Author Topic: Tokyo Olympics boulder climbing knot  (Read 878 times)

Festy

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Tokyo Olympics boulder climbing knot
« on: August 06, 2021, 05:23:56 PM »
What is the knot used on the safety rope where it attaches to the front of the climbers harness?

roo

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Re: Tokyo Olympics boulder climbing knot
« Reply #1 on: August 06, 2021, 06:50:05 PM »
What is the knot used on the safety rope where it attaches to the front of the climbers harness?
Since you have a very specific event listed in the title, perhaps you have a specific screen capture you could share of the knot you are trying to identify.
If you wish to add a troll to your ignore list, click "Profile" then "Buddies/Ignore List".


agent_smith

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Re: Tokyo Olympics boulder climbing knot
« Reply #2 on: August 06, 2021, 11:48:21 PM »
Hello 'Festy',

A point of clarification with the title of your topic thread:
In bouldering, there is no rope and no safety harness!


I think your meant to type 'lead climbing'.

In lead climbing, there is a special type of rope: EN 892 dynamic rope.
It is tied directly into the climbers harness.
The knot is standardised - and is required to be a #1047 Figure 8 (with a backup safety knot).
The backup safety knot is a 'strangled double overhand knot" (it is 'strangled' around the SPart).

Please refer to the competition rules here: https://cdn.ifsc-climbing.org/images/World_Competitions/IFSC_Rules_2020_v151_PUBLIC_compressed.pdf

Refer to: 7.5 B) sub para 2).

...


Commentary:
Climbers (in general) aren't knotting experts or knot geeks.
They don't care about the technical detail about knots.
In fact, some climbers resist learning new knots.
Its sort of like a computer...most users of computers know how to use their computer. But, they don't really know or care about what goes on underneath the bonnet.

In the IGKT forum, you will find knot geeks who do care, and do understand what goes on underneath the bonnet.

If you manage to find closeup video footage of the detail of a climbers F8 tie-in knot, you'll likely see variations in geometry. Most climbers don't understand 'chirality' (handedness) of knots. They just tie their knot the way they were taught. Some will tie with 'S' chirality, while others will tie with 'Z' chirality. Also, the relative position of the SPart as it enters the knot core will vary. The safety judges just look at the overall shape/pattern of the F8 knot - they wouldn't know much about geometric details... because that's in the realm of the knot geek!

Fortunately, the #1047 F8 knot is inherently secure regardless of its chirality and relative position of the SPart as it enters the knot core. This is one of the principal drivers for why it remains the overall most popular tie-in knot (but, knot geeks will choose alternatives).

EDIT NOTE:
Check out this youtube channel: https://www.youtube.com/c/sportclimbing/featured

Here is a lead climbing video: https://www.youtube.com/watch?v=LbrXQ0rugJo (older, but gives you an idea).
I use this video as an example of why I personally don't tie-in with a #1047 F8.
At 10:45 in the video, he struggles to untie his knot (after only one low impact fall)!
'Bowlines' dont suffer from this issue...
« Last Edit: August 07, 2021, 12:35:47 AM by agent_smith »

Festy

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Re: Tokyo Olympics boulder climbing knot
« Reply #3 on: August 07, 2021, 01:42:05 PM »
Thank you AS for that excellent explanation and sorry about the misleading thread title.

Yes, I noticed that all the climbers shown on tv were having a lot of trouble undoing the knot after they were finished their climb.

Also, it was fascinating watching the athletes performing those difficult  climbs.

wysper

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Re: Tokyo Olympics boulder climbing knot
« Reply #4 on: August 08, 2021, 11:51:00 PM »
Hiya Festy,

I have posted this link before (i think).
I am not sure how well it stands up to our knot experts here, but I found it really interesting in relation to the figure 8 and how easy/hard it is to untie.
The vid is about 18min long but worth it if you are interested.
He also has another video on an easy way to tie yourself in using the fig 8. I am not a climber but still found it really cool.

