Analysis of Bowlines paper uploaded for review and comment (PACI website)

[Dan_Lehman]

I am also of the view that there must be a 'collar-capstan' structure.
Indeed, if this structure is absent, it again automatically disqualifies it from being a Bowline.
A further qualifying requirement is that the 'collar' must form around the SPart.
If it forms around an eye leg instead of the SPart (eg an 'ongoing eye leg')
--this earns it the title of 'Anti-Bowline'.
So the badly named 'eskimo' bowline is an 'anti bowline'.
So the difference between a Bowline and Anti-Bowline is with
respect to where the 'collar-capstan' is formed.

You might take X's view of having a "proper collar" --something
Derek seems to favor--, but note that I look only for the (infamous?
--"many dislike ..." : really?) "turNip" --"central nipping loop"
and am happy at that.  We can see what each criterion allows and
disallows.

But please note that you abuse my term "anti-bowline" :
it is defined by the side of the nipping loop that the returning
eye leg enters, NOT by what it might (and hold that it need
not) collar.  The Eskimo bowline is an "anti-bowline" because
in brings the returning eye leg in from the opposite side to that
of a bowline --at which point it can only collar the other
eye leg; it could, however, otherwise make a Mytle-like turn
around the nipping loop.

An example of a non-functional (ineffective) 'nipping loop' is with the Carrick eye knot (#1439 derived) prior to being transformed.

?!  I don't see this as non-functional, but our minds might
be partially so :: one can set the lattice form of the (inchoate)
carrick loop by loading first the (newly envisioned) turNip
so to achieve a *bowline* --what I might struggle to classify
and call a "quasi-anti-bowline", since the turNip really takes
on the *tilt* towards helix typical of them but is held in check
by the rest of the knot, yet the returning eye leg (rudely!)
ignores the turNip in its eagerness to collar the S.Part!
Enter from one side, or enter from the other, OR NOT AT ALL?!
--well, eventually, something gets through the nipping loop
and binds it all together, but not directly.   

Compare the transformed image - Carrick Eye knot #1439 derived - does this structure have a functioning (effective) 'nipping loop'?

It has similar form to a munter hitch - and indeed reminds me of the nipping structure in the 'Karash loop / eye knot' in its single eye form.

I think that we should answer this "no, a nipping loop
doen't collar itself, and is at least "apparently" loaded on
both ends (S.Part & on-going).

Although I should point out that in the 'anti-bowline' - the collar forms around the 'ongoing eye leg' and not the 'returning eye leg'.

NO, you should not point this out --that's wrong,
as explained above.
"anti-" is used as for "anti-cyclone" : a reversal of
direction in like movement otherwise.


--dl*
====

[agent_smith]

But please note that you abuse my term "anti-bowline"

Perhaps...

But I did not wish to go into myriad of detail - other than the observation that I have yet to see an 'anti Bowline' that has a collar-capstan formed around the SPart! Indeed, I dont think it is possible?

Yes - with the collar-capstan formed around an 'ongoing eye leg' - it is obvious that to perform such a maneuver, one must do everything back-ass-wards (or in an anti direction) relative to a standard #1010 Bowline.

For the so-called 'Myrtle' maneuver this is somewhat different...since I might have surmised that one doesn't need to do everything in the 'anti' direction (relative to #1010).

"no, a nipping loop
doesn't collar itself

Is that an absolute definition?

[Dan_Lehman]

But please note that you abuse my term "anti-bowline"

But I did not wish to go into myriad of detail , other than the observation
that I have yet to see an 'anti Bowline' that has a collar-capstan formed
around the SPart! Indeed, I dont think it is possible?

You have seen it, for I've shown it somewhere @IGKT// (IIRC).
But look before you type : before decrying/defaming
the Eskimo bwl just extend it as you seem to desire,
and put the darn "proper ('capstan'?) collar" around the S.Part
--the tail is waiting, Janus calls!

"no, a nipping loop doesn't collar itself

Is that an absolute definition?

Seems to work, vis-a-vis my notion of *apparent*
loading of the central nipping loop (esp. if "loop" is
assumed/defined to be approx. 360degrees) and
thus excluding tear-drop shapes such as made by
the fig.8.


--dl*
====

[agent_smith]

You have seen it, for I've shown it somewhere @IGKT// (IIRC).
But look before you type : before decrying/defaming
the Eskimo bwl just extend it as you seem to desire,

Yes - of course I am aware of the 'Janus Bowline' (aka double bight Bowline) - but this is not what I had in mind. And I am not decrying/defaming the 'Eskimo' Bowline...i am simply stating that i dont like the name. The knot structure is a different matter - I bare no ill will against it - and i have nothing defamatory to say about it either!

