Author Topic: Scotts locked Bowline (failure mode)  (Read 2961 times)

SS369

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Re: Scotts locked Bowline (failure mode)
« Reply #30 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.

roo

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Re: Scotts locked Bowline (failure mode)
« Reply #31 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.
« Last Edit: May 08, 2020, 01:44:29 AM by roo »
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agent_smith

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Re: Scotts locked Bowline (failure mode)
« Reply #32 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...
« Last Edit: May 08, 2020, 03:28:29 AM by agent_smith »

SS369

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Re: Scotts locked Bowline (failure mode)
« Reply #33 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...   ;)

roo

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Re: Scotts locked Bowline (failure mode)
« Reply #34 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.
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agent_smith

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Re: Scotts locked Bowline (failure mode)
« Reply #35 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?
« Last Edit: May 08, 2020, 02:03:27 PM by agent_smith »

SS369

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Re: Scotts locked Bowline (failure mode)
« Reply #36 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.

roo

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Re: Scotts locked Bowline (failure mode)
« Reply #37 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.
« Last Edit: May 08, 2020, 10:52:30 PM by roo »
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Dan_Lehman

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Re: Scotts locked Bowline (failure mode)
« Reply #38 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*
====
« Last Edit: May 15, 2020, 07:40:14 PM by Dan_Lehman »

roo

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Re: Scotts locked Bowline (failure mode)
« Reply #39 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.
« Last Edit: May 13, 2020, 10:49:20 PM by roo »
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agent_smith

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Re: Scotts locked Bowline (failure mode)
« Reply #40 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.

roo

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Re: Scotts locked Bowline (failure mode)
« Reply #41 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.
« Last Edit: May 09, 2020, 12:25:37 AM by roo »
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enhaut

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Re: Scotts locked Bowline (failure mode)
« Reply #42 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
« Last Edit: May 09, 2020, 12:36:19 AM by enhaut »

roo

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Re: Scotts locked Bowline (failure mode)
« Reply #43 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.
« Last Edit: May 09, 2020, 12:39:05 AM by roo »
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agent_smith

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Re: Scotts locked Bowline (failure mode)
« Reply #44 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.