Here is the link to the vid on the fig 8 and why it might be hard to untie.
https://youtu.be/QAr-uHd8h8o

Cheers
Greg

agent_smith

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Re: Tokyo Olympics boulder climbing knot
« Reply #5 on: August 09, 2021, 01:30:36 AM »
There are several glaring issues with the tests carried out in the youtube link provided by 'wysper'.
The youtube channel is called "hard is easy" - and the presenters name is Ben (from Spain).

I've been in contact with him about a few of his videos - to give critical feedback in good faith.

These days - its super easy for people to get offended or get hurt feelings with any kind of critique...I found Ben to be receptive to new ideas and new ways of thinking.

The one thing I do like about his F8 videos is that he isn't doing the same old boring, mind numbing. and groupthink "pull-it-till-it-breaks' type knot testing.
Groupthink link: https://en.wikipedia.org/wiki/Groupthink

He is looking at the cause and effect of jamming.
The problem is that he fails to follow basic '101' rules of testing - such as:
1. No load cell (there is no way to know what peak loads he reached)
2. No way of knowing what is the magnitude of his drop mass (at least we can see that he can lift the drop mass with one hand - he should have identified a specific drop mass; eg 80kg or 100kg).
3. He mixes 2 different variables in one test (bad idea - only test one variable at a time).
4. He does not reveal the rope specifications used in the test! (we can guess its EN892...but, there are variations across different rope manufacturers - he also does not specify diameter - and he does not compare against EN1891 low stretch rope.
5. He does not perform slow pull tests on a test bed to determine the load threshold which triggers jamming...the F8 will jam, no matter which orientation is used, it eventually jams.)

Anyhow, I will be posting a full test report in the "Knot test reports" section of the IGKT forum.
« Last Edit: August 09, 2021, 01:33:27 AM by agent_smith »

wysper

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Re: Tokyo Olympics boulder climbing knot
« Reply #6 on: August 09, 2021, 02:00:52 AM »
Hi Agent smith

Not sure why you put 'wypser' in commas. I sign my name at the end of my posts.

I got the feeling he wasn't trying to do any scientific proofs for rigorous peer testing.
The vibe I got was he was trying to show that if you tie the knot one particular way it was easier to untie.

Anyway, I still think it was interesting and found that if I tied the figure 8 the way he describes, it is definitely easier to untie.

But I guess I was looking for different things from the video.

Cheers
Greg

agent_smith

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Re: Tokyo Olympics boulder climbing knot
« Reply #7 on: August 09, 2021, 03:51:49 AM »
To 'wysper' (Greg):
Quote
Not sure why you put 'wypser' in commas. I sign my name at the end of my posts.
What a strange and odd comment to make.
I thought your forum name was 'wysper'?

I speak and use the English language (ie I am a native English speaker).
They are not commas - they are single quotation marks and they can be used for all sorts of writing styles.

People refer to me as 'agent_smith' or by my real name (note my use of single quotation marks).
I really don't care either way.
I don't get easily offended...

Anyhow:

Ben (youtube video) at least was looking at something other than the mind numbing and meaningless pull-it-till-it-breaks type testing.
I contacted him via email and congratulated him for looking at jamming phenomena rather than groupthink pull-it-till-it-breaks type knot testing.

My fundamental point is:
Ben is publishing his tests to the world - and as such, he has a 'duty' to try to get the basic science correct.
If you're going to the trouble of publishing a video to the world - why not make the extra little effort to get the basic 101 science correct?

Festy

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Re: Tokyo Olympics boulder climbing knot
« Reply #8 on: August 09, 2021, 09:43:10 AM »
Hiya Festy,

I have posted this link before (i think).
I am not sure how well it stands up to our knot experts here, but I found it really interesting in relation to the figure 8 and how easy/hard it is to untie.
The vid is about 18min long but worth it if you are interested.
He also has another video on an easy way to tie yourself in using the fig 8. I am not a climber but still found it really cool.

Here is the link to the vid on the fig 8 and why it might be hard to untie.
https://youtu.be/QAr-uHd8h8o

Cheers
Greg

Thanks for that, Greg.

