I love bends

[xarax]

Huh?  How do you know anything about strength --especially
in rope, which takes considerable force to break, with
some special equipement (maybe a truck & stout tree)?!

   Huh?  How do you know anything about strength --especially in rope, which takes considerable force to break, with some special equipement (maybe a truck & stout tree)?! If I do not know anything about strength --especially in rope, because it takes considerable force to break, you do not know anything either, I suppose, unless you are a weight lifter !   If I do not have a truck $ a stout tree, where did you find yours  ? I thought that cars have not yet been invented, and that trees have not yet grown sufficiently, to serve as a stout...

It is these inner fibres that break, not the supposedly overloaded outer ones, at least in normal materials.

Really ? What are the "tests" that prove your assumptions and disprove mine ?  

A very informative article about knots, at least in "normal" materials, and knots strength, at :
http://allaboutknots.blogspot.com/

[xarax]

   Quote:
"Curves Redistribute the Load and Weaken the Knot
    
   Any curve in a loaded segment of rope distributes the load unequally on the fibers. The load falls more heavily on the outside fibers of the curve than on the inside fibers. By stretching some fibers and compressing others, a curve loads the fibers unevenly. The uneven distribution of load creates strains that weaken the knot at that point. The outside fibers, carrying more of the load than the inside fibers, are placed under greater stress. Under an excessive load, these outer fibers are stretched until they break, just as they are in a green stick if you bend it to the breaking point. The inner fibers, unable to support the increasing load, break soon after. In this way, the curve of the stem creates a weak point that causes a knot in an overloaded rope to fail."

Quote, from AAK , at
http://allaboutknots.blogspot.com/

   It sounds logical to my poor mind...but I will be sure only when the cars will be invented, and the trees will have grown sufficiently, to serve as stouts...

[roo]

  Quote:
"Curves Redistribute the Load and Weaken the Knot
    
   Any curve in a loaded segment of rope distributes the load unequally on the fibers. The load falls more heavily on the outside fibers of the curve than on the inside fibers. By stretching some fibers and compressing others, a curve loads the fibers unevenly. The uneven distribution of load creates strains that weaken the knot at that point. The outside fibers, carrying more of the load than the inside fibers, are placed under greater stress. Under an excessive load, these outer fibers are stretched until they break, just as they are in a green stick if you bend it to the breaking point. The inner fibers, unable to support the increasing load, break soon after. In this way, the curve of the stem creates a weak point that causes a knot in an overloaded rope to fail."

Quote, from AAK , at
http://allaboutknots.blogspot.com/

I'm not going to take sides here, but the issue is quite a bit more complex than this, even though there is some truth here.

Consider the inside curvature.  If there are 100 units of axial stress along the rope at the inside point, and say, 20 units of compressive stress from side contact at that point, the "resultant" (google:von Mises) stress will be 111 units of stress at this point, neglecting other factors.  100 axial & -80 contact compressive would yield 156 resultant stress units.

This is just one aspect of strength reduction.  There are also shear effects and fiber curvature effects and more.

[xarax]

the issue is quite a bit more complex than this, even though there is some truth here.

  Always "the issues are a bit more complex" than our descriptions, of course, and always "there is some truth" in whatever description of reality we attempt.  
   I say two simple things :

#1. All the curved segments of a knot should better be loaded,
$2.The most curved segments of a knot should better be loaded less.
    
   When I examine a knot where a curve is loaded disproportionally, too much or too little ( if we also take into account rule #2, of course ), I consider it as a disadvantage. A basic element of the knot is not used as efficiently as it could...Because the loads would be supported, at the end of the day / of the rope length, so this job would have to be done by the rest of the rope , i.e. through out a shorter rope length. Also, such a knot run the danger to remain almost loose at some areas, even after it is loaded, to not reach a final, stable knot form, and to fail to be as compact as it could.
1. "That is exactly what happened with the "Sidewinder" during my (few and superficial) tests."
2. "The bights belonging to the final tucks stayed loose, as expected".
  
    

[Dan_Lehman]

Huh?  How do you know anything about strength --especially
in rope, which takes considerable force to break, with
some special equipment (maybe a truck & stout tree)?!

