Author Topic: Analysis of Bowlines paper uploaded for review and comment (PACI website)  (Read 196755 times)

agent_smith

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #270 on: December 29, 2015, 11:55:11 PM »
Derek the dunny man returns!

Quote
@Mark  do you find any significant advantage from the final tuck under the collar?

This Bowline variant intrigues me.
Am still unsure of its proper name?? Xarax used the 'link bowline' term I think...? I remain unclear of the significance of 'link' in the descriptor... maybe someone can chime in to assist with the background to the choice of terms for naming this structure?

I also think the knot structure is largely attributed to Alan Lee - as it shares much of the wonderful 'Lee Zep X Bowline' structure - but then deviates in how the tail is maneuvered.

It ticks a few boxes for me:
[ ] stable
[ ] secure (which also includes slack shaking security)
[ ] resistance to jamming
[ ] verifiable (like any knot - you need to learn how to tie it and then develop pattern recognition skills)

and... it has 3 rope diameters inside the 'nipping loop'. Proponents of this theory suggest that the MBS of the knot is raised because the radius of the SPart as it enters the core/nub of the knot is increased.

I have not yet 'field tested' the knot in actual climbing or rescue applications.

But I do like it - and it certainly is deserving of further study.... perhaps a candidate tie-in knot for CTOMS with their 6.0mm technora cord?

Mark

agent_smith

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #271 on: December 30, 2015, 12:00:01 AM »
From Dan...
Quote
Then try the reverse : UNtying w/o access to the ends.
I think that you'll be able to do this, and change your mind!

Yes - indeed.

I have found that 'reverse engineering' a knot by untying it step-by-step (without access to any end) is a valid tool to assess whether it is 'TIB'.

Mark
« Last Edit: December 30, 2015, 06:58:22 AM by agent_smith »

DerekSmith

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #272 on: December 30, 2015, 11:47:04 AM »
From Dan...
Quote
Then try the reverse : UNtying w/o access to the ends.
I think that you'll be able to do this, and change your mind!

Yes - indeed.

I have found that 'reverse engineering' a knot by untying it step-by-step (without access to any end) is a valid tool to assess whether it is 'TIB'.

Mark

Indeed, I often use the technique when seeking components or tying methods, but finding that a collar and a tuck could turn a 5,1 knot into an Unknot was quite a shock.  In hindsight, perhaps it should not have been such a shock, because I can tie the 'Slipped' Myrtle Loop TIB.  I put slipped in single quotes because it refers more to the tying method than the final knot itself which is most definatley not 'slipped'.  I don't know if you use the Constrictor method for tying the Myrtle or not, but I fold a Constrictor, pass the Wend around the fixing point, then pass the end into the Constrictor.  Then I collapse the Constrictor with its contained 'end' and it winds itself into the Myrtle.  However, if I am making it TIB, then I fold the Constrictor, but, instead of the end, I pass a small bight through the constrictor.  When this is collapsed, it likewise gives an extra wrap, plus four diameters through the nips.  For me the advantage if making the knot this way is economy of cord.  I only cut the cord after the knot is complete, rather than having to guess the required cord length before tying.

Derek

DerekSmith

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #273 on: December 30, 2015, 12:56:17 PM »
Derek the dunny man returns!
snip...

Mark

LOL, No Mark. I never went away, I just CBA with being told endlessly that my opinion was wrong.

But back to the 'knot in hand'.  For me a Bowline is a loopknot with a loaded nip and a partially loaded, nipped stabilising collar.  I am sorry, but I just cannot bring myself to include every loop knot that contains a nipping turn into a giant family of Bowline-esque knots.

The knot in hand, yes, it is a loop knot, and yes, it has a loaded nipping turn, but it's claim to being a Bowline, for me, ends there.  Instead, it's function is derived from a second co-nipped nipping loop.  Together, these two co-stabilising nipping loops constitute the functional heart of this knot  The amendments of an unloaded collar and a third wrap to give a tucked, nipped end, enhance the durability of the knot, but do not change its core functionality of co-stabilising twin nipping loops.

Dave Root spotted this basic knot in the wild quite some time ago now, holding up a Myrtle Tree, and after some discussion it was given the name of Myrtle Loop knot.  Unashamedly, I plagiarised the name to call the self-stabilising twin nipping loops a Myrtle C Component, where the 'C' denotes it as a compound component.