DerekSmith

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Re: Tokyo Olympics boulder climbing knot
« Reply #9 on: September 08, 2021, 06:53:23 PM »
There are several glaring issues with the tests carried out in the youtube link provided by 'wysper'.' He is looking at the cause and effect of jamming.
'snip'
The problem is that he fails to follow basic '101' rules of testing - such as:
1. No load cell (there is no way to know what peak loads he reached)
2. No way of knowing what is the magnitude of his drop mass (at least we can see that he can lift the drop mass with one hand - he should have identified a specific drop mass; eg 80kg or 100kg).
3. He mixes 2 different variables in one test (bad idea - only test one variable at a time).
4. He does not reveal the rope specifications used in the test! (we can guess its EN892...but, there are variations across different rope manufacturers - he also does not specify diameter - and he does not compare against EN1891 low stretch rope.
'snip'

Hi Mark,

Your fixation with "basic '101' rules of testing" seems to have led you to missing the point of the work which is encapsulated by the term 'Comparative'.  Absolute and Comparative are two equally viable methods of evaluation.  Having run Analytical Laboratories for many years, I can assure you that Comparative testing is an essential part of the assessors toolkit.  In fact 'Absolute' testing can often be misleading unless rigorous calibration of test equipment is embedded in the test regime.  'Putting a number on something' often leads to a wholly undeserved perception of accuracy.

So, to respectfully correct your critique :-
Quote
1. No load cell (there is no way to know what peak loads he reached)
No load cell was needed because both knots were subject to the same loading.  In fact the greater the range of loading involved, the more robust the observation if one knot form consistently performed in the observed manner.

Quote
2. No way of knowing what is the magnitude of his drop mass (at least we can see that he can lift the drop mass with one hand - he should have identified a specific drop mass; eg 80kg or 100kg).
Again,no additional value is obtained from knowing the value of the drop mass, nor it's fall, nor any initial velocity imparted at dispatch, nor the elasticity of the attaching connections - indeed, any of the system for applying a shock force simulating some degree of fall onto the two knots.  Indeed, again, the greater range of load forces utilised in the trials the more robust the conclusions that may be drawn from the final observations of the performance of each knot in the comparative pair.

Quote
3. He mixes 2 different variables in one test (bad idea - only test one variable at a time).
Unless I have missed something (in which case I hope you will correct me), his test comprises two knots, but only one variable (loose vs tight, or inside vs outside).  This a completely legitimate first order comparison and will yield unambiguous data.  However, had the system under study needed to reflect two interacting variables, this would also have been totally legitimate, but would of course have required a large 2 dimensional test matrix set and far more extensive data interpretation.

Quote
4. He does not reveal the rope specifications used in the test! (we can guess its EN892...but, there are variations across different rope manufacturers - he also does not specify diameter - and he does not compare against EN1891 low stretch rope.
Again, you have missed the point that it is the knot configuration that is under test, not its substrate.  In fact, the wider the range of substrates included in the comparative test, the more robust would have been the outcome.  Had one cord type, size, material have yielded a contradictory result, then that would have triggered a totally different study into the cause of the observed effect, but for this case it was virtually irrelevant other than the question which pertained to the specific situation of climbers using the F8 for tying in, therefore any climbing rope should have sufficed.

Derek

agent_smith

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Re: Tokyo Olympics boulder climbing knot
« Reply #10 on: September 09, 2021, 12:19:18 AM »
This post is directed at Derek:

# Also - apologies, my post is off-topic. But since Derek has chosen to direct his intentions toward me, I am choosing to respond in kind.

In reply:
Quote
Your fixation with "basic '101' rules of testing" seems to have led you to missing the point of the work which is encapsulated by the term 'Comparative'.
I'm unclear of the underlying intent behind the typed word "fixation".
Maybe you are fixated on something else?

One of the so called '101' rules that you allude to is repeatability.
As 'Ben' was publishing his test to the 'world', he does a have a basic duty to get the 101 rules correct.
No one can repeat his tests with certainty and be confident of their results - partly because we have no idea of the type of test article and the force he generated.
It is a 101 basic concept that a force is being generated - and there is a level of force which triggers the initial threshold jamming state of a #1047 F8 knot.
I would also point out that the definition of 'jamming' was not fully described/quantified (see below at end of my post).

