Author Topic: Retucking the thief knot  (Read 17204 times)

xarax

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Retucking the thief knot
« on: September 13, 2011, 11:07:59 AM »
   The thief knot - when tied on most modern materials - is an insecure, dangerous bend, but a bend that can very easily be greatly improved by re-tucking. What is perhaps the most interesting thing about this retucking of the thief knot, is that the particular way we retuck it does not matter : all derived bends are greatly safer, much more secure bends than their parent, untucked knot. ( See the attached pictures for those once-retucked thief-knot-based bends.)
(A different way to retuck the thief knot was shown in (1).

1) http://igkt.net/sm/index.php?topic=2085.0
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xarax

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Re: Retucking the thief knot
« Reply #1 on: September 13, 2011, 11:13:09 AM »
2. Notice that the B3 bend is the "inverted" Zeppelin bend (interchanged standing ends / tails) It should perhaps be expected that the thief knot is somehow related to the Zeppelin bend, because of their symmetry.
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DDK

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Re: Retucking the thief knot
« Reply #2 on: September 14, 2011, 04:06:26 PM »
  The thief knot . . . by re-tucking . . . : all derived bends are greatly safer . . .

The Thief Knot is not secure because of "positive cogging" much like the Grief Knot. The Reef Knot is considered more dangerous than either of these two knots because, in part, it gives the appearance of security which it does not have.  This is not true to anywhere near the same extent with the Thief and Grief Knots.  Obviously, another reason would be that the Thief and Grief Knots are difficult to tie by mistake.

I was able to easily find a retucked Thief Knot (first one I tried) which gave the appearance of additional security but when tied in series with a Grass Bend, it completely pulled apart while the Grass Bend did not.  The retucked Thief Knot I chose was one of those which least mitigated the original positive cogging in the Thief Knot, but, was able to support 200 pounds of load.  A very dangerous bend indeed and not nearly as safe as the original Thief Knot in my opinion.

It should perhaps be expected that the thief knot is somehow related to the Zeppelin bend, because of their symmetry.

If the retucking produces an overhand knot and is done symmetrically, one has a bend which is interlocked overhand knots with central inversion symmetry just as is found in the Zeppelin bend.

DDK

« Last Edit: September 14, 2011, 04:48:03 PM by DDK »

xarax

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Re: Retucking the thief knot
« Reply #3 on: September 14, 2011, 04:51:04 PM »
   Thank you DDk,

I was able to easily find a retucked Thief Knot (first one I tried) which gave the appearance of additional security

  There are not any once-re tucked thief knots other than the ones shown in this thread - except from the "double thief knot" which is formed by retucking through the central opening. Besides this central opening, there are 4 openings from which the working ends can pass for another time, so there are four once-re tucked thief knots. ( A1-A4). If we further allow our working ends to pass through those openings from the other side of the knot, we have 4 more bends, two of which are completely unstable, and, of course, do not give ANY appearance of security whatsoever !  :)  I suggest you tie all those knots shown here, and compare them to the parent thief knot, as I have done here, and not to other bends...You will easily find that all are greatly more secure than the original parent knot, although some are better than the others. ( I prefer the A3). Tie the knots as shown, and tell me, please, about your findings, for each one of them.
   P.S.1.  It is pre-supposed that the re tucking should be done in a way that retains the symmetry of the original knot  I have not explored not-symmetrical re tuckings, because symmetric bends are always better, more secure and stronger, than similar non symmetric ones. The uneven distribution of forces into the knot s nub produces, as a consequence, weak spots, where the local curvature of the rope strands is much greater.
  P.S 2 . I have also not mentioned the "double thief knot" that is formed by retucking the working ends through the central opening, because I have thought that it would only multiply the existing situation of the original, parent thief knot.  
« Last Edit: September 15, 2011, 05:18:33 PM by xarax »
This is not a knot.

DDK

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Re: Retucking the thief knot
« Reply #4 on: September 14, 2011, 06:00:16 PM »
  Thank you DDk,

I was able to easily find a retucked Thief Knot (first one I tried) which gave the appearance of additional security

 . . . There are not any once-re tucked thief knots other than the ones shown in this thread ! . . .  

There are others, see below.  This knot has the same symmetry as the original Thief Knot and is misleadingly secure upon a careful setting of the knot.  I am specifically addressing your claim that "all derived bends are greatly safer, much more secure bends than their parent".  First, I point out that additional security does not always equate with safety.  In the example I give, the additional security makes the retucked knot considerably more dangerous than the original knot.

As far as the use of the Thief Knot (or its "improvements") as a binding knot, I find it to be a non-starter given the difficulty in tying and the fact that we have the Reef Knot.

DDK
« Last Edit: September 15, 2011, 01:41:00 AM by DDK »

DDK

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Re: Retucking the thief knot
« Reply #5 on: September 14, 2011, 06:34:45 PM »
OK, I have reread your post.  Unless I am missing something here, the bend I show is retucked ONCE and illustrates that your statement of simple fact is incorrect.

DDK

DDK

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Re: Retucking the thief knot
« Reply #6 on: September 15, 2011, 02:24:39 PM »
. . . the bend I show is retucked ONCE and illustrates that your statement of simple fact is incorrect . . .
  Yes, I am afraid you are missing something rather simple...Counting !

No, you have miscounted.  Below I show the original retucked knot and then I show it with each working end untucked ONCE.  THE UNTUCKED KNOT IS A THIEF KNOT.  I then again show the knot after retucking each working end ONCE.   I have demonstrated the concept forwards and backwards.  Surely you can now see and understand this simple concept. 