   Huh?  How do you know ...

It is these inner fibres that break, not the supposedly overloaded outer ones, at least in normal materials.

Really ? What are the "tests" that prove your assumptions and disprove mine ?

My question sought an answer, and not gratuitous parroting.
Apparently, you have no "tests" but only conjecture, based
on Dick Chisholm's baseless conjecture.

My opinion is informed by testing that I've had done, testing that
others have done (in some few cases where there's output to be
analyzed --photos, e.g.), and on ruptured bits of rope I've found.
Which testing I referred to, above.
Beyond that, my own stress testing puts knots into much
higher loads than others are doing, in ropes, and that can reveal
transformations in knot geometry not so apparent otherwise.

A very informative article about knots, at least in "normal" materials, and knots strength, at :
http://allaboutknots.blogspot.com/

I've already pointed out that this is nothing but baseless speculation
devoid of confirmation --hardly informative, except about one person's
belief (and willingness to promulgate it nevertheless!).

--dl*
====

[xarax]

  My question sought an answer, and not gratuitous parroting.

   People pay much money to buy parrots, so they can enjoy listening, again and again, their own words...Your parrot, me, was gratuitous for you, so I thought you would have enjoyed it !  
   I had not understood what exactly was the specific question you are referring to, that I failed to answer. If you ask me to publish in Physics Letters my scientific experiments done in my high-tech laboratory, I have think it for a while, I am afraid...because I have to hang again my two 1953 Gunlocke wooden chairs from the central heating pipe on the ceiling of my kitchen, persuade again my son to sit with me on them, her mother to take pictures while she is cooking, etc.  This is the environment of my "tests", and I have said it explicitly. So, let me be my parrot now :
 

That is exactly what happened with the "Sidewinder" during my (few and superficial) tests.

 So, I guess I should consider this "question" a rhetoric one...Because I am no qualified knot tester by any means, and I can do nothing else than reading other people s opinions and tests, and rely on them. I have not done any scientific tests on any knot, and I do not want to do, and I do not intend to do !   It is not my field of expertise, and I am too old to enter into it now. I am only an novice amateur knot tyer, and I am waiting from more experienced people to enlighten me on this subject, while I retain my right to have my opinion, however naive, and publish it. And I am glad that there are many other people here  that are just like me, and do the same I do. The article I have read and I have quoted sounds pretty informative and explanatory to my ears. I am not qualified to argue with it. If I find other articles on the same subject, I will read them too.
   But where are your "tests" ? In which scientific journal are they published, and when ? Are they classified ?  Where is your laboratory ? Is it into a restricted area or something ?  Why you do not argue directly with this writer that reports the "baseless conjectures" and "baseless speculations" I have cited? I have not seen any reply coming out of you, so there would be a dialogue between you and the writer, documented by references on other writers, experiments, tests, statistics, etc.
  

My opinion is informed by testing that I've had done, testing that others have done (in some few cases where there's output to be analysed --photos, e.g.), and on ruptured bits of rope I've found. Which testing I referred to, above.

   I do not doubt that you have done your tests, as you do for me...I am sure you have a great experience on this field, and I would love to persuade you to SHARE it with the rest of us...However, you have failed to do this, at least until now. I am not aware of any publication of yours on tests like the ones you ask from me ! , outside forum posts...Where one can read nothing else than sporadic, mostly, observations, and see pictures taken "in the wild" of your house... I am glad that your "Diamond" bend is finally unearthed, even after such a "looong" time, as you told us. And when you will publish other knots, I will tie them, take pictures of them, examine them with my poor mind and limited knowledge, and publish my opinion. I do not say that I have had, or expected to have, something like that for my knots... But I follow my curiosity and my moral values, wherever they lead me.
    So, you have not answered my questions.
   1. Without parroting yourself gratuitously, tell me, am I right about the "problems" I think I have pointed out in the "Sidewinder", with the help of my "theory" and my "tests"? Do you think that the un-tucked "Sidewinder", retains most of the qualities of the original "Sidewinder" without so much material and complexity ?
   2. Am I right in what I have said about the "proportional" loading of the knot curves, in reverse relation to their curvature ? Should the collars be left as unloaded as we can ?