Quote
No load cell was needed because both knots were subject to the same loading.
?
This statement is non-sensical.
Presumably, I could conclude from your premise that any type of knot test setup that involves 2 knots doesn't require measurement of force.
eg test on say #1053 derived Butterfly bend to probe threshold jamming state requires no measurement - we could just guess the loads generated?
It raises the the question; what is the point of measurement? Testing normally involves measurement of some type - so it is repeatable by others.
And; what is the difference in level of force require to reach threshold jamming state of knot 'A' versus knot 'B'? Is the difference statistically significant?

Quote
Again,no additional value is obtained from knowing the value of the drop mass, nor it's fall, nor any initial velocity imparted at dispatch, nor the elasticity of the attaching connections
?
As above.
It raises the question: What is the value of measuring force? In other words - anyone can publish test results without specifying the peak loads they reached.
I of course think this would create an odd situation - if all testers published their results without specifying force.
eg "I picked up a mass in my hands and dropped it...now all of you other testers around the world can try and repeat my results! And by the way, try and guess what type of rope i used!"

Quote
Unless I have missed something
Your fixation on me has misled you, and caused you to miss many basic 101 rules of testing.
eg... What type of rope was used in the test? What was the drop mass? What was the peak load?
And, he should have tied identical knots at each end (not mix 2 different geometries).

Quote
This a completely legitimate first order comparison and will yield unambiguous data.  However, had the system under study needed to reflect two interacting variables...
I disagree.
As a rule, only one variable should be tested.
With identically tied knot specimens at each end, you have the ability to compare each knot.
One is attached to a fixed anchor point, and the other is attached to a moving mass of unknown quantity.
We are robbed from seeing the comparison between the 2 identical knots - in terms of their individual response to load.

Quote
Again, you have missed the point that it is the knot configuration that is under test, not its substrate.
Again - I think you have missed some basic rules of testing. That is, specify the parameters of the test article. Why make it a guessing game?
It seems that you have no concept that climbing ropes are highly variable in their performance?
I am quite shocked by your apparent lack of knowledge.
For example, are you are aware of the EN892 specification? Are you aware that in each of the 3 sub-categories of dynamic rope, there is great variance in rope diameter, core construction, sheath construction, stiffness and elongation?

Quote
therefore any climbing rope should have sufficed.
This is a nonsensical statement.
See above - there is huge variance between climbing ropes.
Furthermore, in the case of 'twin' or 'half' ropes, it is a requirement that 2 ropes are tied into the climbers harness.
That is, there are 2 ropes which are each subject to load.
Presumably, the tester 'assumed' the case of a 'single' category - and ignored the other 2 cases?
Even if he ignored the other 2 cases, there is still the fact that a climbing rope is tied directly into the harness - which captures the bridge of the leg loops and the waist loop - which provides both stretch and a larger contact angle.

............

Overall, on the surface it appears as a seemingly odd post by Derek.
But what is the underlying intent?
What kind of message does it send to knot testers around the world?
In a general browse of the myriad of knot test papers and videos, it is very rare to find published work that omits things such as the type of test article, the loads that were achieved and the mass that was used to achieve those loads.
My own theory is that it is youtube phenomena - anyone can become a tester and 'publish'.
Note: I do encourage people to test! Testing is good.
Just try to test in a way that makes it easy for others to try to repeat the results.
And at least try to give an indication of the type of rope that was tested and the force that was generated.

Here's 2 really simple questions:
1. What is the magnitude of the force required to reach the threshold jamming state of a #1047 F8 knot tied in EN892 (single category) rope of 9.1mm nominal diameter - tied in specific way #1 (image given to reveal precise geometry)?
2. What is the magnitude of the force required to reach the threshold jamming state of a #1047 F8 knot tied in EN892 (single category) rope of 9.1mm nominal diameter - tied in specific way #2 (image given to reveal precise geometry)?
NOTE: 9.1mm diameter dynamic rope is the average (mean) diameter in common use with rock climbers.
Although I have to admit that Beal (France) are great innovators in rope technology - take for example their 'Opera' EN892 8.5mm diameter rope - which is certified across all 3 categories of EN892. Such a thin rope (8.5mm) is pushing the envelope - and it also uses  bonded 'unicore' which would be interesting to test and compere to a non-bonded sheath/core interface. Again - we don't have any peer reviewed test data on how these unicore ropes compare to non unicore copes (in terms of jamming threshold). I have no clue as to what type of rope 'Ben' tested in his video - its a guessing game (unless he's updated his video or added commentary since I last checked??).