The initial collar-capstan is still formed around the SPart as per the standard #1010 Bowline - is it not?

Its just tail maneuvering which forms another (second) collar-capstan around the 'ongoing eye leg' (and also adds a 3rd rope diameter inside the compression zone of the nipping loop) - there is nothing 'anti' in the initial stages of tying Prohaska's creation. Its all bog standard #1010. Things only go 'south' in the forming of the second collar-capstan. But I guess if you think Prohaska's creation is fully deserving of the 'anti bowline' moniker - I guess thats your prerogative.

By the way - where are you going with all this?

What is your point?

...

Have you had a detailed examination of the photo I provided of the #1439 carrick bend eye knot derived Bowline (in its transformed state)?

Is there a functioning nipping structure?

In its pre-transformed state - I do not find the nipping loop to be functional - it is seized/held in check. Do you see otherwise?

[DerekSmith]

I'm still not sure what value I can bring to this thread.

It seems that Mark is attempting to create a catalogue and analysis of 'Bowlines', but in order to do this, first he must set in place a list of the parameters that define the 'Bowline' Set.

Trying to get a feel for the problem, I believe that the first challenge is to establish a useful 'Scope' to the Set definition.  Set too tightly and the set contains but a single member i.e. #1010 - The bowline.  Yet set too loosely, the set has the potential to encompass the great majority of knotting possibilities and so has no value to Mark in limiting the number of knots he has to include in his analysis.

Of course, it is Mark's paper, and he is at liberty to include any knot he wishes, but it is a technical analysis, and could easily find itself the subject of derision if he included knots which the general knotting world could not countenance as 'Bowlines' unless his Set definition was based on very sound, rational, knot logic.  That is, the Set descriptors can be substantiated and are not subjective.

Doing this against a background of historical name usage, and in a field where the terminology is still in turmoil (nipping loop vs turNip vs hitch, vs loop vs eye vs ring ....), is fraught.  But perhaps if we allow ourselves to be a little less precious over the terminology (a loop = an eye = a ring ...) and if we relegate historical naming convention to the back seat rather than automatically giving it front row priority, then we might be able to help Mark find a Set definition that can help him and at the same time give a reasonable justification for the knots he eventually includes in his analysis.

With this in mind, could I start then with what I consider to be the most obvious parameter - that all 'Bowlines' are Working Knots - that is, they are force machines and it is their nominal dressed working structure that we are classifying.  This automatically eliminates all 'artistically' (i.e. sans active force) manipulated structures, even though these shapes may be utilised in decoratives and knitting circles.

        1. All members of the 'Bowline' Set are working knots whose structures are defined under a nominal loading pattern.

Second, again stating the obvious - all 'Bowlines' are fixed loop (eye, ring, etc.) knots where both legs of the loop are nominally loaded at 50% of the SP load.  That is, both loop legs are nominally equally loaded.

        2. All members of the 'Bowline' Set are fixed loop knots.

Third, as this is a working knot, features of it's creation and destruction can rationally be included.  An important feature of the foundation knot #1010 is that it can be post fix tied, that is, the knot can be tied in its entirety after the end has been passed around or through the anchor point.  Of secondary importance, the foundation knot decomposes completely after the WE has been released.  This has started to move into the subjective, but in my opinion, it is worth including.

        3.  All members of the 'Bowline' Set are post fixing tyable and decompose to nothing after the WE is released to pass through teh anchor point.

Fourth, again sticking with the undisputed - all 'Bowlines' have a loaded helical nipping loop.  But here we need to start being careful to distinguish function from decoration.  In essence, the defining function of the nipping loop is to clamp the WE with sufficient grip such as to allow the 'capstonisation' (if such a word exists) of the applied forces, into the body of the knot , thereby preventing them from drawing the WE out of the knot and destroying it.  To achieve this, I would suggest that it needs to be loaded on one side by the SP in order to be able to drive significant compression force into the nip.  This defining functional characteristic of the 'Bowline' Set also declares the primary weaknesses of this set, namely, loss of nip leads to loss of knot integrity, and concentration of load into such a short length of cordage seriously compromises knot strength over other, stronger, knots.

