Author Topic: What defines a Bowline? - structure, characteristics, topology  (Read 126265 times)

Dan_Lehman

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increased number of parts ...imply a diminished proportion of load - in theory, disregarding friction
   Not "disregarding friction" !
   Friction theory tells us that friction force is independent  of the number of parts, i.e., the total contact area ...

Yesssss, disregarding friction : you miss my point,
which is that the nip upon the tail-side *end* of
the turNip might be diminished and there could
be --YMMV per friction per material-- thus
still delivery of ("flow-through of") more force to
this part than is implied by the number of other
parts (through the turNip) that apparently bear
load "south" (eye-wards) of the nip --where the
SPart has it all, to the "north".

((I think that in practice there might be some
considerable slippage of the turNip'd parts with
thus loading of the tail-side exit from the turNip,
and then comes more nip-grip of those parts,
stopping much further imbalance of loading.))


--dl*
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X1

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Re: What defines a Bowline? - structure, characteristics, topology
« Reply #301 on: July 25, 2013, 09:54:50 AM »
   We all have played with such toys when we were kids, but it seems we have forgotten it ! :) .  If we make a " turn"  with a string around a pencil, and keep the two ends of the string tensioned, we can "walk" the pencil from the one end of the string to the other - provided the pencil is very slippery, or we enable this "axle" to rotate freely into our palm as we drag it towards the one or the other end. If the string is tensioned, and if it does not slip on the surface of the pencil, and if the pencil itself is not allowed to rotate, the turn will not move / walk, even if the pencil is pushed or pulled.
Let me attempt to say the same thing, with MUCH more words - just in case somebody had read the above, but had forgotten it by now   :) :

   There is one thing people forget about the bowline - and which must be obvious when the bowline is tied on a very slippery material, and/or loaded heavily  :
   WHY THE NIPPING TURN DOES NOT "WALK" DOWN THE STANDING PART, towards the tip of the eye ?
   Clearly, the friction between the standing end and the collar is not enough. Then, why ?
   I have tried to show it with a little experimant : Take a string, make a nipping turn on it, make the nipping turn encircle a perpendicularly placed pencil, and keep the string tensioned constantly. Now, push the pencil, while keeping it parallel to itself, that is, perpendicular to the sting, towards the one or the other end of the string.
   Surprise ! The pencil will be translated, because it can be rotated ! I did not say that you should nt allow it rotate, did I ?  :)
   And by it being translated, the nipping turn will "walk" - meaning that the segment of the string coming from the one side will wind around the pencil more, and the segment of the string coming from the other side will unwind. 
   What can prevent the translation of the pencil ? The prevention of its rotation. What can prevent this rotation ?
   In the example of the pencil, nothing. You were told to push the pencil, but not to prevent its rotation. In the reality of the bowline, where the ?pencil? is the two ( or three, in the case of double collar bowlines ) legs of the bight component, the fact that this bight component is attached,  re. rotation, to the standing end. It can not rotate around itself, it can not revolve, because of this standing end penetrating it at the region of the collar...
    One would say : there is another way the pencil can remain un-rotated, but be translated nevertheless : if the string that turns around it slips on its surface, i.e. in the case of a very slippery or sweated pencil !  Well, yes, it can, in the example of the pencil, and when the student has not made its homework...
     However, in the case of the bowline, there is sooo much friction between the shrinking squeezing nipping turn and the two or three legs of the bight component, that this poor bight component can not even think of been left free to rotate around itself / revolve !
    So, at the end of the day, the nipping turn does not walk along the Standing part, because the standing end prevents the ROTATION of the bight component, and preventing rotation of the bight component means preventing translation ( preventing walking ) of the nipping turn.
« Last Edit: July 25, 2013, 09:57:24 AM by X1 »

X1

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   The prefix anti- is used in English language to denote mainly two things :
 
  1. Against, opposed to, preventing or relieving
  2. Being in a state spatially opposite to another.
 
  Its use in the case of the "Eskimo" bowlines was advocated by dan Lehman, who considered this characteristic as a very important quality of the "Eskimo" bowline, and its derivatives. It is true that we should distinguish between the "Common" bowlines, where the bight component collars the Standing end, and the "Eskimo" bowlines, where the bight component collars the eye leg of the Standing Part s side. Also, it is true that the side through which the eye leg of the Tail side enters into the nipping turn is very important. However, this distinction should be neutral, without any connotation that there is a confrontation between those two forms of the bowline. Just because I happen to live in a country where the prefic anti- in the words is used for many years, and many times each day  :) , I felt that the ambiguity would have to be pointed out. I had also proposed an alternative description, which uses, as prefixes, the corresponding notations (+) and (-), which sound more neutral to my ears.