Jamming definitions given as follows:
[ ] Threshold jamming state: The knot can eventually be loosened and untied by hand (without the use of tools) - but only after considerable effort and time.
[ ] Maximal jamming state: Loosening the knot is beyond the level of human hand strength - tools are required to loosen the knot (but damage will be negligible/trivial).
[ ] Irreversible jamming state: The knot is fused/welded and cannot be loosened and untied without causing severe and permanent damage (due to the use of tools and considerable force)
« Last Edit: September 09, 2021, 02:11:23 AM by agent_smith »

Dan_Lehman

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Re: Tokyo Olympics boulder climbing knot
« Reply #11 on: September 09, 2021, 07:47:41 PM »
Quote
1. No load cell (there is no way to know what peak loads he reached)
No load cell was needed because both knots were subject to the same loading.  In fact the greater the range of loading involved, the more robust the observation if one knot form consistently performed in the observed manner.

Quote
2. No way of knowing what is the magnitude of his drop mass (at least we can see that he can lift the drop mass with one hand - he should have identified a specific drop mass; eg 80kg or 100kg).
Again,no additional value is obtained from knowing the value of the drop mass, nor it's fall, nor any initial velocity imparted at dispatch, nor the elasticity of the attaching connections - indeed, any of the system for applying a shock force simulating some degree of fall onto the two knots.  Indeed, again, the greater range of load forces utilised in the trials the more robust the conclusions that may be drawn from the final observations of the performance of each knot in the comparative pair.
Well, it could be helpful to know forces if e.g. they might
come at what would be seen as far in excess of expected
forces.  (E.g., testing the abseil-lines joining "EDK" (offset
water knot)
and finding that it ultimately "rolls" at ... and
then breaks at ... can be helpful in seeing that one's expected
oh, couple hundred pounds forces will be WAY shy of the
forces where behavior was affected in the tests.)

Quote
Quote
4. He does not reveal the rope specifications used in the test! (we can guess its EN892...but, there are variations across different rope manufacturers - he also does not specify diameter - and he does not compare against EN1891 low stretch rope.
Again, you have missed the point that it is the knot configuration that is under test, not its substrate.
It's often misleading to see physical behavior
attached to a non-physical "knot" rather than
to the particular object in a particular medium.

But I do think that the testing had things to open
one's eyes to --just the fundamental difference between
what I call "interior/exterior" loading, finally!

Now, overall in knots there's a glaring lack of focus
on specificity --of reasonable exactness of a properly
dressed & set knot.  No, the "<knot_ID>" just reaches
to a general overall construction, and that's it; from there,
various tyers tie variously shaped knots and then ... who
knows what's going on.
Though this is NOT to suggest that knots must always be done
in some quite specific way; but there's a big gap to close, as things
stand.  (It might well be the case that the variability is expressly
recognized, and some assurances given that the range of behavior
is all in a good safe zone.)  But if one's going to generate test
values to bandy about, there should be precision so we can know
how to understand differences likely to arise with others' numbers.
--and not to attribute such variation to a *knot*.

 ;)
« Last Edit: September 10, 2021, 05:01:11 PM by Dan_Lehman »

agent_smith

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Re: Tokyo Olympics boulder climbing knot
« Reply #12 on: September 10, 2021, 01:01:55 AM »
Well at least I think it is fair to say that the original posters question has been answered:
Quote
What is the knot used on the safety rope where it attaches to the front of the climbers harness?
Answer = #1047 Figure 8 (although in 'bouklering' - there is no rope and no harness)

With regard to all of the followup posts, this is really drifting to a discussion about the youtube video posted by 'Ben' about the jamming characteristics of the #1047 F8 knot.
I have been in contact with Ben (and Ryan Jenks) and given feedback about their knot test videos.