        4.  All members of the 'Bowline' Set have a fully loaded (i.e. SP load vs loop load) helical nipping loop, whose function is to provide end locking of the WE, (and following from this, the WE must leave the knot via the nipping loop)

Fifth, the helical nipping loop is notoriously unstable and must be prevented from morphing into an open helix.  In the #1010 of course, the helix is stabilised by a bight held taught by the opposing forces of the loop and the SP.  This effect is achieved by a long bight collaring the SP and extending through the nipping helix and into the main loop.  Other means of stabilising the nipping helix are possible though, and here we step firmly into subjective territory.  I can find no rational argument to support expanding the set by including all other possible means of stabilisation or even including specific alternatives such as a second nipping helix as in the example of the Myrtle Loop knot.  So, I will set this one as bight stabilised at the moment and leave it open for someone to come up with a logical argument for including different methods of helix stabilisation.

        5.  All members of the 'Bowline' Set have the nipping helix stabilised against opening by a long bight retained tensioned by loading between the loop and its collar around the SP.

I think that those five definitions are all logically sustainable and of course, they define a Set which includes #1010.  The question is, is it wide enough to encompass the set of knots that Mark would LIKE to call Bowlines?



Derek

[KC]

Can't remember where/when; but i first learned of the 'eskimo' as a 'jacked-bowline'.
.
As most lacing structures the eye of the Bowline is meant to pull along it's length,
and then too along the ropes length/not 'splayed'.
.
eskimo/jacked thingy professedly would have it's locking mechanism turned, so then be more apt to then be able to have pulls across eye/perpendicular to line. 
This for me came to be in use for
loading a pulley with (red)line loaded in it
-from the ground to lay over the target branch it will hang on
-with the eskimo /jacked (blue line)as the eye of a bowline holding the pulley placed on the pulley system top and around it's lowers
-then inverting the deal on a branch overhead;
-to leave the bowline choked like a sling, with the (blue)length of the line for removal to the ground
-holding the pulley/(red)rope for rigging.
.
this can take a lot of line especially for an 80' height, loading in not just single redirect/1st class lever pulley system,
but advancing to  2 or 3/1 systems etc.
because the systems and holding line already take a lot of line;
but then would need 2x that much to have the pulley system lay across target support, both ends on the ground!
.
using the blue/bowline line as sling would put a spread apart force on the bowline eye/not pulling down the length.
So 'jacked' position by 90degrees would then lock when the pulls themselves where 90 degrees different
(being horizontal rather than vertical)
.

[agent_smith]

using the blue/bowline line as sling would put a spread apart force on the bowline eye/not pulling down the length.
So 'jacked' position by 90degrees would then lock when the pulls themselves where 90 degrees different
(being horizontal rather than vertical)

Yes, this has been pointed out before by others.

You are describing 'ring-loading' - this particular 'anti-Bowline' (aka poorly named Eskimo Bowline) structure - when ring loaded - mimics the function of a Sheet Bend. It is resistant to the effects of ring loading .
   In contrast, #1010 standard Bowline is vulnerable to the effects of ring loading.

The same can be said of #1034 1/2 (L/hand Bowline) - it too is resistant to the effects of ring loading - although not as effective as the 'anti-bowline' because there is no collar-capstan. The presence of the collar-capstan in the 'anti-bowline' in its ring-loaded configuration boosts its performance.

[agent_smith]

Trying to get a feel for the problem, I believe that the first challenge is to establish a useful 'Scope' to the Set definition.  Set too tightly and the set contains but a single member i.e. #1010 - The bowline.  Yet set too loosely, the set has the potential to encompass the great majority of knotting possibilities and so has no value to Mark in limiting the number of knots he has to include in his analysis.

The reference to 'loose' and 'tight ' - I have previously preferred 'narrow' versus 'wide' - per legal construction used by Judges in a court of law. Creating too wide a definition of certain issues in legal proceedings is problematic.

I would prefer if you avoid suggesting that this is my issue or my project alone. I have seen this matter as a problem waiting for a solution for a long time now....and I can actually see a tiny little light appearing down the end of a very long tunnel.

Of course, it is Mark's paper, and he is at liberty to include any knot he wishes, but it is a technical analysis, and could easily find itself the subject of derision if he included knots which the general knotting world could not countenance as 'Bowlines' unless his Set definition was based on very sound, rational, knot logic.

Yes, it is 'my' paper - but I usually see myself as 'editor' first and author second. I am relying on input and advice from several sources - chiefly from amongst the IGKT.

