Author Topic: Critique of existing/published knot test reports  (Read 1319 times)


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Critique of existing/published knot test reports
« on: July 09, 2018, 07:28:06 AM »
I am identifying a selection of existing knot test reports (video and/or written form) and providing fair and balanced criticism.

Tester details:
Richard Mumford
Company: Climbing Innovations
Application context: Tree climbing / arborist
Publication date: 29 Jan 2018
Testing lab type: Presumed 'Pseudo lab' (not a certified lab and not accredited by a third party agency)

Link to video:
This is another example of a tester aiming at the default #1010 Bowline - and presumably assuming that this is the only type of Bowline in existence. The author makes it clear that he is not a supporter of the Bowline (preferring instead the #1053 Butterfly eye knot.
Note: The author's context is tree climbing.

Some criticisms (list is not exhaustive):

Testing commences at 12:47 elapsed time...
1. The default mindset is to probe MBS yield point of knots (ie pull-to-failure mindset).
2. The author presumably places a lot of weight on knot 'A' versus knot 'B' pull-to-failure (presumably the winner of the contest is a superior knot? - This is an implied assumption).
3.  Dressing of the #1053 Butterfly assumes parallel eye legs (he does not investigated crossed eye legs)
4. The author does not make a clear distinction between 'eye loading' and 'through loading' of the #1053 Butterfly eye knot (it is just assumed that viewers will know and understanding the differences).
5. There does not appear to be any scientific rigor in terms of gathering a statistically valid sample (only appears to be a sample of 1).
6. Vague on age of test cordage/rope.
7. At 19:55 elapsed time he 'ring loads' the eye of #1053 Butterfly. As this forms a round sling, the load to reach the MBS yield point is naturally much higher than in linear loading profile (no supporting comments offered...just assumed that viewers will know this).
8. At 21:05 elapsed time he tests #1010 in a ring loading profile (the author appears to be ignorant that this is a loading profile that is a known vulnerability of comparison to #1034 1/2 which is resistant to ring loading...he missed an opportunity to use #1010 as a control against #1034 1/2).
9. No firm conclusion drawn or stated from his tests. What was he ultimately trying to prove? Did he prove what he set out to do? What were his conclusion drawn as a result of his test efforts? It appears unclear or implied...

Just some quick observations...again, the list is not exhaustive.

I wonder if the author had contacted the cordage institute or IEEE prior to testing that he might have made less errors?
« Last Edit: July 09, 2018, 09:47:52 AM by agent_smith »


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Re: Critique of existing/published knot test reports
« Reply #1 on: July 09, 2018, 10:37:14 AM »
I haven't studied Mumfords video in detail, so largely first impressions from me.

I think Mumford misses the point in break-testing the bowline vs the alpine butterfly. There was no mention that I viewed of how easy it is to untie either knot after load (I admit I skipped the first few minutes). At ~17:30 I did see a broken alpine butterfly knot that still appeared jammed. An RH Bowline, or a simple locked-bowline, does not jam and that is worth a lot.

Also, for what it is worth, an alpine butterfly used as an end loop is better from one direction than the other. The 'better' loading side I do not remember. One side jammed and the other side was more resilient at high load, based on my home-tests from a couple of years ago.


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Re: Critique of existing/published knot test reports
« Reply #2 on: July 10, 2018, 10:20:02 PM »
Title of report: Which bend for joining ropes
Company: Over the edge rescue
Some criticisms of this report (list is not exhaustive):
1. There are no photos showing precisely how the knots were tied  ...

Wow, I'm amazed that both the "Overhand 1.5" --what Mark
recommends using (a dbl. oh. in choking strand)-- and esp.
the "Double Overhand" ("EDK-backed EDK") "rolled"!!
I say especially for the latter, as any rolling implies
that somehow the base knot has opened and *swallowed*
the stopper back-up!?

