or weakening due to friction upon load tightening. The movement under strain is mitigated more so if well tightened. IMO

I'm sorry you don't think that the collar should stay tight. My personal belief is that it should, as should the other parts.

As for the locked bowline, I tighten it in no particular order, just get it tight. When it is snugged well, I take and check it by pulling the eye legs apart (ring load it). I consider it ready for my use then.

Yes, the collar bends the SP and tail, but that straightens some under load.
It is then near to impossible to grasp the collar and pull it as shown in your video. Or I am such a weakling that I just can not do it.
As a climber and a man who works with his hands strenuously all day, I don't think the latter is quite so.

Once the collar is flexed back and forth the knot parts can be loosened for untying.
I have never been able to fail it, in any way, in various cords and ropes that I own ( a huge collection of many makers media) tied the way I do. Although, in tiny string or yarn it forget about untying it.  ;)

I have never claimed that this "lock" is the end all, be all. It is just a Simple lock, that works, for the #1010 common bowline.
Used correctly, it is a competent addition to secure the #1010.

One should have confidence in their tie in and if you lack this, use something else, by all means. It is your life on-a-line.
All knots (even spliced eyes) can fail, somehow, someway, whether by insecurities, jamming or breakage.

SS
Title: Re: Scotts locked Bowline (failure mode)
Post by: Dan_Lehman on May 17, 2020, 11:00:42 PM
Scott, do you set and dress this knot by tugging on the returning eye-leg until the collar folds the knot in half?
That was an admission some years ago,
but I think he's adjusted since then.  IMO, that is
NOT a properly set bowline (and in any case
is destined upon expected loading to pull out the
collar --can't load the nipping turn w/o getting past
the (too-tightly set) collar otherwise, though it
can be that the SPart yet is overly bent even so.
Also, the one-diameter bend is a hard thing to sell
to firm rope!

And such a binding isn't all so stable : in e.g. the
Perfection/Angler's loop (#1017), that is how the
SPart encompasses the eye legs, and can jam
rather firmly (but maybe its jamming has been
over-rated, for practical uses), but both of the
surrounded parts are under tension along with
the surrounding one; whereas in the BWL of a
tucked-out tail, the tail is NOT loaded,
and the 2dia widening the collar into tightness
can shift into a perpendicular-to-that orientation
(vs. collar-bight apex, one below the other,
so effectively a 1dia turn just backed up by
a 2nd 1dia part) --like having utility poles
in a straight line vs. in a triangular (for 3) group
such as can be found at piers.

Quote
I don't think of the collar of a bowline as something required to stay tight.
There is a variation --an extension-- that provides an
opposed-bight collar, which then can oppose the
basic one for a good tight nip on the SPart.
(Follow from the common BWL taking the tail
as the SPart's draw will take it (as done in the
Yosemite BWL and around on the outside
of the near side of the collar, back in on other
side between SPart and that collar side,
and --this is key to being able to loosen it--
then tuck out through nipping turn with
slight twist over/around SPart --which is what
makes this so-tucked tail a tool/lever to use
to prise out some bit of SPart, later, to loosen.

THIS knot can be set tight, as the SPart need
not bend one way or other, the opposed-bights
come together around IT.
AND I think it will defeat the particular loosening
mechanism you discovered fortuitously.  (bonus)


--dl*
====