Author Topic: PET (Glossary of Terms)  (Read 6330 times)

Mobius

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PET (Glossary of Terms)
« on: April 06, 2015, 08:07:45 AM »
Well, I have only been tying and studying knots in earnest for a couple of months and I fully admit that acronyms like TIB had me guessing for quite awhile. The nomenclature in the knotting world is less than obvious in many cases and words like 'bight', 'bend' and 'hitch' do not always imply the same thing.

A notable definition: "That all Bowlines can be tied in a one-stage tying process a concept known as Post Eye Tiable (PET)"

I thought PET meant that the knot could be tied in a practical manner to a ring (endless rail), not that it had to be a "one-stage" process. Is the above definition right? If so, why is it so desirable? Some otherwise very good knots require a simple knot first (eg an overhand knot perhaps) before they are tied to an endless rail.

PET seems to be one of those 'holy grail' terms. I would not dismiss an otherwise good knot because I could not tie it in "one-stage". How easy it is to tie overall is a far more important aspect, right?

Cheers,

mobius

[Edit: Someone new to knotting might do a site search one day on "glossary", with the aim of finding out what certain obscure acronyms mean. I did exactly that a couple of months ago and I thought I would define a few of the well used ones here to help someone get started :) I have no intention of keeping it updated, and I hope no-one accuses me of promulgating undesired acronyms.

PET - Post Eye Tiable. This is the concept of tying a rope end to an endless rail (or a toroid) where the knot can be fully formed in a one-step process after the rope has been passed around the rail, or through a ring. That is, a knot-free rope first makes a loop around the endless rail, then the knot is tied.

TIB - Tiable in the bight. Here bight refers to a mid-line section of rope away from the ends and where the rope ends are not used to tie the knot.

SPart - Standing part of the rope.

EEL - Either End Loadable. The SPart and eye together is clearly the way many loops are loaded normally. However, if a loop was tied TIB and someone loaded the 'Tail' and eye (considered by some/many to be a new knot since we swap what was the SPart and what was the Tail) then it would be useful to know that the original loop satisfies EEL, from a security viewpoint.

... work in progress]
« Last Edit: May 23, 2015, 03:58:03 AM by mobius »

Mobius

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Re: PET (Glossary of terms)
« Reply #1 on: April 06, 2015, 02:46:16 PM »
Thanks xarax,

I will start with this one tomorrow when I'm fresh: http://igkt.net/sm/index.php?topic=4941.msg32500#msg32500

Cheers,

mobius

Mobius

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Re: PET (Glossary of terms)
« Reply #2 on: April 08, 2015, 08:22:47 AM »
   I will try to make my reply as short as possible, because I have already spent a lot of bits and bytes of this Forum on this issue.
   Search for the word "relic", and read the posts where this word is written in relation to the bowlines.
   I short, a non-PET end-of-line loop may even become dangerous.
 

Strangely enough, I was browsing in a book store today and stumbled across a newly written guide to mountaineering/climbing. The knot recommended for end-of-rope loop applications was a retraced Figure 8 (relic). Knot sites still advocate this knot, so I assume it is still currently used.  A nice looking loop to be sure, and no doubt it has earned security status through successful use, however it certainly is not 'one-step'  and therefore not PET, as I understand it.

One is left wondering (and I am happy to learn new things about knots through discussion) whether the climbing fraternity is lacking judgment, or the PET concept is really not so important to climbing applications?

Cheers,

mobius

[edit added the word rope]
« Last Edit: April 09, 2015, 11:39:36 AM by mobius »

Sweeney

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Re: PET (Glossary of terms)
« Reply #3 on: April 08, 2015, 11:08:05 AM »
   I will try to make my reply as short as possible, because I have already spent a lot of bits and bytes of this Forum on this issue.
   Search for the word "relic", and read the posts where this word is written in relation to the bowlines.
   I short, a non-PET end-of-line loop may even become dangerous.
 

One is left wondering (and I am happy to learn new things about knots through discussion) whether the climbing fraternity is lacking judgment, or the PET concept is really not so important to climbing applications?

Climbers use the retraced figure 8 because they trust it and as lives are often at stake this trust is crucial. Any loop may become dangerous if tied incorrectly - some may be more error prone than others - but the retraced figure 8 is easily checked and its non-PET status is irrelevant to users. Xarax has certainly written at length on this issue and with what he has said is well worth reading but if you are risking life and limb be careful to look to users of knots in the real world as well as knot theory.