Also, consider that canyoneering cordage should be
less stretchy than dynamic rope and thus more
resistant to stretching & opening at the choke.
However, the report does remark that
Observation: the rope was stiff
and did not easily fold in half
which suggests that the tied & set knots
probably offered a head start to opening
(which might indeed be a behavior to be expected
in actual use).

It would be great to see videos of the knots under
test loads.

Btw, the supposed "%" column needs to honor
that heading and omit decimal/radix points
--e.g., it would be "69%" not "0.69%".



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Re: Critique of existing/published knot test reports
« Reply #3 on: August 08, 2018, 04:16:32 PM »

When we get our Review Board, would you mind reposting each of these reports into their own threads please.

With regard to the report by Grant Prattley on Sheetbend vs Bowline, I must commend you on your restraint and your ability to deliver a rational critique.  On reading the report, I found myself spluttering in 'Victor Meldrew' fashion.  How could someone involved in professional rescue and a self acclaimed Consultant at that, dare to put such material into print?  I am afraid I cannot be as professional as you and must refrain from commenting on the the intended object of this report.

It is said that dog owners tend to look like their dogs, perhaps then it is probable that Surnames are apt to reflect our nature?

However, his 'innovative' approach to the concept of 'knots' is both challenging and thought provoking, and is very close to Dave Roots 'dot notation'developed over ten years ago.

It starts with the cord, after all, no cord, no knots.  The function of the cord is its ability to transmit tension from one end, along its length to the other.  When the cord is displaced by an object, a tangle or a knot, lateral forces start to bind the knot in predictable ways.  When the cord is displaced by an object (a capstan, or tree branch etc) it may even be captured - hitch like, but it need not be a knot.  When the cord is displaced by a 'tangle' as often auto creates in your EDC pocket cordage, it might be able to make a jam, but it is still not a knot (although some might say it is 'knotted').  Then finally we have a deliberately constructed displacement on the cord - a knot - or Cord.Knot  and of course, this is where Mr Prattley is quite correct - we can indeed have a knot that is not a Hitch, nor a bend etc. - simply a knot.  A strangle in the end of a Cat-o-nine tails, is not a stopper, it has an entirely different purpose.  So, thank you Mr Prattley for bringing that to my attention.

Also, I must concede that a bend does not have to be made using two different pieces of cord.  We can legitimately 'bend' together the ends of a length of cord in order to fashion a continuous loop.  Again, thank you Mr Prattley for that reminder.  But, when we pass that loop over an object in the form of a hitch, can we still legitimately call it a bend?  And then, we take a spare end to load the loop, is the bend - hitch - loop still just a bend?  No, we have changed the loading configuration of the Sheetbend.  Loading configuration is God of the definitions and has converted our Sheetbend into the Antibowline.  He is comparing two Loopknots.

So thank you Me Prattley for an interesting excursion back through naming logic.

However, a far greater worry, although I could not see the structure of the knots he tied, he suggests that they collapsed under the puny loading of ca 120kg.  I seriously hope I never need him to come rescue me...


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Re: Critique of existing/published knot test reports
« Reply #4 on: August 08, 2018, 07:18:08 PM »
I can't find anywhere a clear reference to the structure / tying method for the Overhand 1.5, can someone give me a link pls.



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Re: Critique of existing/published knot test reports
« Reply #5 on: August 08, 2018, 07:49:01 PM »
I can't find anywhere a clear reference to the structure / tying method for the Overhand 1.5, can someone give me a link pls.


See if this helps you Derek.


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Re: Critique of existing/published knot test reports
« Reply #6 on: August 08, 2018, 09:50:52 PM »
Thanks Scott - perfek.