I have known this knot from my childhood on the farm, but like so many knots in use, it did not have a name.  However, one thing was for sure, tied in hairy bailer twine, it did not so much 'jam', rather, with a couple of sharp snaps, it virtually fused...  over time, with weather and abuse of use, you might be forgiven for thinking it to be some form of organic splice.  But then, that was down to the cordage, I have also seen it slither open as if it were some living snake when made with some nice firm shiny polyester braid.

Unfortunately, all the attributes you ascribe to it, even in this 'embellished' form, are essentially dependent upon the cordage it is made in, and with the array of climbing ropes growing in profusion, classifying a knot without reference to its cordage might soon become a dangerous process.

I have not tried the new 6mm Technora cord yet, but I do have some cord samples that I would only trust in very long splices, they just flow so easily under load.  They just seem immune to frictional amplification via turns and nips...

Derek

DerekSmith

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #274 on: December 30, 2015, 05:04:58 PM »
Well, that really is quite amazing.



I have confirmed that the Myrtle C Component at the heart of this Myrtle Loop knot is a 5,1.

Yet only one tiny modification is necessary to destroy this, and render it into the Unknot.

It is not the collar, nor the tuck under the collar.  Just the action of passing the end back into the nip, means that this knot can then be be TIB.

Well done Xarax...  I bow to your observation.

However, have you been able to reverse the reversal, and create the knot 'In Bight' so to speak?

Derek

Mobius

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #275 on: December 31, 2015, 01:10:15 AM »
Derek the dunny man returns!
snip...

Mark

LOL, No Mark. I never went away, I just CBA with being told endlessly that my opinion was wrong.

But back to the 'knot in hand'.  For me a Bowline is a loopknot with a loaded nip and a partially loaded, nipped stabilising collar.  I am sorry, but I just cannot bring myself to include every loop knot that contains a nipping turn into a giant family of Bowline-esque knots.

The knot in hand, yes, it is a loop knot, and yes, it has a loaded nipping turn, but it's claim to being a Bowline, for me, ends there.  Instead, it's function is derived from a second co-nipped nipping loop.  Together, these two co-stabilising nipping loops constitute the functional heart of this knot  The amendments of an unloaded collar and a third wrap to give a tucked, nipped end, enhance the durability of the knot, but do not change its core functionality of co-stabilising twin nipping loops.

Dave Root spotted this basic knot in the wild quite some time ago now, holding up a Myrtle Tree, and after some discussion it was given the name of Myrtle Loop knot.  Unashamedly, I plagiarised the name to call the self-stabilising twin nipping loops a Myrtle C Component, where the 'C' denotes it as a compound component.

I have known this knot from my childhood on the farm, but like so many knots in use, it did not have a name.  However, one thing was for sure, tied in hairy bailer twine, it did not so much 'jam', rather, with a couple of sharp snaps, it virtually fused...  over time, with weather and abuse of use, you might be forgiven for thinking it to be some form of organic splice.  But then, that was down to the cordage, I have also seen it slither open as if it were some living snake when made with some nice firm shiny polyester braid.

Unfortunately, all the attributes you ascribe to it, even in this 'embellished' form, are essentially dependent upon the cordage it is made in, and with the array of climbing ropes growing in profusion, classifying a knot without reference to its cordage might soon become a dangerous process.

I have not tried the new 6mm Technora cord yet, but I do have some cord samples that I would only trust in very long splices, they just flow so easily under load.  They just seem immune to frictional amplification via turns and nips...

Derek
Hi Derek,

Interesting background knowledge regarding the knot's name, thank you.

If you are interested,  my recollections of the TIB knot Mark shows was that under load the final tucks definitely do add structure to the linked component  and the knot was secure and stable after rolling a little. Rolling sounds bad, however 'leans over' might be a better description. I have some images at home which I could share after my holidays.

Cheers,

mobius

DerekSmith

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #276 on: December 31, 2015, 10:26:08 AM »
Hi Mobius,

I hope the holiday is going well, back here in England we are 'enjoying' seemingly perpetual rain and wind, and I don't mean the wind occasioned by Christmas sprouts and chestnut stuffing.

Yes, I would be interested in your findings on this structure, but please do not forget to include the nature of the cordage used in your tests.  With this knot, it matters....

Derek

agent_smith

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #277 on: January 02, 2016, 11:54:52 AM »
Something else I'd like to add is that this knot is (in my opinion) well suited as a tie-in knot for lead climbing / mountaineering activities. It is a more 'efficient' eye knot than my other tie-in knot... the EBSB Bowline. It also meets Xarax's preference for no sharp turns within the structure (ie there are no sharp U turns or full turns of the working end around a single rope segment/cross-section as it winds its path to conclusion).