Sweeney

Mobius

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Re: PET (Glossary of terms)
« Reply #4 on: April 08, 2015, 01:44:56 PM »

Climbers use the retraced figure 8 because they trust it and as lives are often at stake this trust is crucial. Any loop may become dangerous if tied incorrectly - some may be more error prone than others - but the retraced figure 8 is easily checked and its non-PET status is irrelevant to users.

Thank you for the response, I thought what you said was probably the case.

Cheers,

mobius

xarax

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Re: PET (Glossary of terms)
« Reply #5 on: April 08, 2015, 03:02:55 PM »
  Any loop may become dangerous if tied incorrectly... Xarax has certainly written at length on this issue and with what he has said is well worth reading but if you are risking life and limb be careful to look to users of knots in the real world as well as knot theory.

   All each-and-every day sailors and fishermen are "users of knots in the real world" (sic) - especially the old ones !  :) . It is always worth the time required to read the very first sentence of ABoK ! )
   However, I understand that you have not understood a thing of the reasons why a relic knot, still knotted in the line after the loop has been released and the previously attached-to-the-anchor object starts to move, is dangerous. You are obviously no seaman !  :)  I have to inform you that sailors, fishermen, and a few only other professionals ashore ( as surgeons ) were those who have devised, improved and used knots throughout history - climbing is a relatively recent sport, and knot theory a relatively recent branch of mathematics. Do not expect much knowledge about the universe of practical knots coming from those activities.
   Whoever still does not understand why a non-PET knot may become dangerous, is advised to read AGAIN what I have written- or buy a house by the sea and a sailing or a fishing boat, and start his life again !  :)
   
   In passing, climbers know well the tragic incident at Eiger, with a relic knot, which should had not been there :
  " While abseiling however, Kurz could not get the knot that joined the two ropes to pass through his carabiner..."
   http://en.wikipedia.org/wiki/1936_Eiger_north_face_climbing_disaster
   Therefore, after so much effort I had put, and probably wasted, to explain this matter, I, too, can only say :
   "Ich kann nicht mehr"

   here is a perfect knot for those who do not want a PET loop, or a Zeppelin-like knot ( probably because they do not tie knots, or they do not use knots, or they do not use their brain while they decide which knots they should use - or simply because they were not endowed with having a brain in the first place ( no pun intended - cnidarians, as a species, live without a central neural system for BILLIONS of years !  :) )). It is called Zeppelin loop, and it is neither a Zeppelin-like nor a PET loop - nevertheless, it is an ugly tangly which, if you tie and try long enough, will help you manage to appreciate in what a bowline-like PET loop differs, without reading anything, or anything else, of what I have written, I am sure ! 
« Last Edit: May 18, 2015, 02:56:44 AM by xarax »
This is not a knot.

xarax

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Re: PET (Glossary of terms)
« Reply #6 on: April 08, 2015, 05:18:56 PM »
   Let me try, once again, and as analytically yet simply as possible, explain why a "relic" knot still tied in the line of a just released loop is dangerous.
   The moment the continuation of the returning eye leg ( the Tail End ) has been pulled out of the nipping structure tied on the continuation of the Standing End ( the Standing Part ), the loop "opens up", and it can not keep any object attached to the line at its other end, stationary = at a constant distance from the anchor ( the bollard, the ring, the stake, etc ). Therefore, the object at the other end of the line, is now free to distance itself from the anchor, and move, dragging the line along with it, just because the loop which has been "opened up", behaves like it is not encircling the anchor any more.
    Now, two things may happen.
1. If the released loop was PET, by pulling the continuation of the returning eye leg out of the nipping structure, this nipping structure degenerates into the unknot, and the segment on which it was "knotted" becomes a straight line - which, as it is dragged by the moving object, does not run the danger to be caught on some obstacle it will meet in its path. A knot tied on a moving line can be stuck within a narrow passage, or be a factor a swirling line can become even more tangled and "knotted".
2. If the released loop was not PET, by pulling the continuation of the returning eye leg out of the nipping structure, this nipping structure remains "knotted", it is still forming a "relic" knot ( be it an overhand knot, a fig.8 knot, etc - but not un unknot ) - it is still forming a stopper ! And guess why stoppers are called like this !  :) :)
    This stopper, is not only annoying, because it has to be unknotted in a second stage. It may also become dangerous, because, dragged by the object at the other end of it, the line of the released loop can slip around the rim of the bollard, the ring or the stake, and move. A moving line, with a relic knot still tied within it, is something dangerous, not because the knot which has already been partially untied runs any danger to become more unknotted, but because the remaining knot is still unknotted ! And in an environment where everything tends to move, this line with a now not-functional, useless nub on it, is asking for a trouble. We can not always manipulate lines and tie and untie knots, while they, or we, do not move ! THAT is what a sailor or a fisherman can understand, but Sweeney, for example  :) :), can not ! The line may already be tensioned, or may be loose but become tensioned in the blink of the eye, because there are waves and gusts of wind out there, which push and pull the object / boat from all sides ! A loose line becomes tensioned, and vice versa, all the time, and at an instance. On such a line, a still knotted segment is potentially and probably dangerous, especially because, the moments just after an object free itself and is able to start moving away from the anchor, are the most critical. A previously static / stationary system now becomes a dynamic / moving system, and all the parameters which were determining the previous state now change - and they may change in an unpredictable, so potentially dangerous way.
    One may argue that, immediately after he has released the 'first" knot, the one on the Tail End, he can very well untie the "second" knot, the one on the Standing Part, because both knots are tied on the same point, within the reach of the knot tyer s hands and fingers. However, this is exactly what a no-seaman, Sweeney, for example  :) ( I use the same example, for no particular reason... :) ), can not understand : A loose line may become a tense line, and this may happen at an instance. Once the mechanism which immobilizes the whole three-part system ( anchor, line, object ), the loop, has been opened up, and it is not attached on the anchor any more, while it is still attached on the object which can now move, the line is free to slip around anything it was attached on previously, AND THROUGH OUR FINGERS as well ! It is not only annoying to untie two "knotted" segments, it may also be impossible, during the short time frame and the under the unfavourable circumstances described above.