   I have counted the words in contemporary English language where the meaning of the anti- is the first :; a number close to 60.

antacid, antagonist, anthelmintic, antiaircraft, antibacterial, antibiotic, antibody, anticholinergic, antichrist, anticlerical, anticline, anticoagulant, anticodon, antidepressant, anti-diarrhoeal, antidiuretic, antidote, antiemetic, antifeedant, antiferromagnetic, antifouling, antifreeze, antigen, antigravity, antihero, antihistamine, anti-infective, anti-inflammatory, antiknock, antilock, antilogy, antimacassar, antinomy, antioxidant, antipathy, antipersonnel, antiperspirant, antipruritic, antipsychotic, antipyretic, antiroll-bar, antirrhinum, antiscorbic, anti-Semitism, antisense, antiseptic, antiserum, antisocial, antispasmodic, antistatic, antithesis, antitoxin, antitrust, antivenin, antiviral, antivivisection,.
   See also : http://en.wikipedia.org/wiki/Special:PrefixIndex/Anti

   I have also counted the words where the meaning of the anti- is the second : a number close to 10 ;

anthelion, anticlockwise, anticyclone, antilogarithm, antinode, antiparallel, antiparticle, antipodes, antistrophe, anti-symmetric, 

   The number of different words is not a proof, of course, that the one meaning is more or less frequently used than the other. However, the 6 : 1 ratio tells something, I believe...

   This is the reason I do not like the anti-bowline characterization of the "Eskimo" bowline and its derivatives, and I prefer to use the (+) and (-) notation.
   The interested reader is kindly requested to figure out a way of denoting diametrically opposed qualities, points, sides, locations, orientations, etc, without denoting any confrontation that supposedly, sooner or later, will be resolved by the dominance of the one over the other.
   
   Contraria sunt Complementa    :) :)
 
   
« Last Edit: July 26, 2013, 02:25:19 AM by X1 »

alpineer

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Re: What defines a Bowline? - structure, characteristics, topology
« Reply #303 on: July 26, 2013, 01:25:04 AM »
Myself, I prefer the term Offset Bowline.

Dan_Lehman

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   The prefix anti- is used in English language to denote mainly two things :
 
  1. Against, opposed to, preventing or relieving
  2. Being in a state spatially opposite to another.
 
  Its use in the case of the "Eskimo" bowlines was advocated by dan Lehman, who considered this characteristic as a very important quality of the "Eskimo" bowline, and its derivatives. It is true that we should distinguish between the "Common" bowlines, where the bight component collars the Standing end, and the "Eskimo" bowlines, where the bight component collars the eye leg of the Standing Part s side. Also, it is true that the side through which the eye leg of the Tail side enters into the nipping turn is very important. However, this distinction should be neutral, without any connotation that there is a confrontation between those two forms of the bowline. Just because I happen to live in a country where the prefic anti- in the words is used for many years, and many times each day  :) , I felt that the ambiguity would have to be pointed out. I had also proposed an alternative description, which uses, as prefixes, the corresponding notations (+) and (-), which sound more neutral to my ears.

   I have counted the words in contemporary English language where the meaning of the anti- is the first :; a number close to 60.
...
   I have also counted the words where the meaning of the anti- is the second : a number close to 10 ;

anthelion, anticlockwise, anticyclone, antilogarithm, antinode, antiparallel, antiparticle, antipodes, antistrophe, anti-symmetric, 

   The number of different words is not a proof, of course, that the one meaning is more or less frequently used than the other. However, the 6 : 1 ratio tells something, I believe...

   This is the reason I do not like the anti-bowline characterization of the "Eskimo" bowline and its derivatives, and I prefer to use the (+) and (-) notation.
   The interested reader is kindly requested to figure out a way of denoting diametrically opposed qualities, points, sides, locations, orientations, etc, without denoting any confrontation that supposedly, sooner or later, will be resolved by the dominance of the one over the other.
   
   Contraria sunt Complementa    :) :)
 

Partially correct : I use "anti-bowline" soley to distinguish
the direction of the tail's return through the turNip
--that is how the Eskimo bowline comes into the (sub)set,
nothing to do with its collaring an eye leg (but that is all
it can collar, given direction; but it could loop, instead).
It was "anti-cyclone" that I thought of, though the more
commonly used "anti-clockwise" should've come to mind.

