As there are many knots ( so, far more than we need ) and more than one knot tyers ( so, far less than we need ), I seldom agree with somebody 100 % ! 
So, I would remember this dayâŚ
I prefer the more symmetrical DH bend ( the ABoK#1420 ), although the other one, in both variations, is probably more âpracticalâ.
Also, I have to mention that I have another bend at number 0 :)( because it is not a âpracticalâ bend ), the Symmetric Sheet bend.
I am interested in symmetric bends, and symmetric bends only --not for their aesthetics, but because of the fact that the [b]rope segments of each link are evenly loaded[/b], so they would reach their strength limit at about the same time - in a symmetric bend there would be no "weak link" ( I believe that this is a reasonable expectation, even after we take into account some more subtle effects, that can lead to a symmetry breaking). Moreover, I believe that any mistake in the tying of a symmetric bend [u]would be noticed immediately[/u], because the result would be evidently asymmetric, and would be [u]caught by the eye at once[/u]. It is easier to spot an asymmetry within a symmetric background, than the opposite.
Iâve tried to point out, previously, that these two assertions are
not assuredly true --indeed, that re visible recognition is clearly
quite false (both (a) that symmetry is readily perceived, and (b)
that asymmetric structures are difficult to see as correctly formed).
Re the assertion of symmetryâs effects on knot forces, one must realize
that the actual nature of joined rope ends will often differ and such
difference can lead to different behaviors under force; it can in any
case be that one part gets the jump on the other in tightening,
and that such imbalance aggravates itself (the more one end
impedes by a tighter nip the other endâs part getting equal force
delivered to nip the first, the firstâs advantage will be furthered).
It is also conceivable that differently shaped parts in an asymmetric
end-2-end knot nevertheless have similar strengths --and I put
forward the butterfly knot as a possible case in point (as well
as a variation derivable from the zeppelin knot).
How can you hold this opinion?
Surely the DBH shows an entanglement/knotting
that goes beyond that of the DSB --with increased
pressure upon the nip of the tails, which receive force
only after the line leading to them makes fuller curves
than for esp. the bight-halfâs tail of the DSB (which,
you should note, has been found to slip).
Dave Richards notes that there was evident slippage in the cases of [static 12.7mm rope] with the [i]fisherman's knot[/i] and the [i][u]double sheet bend[/u][/i], [dynamic 10.5mm rope ] with the (single) [i]sheet bend[/i], and [accessory cord, 7mm] with [u]both sheet bends (single & double)[/u]; he thus tied off the tails with either [i]2 half-hitches[/i] or an [i]overhand stopper[/i].
Now, Richards didnât test the DBH --of either form (tails together
or opposite); and there are options to how one places the tails,
as X1 has elsewhere noted). But to my mind, there should be
a belief in its greater security based on appearance and analysis
of that, than of equal --esp. with regard to security when slack,
being jostled about and all (and consequently, much greater
difficulty at being untied).
âdl*
I stand corrected, Danâs statements certainly make sense regarding the DHB VS. the DSB. I would have to assume the DHB is considerably more secure AND stronger than the DSB, not sure why I even compared the two really.
Yes, they are not assuredly true.
No, it is not clearly quite false !
Moreover, they are much more true than they are quite falseâŚ
I could refer to scientific studies that measure the great ability of the âeyeâ to recognize, subconsciously, in fact, almost to measure - the asymmetries of a human face, and perceive as âbeautifulâ a face with less asymmetries (1). If we take 100 pictures of women, and merge them to one, where each characteristic would be the mean of all, the resulting face would be judged as beautiful by the great majority of men. Why "Because the asymmetries would have been smoothed out .
Yes, it is conceivable, indeed, but, statistically, it is highly improbable.
We have seen that even minor differences in shape lead to great differences in strength - and you go even beyond this, and you point out, correctly, that some other subtle results can distort the symmetric distribution of forces even in the cases of identically shaped links. The conceivable possibility that all those differences will cancel each other out, and the two links will be left with similar strengths, would materialize very rarely, if ever.