Quote
I am sorry, but I just cannot bring myself to include every loop knot that contains a nipping turn into a giant family of Bowline-esque knots.

The knot in hand, yes, it is a loop knot, and yes, it has a loaded nipping turn, but it's claim to being a Bowline, for me, ends there.

This of course depends on what your definition of a 'Bowline' is.

Per Dan Lehman, the key component of all Bowlines is the 'nipping turn' (which Dan likes to refer to as a 'TurNip'). A poll was taken on this some time ago and the consensus view was 'nipping loop'. While I am not a parrot - and certainly knot parroting Dan... I have considered his proposition and concur.
The 'nipping loop' is loaded at both ends and compresses all material encircled within its helical structure. The absence of a nipping loop excludes other eye knots (eg #1047 F8 eye knot) from the Bowline family. The collar is also an important component - and it must not experience load - to the extent that it is likely to jam. Indeed, when untying a Bowline that has been under very high load, it is the collar that is the easiest segment to manipulate initially when untying. The nipping loop (which must be loaded at both ends - the SPart providing 100% of the initial entry load and the ongoing eye leg providing the opposite 50%) + the collar, together are the structural requirements to fulfill the definition of a Bowline. The 2 components are holistically paired.
NOTE: This is my view of a Bowline - and it captures the essence of Constant Xarax and Dan Lehman...:
[ ] Dan Lehman: The nipping turn is the essence of all Bowlines
[ ] Constant Xarax: All Bowlines have a collar structure (he also posited that a nipping loop must be loaded at both ends - the SPart at 100% and the ongoing eye leg providing the other 50%).

I think the IGKT still cant agree on the nomenclature of a knots structure - evidence for this is that several IGKT members still use their own names - and they appear to all differ.

Ashley places Bowlines in the category of 'loop knots' - and yet, there has been some general consensus that 'eye knots' is a better descriptor. Support for use of this descriptor can be found with eye bolts and eye splices. For example, would an eye bolt be better described as a loop bolt and an eye splice renamed as a loop splice?

Quote
Instead, it's function is derived from a second co-nipped nipping loop.  Together, these two co-stabilising nipping loops constitute the functional heart of this knot
I respectfully disagree that there are 2 nipping loops in this knot. The second 'loop' which you refer to is not loaded at both ends and so it does not fit the definition of a 'nipping loop' [loaded at the SPart end and loaded at the Ongoing eye leg end].

Since this knot also has 3 rope diameters captured within the nipping loop - it might be a candidate tie-in with 6.0mm technora cord (ie the CTOMS 'TRACE' system).
« Last Edit: January 03, 2016, 02:30:00 AM by agent_smith »

DerekSmith

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #278 on: January 02, 2016, 06:54:15 PM »
Hi Mark,

I would not dream of contradicting anyone's opinion, and this is very much the area of these comments.  Hopefully though we can constructively debate our various perspectives in order to better understand each others basis for their stances.

I would agree that making this knot is very efficient, especially if using the Constrictor fold method, followed by a wrap and a re-tuck to form the collar and the final third diameter in the nip.

I think there is room to debate the term 'sharp', as the loaded line executes a full 360 degree turn (around 3 diameters) and is loaded 100% one side and -50% the other, unlike knots at the other end of the spectrum such as the Fig 8 where the loaded line executes several partial turns, gradually transferring force in the process.  For me, the term 'sharp' also contains an element of 'concentration'.  In the 8, load is transferred through a series of segments, through a series of cords, from the load cord to the two loop cords.  Transfer is 'distributed' over quite a length of cordage.  However, in the Myrtle, the load is born in a single component, the 'Turnip' as Dan would have it.  100% load is applied one side, then 360 degrees later it meets -50% loop load and in the passage around the nip. it meets the other -50% from the return leg of the loop.  There is massive meeting of force here in this single small component featuring little more than 9 diameters length of cord.  This, combined with the distortion from a full 360 degree tight turn, is, for me, a recipe for cord failure, and is a more rational consideration of the function of this component than to resort to the use of disputable terms such as 'sharp'

This of course depends on what your definition of a 'Bowline' is.

Indeed, Dan does hold that the 'Key' component of the Bowline is the nipping loop,  However, how he manages to argue that, in a two component knot, either of the two components is more 'key' than the other, I do not know.  Certainly, the Turnip is the major load processing component, but we must not dismiss the load processing function of the collar, even though I do acknowledge that the major function of the collar is to stabilise the orientation of the Turnip.