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Re: Critique of existing/published knot test reports
« Reply #7 on: August 08, 2018, 10:35:33 PM »
Perhaps not best place, but let me post here some
interesting reading regarding standards bodies
--i.p. of USA-based folks balking at ISO's seeming
catering to European interests!?
is quoted below, and comes in response to this article
of 2000-August issue (I'm only 18 years behind!) :

Plain Talk on the TBT and
Vienna Agreements
Bravo, Mr. Thomas, for laying out in detail the problems with the direction the ?international? standards organizations are taking [Plain Talk for A New Generation by Jim Thomas, August 2000 SN]. Many people have argued for years that the purpose of European-dominated bodies is to further the influence of Europe. It has become increasingly apparent that recent declarations and developments support this view. I appreciate the fact that you have made a very strong statement defending America?s time-tested standards development process, and I think it imperative that ASTM become more vocal in defense of the voluntary consensus process as embodied by ASTM. Now is the time to make our case, individually and collectively, otherwise the system which has worked so well for over 100 years risks being relegated to the drafting of suggestions for ISO.

Ernest Dale
Las Vegas, Nev.

Your Plain Talk on TBT and the ISO/ CEN Vienna Agreement was excellent. I?ve been attending ISO meetings for only a short time and have encountered the exact problems with the Vienna Agreement you describe. I often have to justify my ISO involvement to upper management and your article would give them a wider view of the dynamics of the entire process and what?s at stake.

Jeff Winter
Product Development Engineer
Dayco Products
Springfield, Mo.

Your article regarding the ISO/ CEN Vienna Agreement matter, relative to how CEN products get preferred treatment in the ISO process, expressed the situation very well. If something is not done before too much longer to make, as you say, the United States a full partner, things could get much more difficult for all concerned, including the ?international? standards endorsement process. The fact that, in the United States, our technical standards process is not government-controlled and directed seems to cause no undue amount of concern with other countries where the government element controls subject. They do not understand us, especially since the United States? interests in standards so often do not speak with ?one voice,? and we do not understand how they work under government control either, as a rule. Anyway, I hope your article results in some positive actions via the WTO or otherwise to remedy the situation with ISO/CEN Vienna Agreement.

Paul Gill
NASA Technical Standards Program

I read with considerable interest your article concerning the ISO/CEN Vienna Agreement. While I have been involved in several discussions on the matter in my technical standards consulting activities, I guess I have not clearly understood the basic issue until I read your article. You have done an excellent job describing the situation and ramifications of decisions being made.

However, as I read further into your article I was looking forward to a statement on actions the United States should or could take to reverse the situation, given that you have noted that the United States seems to be speaking with ?one voice? for a change. Unfortunately, your remark in the end that, ?It?s time to take stock and for the United States to take its rightful place in Geneva as a full member, with all respect due? leaves me a bit perplexed as to just who should do what to whom and how. If the United States has only one vote on the WTO, ISO, etc., involved organizations, that would not seem to be adequate to carry enough weight to override actions relative to the ISO/CEN Vienna Agreement.

Is there an alternative? It looks like the United States against the rest of the world because we are different, right or wrong. However, I do recognize that in the international arena, as with the national activities, economics and what works best prevails insofar as to what ?standard? is utilized, regardless of source. ASTM?s standard products and others will be used, if they fit an international job, whether they have been endorsed as an ISO, ESSA, or other of the Geneva organizations? products I suspect. I hope your excellent article, however, does have some influence in getting everyone in the United States working on the same team from international aspects relative to standards products.

William W. Vaughan
University of Alabama?Huntsville

I commend you for your tough stance in ?Time to Take Stock.? The Cordage Institute has been fighting the ISO ?closed shop on standards? for some time. In the standards setting arena, the Cordage Institute is not large but we do feel strongly that the U.S. approach to standards development is far more democratic and open to global input than ISO. A new ISO WG 21 has been established for rope and cordage and our counterpart in Europe?Eurocord?has been designated the secretariat. They are also the secretariat for CEN standards and they are saying they may use our standards as drafts. If this is done at the CEN level, by virtue of the Vienna Agreement, there can be a potential end run to ISO without any input or voting from other than EU interests. We are not clear on exactly how this type of procedure will play out, but it does illustrate how the ISO so-called ?international? standards are not universally transparent, are not open to due process, and are certainly not representative of global equality.

Gale Foster
Technical Director,
Cordage Institute
Hingham, Mass.