Counting senses!  Well, maybe we should work towards
righting that imbalance!?  In any case, it was a convenient
moniker that had a rationale, and I wanted a label/name.   ;)

--dl*
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Dan_Lehman

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the nip upon the tail-side *end* of
the turNip might be diminished and there could
be --YMMV per friction per material-- thus
still delivery of ("flow-through of") more force to
this part than is implied by the number of other
parts (through the turNip) that apparently bear
load "south" (eye-wards) of the nip --where the
SPart has it all, to the "north".

((I think that in practice there might be some
considerable slippage of the turNip'd parts with
thus loading of the tail-side exit from the turNip,
and then comes more nip-grip of those parts,
stopping much further imbalance of loading.))

you miss my point

That was no sooo difficult, was it ?
Considering that I still miss it now, because you should be nominated
by the Pulitzer prize for those tangled "sentences" :
And sometimes I might cast a vote for that award, myself!  ::)

Partly, of course, the problem is that we don't have
a sound nomenclature for discussion --which in part
betrays the secret that knots haven't been very much
talked about, thought about over all these years?!

But let me try again.
"*end*" is something I use to denote a part exiting
some circumscribed area of interest; if that were
a nub of an end-2-end or eye knot, there would
be four "*ends*".  But it does sound like "tail",
which I try to use to mean "end" in the common
sense (and "bitter end", though I fight against
corrupting the sense of "bitter" deriving from "bitts").

But, let's break from this a moment and think of
the complex bowlines that have extra passes
of parts --the working end going back'n'forth--
through the turNip.  In the basic bowline
we think that each eye leg has 50% of the load
in opposition to the 100% of the SPart.  You have
remarked about the nipping loop wanting to walk
into the eye, and that points to the need for the
SPart's 100% to somehow be reduced to only
50% by time it exits into the eye.  Well, in a
sheet bend there is NO load on what would
be this continuation --the SPart turns around
the bight legs, nips its tail . . . : period!

I just wanted to suggest that in some of those
complex bowlines with now say 3 diameters,
i.e. 3 parts running through the central nip,
that the apparent distribution of force across
them all might not be so even, and that if
the usual 50% on that nipping loop's continuation
is diminished --by these other parts taking on load--,
there might be some slippage  & adjustment.
(And one might wonder if even there could be
such a change of mechanics to impart more
than 50% around the nipping turn?)


--dl*
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X1

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   Partially correct : I use "anti-bowline" soley to distinguish the direction of the tail's return through the turnip --that is how the Eskimo bowline comes into the (sub)set, nothing to do with its collaring an eye leg ( but that is all it can collar, given direction; but it could loop, instead).
   
   You deny the most important thing that could had lead you to this characterization - the distinction between the direction/side the eye leg of the Tail enters into an already formed nipping turn, in the cases of the Common and the "Eskimo" bowline. This is what one has to pay attention BEFORE he makes the collar - so it is the most important distinction re. the tying procedure. Only AFTER he has followed the proper path, and AFTER he has collared the eye leg by forming an "Eskimo" collar, he can see that, in fact, following this and not the opposite direction, and entering through this and not the opposite side, he did the only thing he could do, in order this knot be stable. On the same token, only AFTER he has followed the proper path, and AFTER he has collared the Standing end by forming a "Common" bowline s collar, he can see that, in fact, following this direction and not the opposite direction, and entering through this and not the opposite side, he did the only thing he could have done, in order this knot be stable.
   
   The direction / side through which the eye-leg enters into the nipping turn of a Common or an "Eskimo" bowline is MUCH more important, re. their tying process, than the direction / side through which the Tail enters into it !

   
Counting senses!  Well, maybe we should work towards righting that imbalance!?  In any case, it was a convenient moniker that had a rationale, and I wanted a label/name.   ;)
   
   It is amusing that, of all the other members of the Forum, it as only me who spotted this "imbalance" - the only person that can happily live with it, because the anti- prefix, in about half of the initial / ancient and the present uses in his mother language, as well as all the geometrical / mathematical uses, is NOT imbalanced !  :)  Also, it is used many more times with the meaning of "instead", "in place of", than in English. The  Greek ancient and modern most common wordσ : αντι-κρυ, for example, meanσ facing, vis-?-vis, across / over the way, on the other side of. The word : αντι-περα means across, on the other side ( of the road, the river, etc,). The words αντι-θετο, αντι-στροφο, mean reverse. The word : αντι-κειμενο means object, and αντι-κειμενικα means objectively. Αντι-στοιχος means corresponding, equivalent, respective. And so on...
   