   What am I doing ? I repeat the same things over and over again, when I know that there is no ear nerve, or no ear drum, or no elastic medium between the ear and my mouth - and I am not postulating the existence of brains, at the two far ends of this line !  :) The simplest advise is this : Tie and untie the infamous fake so-called "Zeppelin loop", many times. At the end, you will fall in love with the PET loops !     
« Last Edit: April 08, 2015, 05:20:06 PM by xarax »
This is not a knot.

Mobius

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Re: PET (Glossary of terms)
« Reply #7 on: April 09, 2015, 05:34:00 AM »
Thank you xarax for such lengthy (and may I say passionate :) ) responses. I now don't doubt that PET is a very good quality for a knot to have, and though while I will strive to learn many different loop knots, I will most likely endeavour to focus on loop knots that have the PET property.

BTW, I am not negating my support of Sweeney's post. I think the essence of why the Retraced Figure 8 Loop (RF8L) is prevalent in climbing circles is how verifiable it is. Other loops maybe encompass some of the following aspects (all maybe :) ); secure, easy to tie/untie, non-jamming, PET, TIB, however the RF8L is a very good knot to tie since you know you got it tied right from it's distinctive look. If I was hanging off some cliff face in the wind and rain, knowing I had tied my RF8L tied correctly would give me a good feeling :)

Perhaps the trick is to find a loop knot for climbing that is: secure, easy to verify, easy to tie/untie, non-jamming, PET, TIB. The order of importance is interesting, not sure I have it right.

Cheers,

mobius
« Last Edit: April 09, 2015, 05:35:03 AM by mobius »

Mobius

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Re: PET (Glossary of terms)
« Reply #8 on: April 09, 2015, 06:20:04 AM »
Perhaps we need a new acronym: VET - Verifiable Easy Tying

ie. after you have tried to tie some secure knot, the resultant form should be distinctive enough in appearance for you to know you have it right, or not. Reasonable?
« Last Edit: April 09, 2015, 06:33:45 AM by mobius »

Dan_Lehman

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Re: PET (Glossary of terms)
« Reply #9 on: April 09, 2015, 06:52:48 AM »
I thought PET meant that the knot could be tied in a practical manner to a ring (endless rail),
 not that it had to be a "one-stage" process.
You are correct : the point is that one need
tie nothing until bringing the tail back from
forming the eye (say, around a big object for
which sizing the eye would be difficult),
AND THEN the entire knot can be formed
(e.g., the common bowline).

As for the now too-long-winded exclamations about
the imagined dangers of non-PET eyeknots (of which
you have quickly found one of the most common ones
used for critical, life-support purposes), just select the
words worth heeding:
for all of
Quote
Whoever still does not understand why a non-PET knot may become dangerous
 is advised to read AGAIN what I have written
take one of
Quote
As I said a few days ago, in relation to something else I had written, :
"Believe ... nothing at all of what they say or write"!
and call it a night!
 ;)

Yes, we've gotten to using some shorthand notations
for common and sometimes awkward expresssions.
"TIB" was my chop for "Tiable In-the Bight", and I also
condensed "standing part" into "SPart" or sometimes
gave some tiny suggestive indicator in 'S.Part'.