  As for the knots strength , in general, I suggest you start a new thread, and publish there some of your tests, for people to be informed about, and critisize them publicly. I would be very glad to read what you will tell us in an ordered and scientifically objective manner...  

P.S. Another source of information about climbing hitches, mainly. I am still laughing with the joke of asking ME to answer THAT WAY questions about knots...
http://www.paci.com.au/downloads_public/knots/14_Report_hitches_PBavaresco.pdf

[Dan_Lehman]

  My question sought an answer, and not gratuitous parroting.

  I had not understood what exactly was the specific question you are referring to, that I failed to answer.

The question is how it was you came to your assertion about strength.
The answer seems to be that you read Chisholm's article, not that you
(nor he) had done any actual testing or knew of such testing results
that would support your assertion.

...because I have to hang again my two 1953 Gunlocke wooden chairs from the central heating pipe
on the ceiling of my kitchen, persuade again my son to sit with me on them,
her ["her"?!] mother to take pictures while she is cooking, etc.
This is the environment of my "tests", and I have said it explicitly.

     
No, I don't think that you EVER said anything like this,
and it most certainly rates a picture, or several!!!
Not least of all (but maybe not most) to show what is being
tested by this homespun endeavor.
(My standing in a pulley is far less *colorful*, but likely far
more forceful.)

That is exactly what happened with the "Sidewinder" during my (few and superficial) tests.

Here's another rub : your "sidewinder" appears to be my name
taken for your treble harness bends --that's an unwanted confusion
(you "said" that you found my knot too convoluted to tie, yes?).

Because I am no qualified knot tester by any means, and I can do nothing else than
reading other people s opinions and tests, and rely on them. I have not done any scientific tests on any knot,
and I do not want to do, and I do not intend to do !  

Whoa, what happened to the two-chairs-sitting from the ceiling
--did you do that (for what purpose), or not?

...while I retain my right to have my opinion, however naive, and publish it.
And I am glad that there are many other people here  that are just like me, and do the same I do.
The article I have read and I have quoted sounds pretty informative and explanatory to my ears.
I am not qualified to argue with it.

Here I submit you go wrong : it is of no benefit to have a bunch
of uniformed opinions floating around, which either take some
effort to scrutinize and find wanting of basis, or just ignored.
That is noise of the sort lowering the signal-to-noise ratio --it wastes
time & resources.  You should not regard that article as informative,
as it gives no seeking of empirical results to support the conjecture;
it is shooting from the hip.  You are certainly qualified to read that
and find that basis missing; you should have asked How did he come
to these conclusions --did he break knots and examine them?  --did he
find such experimental basis in others' testing? , to which the answer
is "no".

Beyond this, you of course have tied and examined bowlines --i.p.,
in the question of capsizing, seen in some mooring lines of trawlers
as I showed.  Can you really look at this knot and believe what
Chisholm asserts about it being so deflected at the point of entry,
his "stem" & "point X", that it will break there (and as a relatively
low load, given such very slight deflection (if any!) there)?!  I
should think NOT.  That collar, which is so easily pushed back
after heavy loading, nevertheless causes the knot to break (before
any other weakening of it by other curves does so)?!
I think that alone only need sit in your chair, neverminding
a suspension of belief by suspension of chair, to analyze this
assertion and find it highly dubious.

If I find other articles on the same subject, I will read them too.

But you might like to consider this draft thesis:
personal.strath.ac.uk/andrew.mclaren/KatherineMilne2004.pdf
which points to an entirely different part of the bowline (and
double bowline) for failure; pity she didn't think to use marker
strands in the rope!  --a still camera could capture that, before
and after, and thread & still camera are surely less dear than
a high-speed camera.

But where are your "tests" ? ...
Why you do not argue directly with this writer [who] reports the "baseless conjectures" ...

