Author Topic: Oval loop  (Read 4077 times)

X1

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Oval loop
« on: July 23, 2012, 11:31:28 AM »
   The Oval loop. Corresponding to the Oval bend, shown at (1) (See the attached pictures). I believe that it presents an interesting mechanism of securing the tail, which is not so common in loops or bends. In the original Oval bend, the fact that the first curves of the standing  parts are going around the centrally located pair of adjacent opposing tails, as well as the overall two-sides symmetry, reminds of the Zeppelin bend. However, in the Oval bend the two links are topologically equivalent not to the overhand knot, but to the unknot - so this bend can be transformed into a bowline-like end-of-line loop.
   I have tied all  the symmetric bends I know, where the two links are topologically equivalent to the unknot - and not to the overhand knot, to the fig.8 knot, the fig.9 knots, the double overhand knot, etc. I have tried all  the possible corresponding end-of-line loops of those bends, as well as of their "reversed" knots ( where the standing ends and the free ends are interchanged). Guess what interesting I have found, except the few loops I have presented till now : Nothing !  :) A round Zero ! It is evident that this is not the way to search for bowline-like, end-of-line loops...I have seen that the corresponding to those symmetric bends loops suffer from one or more of the following :
   1. They are too complex, although they can be simplified a lot - but then they lose any resemblance to the original symmetric bend. A loop is a more "easy" knot than a bend, in the sense that, having three limbs loaded, it is now easier to secure the single tail into the knot s nub - which, in its turn, is squeezed by three tensioned ends, from three sides. So, rope segments, elements of the knot, that were nessesary to securely fix the bend s tangle, are now redundant . This makes most symmetric bends, when they are transformed into corresponding end-of-line loops, consume more rope length than nessesary.
   2. The asymmetric loading distorts the loop knots too much, so they do not resemble the original symmetric base knots any more. In most of those loops, the distribution of tensile forces within the knot s nub is now greatly imbalanced, and the overall form is not inspected very easily any more, for the knot tyer to be sure, in a glance, that the knot is correctly tied.
   3. The rope segments follow very tight curves, that could have been avoided in a not-symmetric knot. Alhtough these curves were nessesary in the original bend, now they look like they could have been avoided, if the rope segments were driven to follow different paths into the knot s nub.
   3. The tying method of the corresponding end-of-line loops are different, and less easy to remember, than the tying method of base symmetric bends. A knot that was very easy to tie and inspect as a symmetric bend, now looks like a puzzle, and the knot tyer is not sure through which opening of the "nipping structure" he has pass his working end ...
   In short, we can tie better and simpler bowline-like end-of-line loops, if we do not follow the complex patterns we were following in the case of the symmetric bends. With the notable exception of the symmetric sheet bend, all the other symmetric bends are more complex than the standard bowline...and this tells us much about how efficient is the nipping loop + collar mechanism.

1) http://igkt.net/sm/index.php?topic=3741
« Last Edit: July 23, 2012, 01:21:56 PM by X1 »

Dan_Lehman

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Re: Oval loop
« Reply #1 on: July 23, 2012, 09:29:28 PM »
This "oval loop" looks like something a person fiddling
in rather firm rope/cord might come up with; it is
less likely to appeal to one fiddling soft/flexible material.
Because so much depends upon the mere tails of the
knot preventing this capsizing, w/o additional support!

Tied in those cords of the latter character that can be
salvaged from shopping bags (serving qua handles),
this knot can capsize --or, in my sole test loading,
it has done so on one side only (and I manually
forced the other initial u-turn to fold around the
nub just so, for symmetry).  The capsized knot has
some interesting aspects, but I'm hardly moved to
forget about all the interlocked-overhands end-2-end knots!
(Which, to other points in the OP, do yield some
good, strong, easily untied eyeknots --regardless of
one's view of symmetry in loading (e.g., it might be
that the infamous "zeppelin" knot is stronger qua
eyeknot than end-2-end knot (as might be the fig.8?!)!


--dl*
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X1

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Re: Oval loop
« Reply #2 on: July 23, 2012, 10:54:55 PM »
This "oval loop" looks like something a person fiddling in rather firm rope/cord might come up with; it is less likely to appeal to one fiddling soft/flexible material.
Because so much depends upon the mere tails of the knot preventing this capsizing, w/o additional support!

   Correct. ( That may be a reason why it was not known till now...). I might add that it also depends upon a rather balanced distribution of the tensile forces between the two legs of the bight.
   However, with the stiff kermantle climbing ropes that I use, it is tied and dressed easily, and it holds very well. I have not examined its capsized form(s).