To say that your article in the August 2000 SN is insightful is doing it a great injustice. The article laid out the real issues surrounding the attempts by the (primarily) European Community to control world trade through the manipulative use of a puppet standards organization which supposedly represents the interests of the world community. Your presentation is the clearest stated position from the United States voluntary standards community that I have seen to date. Someone must step up to provide the needed leadership to protect the interests of the American (and other affected countries?) public. These unfair attempts by the European Commission for Standardization to place standards barriers to free trade will ultimately affect the pocketbooks of all Americans (and affected others).

I sincerely hope that ASTM will continue to speak out and provide the much needed leadership to address this issue to its ultimate resolution. Your article, however, left a void which I encourage you to fill. As a member of ASTM, and other voluntary standards organizations, I want to provide assistance to prevent this great injustice from occurring. I suspect other ASTM members feel the same after having read your article. Your article did not provide any suggestions regarding grassroots support in the political arena. I would assume there are specific politicians and public servants to which we should voice our opinions. Names and addresses would be of assistance.

Jim, you?ve got our ire up; help us direct it!

Robert Hardison
Newport News Shipbuilding
Newport News, Va.

My congratulations to Jim Thomas on a job well done in his Plain Talk for a New Generation article in this issue. He gets right to the point and doesn?t dance around the issue. Dare we hope for support from other nations now? Dare we hope for more open and honest communication? In any event?job well done. I?ve shared the article with some of my colleagues, and they feel the same.

Walter G. Baumgardt
ASTM Committee D20 on Plastics

Apparently, ASTM?s leaders have finally recognized the threat to U.S. business and standards that is represented by the European and ISO attitudes toward international standardization. Why has it taken so long?

Until an October 1994 meeting of ISO/TC135/SC7 in France, I had not heard of the Vienna Agreement. However, upon learning of its provisions, the serious threat that it posed to U.S. interests was immediately apparent to me. I attempted, unsuccessfully, to have SC7 complain to ISO leadership about the Agreement. On Oct. 31, 1994, I alerted ASTM and ASNT to the issue by letter. Dr. Leonard Mordfin, chairman of ASTM E07.91, understood immediately. He conveyed our concerns further within ASTM, wrote to ANSI objecting to the Agreement, and early in 1995 published an article on the issue in Standardization News.

Unfortunately, despite these efforts and further prodding, neither ANSI, ASNT, nor ASTM took any other action until 1996. ASTM then published Helen Delaney?s article about one company?s experience, and Jim Thomas mildly reproached the U.S. government in a speech before a Congressional committee. Nothing further was done until minutes of an October 1996 meeting of CEN/TC138 reached me through a European friend. These minutes reported a frontal effort by CEN to commandeer the primary ongoing activity of ISO/TC135/ SC7, so I again wrote to ASNT and ASTM about the pernicious potential of that Agreement. Nevertheless, in June 1997, Standardization News quoted the president of ANSI as claiming, ?The concept of ?block voting? in ISO?is a red herring.?

However, as a result of my 1996 letter, ASNT did begin an active effort to spur defense of U.S. interests. These efforts included hiring a lobbyist, meetings with ANSI officers, increased attendance at European meetings, and testimony before Congress regarding the inimical effects of the Agreement. What is difficult to understand is the glacial response of all affected non-European organizations, especially ASTM and ANSI. The threat to their interests was obvious and, beginning in 1994, was repeatedly pointed out to them, yet they have done little or nothing to ameliorate the threat to the United States.

I am pleased that ASTM?s leaders now appear to understand the problem. If they will join vigorously in ASNT?s efforts, then perhaps ANSI, our government, and others will come to realize the need to replace the Vienna Agreement with a fair, even-handed protocol on international standards development, a protocol that allows equal voice to all interested, competent parties regardless of their affiliation.

George C. Wheeler
Schenectady, N.Y.

Copyright 2000, ASTM
« Last Edit: August 08, 2018, 10:40:22 PM by Dan_Lehman »