Ben is definitely purchasing the new linescale 3 load cell (and so am I).
This is good - because he will be able to publish the loads he achieved on particular knots and contexts in which knots are used.

Another issue is that giving critical feedback is fraught with risk.
Some people simply cannot accept criticism in any form - and become offended or have their feelings hurt.
Some only want to hear congratulatory feedback - but that's not how you learn.
My feedback is not calculated to cause harm - it is intended to help Ben improve his test design so that others can try to repeat his results.
And here is a key word; repeatability.

Another aspect is that Ben is publishing to the world - and most laypeople (by default) will perceive him as an 'expert'.
His methods and his test results are then perceived to be accurate by default.

I reaffirm that in his drop tests (which all had an unknown mass and unknown peak load) - he should have tied identical knot specimens at each end termination.
In fact, in his tests - he mixed 2 different knots.
I have always held the view that you should only test one (1) variable at a time.

By tying two (2) identical knots - the same knot specimen at each end termination - you now have an opportunity to directly compare how both knots responded to the impact force of the fall.
One knot is attached to a fixed (stationary) anchor point, and the other is attached to the moving load. I'll refer to this test configuration as test article 'A'.
Now it is of interest to know if there are any differences between each of the knots - for example, was the knot at the fixed anchor point easier/the same/harder to untie relative to the knot at the moving mass? In other words, what is the relative degree of jamming in one knot compared to the other identical knot? If there is a difference, what does this tell us?

You then repeat this test configuration using the other knot specimen - which I'll describe as test article 'B'.
You can then compare test article 'A' against test article 'B'.

Ben's method of generating force was not tightly controlled.
He simply lifted the mass in his hands to some height - and then released it.

Normally, you would ensure that the peak loads are identical across each test drop.
Instead of lifting the mass by hand - he could have used a simple hoisting system - and lifted the drop mass to a specific position/height.
This also implies a 'fall-factor' - ie the overall length of the rope versus the length of the fall.
In my view, Ben's approach would have been subject to variation - that is, the force generated in each test drop was not consistent.

Ben had no way of ensuring that the peak loads he generated were consist from one test to the next.

Now this is not offensive - its just feedback - and its a factual statement.
Ben agrees - and he is purchasing the new linescale 3 load cell.

He also acknowledges that it would have been good to identify the type of rope he used in the tests! (rather than leaving it as a guessing game).
There is huge variance in dynamic climbing ropes.

I also remarked previously that Ben did not define the term 'jamming'.
Jamming was the principle point of his test - and yet, he did not define it.

What is jamming?
How do we define jamming?
Are there different degrees of jamming?

I certainly believe that there are indeed different degrees of jamming.

EDIT NOTE:
One other aspect of Ben's test regime that could be improved is to also run a series of tests using slow pull method on a horizontal test bed.
That is, slowly increase load on the test article to determine the load at which point initial threshold jamming occurs.
Lets say for the argument that initial threshold jamming is triggered at 4.0kN in test article 'A'.
It would be interesting to compare this to a dynamic drop test - of equivalent peak load (ie 4.0kN).
It should be possible to set the test drop to yield 4.0kN - Ben could determine the drop parameters empirically if need be.
Although it would be super easy to perform the drop test first - measure the peak load from that drop, and then perform the slow pull test to the same force.
I personally would start at 3.0kN, and then scale up in 1.0 kN increments until threshold jamming is triggered (on a horizontal slow pull test bed).
Once the threshold jamming value is known - it can be compared to the dynamic drop tests.
Again, Ben would have to set his test rig to yield 4.0kN force (F=Ma, so he could work it out with math - but can also just do it empirically as I already mentioned).
Of course - the type of rope used in the test needs to be specified (obviously) - because there is huge variance in dynamic climbing ropes.
I would also repeat the tests using low stretch EN1891 type A rope of the same diameter.