While I concede that knots without a 'Turnip' should not be classified as Bowlines, I equally insist that knots without a structurally stabilising collar likewise cannot be classified as a Bowline.

Ashley places Bowlines in the category of 'loop knots' - and yet, there has been some general consensus that 'eye knots' is a better descriptor.

' When is an Eye not an Eye?  Answer - When it is a loop...'

Obviously, both an Eye, and a loop are both loops, but, while all Eyes are loops, not all loops are Eyes...  While a tiny loop only one or two diameters across can be safely be referred to as an Eye, a large loop tens or hundreds of diameters across does not really lend itself to being called an 'Eye'.  Where is the grey zone when a loop also becomes an Eye?  I don't know, but I would feel a bit daft calling a loop of more than 5 or 6 diameters and Eye.

So, as the Bowline functions with any sized loop, it is clearly a 'Loop knot' that can also be made right down to Eye knot size.  So, once again, I am with Ashley on this one.  The Bowline is a Loopknot...

I respectfully disagree that there are 2 nipping loops in this knot. The second 'loop' which you refer to is not loaded at both ends and so it does not fit the definition of a 'nipping loop'

I would agree with you on this one were it not for the fact that a nipping loop does not have to be externally loaded on both ends in order to function.  For a nipping loop to function, all that is required is for one end to be secured, the round turn frictional amplification is then sufficient to transfer the applied load into the nipped core.

This end gripping function is achieved in the Myrtle because each Turnip grips and holds its companion once the knot is dressed and set.

By way of demonstrating this argument, consider the Constrictor, a two turn nipping loop arranged to self nip and hold its ends.  After dressing and setting, neither end requires any load application for the nipping loops to function perfectly.

Perhaps we could look a little closer at your definition of 'Nipping Loop'

Derek

agent_smith

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #279 on: January 03, 2016, 02:06:57 AM »
Derek, I have amended my previous post to include explanatory notes to further elaborate on my proposition. In particular, the reference to sharp U turns and other turns which force the rope into tight radius turns... I should have been clearer to point out that it is sharp turns around a single rope diameter/cross section. This is what Xarax did not like - turns around 2 or more rope diameters were viewed as preferable. For example, the 'Yosemite finish' to secure a Bowline forces the 'working end' to wind around a single rope diameter.

The presence of a nipping loop (loaded at both ends) is a key concept - advanced by Dan Lehman.

The presence of a collar structure - is a key concept advanced by Constant Xarax (he actually used the term 'proper collar' - which I think meant to include the concept of a 'capstan effect' created as the collar makes a 180 degree U turn around the SPart).

Xarax also posited that the nipping loop must be loaded at both ends:
[ ] one end is formed from the SPart
[ ] opposite end is formed from the 'ongoing eye leg'.

The concept of an 'ongoing eye leg' and a 'returning eye leg' was advanced by Xarax.

The opposite end of a nipping loop must have load supplied by the ongoing eye leg.

I think Xarax was trying to tell us that the nipping loop acts to compress material captured within the helix - that is, it is a compression zone.

Following this strict definition, the second nipping loop which you referred to in the 'Myrtle/link Bowline structure' is not loaded at each end by the respective SPart and the ongoing eye leg.

Dan Lehman examined #1033 (Carrick loop) - to see if it would fit the definition of a Bowline.
#1033 has a collar structure and it has a nipping loop that is loaded at both ends. The source of one end is the SPart and the source of the other end is the ongoing eye leg. There is also a collar structure.

This in my view fulfills the definition of a 'Bowline'.

Ashley of course did not examine these structural components in detail as is now done in the 21st century at the IGKT. Ashley was content to catalog as many knots as he could using the resources available to him at that time in history. We now have the benefit of social media to connect many minds from around the world - something that Ashley did not have the benefit of. We are now able to dig deeper and examine structural details of knots that Ashley did not contemplate.

I think this subject definitely remains open for healthy debate - it is far from a complete theory.

I wish Xarax would weigh in with his comment...

...

Quote
Where is the grey zone when a loop also becomes an Eye?  I don't know, but I would feel a bit daft calling a loop of more than 5 or 6 diameters and Eye.