-
Jones, B., Little, A., Penton-Voak, I., Tiddeman, B., Burt, D., & Perrett, D. (2001). Facial symmetry and judgements of apparent health: Support for a âgood genesâ explanation of the attractiveness-symmetry relationship . Evolution & Human Behavior, 22(6), 417-421.
P.S. The Alpine Butterfly bend and all the variations of the Zeppelin bend are suredly more or less symmetric bends - the single or double Sheet bend, and the bends presented at (2) and (3) are clearly not.
Hi X1,
At the end,I continue to keep wondering if it is possible that there is a symmetric bend,that does not have the same kind of symmetry of the Zeppelin bend,that it can be considered a rope-made hinge.(EDIT:maybe the very beautiful bend by kd8eeh is an example of this?):
http://igkt.net/sm/index.php?topic=4016.msg24885#msg24885
Bye!
Me too !
The falsely tied Zeppelin bend is such a knot, that is for sure. It is also more symmetric than the Zeppelin bend. Also, the âslipped overhand knot bendâ is a rope-made hinge, evidently. The two variations of the recently presented ZB bend and the three Double Zeppelin bends, too.
The SS bend and the Whatknot are close ( In fact, the SS bend can be considered as a more symmetric Whatknot - because the Whatknot itself is symmetric, although it does not look so ). The Oval bend is fifty-fifty. The Hugo bend is 75% (?)âŚ
Some of the pseudo-Zeppelin loops shown at (1) can be considered as rope-made hinges. The Angler s loop, and a couple of the Lee bowlines also use the tail as a pivot - although not only as a pivot.
May be you can explore the bends and loops you know, and discover some more that I have escaped my attention or have been deleted from my memory. However, we should not be too confined in any theoretical scheme. The only real benefit would be the deeper understanding of the mechanism itself, that can lead to the discovery of knots we do not know yet - or to an explanation, even prediction, of something that was not explained or predicted, in the behaviour of knots we already know.
You have quickly --or is it adroitness, here?-- forgotten the
issue : ease of recognition ⌠--not what is perceived as beauty.
So, studies show âgreat abilityâ of the eye to recognize asymmetry:
QED for me?! --not what you meant to say, but said it anyway.
And above, you note that recognition âŚ
of high symmetry of the [i]Zeppelin bend[/i]is not so readily apparent, as it is ...
[symmetry that is[u] not noticeable[/u] by looking at a single side of the knot,
QED II (for me, not you).
[quote="Dan_Lehman post:22, topic:4573"] It is also conceivable that differently shaped parts in an asymmetric end-2-end knot nevertheless have similar strengths [/quote] Yes, it is conceivable, indeed, but, statistically, it is highly improbable.We have seen that even minor differences in shape lead to great differences in strength - and you go even beyond this, and you point out, correctly, that some other subtle results can distort the symmetric distribution of forces even in the cases of identically shaped links. The conceivable possibility that all those differences will cancel each other out, and the two links will be left with similar strengths, would materialize very rarely, if ever.
Where have we seen these results?!
Rather, the improbability is that one will match in tying
âif even having symmetrically natured ropes (where two)â
the symmetry of ideal,
and that these subtle differences will deny the ideally
symmetric knot of its supposed perfect equalization.
What is at question, then, is more a matter of stability,
and thereâs nought to say that asymmetry will be weaker
âone canât take a thing (supposed strength of a shape) and
just put it into a different context and expect the same
result (that the shaped thing really has its same shape).
(E.g., CLDay reports that testing showed overhand knots
to be stronger in one handedness vs. the other --or maybe it
was that the fishermanâs knot so orienting them was soâ;
that could (mis?)lead one to conclude that the opposite-handed
(i.e., with component overhands of each handedness)
fishermanâs knot would assuredly be bad, as it has one
component of either handedness; but thatâs omitting the
fact that in so orienting the components to be opposite in
handedness, one builds a different knot --those components
are in a different (albeit similar) context! Now, frankly, Iâll
guess that it is enough similar that the has-the-weaker-form
condition yet is determinant, but it bears testing; maybe that
weakness is slightly ameliorated --or maybe aggravated!)