"Bight" is odd as you allude in sometimes meaning only
"without ends" (and a sense of a straight segment to
be formed into ...) and other times "a U-turn", sort of
equal to "loop", which itself is heavily overloaded.
Hence, re the latter, I opt for "eye knot" to join the
commonly used "eye splice".

But the nomenclature challenges are tough, and remain.

--dl*
====

xarax

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Re: PET (Glossary of terms)
« Reply #10 on: April 09, 2015, 07:01:40 AM »
   The fig.8 eyeknot is a GREAT knot, and a most BEAUTIFUL knot as well, period. It is no coincidence that it is included in all "lists" of "best" knots - mine s too. ( http://igkt.net/sm/index.php?topic=1150.msg33735#msg33735 ). That does not mean it is the best in each and every aspect of it, or that it hasn't any shortcomings... I believe that we have TIB and PET loops ( bowline-like loops ) which are also very secure, and as easily tied and even more easily untied, than the retraced fig.8 knot. 
This is not a knot.

Sweeney

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Re: PET (Glossary of terms)
« Reply #11 on: April 09, 2015, 08:17:21 AM »

   I did nt like that vitriolic :
   
... but if you are risking life and limb, be careful to look to users of knots in the real world

Xarax has taken exception to this remark assuming (wrongly) some personal slight. My point was simple and as future readers may misunderstand it I will explain. If you are going to risk life and limb then it's no use just reading books, watching videos and reading posts - that is the virtual world. You need to be taught in the real world with someone with experience at your side - someone to help ensure you can tie and dress an appropriate knot properly - whether PET or not.  Safety is paramount.

Sweeney
« Last Edit: April 09, 2015, 08:18:32 AM by Sweeney »

xarax

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Re: PET (Glossary of terms)
« Reply #12 on: April 09, 2015, 03:48:53 PM »
 
  Safety is paramount.

  Nobody can deny that - and I do not see any reason one has to repeat it time and again, in a Forum of knot tyers.
  However, the possibility of a "relic" knot, still tied on the one end of a line ( which is already released and dragged by a now free to move object, attached on its other end ) to slip through our fingers before we are offered the possibility to untie it, and then be caught somewhere, and so become a real and present danger, is a matter of safety ! ( Dan Lehman, who imagine imaginations, was quick8 to deny this fact, as he needs/likes to do with every knot and every knot tyer - except his and himself, of course ... :))
   No any knots still knotted on any lines, when they are not needed any more. When you can tie a knot which can be tied and untied in one stage, do it. This is a simple advice regarding SAFETY. Knots are dangerous when they become unknotted, but they can also become dangerous if they are not unknotted when they should.
« Last Edit: April 11, 2015, 11:07:41 AM by xarax »
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xarax

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Re: PET (Glossary of terms)
« Reply #13 on: April 28, 2015, 11:24:03 PM »
   While I was trying to describe some EEL eyeknots ( EEL = Either End Loadable ), I had realized, once again, the limitations of the "traditional" knotting nomenclature.
   In particular, when we have a PET eyeknot which can also be loaded by either end ( without any drastic transformation of its nub, of course ), it is reasonable to ask for something more : to be PET in relation to either end, too - for the same reasons we had asked for a PET eyeknot, in relation to one end only, the Standing end. That is, the two knots tied on the Standing Part, at the continuations of the two eye legs, at the two sides of the tip of the eye, should better be PET, both of them. So, if we untie the eyeknot using either of the two ends, the moment we would pull it of the nub, the whole knot will be unknotted, without leaving any "relic" knot near the other end ( which should be untied at a second stage ).
   How we could call such a eyeknot ? For the time being, I use the term PEET or PEEET ( Post Eye - starting from - Either End, Tiable ). Any better (= shorter, more easily and clearly denoting this feature ) word ?
This is not a knot.

Mobius

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Re: PET (Glossary of terms)
« Reply #14 on: April 29, 2015, 03:37:40 AM »
Here is my $0.02 on the matter:

I would use PETEE. Post Eye Tiable, Either End

That does not corrupt the original PET acronym and keeps the latter EE consistent with EEL (Either End Loadable). A 5 letter acronym is rather a mouthful, though I think PETEE is a more logical acronym than either PEET or PEEET.

On another matter, I think we need a Glossary of Terms for this site. The meanings of the acronyms we use are not obvious. Someone new here does not want to be looking at PETEE and thinking "not another bl...y acronym, what does that mean"?  ::)

Cheers,

mobius
« Last Edit: April 29, 2015, 03:41:07 AM by mobius »