1. Test article 'A' is slow pulled to 4.0kN on a test bed; and
2. Test article 'A' is subjected to an impact force of 4.0kN.
The same test series is performed on test article 'B'.
This would provide a very interesting comparison.
To the best of my knowledge - no body has done this.
« Last Edit: September 10, 2021, 04:42:06 AM by agent_smith »

DerekSmith

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Re: Tokyo Olympics boulder climbing knot
« Reply #13 on: September 14, 2021, 12:37:48 AM »
This post is directed at Derek:

# Also - apologies, my post is off-topic. But since Derek has chosen to direct his intentions toward me, I am choosing to respond in kind.

Likewise, apologies to the OP for my continuing this post off topic, but excuse my actions as I think the opening question has been answered.  Ideally this ongoing discussion is important enough to warrant its own thread - perhaps an admin could split it off for us??

Quote
In reply:
Quote
Your fixation with "basic '101' rules of testing" seems to have led you to missing the point of the work which is encapsulated by the term 'Comparative'.
I'm unclear of the underlying intent behind the typed word "fixation".
Maybe you are fixated on something else?



@Mark.  I do not know what standards of politeness you are used to operate to, but where I come from it is the height of bad practice to edit a quote from another poster.  No matter how trivial, by altering the emphasis by emboldening parts of the quote, you risk changing the tone and intended tenor of the posters text.  It is ill mannered and risks bringing the reliability of all your reply and future post into question.

I do not expect you to humble yourself with an apology, but I do request you not to descend to these sort of antics in the future.

Second, you repeatedly refer to the knot in point as the #1047 F8 knot.  Let us be precise here, we are talking about a climbers F8 tie in knot which is not the #1047.  Ashley, the author of the term #1047 describes an inline loop knot TIB with both legs loaded.  He even describes that the loading may be in parallel of in opposition.  While the form of the knot core may be identical, as you well know, the loadings and usage of a knot are just as important in defining the knot we are studying - maintaining a little precision here will aid the clarity of our thinking and further discussion don't you think?

Quote
The problem is that he fails to follow basic '101' rules of testing - such as:
1. No load cell (there is no way to know what peak loads he reached)
2. No way of knowing what is the magnitude of his drop mass (at least we can see that he can lift the drop mass with one hand - he should have identified a specific drop mass; eg 80kg or 100kg).
3. He mixes 2 different variables in one test (bad idea - only test one variable at a time).
4. He does not reveal the rope specifications used in the test! (we can guess its EN892...but, there are variations across different rope manufacturers - he also does not specify diameter - and he does not compare against EN1891 low stretch rope.
'snip'

Forgive me please for quoting from one of your previous posts but I am having a real problem with your "basic '101' rules of testing".  As I mentioned previously, I have spent my carreer running analytical laboratories involved in Physical, Chemical and Biological testing, and I have to ask - Where did you get your basic 101 rules from?  Are they your own creation? 

Let me please give you two very real 'Rules of Testing' :-

1: Define the goal and scope of the test.
2: Eliminate Analyst Bias.

Ben achieved this admirably.  His goal was to identify why some climbers had serious problems untying their F8 tie in when he never had a problem.  He set the scope to climbing rope with a moderate fall loading and even included a number of rope samples, recognising the variation that exists in climbing ropes and applied a number of loading scenarios focused around a short hard fall.
As his assessment was to be comparative, he eliminated test variation by subjecting his single variable to identical conditions and even took steps to eliminate assessment bias by blinding his samples (although the results were so extreme and consistent, there was no need for the blinding).

The examination was of such an excellent design it addressed the defined goal perfectly and yielded reproducible and unquestionable results and conclusions.  By blinding his test pieces, he even managed to randomise the knot form that was attached to the load point in case there was some shock effect.

All in all, from a professional Analysts stand point I totally fail to fault his test design (although H&S would have serious censure of his table/chair/load lifting antics).

1: He defined how to dress and set the F8 , then showed that the knot untied easily (seconds) while a loose knot was difficult to untie.
2: He identified the 'correct' knot dressing structure and again showed the correctly dressed and set form untied easily while the 'crossed' form would not untie easily, even using a tool for assistance.
3: He identified two loading configurations - Inner collar' and 'outer collar' and again showed with 100% reliability that 'outer collar' loading led to an untiable knot after drop loading

His tests were all comparative, so he did not have to measure the test force and by doing so eliminated any error of different test loads that could have occurred if the test had not been comparative.  Designing in test simplicity and designing out error generating steps is an important part of test design.