[u]Facial[/u] symmetry and judgements of
Send them a Janus bowline ! ;D
âdl*
I can not say that a symmetric thing is more easily recognizable than an asymmetric one. In fact, I had never said such a thing.
However, that was NOT the issue, but you have forgotten it. The issue was to determine if a thing/knot we know in advance that is supposed to become/look symmetric at the end of the tying procedure, will be easily recognized as mistakenly tied if it will be mistakenly tied, or not. And if a thing/knot that we know in advance that it is supposed to become/look asymmetric in the end, will be easily recognized as mistakenly tied, if it will be mistakenly tied, or not. I have argued that, if the thing/knot that was supposed to become symmetric at the end, turns out to look asymmetric, and ugly, because it was tied wrongly, that would be recognized with great ease, at a glance. It will be like a fly in the ointment ⌠On the contrary, if a thing/knot that was supposed to become asymmetric at the end, is wrongly tied, it will most probably look asymmetric- so it would not differ from what it was supposed to look ! How would the eye be able to distinguish between an ugly, asymmetric thing, and another ugly, asymmetric thing ? It is like some ointment on the fly⌠It will not, so the knot tyer runs the danger to tie the knot wrongly, and, because the end result will still be ugly and asymmetric, fail to recognize it ( the mistake, not the ugliness ! )
You see, beauty has played an evolutionary role as well - to say nothing about the beauty in the symmetries of the natural laws.
Beauty matters !
Yes, but the fact that the Zeppelin bend is more symmetric than the bend presented at (1), is noticeable at a glance !
So, if you say that the more or less apparent symmetry of the Zeppelin bend, or of any other symmetric bend, is LESS apparent than the asymmetry of the knot presented at (1), you should/will visit an eye doctor sooner than later ! QED ( for the doctorâŚ)
I do not deny this⌠but I had never spoken of "perfect equalization" . It seems that you find hard to deny the simple comparison of the differences between the relative strengths of the two links in the cases of a symmetric and of an asymmetric knot, and you call the cavalry of the absulute !
You take a Janus bowline, and I will take the Tweedledee bowlineâŚ
(We will share the AthenaâŚ)
Hmmm, in a quick check in flexible solid-braid cord,
I was liking the slack-secureness of this knot, seeing
that loading didnât increase that security --i.e., didnât
over-tighten (jam) it. Iâll take your word that in some
firmer material, such security doesnât come easily.
However, OTOH, I also like how this knot can be left
less tightened, for pure ease of untying --after, e.g.,
use to join bigger ropes used for towing a vehicle out
of being stuck. I like how the SParts are deflected
around the twin wraps and then make their U-turns
which nip the tails --thinking this initial bending over
twin (not a single) parts of rope is kind to the rope
and efficient in strength. And then, as noted, this
loose form will be readily untied.
.:. So, a tool to be used appropriately.
âdl*
Have to say that I really like this thread - there is some really interesting technical content here.
For example:
It may sound a little too abstract or general to some, but ALL bends ( end-to-end knots) belong to three, and three only, broad categories. *(1) The most important part of any bend is its Standing parts first curves. It is there where the loaded bend will make it or brake it. So, it is reasonable to classify bends according to the specific characteristics of those curves, and not of the rest of their two links entanglement. The first curve of each link of a bend can make a turn ( can bend ) around : 1. The other link s straight part of the standing part - the straight continuation of the standing end. 2. The other link s first curve of the standing part. 3. The other link s tail.
And, the thread has hasnât degenerated into a slanging fest (which has really brought my interest back to the IGKT forum again).
I have to study this material and see if any of it can be tested.
Mark
Just another example of a true Zeppelin-like knot, a rope-made hinge where the two main bights of the two links are not hooked the one to the other, but connected through their tail pair, which play the role of the pivot.
A slightly different dressing of the same knot, is shown in the fourth picture. A great advantage of the Zeppelin bend, is that the âpivotâ remains almost perpendicular to the axis of the loading - therefore it confronts shear forces mainly rather than oblique friction forces. When this beneficial orientation is compromised, and the pair of the tails is not at a right angle to the pair of the standing ends ( like it happens in the bend shown in this post), the âpivotâ has to withstand stronger friction forces, and function as a âwedgeâ - just as it happens to most other bends.