I'm hardly moved to forget about all the interlocked-overhands end-2-end knots!

   I do not forget them, I find them less clever, and less interesting, than the bowline-like loops. I have also seen that, when we do not need an end-of-line loop that should be untied quickly and in one step ( as the bowline-like loops ), we can use one of the many double loops.... that are stronger and more secure knots, by default.

it might be that the infamous "Zeppelin" knot is stronger qua eyeknot than end-2-end knot (as might be the fig.8?!)!

   Most probably... but this does not make the so-called "Zeppelin loop" more clever and/or less ugly !  :)
   One can not criticize the fig.8 bend and loop, of course - beautiful, symmetric, balanced, secure, useful... I wonder if there are any circumstances where one will not be able to tie a fig.8 loop, and would  prefer the dumb and ugly so-called "Zeppelin loop" instead...
« Last Edit: July 23, 2012, 10:56:59 PM by X1 »

roo

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Re: Oval loop
« Reply #3 on: July 23, 2012, 11:26:19 PM »
One can not criticize the fig.8 bend and loop, of course
I can:

http://notableknotindex.webs.com/figure8loop.html

Why do you think we've had so many threads looking for alternatives?
« Last Edit: July 23, 2012, 11:28:09 PM by roo »
If you wish to add a troll to your ignore list, click "Profile" then "Buddies/Ignore List".


X1

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Re: Oval loop
« Reply #4 on: July 24, 2012, 12:16:19 AM »
   The question mark I was referring to was about the strength of the fig.8 loop, in comparison to the fig 8. bend. I believe that the shortcomings of the so-called "Zeppelin loop", in comparison to the genuine Zeppelin knot, the Zeppelin bend, are so many, that even if the loop is stronger than the bend ( which might be the case, indeed), we should not consider it as an alternative to the fig. 8 loop. In the case of the fig. 8 bend and loop, the situation is different, because these two knots are almost indistinguishable, even if they are heavy loaded. So, the question of the relative strength of the two knots is the last thing that we should consider, I believe.
   There is a number of double nipping loop bowlines that are very secure knots, and they do not have any of the disadvantages of the fig.8 loop correctly described at (1) - the Water bowline, the Girth-hitched bowline and the double, crossed nipping loops bowline shown at (2), for example. When we add a second collar, the "mirror-ed" versions of those bowlines are real alternatives to the fig.8 loop, indeed - AND they retain the great advantage of all bowlines, that they can be untied in one step, leaving no trace, no knot still tied on the standing part after the removal of the collar structure.

1) http://notableknotindex.webs.com/figure8loop.html
2) http://igkt.net/sm/index.php?topic=3951.0

Dan_Lehman

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Re: Oval loop
« Reply #5 on: July 24, 2012, 05:21:15 PM »
...  even if the loop is stronger than the bend ( which might be the case, indeed), we should not consider it as an alternative to the fig. 8 loop.

One would consider it an alternative (if indeed it is stronger
(or if one realizes that strength difference is irrelevant))
because it doesn't jam (so readily), yet has some good
slack security.  Sure, there are alternatives --I probably
have discovered more eye knots than other types, and
maybe more than any two-three other types combined
(I'm not sure why, but ...).


--dl*
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ps : Oops, yes, my feelings about "flexible material" indeed were
spawned for the >>end-2-end<< knot, not the eyeknot!  (And
I see it --my observation-- has been whisked away to a distant
but related (old) thread, appearing out-of-the-blue, there!   ;)

As for stiffness of rope ... , that can be deceptive : it can enable,
even coerce, structures that when push comes to shove --when
the considerable forces such ropes might be subjected to--, THEN
one finds that the flexibility inherent in the material manifests
in failure.  I.e., the big load can do what manual play doesn't imagine.
« Last Edit: July 24, 2012, 05:34:25 PM by Dan_Lehman »

X1

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Re: Oval loop
« Reply #6 on: July 24, 2012, 11:24:42 PM »
...my observation-- has been whisked away to a distantbut related (old) thread, appearing out-of-the-blue, there!   ;)

   I have replied, and I have posted my comments where they should have been posted :  at the original thread, where I have presented the base bend for the first time. There was a reference in the "new" thread, of the corresponding loop, to the "old" thread, of the base bend, and I have thought that I should include your observation and my comments on it where they make more sense. ( One reason that I like knots, is that there are they do not age, as I do !  :))