I should put up some few photos of broken bits of
3-strand knotted rope, to show the evidence of the
break coming on the strand (it is often a single strand
that breaks, and then testing is arrested) leading to the
concave part of a bend, a place of great compression.
Conceivably, different materials exhibit different behavior;
it is more *traceable* in the laid rope, by following the
broken strand's now-vacant groove, than in braided rope,
esp. where there is more devastating or complete breakage.
With marker threads in both a broken token AND a paired
unbroken one, one has some chance to assess, from its
position among the *rubble*, where it lay on breakage.
(Or even in a single token, if one has photographed the
knot with its markers in high-tension position, the post-mortem
can be instructive.)

It has been several years, now, since corresponding with
Chisholm, and I forget why that ran dry --likely one or both
of us going in other directions.  I still have comments about
a ski-patrol knots survey he did, which was a refreshing look
into "the wild" and what was actually done, what was believed.

--dl*
====

[Dan_Lehman]

Now (separate post, 2nd follow-up), I think your What about my questions...?
comes back to this assertion, which I questioned, and which ... got long posts.
I still ask : how you come to make assertions about strength if you have
no means to see the ropes highly loaded (even --if not broken), which
at least makes some progress at finding the under-load geometry.  I don't
think that your body weight alone (chair-sitting) will have much effect
on the climbing kernmantle you seem to be working with.  (And my
pulley use takes often a re-anchoring (tugboat-hitch-like turns) as I
take up stretched-out rope to re-stress.)

What I had done, pre-destruction-testing, was to give a "jump-test"
in which I would stand and bounce on the knot(s) in quarter-inch
rope (usually) --and only in ones I expected to be able to untie!
(Failed expectations led to painful work.)

... impart gradual deflections into the S.Parts before they inevitably made their 1-diameter U-turns, presumably taking off some load and yielding strength.
Unfortunately, even were this a valid plan...

 
   On the contrary, I have found this plan to be too valid with the material I use. And that is the problem ! If the central crossings takes off most of the load, they do not yield strength ! The loads must be somehow "proportionally" distributed into the knot s nub, "proportionally" in relation with the angle of the Standing part s deflection/turn. The collars must not bear all or most of the load, but they must bear some load ! If the Standing part(s) block in the central core of the knot, before they arrive at the collars, the knot is not working properly. That is what it happened to the "Sidewinder" knots I tied with my ropes.
   The collar is a basic element of many practical knots. The knot tests persuaded many people that the collars should be loaded as little as possible, because the use of a U-turn on a knot has a deteriorating effect on the strength of the rope. It leaves the inner, inside track fibers inside the rope, that run the shorter distance, unloaded, while the outer "outsiders" bear all the tension. This is correct, provided we do not go as far as to take almost all the load out of them, leaving the rest of the structure overloaded. That is exactly what happened with the "Sidewinder" during my (few and superficial) tests.

I'm not sure about what you mean by "If the S.Parts block
in the center of the rope, before they reach the collars ..." ;
but I think that greater strength comes in cases where there is
much gripping of the loaded line, much material-vs-material
spread, rather than aspects of curvature.  ALTHOUGH, with the
very slippery HMPE, it seems that there just can't be all so much
effective gripping (or not without using a lot of material to achieve
it).  Still, anglers at least do tie the "gel-spun" stuff in Bimini twists
and get good results (though one must dig to see how the reported
% strengths are figured --often from rated tensile strengths
that are grossly understated!).

About "proportional loading of knot curves ...",
hmmm, my idea I thought was something along these lines :
that initial curvatures would each be helping to offload force
from the rope's flow into the knot that by the time it got to
that hard-U-turn there just wasn't so much force on it (and
so the curvature there could severely weaken the rope in
terms of tensile strength, but simply wasn't going to be
taxed enough to determine knot strength.



It's a poor comment on testing to date to be so much in
the dark on these questions, and to see even of the few
tests that get done, not enough information produced.

And to still have so much on my To-Do list, in this regard, alas.


 

[squarerigger]

Dear Dan and Xarax,

You both are referring to testing that appears not to have been performed under repeatable conditions and with enough 'tell-tales' to reveal what is happening successfully and in a form that is able to be reviewed by and agreed to by both of you.  Wouldn't it be great if you could both work on finding a source of such competent testing and agreeing on what that testing should be?  Maybe then you could cooperate on finding the funding and/or location for such testing?  That would save an lot of awful to-and-fro argument with neither of you shifting position much on suppositions.....just a thought.   