DDK

xarax

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Re: Retucking the thief knot
« Reply #7 on: September 15, 2011, 03:25:03 PM »
   I have edited my previous posts, that might have been/ have sounded a little harsh...I would be glad if we discuss the bends shown in this thread, as well as any other bends that might be considered as improvements of the thief knot. I admitt I have never really understood the working of this "positive cogging" effect, so it came as a surpise to me that all those different modification of the parent knot, were able to cancel it out !
« Last Edit: September 15, 2011, 05:07:07 PM by xarax »
This is not a knot.

Mike in MD

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Re: Retucking the thief knot
« Reply #8 on: September 15, 2011, 05:50:30 PM »
Hi,

I don't recognize the term positive cogging.  I have done a search within the forum and found only this thread.  Since I am a junior member and may plead ignorance, may I ask for an explanation of this term.  

Thanks,
Mike

edit: it seems that if I click *Search* while looking at this thread, the search engine searches only this thread.  I didn't expect that.  Also, the cogging demonstration with the grief knot is very informative.
« Last Edit: September 15, 2011, 09:22:47 PM by Mike in MD »

xarax

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Re: Retucking the thief knot
« Reply #9 on: September 15, 2011, 07:35:39 PM »
   Mike, I am a not-so-junior a member, but I, too, feel that I may plead ignorance about this characteristic of knots, since so little is written about it, and much less is explained, or predicted, by the use of this notion.
  Have a look at :
http://igkt.net/sm/index.php?topic=1597.msg10962#msg10962

(This particular subject belongs to the "Theory of Practical knots" Forum.)
 
This is not a knot.

DDK

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Re: Retucking the thief knot
« Reply #10 on: September 16, 2011, 12:29:23 AM »
  I have edited my previous posts, that might have been/ have sounded a little harsh...

Your style of editing leaves many things to be desired.  To hold and argue stubbornly a particular (wrong) position and then, upon realizing your mistake, to make additions and subtractions to previous posts to mitigate your obvious foolishness is disappointing.  I am speaking specifically of your additions of comments regarding the "double thief knot" and subtractions of your insistence that I was not able to count a number of retucks (which, as it turns out, was your miscounting).

A simple, "I was mistaken" would have been a much better way to go.

DDK

xarax

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Re: Retucking the thief knot
« Reply #11 on: September 16, 2011, 12:51:23 AM »
...your obvious foolishness...

I do not reply to such things.
This is not a knot.

SS369

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Re: Retucking the thief knot
« Reply #12 on: September 16, 2011, 01:33:51 AM »
I'm hoping we'll get back on topic.
If there's more tit for tat to do, please take it to pm.

SS

DDK

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Re: Retucking the thief knot
« Reply #13 on: September 16, 2011, 03:21:37 AM »
  . . .  You will easily find that all are greatly more secure than the original parent knot, although some are better than the others. ( I prefer the A3). Tie the knots as shown, and tell me, please, about your findings, for each one of them . . .

My findings on A3:

I encountered some difficulty in reproducing the bend shown.  In part, I believe it is because I was using pieces of the same rope (same color, markings, etc) to tie the bend.  Likely, it would be simpler with two distinct ropes, but, unlikely to be as simple as producing the Figure 8 Bend (which I would consider the Gold Standard for retucked Thief Knots).

The bend became somewhat jamming as I applied moderate load.  I find this to be true for many of the retucked single carricks in which interlocked overhand knots are produced1.  This may be a general behavior and differs from the non-jamming retucked Reef or Thief Knots which are interlocking figure 8 knots2.  I did not increase the load on A3 due to its already perceived jamming and cannot speak to its security at high loads (i.e. capsizing, slippage or the like).

DDK

1  Same holds true for the "Twice-Twisted Zeppelin Bend"  http://igkt.net/sm/index.php?topic=3204.msg19303#msg19303
2 http://igkt.net/sm/index.php?topic=3196.msg19099#msg19099

xarax

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Re: Retucking the thief knot
« Reply #14 on: September 16, 2011, 02:09:15 PM »
   Thank you DDK,

   Now you are talking !  :) You should not have any difficulties in setting and dressing those knots, if you start from the loose thief knot as shown in the attached picture.( Notice that I have placed the yellow-red marble into the 3 rd opening, for the A3. I have followed this simple notation for all those bends. For the B series, one has to pass the working end(s) from the other side.) May be I should have posted this picture from the beginning, to save us from exchanging meaningless bits and bytes. :)
   Regarding the "jamming" issue, I am the least qualified person to speak about it...I do not understand if the "jamming" of a knot is a quality that exists or not, or a quantity that varies continuously,  in relation to the loading and/or the slippage characteristics of the knotted material. ( There might also be a relation between the jamming of a knot, and the resistance of the rope material to compression...) I, too, have made the vague observation that pretzel shaped interlocked-overhand-knot bends have a greater jamming tendency than "8" shaped ones. ( So, there is already a difference between the members of the class of the overhand-based bends, before the difference between the overhand-based, and the figure 8 -based bends.) I can only guess that the more effective compression of the encircled central nub, achieved by a pretzel shaped overhand knot, is what makes the difference.  
   Go on, try the rest of those bends. You could also compare them to the differently re tucked thief knots presented at (1), that are not so prove to jamming, I believe.
   The main problem that made me post those bends of this thread remains : How, on earth, the "clogging" effect is cancelled so effectively, however we retuck the thief knot ? We pass the working end(s) from whatever opening, very different bends are produced, but anything we do makes this "clogging effect" disappear ! When I will understand why is this so, I would have understood something about this effect.
  
1)  http://igkt.net/sm/index.php?topic=2085.0
« Last Edit: September 16, 2011, 05:48:39 PM by xarax »
This is not a knot.