I have a vision that it will be important to showcase certain knot structures to illustrate the core function of a Bowline.
For example, I am of the view that the following knot structures must be compared and contrasted against the #1010 standard form:
[ ] #1431 Sheet bend
[ ] #1033 Carrick loop
[ ] #1152 Sheepshank
[ ] anti-Bowline (with collar-capstan formed around ongoing eye leg)
[ ] karash loop (single eye knot version)

I will be exploring the core function of a Sheet Bend - and closely comparing it to the core function of a standard #1010 bowline.

I will also be exploring various 'nipping structures' - which stray from the #1010 standard helix form.

I would suggest that it needs to be loaded on one side by the SP in order to be able to drive significant compression force into the nip

I was reading very carefully to learn what your position is with respect to how the single helix 'nipping loop' is loaded (ie SPart side alone or both ends loaded).

I of course am compelled to ask the million dollar question..."Is there a Bowline in existance that has a nipping loop that is only loaded at one end - ie the SPart end loaded (not both ends loaded)?

If there is, where and what is it? I would like to see a detailed photo please.

//////////////////////////////////////

Other than that, I am in general agreeance with your 5 points...except for the remark that the ..."The WE must leave [exit] the knot from the nipping loop". It could of course also exit/deviate via the collar-capstan in parallel to the SPart.

[Dan_Lehman]

You have seen it, for I've shown it somewhere @IGKT// (IIRC).
But look before you type : before decrying/defaming
the Eskimo bwl just extend it as you seem to desire,

Yes - of course I am aware of the 'Janus Bowline' (aka double bight Bowline) - but this is not what I had in mind. And I am not decrying/defaming the 'Eskimo' Bowline...i am simply stating that i dont like the name. The knot structure is a different matter - I bare no ill will against it - and i have nothing defamatory to say about it either!

The initial collar-capstan is still formed around the SPart as per the standard #1010 Bowline - is it not?
...

Read carefully, please.
"IT" is NOT --and that was the point.
You can take what you replied, and then cut the
returning eye leg and fuse it to the tail, that will
get you what I remarked at --and the anti- certification!
(In fact, that was how I came upon some very interesting
*bowlines*, if not this one itself, which sometimes I think
I prefer to the non-anti one, but I'm not sure why.  By
looking at a diagram and re-connecting parts to different
parts --something that can happen accidentally, too!
(We proudly call that serendipity, unless no one is looking,
and we claim ingenuity later.    ))

Have you had a detailed examination of the photo I provided of the #1439 carrick bend eye knot derived Bowline (in its transformed state)?
Is there a functioning nipping structure?

In its pre-transformed state - I do not find the nipping loop to be functional - it is seized/held in check. Do you see otherwise?

You remarked at my criterion ("360deg") for qualifying
a nipping loop and that went with rejecting it of the
crossing-knot form, where I find it collaring itself.

And from the lattice form of your 2nd-of-four images,
I can load the S.Part & on-going eye leg so as to lock
in that apparent nipping loop and satisfy my desire for
a *bowline* --just as done w/#1033 (which thus formed
is IMO a knot worthy of much better awareness & usage!).
(But a dislike : the nipped part of this surprise bowlinesque
eye knot makes the S.Part turn around 1dia, effectively,
as the would-be 2nd actual strand nipped aligns with
the axis of tension.  This can be altered in some ways.


--dl*
====

[Dan_Lehman]

An important feature of the foundation knot #1010 is that it can be post fix tied,
that is, the knot can be tied in its entirety after the end has been passed around
or through the anchor point.  Of secondary importance, the foundation knot
decomposes completely after the WE has been released.  This has started to move
into the subjective, but in my opinion, it is worth including.
//
 Fifth ... Other means of stabilising the nipping helix are possible though,
and here we step firmly into subjective territory.  I can find no rational
argument to support expanding the set by including all other possible
means of stabilisation ...

One could look upon the significant aspect of your Point 3 as defining,
and see what it garners as a set.  So, I don't understand why you
"find no rational argument ..." for this, and instead want to limit
the set by further criteria?  --to what point?  There might be some,
but I hope that people can see a point to defining this broader set
--whether called "bowlines" or something else, which would be
said to include *bowlines*--, as it has such a character to it.

As for "helical loop", I feel Occam wanting to slice away a seemingly
gratuitous adjective : do you have other "loops" in knotting?
I can conceive of doing clever things with hollow-braid (loose)
cordage by tucking through the braid, but, in general, one
would rather oppose "loop" and "helix" --neverminding the fact
that the former is an extreme(ly tight) case of the latter.