SR

[xarax]

The question is how it was you came to your assertion about strength.
The answer seems to be that you read Chisholm's article, not that you
(nor he) had done any actual testing or knew of such testing results
that would support your assertion.

No ! The answer IS ( is, does not seems to be, to anybody, except you, perhaps...) that I have read AAK article, AND I found it reasonable, AND I have not read your article ( that seems, to me, to be classified ). IF, and when, I will read your article, the one you have written but remains classified, or the other that you will write and publish before I die, and IF I will find the former or the later of those articles MORE reasonable than AAK s article, THEN, and ONLY THEN, I will cite your article too ! Are you satisfied with my commitment?  IF yes, THEN unearth the unpublished classified article, or start writing an ARTICLE, not a reply in a forum, and publish it, to be criticised as AAK has done. Until THEN, do not waste your valuable time "responding" to me the way you have responded...

No, I don't think that you EVER said anything like this,...

   True. literary. I thought the essence was a subset of the meaning "superficial", that I have used as an adjective for my "tests", haven t I ? Read your quoting of what I have said :

That is exactly what happened with the "Sidewinder" during my (few and superficial) tests.

your "sidewinder" appears to be my name taken

  I have been accused a a thief of pictures and names not long ago in this forum, so I am accustomed of it !   You were the self appointed lawyer of my accuser then, with performance of much lower quality than your tying skills, I am afraid...Are you going to test your talent as an accuser now ?
   I have put the name "un-tucked "Sidewinder" bend in my pictures of the knots that you describe as "treble harness bends", because that is exactly what they are: Your original "Sidewinder", when I un-tucked the tails. AND because I felt it was an obligation for me to cite the name of the parent knot. AND because I felt that it was not right for me to name those knots, derived from your "Sidewinter" knot,  before you see them and approve any proposed name.
   So, I did not gave, to the knots derived from your knot, another name, because I felt it was inappropriate. On the contrary, you describe "my" knots as you wish, out of a supposed authority that was given to you from above, I suppose. I do not have any problem with this, you can name any knot with any name you wish, but you can not say that I have "taken your name", and I have created "un unwanted confusion". Would it be better for me to publish those knots as mine, with my name, without any reference to you or your "Sidewinter" ?
   Oh ! Sometimes people seem, to me, more convoluted and complex than even the most convoluted and complex knots...  

(you "said" that you found my knot too convoluted to tie, yes?).

 
I have un-tucked a knot that I have not tied...Good !
Or, I was not be able to tie your convoluted knot. Better still !  
QED

Whoa, what happened to the two-chairs-sitting from the ceiling
--did you do that (for what purpose), or not?

   May be I have just DREAMED of it...
   Whoa, if that are the "tests" that you wanted me to publish, or if you will publish that kind of "tests", please, do not bother ! Keep them within closed doors in the restricted area of your hi-tech laboratory !  

...it is of no benefit to have a bunch of uniformed opinions floating around, which either take some effort to scrutinize and find wanting of basis, or just ignored.
That is noise of the sort lowering the signal-to-noise ratio --it wastes
time & resources.

I have plenty of time...proven by the time I spend to reply to you, or tie and post pictures of "treble" knots... But I think you do have plenty of time, too, because you have also replied to my "treble" knots, and you have not "just ignored" them. Or is it because you think they are somehow yours, and want to be a caring father, or grand-father ? Father or Grand-father of "trembling" children or "trembling" grand-children, make your noises and leave other people make theirs ! There can be moments of harmony, even in an environment with the lowest signal-to-noise ratio.  

to analyze this assertion and find it highly dubious.

   Have I cited this assertion ? Does all articles that are published, or are going to be published, are they 100% correct, with 0 mistakes ? IF your articles, the classified one or the one you are dreaming about, are going to be SUCH articles, 100% correct with 0 mistakes, THEN, please, do us a favour : Keep them classified or unwritten, in the restricted area , locked and earthed for 2000 years. Because we already have one Bible, you know, two would be too much !  

But you might like to consider this draft thesis...