   So, there are two things we should do :

1. Decide which is the most important thing : the direction / side through which the Tail enters into the nipping turn, OR the  direction / side through which the eye leg of the Tail enters into the nipping turn.
2. Find a ":balanced" label/name denoting this.
   
   You will not only offer salads like this vegetarian "TurNip" of yours ! Cook a real food here ! ( the last one , the post-eye-tiable = PET, was edible / is digested...)
 
« Last Edit: July 26, 2013, 12:38:17 PM by X1 »

X1

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"*end*" is something I use to denote a part exiting some circumscribed area of interest; if that were a nub of an end-2-end or eye knot, there would be fourb "*ends*". 

   You forget that you had used the word "limb" for such a part - a more proper word, that denotes a protrusion . extension of a central body.

   
   in some of those complex bowlines with, say ... 3 parts running through the central nip,
   the apparent distribution of force across them all might not be so even.
   if the usual 50% on that nipping loop's continuation is diminished -- by these other parts taking on load- -,
   there might be some slippage & adjustment.
   (And one might wonder if even there could be a change of mechanics to impart more than 50% around the nipping turn?)
 
   Why do I understand it NOW ? Is it because I have drunk some magic anti-poison, and became smart overnight ?  :)
   Thank you.
 
« Last Edit: July 26, 2013, 12:57:50 PM by X1 »

Dan_Lehman

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"*end*" is something I use to denote a part exiting some circumscribed area of interest; if that were a nub of an end-2-end or eye knot, there would be fourb "*ends*". 

   You forget that you had used the word "limb" for such a part - a more proper word, that denotes a protrusion . extension of a central body.

   
   in some of those complex bowlines with, say ... 3 parts running through the central nip,
   the apparent distribution of force across them all might not be so even.
   if the usual 50% on that nipping loop's continuation is diminished -- by these other parts taking on load- -,
   there might be some slippage & adjustment.
   (And one might wonder if even there could be a change of mechanics to impart more than 50% around the nipping turn?)
 
   Why do I understand it NOW ? Is it because I have drunk some magic anti-poison, and became smart overnight ?  :)
   Thank you.

Beware that I feel myself having gone in BOTH directions
on musing force distribution : that there is less on the
eye-side of the turNip --so, more to sheet bend forces--
and more --hmmm, I think thinking that somehow
there becomes less nip on that eye side exit.

Yes, "limb" is something uttered.  It seems to connote that
the nub is a unit, with *body* connotations; whereas "end"
looks to the nub as a tangle of 1-to-N pieces of flexible (knottable)
material, each of course having two "ends" (and the nub
having 2N ends).  If we were focused on some discussion
of knots in the *tangle* senses, more "theoretical" than
"practical", "ends" should come off perfectly well --as,
after all, we might be consciously leaving possible loading
to a later part of the discussion, even remarking how
different loadings yield a variety of *knots*.  But speaking
in a practical-knots dialogue, "end" comes with some
common sense that runs against my use above.


--dl*
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alpineer

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S-bowline ( for the "Common" bowline ) and Z-bowline ( for the "Eskimo" bowline ?

It won't work X1. Why? Because coiling direction doesn't per se :) determine handedness. Because handedness doesn't determine whether a bowline is common or Eskimo. Take two separate cords and tie the bowline form. Same handedness produces both common bowline and Eskimo(offset) bowline versions. Said another way, one can produce the common bowline in both Right-Hand coiled and Left-Hand coiled versions, and of course vice versa for the Eskimo bowline.
Good try though. I've been spending some time thinking about this recently myself, specifically, how to define the Tresse Bowlines in less ambiguous and dyslexia resistant terms.
« Last Edit: July 28, 2013, 07:03:46 PM by alpineer »

alpineer

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Re: What defines a Bowline? - structure, characteristics, topology
« Reply #310 on: July 28, 2013, 07:25:00 AM »
  It this convention that offers the opportunity to relate the handedness of the nipping turn to the direction the eye leg of the Tail as it enters into it, in the cases of the "Common" and of the "Eskimo" bowline. 
 

And what is this relation of the nipping turn to the direction in which the 'eye leg of the tail' (sic) enters it?

Also, I don't support the re-labeling of front/rear views of the bowline. Doing so serves only to confuse matters unnecessarily. Naming convention doesn't affect which particular view of the bowline better shows it's routing. So, why bother? The argument for re-labeling is moot when one simply acknowledges that both aspects of a knot should always be shown.