(Indeed, one might think of "anti-helix" where the turn comes
back vs going away, so that the "crossing point" feels pressure
of its adjacent strands --making this canonical, as practical forces
will often see the "loop" open, lose such contact.  Canonically,
though --and I'm thinking this applies to my "*apparent*"--,
that would be a separator perhaps of "anti-bwls"!?)

As for #1033, let's look at this more intelligently than forcing
into a lousy form.  (Egadz, Ashley's drawing of the supposed
set knot is rubbish!)  As an eye knot for resisting capsizing
and for being easy to untie, it's quite good, in a form not
hauled tight --just as one doesn't haul #1010 tight.   I'd
like to see this tested!


--dl*
====

[knot rigger]

Is this knot a bowline? or not?  If it is, why is it? If it's not, why not?

[alpineer]

It's the standard #1010 Bowline secured with a Half-Hitch on the returning Eye Leg, tail then passed through the collar, followed by a second HH on the S.Part, finishing with the tail passing (pointlessly?) back through the Eye.
So yes, it's a Bowline... with additional tail maneouvers to enhance security. 

[agent_smith]

To any interested IGKT members...

I have uploaded VER 2.2 of the Bowlines Analysis paper (31 Jan 2016).

Its a PDF file and its unlocked - not password protected.

Go here to download it: http://www.paci.com.au/knots.php


I welcome constructive criticism.

If you want your name deleted from the paper - please let me know and I will do so.

There are undoubtedly going to be typos and other technical errors. Its a work-in-progress. So abusive remarks and/or comments of a defamatory nature would be unwarranted and unwelcome.

I have acted in good faith at all times...I just want to get this technically correct/accurate. I also would like to acknowledge those persons who have posited / theorized / shared their knowledge. Xarax is absent - so I had to take some educated guesses at his theory re the 'proper collar'.

I look forward to improving the paper with your considered feedback.

Mark

[DerekSmith]

Mark,

Well done on producing such a professional document.

I have a couple of points I would like to discuss, but first up, a safety issue, the Myrtle you show on P18 is not a Myrtle, I think Dan has called it a 'False Myrtle'.. it is made from two Z nipping loops which are subject to positive cogging.

The Myrtle MUST be made from one S helix and one Z helix, it is the only safe form.  Two Z or two S are both positive cogging.

I believe in the example you give of coiled springs, the S form is what you have called 'Left Hand' and the Z form you have called 'Right Hand'.  Is there a rationale for calling them 'Left' and 'Right'?

Derek

[DerekSmith]

OK, responding to version 2.2.   I see a significant reference to the 'Capstan Collar'.  Reading back, I see this seems to have been sold to you by Xarax.

While Constant was technically correct in holding that the turn of the bight around a static object (the SPart in the case of the Bowline) can exhibit the Capstan effect, in reality, in the Bowline, this does not exist.

If you take a turn around a static object (a capstan), and load both ends equally, there is essentially(except - see Note 1) no capstan effect.  The capstan effect comes into play when the ends are differentially loaded, then the coefficient of friction and the 'amount of turn' come into play in shedding a proportion of the differential force into the static capstan.

You might be tempted to argue that indeed, one leg is loaded with 50% (from the loop), while the other is the WE and so is zero loaded.  However, the reality of the situation (in normal CF cordage) is that the nipping helix (containing a nominal two cord diameters) holds essentially all of the returning force from the loop leg, so in reality, the collar sees only a tiny fraction of the loop load and so there is no differential loading for the capstan effect to come into operation.

In fact you demonstrate this nicely on page 20 where you show that the loop force was unable to penetrate the nip in order to tighten up the collar, and you make the point that "Even at 1 metric ton, the collar can still be manipulated".  This would not have been the case if any significant amount of force had escaped the nip and brought to bear a capstan effect around the SPart.

I am sorry, but in the case of #1010 the assertion of a working 'Capstan Collar' is a seriously misplaced application of cordage science, and using the term 'Capstan Collar' is likely to provoke disagreement with use of the term or the functionality it implies.

Derek

[Note 1.  Where a bight collar exists around a static object (capstan) and both ends of the cord are loaded equally, the capstan effect comes into play in that the loading is shed progressively into the static object, such that the loading in the cord at the mid point of the bight collar is slightly lower than the applied load.  If the cord takes multiple turns around the static object, the the centre turn will be significantly lighter loaded than the applied loads.]