NOW you are talking (and not writing a lawyer s speech, either for the prosecution, or for the defence...) Thank you very much ! That is informative to me, and you should better have cited it from the first moment, instead of "replying" nonsense to nonsense !
 

I should put up some few photos of ... to show the evidence of

Indeed you should ! It is long overdue ! But I am glad you have taken this decision, which would be most beneficial to me, and to the forum, I believe. Better late than never! You should have done it already. THEN you would have been right to argue with AAK, me, or whoever, and not just yell...

End of Part 1...

[xarax]

how you come to make assertions about strength if you have no means to see the ropes highly loaded (even --if not broken), which at least makes some progress at finding the under-load geometry

 
   I did not make any assertions ! I had only cited (a paragraph of ) an article that seems informative to me, and, what is more important perhaps, reasonable. I also made hypotheses, speculations, and expressed thoughts. I also performed a few and superficial "tests" in my kitchen ! I expect more experienced people, like you, to SHARE with me, and us, any relevant information. Knot strength is probably the most difficult subject to explore, ( and also, probably, one of the less interest for the amateur knot tyer). Would you expect ME to make scientific experiments (tests) in my kitchen ? Or it is your rhetoric style again ?
[/quote]

I'm not sure about what you mean by "If the S.Parts block

 Sorry for my poor English. Yours are often worse ! I meant that the Standing parts are squeezed in this area more forcefully than anywhere else, to the point that the induced friction would (almost) block any slippage, if the rest of the knot was absent. So, their portion beyond that area play only a minor role in preventing slippage. There is too much gripping of the loaded line there.

ALTHOUGH, with the very slippery HMPE, it seems that there just can't be all so much effective gripping

 
   You should read more carefully, even the texts by people you do not think that they know anything more than you think you do. I have been careful to state, explicitly, that what those observations were on my kermantle climbing ropes. And I do not have any doubt that, even on those ropes, the material of the "mantle" may be more or less slippery, and that would effect the friction characteristics of the central area. Why there in no indication of the friction characteristics of the mantle, as it should ? Also, I have some very stiff ropes that also function quite differently. Oftentimes, results with those ropes, and results with more soft ones, are quite different, even contradictory. Most of the times, with most of the ropes I have used, the central area of the "Sidewinter" seemed more gripping ( almost too much), not less gripping, than it should. That had the effect on the knot to be left with partially loaded collars ( "partially" from an "optimum" value, where the loadings should that are to be distributed to the various areas of the rope strand, are inversely "proportional" to the rope s curvature at this area. The bigger the curvature, the lesser the maximum allowed load).

 by the time it got to that hard-U-turn, there just wasn't so much force on it !!
   Exactly!  
...and so the collar(s) played only a very minor role in the knot s ability to block the motion of the Standing part(s) during a slip. If there was not so much force on the Standing part(s) when it(they) arrive(s) at the collars, why do we need this collars, and have put it there in the first place ? The collars should be loaded as much as they could, or they better not exist at all ! It is pity, such effective friction mechanisms, as the collars are, to be used only to make free U-turns around the knot s nub, without participating in the knot s main function, the prevention of slippage of the Standing Parts. Rope strands forming collars that are too lightly loaded, seem to me a waste of material, to say the least.

It's a poor comment on testing to date to be so much in the dark on these questions, and to see even of the few tests that get done, not enough information produced.

And you were expecting ME to do tests, and produce information !  I am here to pose questions, not answers !  And play with some rope tangles that might have escaped the attention of other people...I am no knot expert, and I do not want to be, even if I could ! I better find a mistress, before it is too late.  And women do not give much attention to ROPE s strength, I can assure you !

And to still have so much on my To-Do list, in this regard, alas.

   Correct ! And you better start doing something TODAY, because time flies...Instead of wasting precious moments of the rest of your life as a lawyer of the prosecution or the defence, in a virtual courtroom with almost no participants, you can start doing something positive, creative and not merely censorious or critical ! You can start publishing your notebooks, for example ! What are you waiting for ?   I noticed in the picture , that they are very "oooold", indeed ! Are you waiting them to boil ? In a few years, they will fade out and perish, I am afraid, as we all will...