P.S. It's 'tail side eye leg' and of course 'SPart eye leg' for the other leg.         
« Last Edit: July 28, 2013, 08:09:24 AM by alpineer »

alpineer

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Re: What defines a Bowline? - structure, characteristics, topology
« Reply #311 on: July 28, 2013, 07:22:09 PM »
Reply #315 has been edited, hoping for clarity.
 
« Last Edit: July 28, 2013, 11:50:09 PM by alpineer »

SS369

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Re: What defines a Bowline? - structure, characteristics, topology
« Reply #312 on: July 28, 2013, 07:39:31 PM »
Reply #315 has been edited for hoped for clarity.
Whoops. Is there a way to edit image caption? It should read "Z & S Common Bowlines".

Yes, edit it out, rename the picture and resubmit it.

SS

alpineer

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Re: What defines a Bowline? - structure, characteristics, topology
« Reply #313 on: July 28, 2013, 10:57:28 PM »

  Well, it is still not clear to me... :)  I also do not understand the meaning of your mirror-symmetric triple-nipping-turn based Common bowlines...
 

Please answer this simple question. Do you understand that these mirror symmetric bowline's nipping turns exhibit opposite handedness? Both bowlines (in the photo I posted above) show Dan Lehman's preferred view. My point here is that the handedness per se of the nipping turn(s) does not redress all relations of the Working End's direction of entry into the nipping loop for all legitimate common and Eskimo bowlines. It makes no sense to me to eliminate - in your starting assumptions - half of the bowline population in order to solve (half) a problem. That's an inconvenient convenience. :) One more question, please. If this is you're intention, why bother. It seems to me all that would be accomplished is to provide another way of introducing more dyslexia inducing confusion into a world rife with such hazards. 
« Last Edit: July 29, 2013, 01:48:17 AM by alpineer »

X1

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Re: What defines a Bowline? - structure, characteristics, topology
« Reply #314 on: July 29, 2013, 03:56:07 AM »
      Let me try again..  :) 
     
     As I had explained earlier, I think that the path the orientation of which we should describe in the first place, is the path followed by the eye leg of the Tail side, as it enters into the nipping turn. When this path will be determined, the end / limb of the nipping turn which has to be encircled / collared by the continuation of this eye leg, and the path which has to be followed by the Tail when it will enter into the nipping turn, would be uniquely determined as well.
 
   There are 4 distinct nipping turns, according to :

a.    The "over" / "under" mutual position of the two limbs of the nipping turn at its crossing point, i.e., if the Standing end goes "over" or "under" the eye leg of the Standing Part.  A convenient ( = Convenient ) way to represent a bowline is to show the 'Common" bowline tied on an over-then-under nipping turn, and the "Eskimo"  bowline tied on a under-then-over nipping turn. This way the crossing point of the bowline cannot be hidden underneath the legs of the collar
b.   The handedness of the helical structure of the nipping turn. The helical threads most widely used (= Common ) bolts and nuts are right-handed .     
 
     Let us imagine the nipping turn as a nut, and the working end as a bolt that enters into it.   
     Is there a unique relation between the handedness per se of the helix of the bolt and nut pair, and the kind of the bowline ( "Common" bowline or "Eskimo" bowline ) this working end can tie ?   

1.   If we consider only the representations of the bowlines where :

a.   The "over" / "under" position is the Convenient.   
b.   The handedness is the Common.
   
     then we can see that :
     The Common bowline is related to the right-handed helix ( the S helix).
     Only a right-handed bolt / working end can tie a Conveniently represented Common bowline - and a Conveniently represented Common bowline can be tied only on a right- handed nut / nipping turn.     

2.   If we consider only the representations of the bowlines where :               

a.  The "over" / "under" position is the Convenient.               
b.  The handedness is the opposite of the Common.

    then we can see that :
    The "Eskimo" bowline is related to the left-handed helix ( the Z helix).
    Only a left-handed bolt / working end can tie a Conveniently represented "Eskimo" bowline, and a Conveniently represented "Eskimo" bowline can be tied only on a left-handed nut / nipping turn.   
    Therefore, I propose that the class in which the Common bowlines belong be labelled as "S-bowlines", and the class in which the "Eskimo" bowlines work be labelled as "Z-bowlines".

1. http://en.wikipedia.org/wiki/Right-hand_rule
2. http://en.wikipedia.org/wiki/Screw_thread#Handedness
« Last Edit: July 29, 2013, 11:32:06 AM by X1 »