Yes, Ben is publishing to the World, just as you and I are when we post our opinions.  In this case Ben has made excellent conclusions, valuable insights into dressing and using the F8, and set an excellent example in experimental design.  I commend his work.

Derek

agent_smith

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Re: Tokyo Olympics boulder climbing knot
« Reply #14 on: September 14, 2021, 12:39:18 PM »
Once again, this post is directed to Derek Smith.

Its all waaayyyy off topic, and I'm not sure how long it will remain open for business?

I enjoy reading your posts Derek - particularly your choice of typed words such as 'fixated', 'missing the point', and now; "I am having a real problem with your "basic '101' rules of testing", and; "ill mannered and risks bringing the reliability of all your reply and future post into question".

Wow! Really?

I was expecting you to resort to stating; "the lone view", and "alone' - but maybe that will come in a future post of yours?

Lets see... yes, I am 100% guilty as charged  - I bolded your text. Of course - it goes without saying that I I00% disagree that bolding your key words of 'fixated' and 'missing the point' alters the tone and tenor of your underlying intent.
With or without the bold text - the underlying meaning remains intact.

I am happy for you to continue to debate bolded text :)

Lets see, what else do we have from you?
Quote
ill mannered
Hmmm, really?
I am genuinely wondering what version of reality you are alluding to?
That is, I am being genuine - I am genuinely wondering how you reach your conclusions?

Quote
I do not expect you to humble yourself with an apology, but I do request you not to descend to these sort of antics in the future.
!
Wow - antics and the future!
I enjoy reading your narrative - its quite stimulating.
I wonder what the future holds?

Okay - what else have you typed lets see:
Quote
I do not know what standards of politeness you are used to operate to
Hmmm - I can confirm that if the roles were reversed, and I walked a mile in your shoes, I would definitely focus on the facts and refrain carefully crafted personal insults. But heh - thats just me.

Lets see, what else have you typed?
Quote
Let us be precise here, we are talking about a climbers F8 tie in knot which is not the #1047
Astonishing!
Of course, it goes without saying that I absolutely 100% disagree with your view.
Ashley is not the final arbiter of loading profiles - and he didn't publish that #1047 could also be tied (or arrived at) via a re-threading tying method - just like #1053 Butterfly can be loaded in a number of ways and can be tied via a re-threading tying method.
The geometry of the knot is identical regardless of loading profile. It wasn't necessary for Ashley to create a #1047a and #1047b for different loading profiles. We also know that #1047 F8 can be biaxially through loaded - with the SParts aligned 180 degrees in opposition -  so the core is offset from the axis of tension (in which it is unstable).

Anyhow, I am happy for you to consider #1047 F8 (TIB version) tied mid-line with both SParts loaded as an entirely different species compared to #1047 F8 tied end-of-line via a re-threading tying method into a climbing harness.

What else have you typed?
Lets see...
Quote
Forgive me please for quoting from one of your previous posts
You're forgiven. But I'm quite sure you will continue to do so :)
Am also quite sure that you will continue with very carefully constructed posts that carry an undercurrent of malice.
I find it amusing - but I think you should just give up on your malice  - I don't think you will humble yourself and apologise, nor do I agree with you concept of politeness.

...

As for the remainder of your post - I am happy that you believe Ben did an admirable job with his tests.

I am definitely appreciative of his efforts - but I stand by my given feedback which highlights areas for improvement.

In particular, not defining 'jamming' is something he could improve upon, using a load cell to measure force is also something I encourage him to do with any future testing. Also, actually measuring the load at which threshold jamming is triggered both in slow pull tests and comparing it to dynamic drop tests of the same magnitude. I also think he should specify the type of dynamic rope he is using - because there is huge variance between ropes and rope brands.

These are my opinions - and I am happy for you to disagree.
Maybe I hold the lone view?
In which case, I am happy to be alone :)