I publish it to show, just another time, what is the main characteristic of the genuine Zeppelin knot, the Zeppelin bend - and what the fake, so-called âZeppelin loopâ does not have⌠while the loops presented in (1) do . However, I have seen that it has recently became something of an easy ( and cheap ! ) fashion, for people that have not been able to understand what a Zeppelin-like knot is, to advocate this fake / so-called âZeppelin loopâ here and there in the Web, in poorly written âso-called articlesâ like this lamentable one :
http://en.wikipedia.org/wiki/Zeppelin_loop
( Notice that, in this ONE SINGLE LINE âARTICLEâ, there is only ONE SINGLE REFERENCE - a truly notable contribution to the case of the so-called âZeppelin-loopâ, indeed !
Regarding the Zeppelin Bend and Zeppelin Loop; identical knot bodies and practically identical properties = unrelated in your world? Must be a lonely place.
Having 50% of the main load on one tail doesnât make the knot jam and it slightly increases the security of the knot form.
It seems like a fair trade to me.
These unnamed dozens usually have other defects, such as instability, insecurity, unjustifiable complexity, and so on.
[quote="roo post:33, topic:4573"] it slightly increases the security of the knot form. [/quote] Really ?Yes, really.
So the Zeppelin bend is not secure enough ?There's nothing wrong with improving security.
Or you have not been able to find the [i]dozens of dozens[/i] of other secure bends that can be turned into secure loops ?See my first point. When these unnamed "dozens" are actually named, they usually aren't very impressive.
Do you consider as an "invention" of yours the simple fact that a loaded tail makes a bend, ANY BEND, even more secure ?No. What a weird response. Some bends capsize when you pull on their tail. Some jam.
There are [i]dozens of dozens[/i] of end-of-line loops,The unnamed ghosts are multiplying! I guess I should expect that they remain unnamed. The last time you named your ultimate loop, it was an order of magnitude more complicated than the Zeppelin Loop, while being quite a bit less secure.
that are secure and do not jamSays the poster who prefers not to test knots.
, and [i]dozens[/i] of them are even bowline-like, i.e. post-eye-tiableWhen you're at the end of the rope (such as when tying an end loop), it is a trivial matter to tie an overhand knot. Even for unusually large loops, an overhand knot tied near the end of a rope can be rolled quickly to another position if you know where to place your fingers.
- and I have even shown some of them that are secure, do not jam, are post-eye-tiable, [b]AND[/b] they are tiable in the bightWhile this is a different topic, why aren't you using the Butterfly Loop as an on-the-bight loop (or some other standard) instead of one of your usual unvetted, complicated creations?
Your last ultimate loop knot didnât pass muster. But since you have so many unnamed contenders, why donât you test them against each other and sort them and when you find your next ultimate loop (singular), start a new thread to dazzle us.
Iâd like to give you some criteria:
- Simplicity
- Simplicity
- Did I mention simplicity?
- Security (slack shaking, unusual load paths, etc).
- Jam resistance (try small diameter nylon rope)
- Easy to check
- Efficiency of rope usage
Please. You heavily edited your original response many days later (June 18!) and you know it. Your original response was that you refuse to respond.
After this disgusting attack is there any wonder why people might not want to dialog with you? I donât think I can count the number of threads where the only person responding to you is, well, you.
Iâve pointed out this to you before as just one example of my critiques:
http://igkt.net/sm/index.php?topic=1094.msg7456#msg7456
No silence there.
I also find it absurd that Iâm supposed to know when youâve secretly changed the entire content of your posts days or weeks later and respond accordingly.
Maybe you should do a forum search before you keep repeating the same falsehoods.
For more examples:
http://igkt.net/sm/index.php?topic=1906.msg13150#msg13150
Wow. Nice non-apology.
I donât know why you think Iâm under some sort of obligation to evaluate everything you post.
Going separate ways and cool off for a few days, is long overdue.