[Dan_Lehman]

Dear Dan and Xarax,

You both are referring to testing that appears not to have been performed under repeatable conditions and with enough 'tell-tales' to reveal what is happening successfully and in a form that is able to be reviewed by and agreed to by both of you.  Wouldn't it be great if you could both work on finding a source of such competent testing and agreeing on what that testing should be?  Maybe then you could cooperate on finding the funding and/or location for such testing?  That would save an lot of awful to-and-fro argument with neither of you shifting position much on suppositions.....just a thought.   

SR

Prior to finding the funding,
we sChOULD articulate the shortcomings and try specifying
the conditions & outputs desired for testing.  After all, how
hard would it have been for Katherine Milne --who with her
university setting & guidance used a high-speed camera(!)--
to have MARKED the rope so as to be able do do post-mortem
on it, rather than squinting at blurry rupture imagery?  --have
the high-stress, about-to-break still photos showing where
in some series of marks A-B-D-...K-... are situated pre-break,
then see between/among which points the break occurred.

So, yes, this is a doable product (test critiques & specifications
arising from) that could be suggested to those folks who have
the means for doing the testing.  And maybe we gain some
credibility for it from which to influence subsequent testing.

In one small step in this direction I did get some bit of testing
done via Brion Toss & NERopes, in 12-strand Dyneema.  Although
I wasn't present and influential on-site (for pics, for gaining some
intimate knowledge available only by such proximity), I did put
in some markers in the ropes, and with a pulley was able to give
them a pretty firm setting (in material that has little elasticity to
stretch beyond this --i.e., pretty much WhatYouSeeIsWhatYouGet)
prior to mailing them for testing (where they got MUCH tighter set!).

And Agent_Smith, though cursing me with each stitch, has tried
the marking, himself (methinks a course in sewing would help
him ease that part --though I confess it's easier to tell HIM to do
it than it was to do it myself    ).

Photographing test specimens should be de rigueur --cameras are
cheap/good, these days!  That would help get past what should
be an obvious critique of knots tests --not knowing what it was
that was actually tested.

I think a thread on
 Knot Testing : Survey=>Critique=>Criteria/Desiderata/Specification
belongs under the Practical heading.


--dl*
===

[xarax]

   Dear Chin,

   I have just completed my excavation at the recently unearthed monument of the IGKN-IGRR(*1) Great War. I have made a very important discovery, a most beautiful knot that was tied by some obscure IGKT priest, and buried here. We had not any information about this knot to this day, because it seems that this priest was deliberately speaking and writing in a secret, incomprehensible language, to not be understood by the IGRR soldiers, and all his written sacred notebooks were destroyed during a battle.
   This knot reminds me an ancient picture that has been transplanted in our brain chips, "The Violin Of Ingres" ("Le Violon d Ingres"). Also, I was told that there was a "musical instrument", (I don't know what this means, though), with a similar name.
   You know, "knots" were tools humans used before the Grand Ties Untying. Ropes were made by atoms, not by proton-electron strings as now, so humans tied "knots" to fasten the ropes together.
  I hope the artefacts of our excavation will be soon beamed to the New Beijing.
  Kiss the children, and do not forget to pray in the name of our great leader, the master LT (*2)
  
  Your beloved husband
  Ching Chong Choung
    

*1) IGRR : International Guilt for the Rights of Ropes
*2) Liberator from Ties

[SS369]

Dearest Choung

It is with a most heavy heart that I must tell you that I and the children have been swept away into the ether-world. We hope and pray that someday when you are done with your worldly travels and have vanquished all that the tangles of the worlds you encounter that you will rescue us from the lair of the Knot Eaters.

It looks like you have tied a "Ropeous Boneous Bendous" to try and lure them away from us. I hope that your trickery does knot fail !

 

And now back to the rest of the story....

[SS369]

I like this Violin/Bone bend.
I just tried it with dissimilar sized ropes 10.55mm and 8mm (new BlueWater ropes) and it cinches up nicely.
I made a sling of it with those ropes and applied foot and arm strength to it and I am able to untie easily.
No, not scientific, but if it didn't at least pass this first test for me I wouldn't bother to go further. Personally

SS