I dont believe that scale enters into the definition of an 'eye'.
In my view, it comes down to purpose (function). What is the purpose of an 'eye'? It is to allow connections. It is a connective interface.
When I tie #1047 (F8 eye knot) or #1010 (R'hand Bowline) - I have want/need to make an attachment of some sort. For climbers/mountaineers, this would be to a carabiner. Irrespective of how large an 'eye' I tie, it still allows me to make a connection (eg to a carabiner or to slip down over a post/bollard).

And of course - the eye is fixed, it is not a noose.

Theoretically, I could manufacture an eye bolt with an eye many diameters in size...it is still an eye bolt (just a very large eye bolt). Same can be said of an eye splice - the 'eye' can be as big as you want - it does not alter the fact that it is an eye splice.
« Last Edit: January 03, 2016, 07:15:17 AM by agent_smith »

Dan_Lehman

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #280 on: January 03, 2016, 05:22:23 AM »
I think there is room to debate the term 'sharp',
as the loaded line executes a full 360 degree turn (around 3 diameters)
and ...
Here it should be noted that merely counting the number
of diameters surrounded does NOT solely determine sharpness
--e.g., were those diameters in a row (or, as one can find sometimes,
the initially contacted first two--, the turn would be a 1dia turn (think
of running a line down along a row of trees and turing around the
last in the row).
And, while to some simple degree --a bit above "simplisitic"--,
more diameters are better, rounder, there is also the matter
of shape.  I recall seeing a photo of an Instrom(?) test device's
rope-receiving anchor : it has a diminishing-radius bend for
the line to curve around; one can simulate such curvature
sometimes in a knot.  (And one can remark that such careful
tweaking is matter not of practical concern but only for those
keen to understand knot mechanics!)

Quote
... the Fig 8 where the loaded line executes several partial turns,
 gradually transferring force in the process.
Let me suggest that this knot (by which we mean
the eye knot, usually) benefits from the compression
around the S.Part from the turns of the eye legs,
before the S.Part makes its U-turn around them.



Quote
Indeed, Dan does hold that the 'Key' component of the Bowline is the nipping loop,
However, how he manages to argue that, in a two component knot,
either of the two components is more 'key' than the other, I do not know.
?!  You're confusing "key" with "defining".
Yes, somehow one must stabilize a [please note exact
typing >>>] "turNip"  [<-one capital only!],
but IMO it is the principal engagement of this structure
that characterizes *bowlines*.   And so I include
the Myrtle, and also become aware/bothered by
the fuzzy boundary of the central nipping loop (aka
"turNip"), as it goes from minimal to greater helix
--at some undefinable point one doesn't want to call
it a "loop", but ... .  <sigh>

Quote
the Turnip
Understand my cutesie term's origin : my game
of letter-fusing of adjacent words,
where shared letters are imaginatively run together
and so rise from lowercase in each to uppercase in
the fusion ::
 'turn' ><'nip'
>'turn''nip'<
>>'turNip'<<
("whaTHEck?" you say?!)   ;D

Quote
' When is an Eye not an Eye?  Answer - When it is a loop...'
The eye is a functional aspect of the knot --what
classifies it among other kinds/types/classes of knot.
And the "eye" is indeed adopted because "eye splice"
is universally understood, and "loop" is SOO overloaded
with competing senses --better to stay clear.
("loop" and "bight" compete, e.g..)


Quote
while all Eyes are loops,
NOT if you follow many knot-books' defining "loop"
as a 360-degree turn (a circular thing), which many
do in distinction from "bight".

I respectfully disagree that there are 2 nipping loops in this knot. The second 'loop' which you refer to is not loaded at both ends and so it does not fit the definition of a 'nipping loop'
This is a tricky area, and X. of course wanted such
distinction to make the sheet bend have no loop
but a "hitch".  One might reflect on these similarly
shaped knots and wonder how much of that "ongoing
eye leg" contributes to the ability of the turNip to nip
--something, e.g., one might think is done (variously
well per material & foreces) in the sheet bend
(or in the water bowline which has that clove hitch
crossing part between arguable turNips though it can be
challenged how much action comes via it!

Quote
I would agree with you on this one were it not for the fact that a nipping loop does not have to be externally loaded on both ends in order to function.  For a nipping loop to function, all that is required is for one end to be secured, the round turn frictional amplification is then sufficient to transfer the applied load into the nipped core.
Well, I've echoed, reiterated, concurred in this point.

--dl*
====

agent_smith

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #281 on: January 03, 2016, 07:43:52 AM »
Quote
Quote

    I would agree with you on this one were it not for the fact that a nipping loop does not have to be externally loaded on both ends in order to function.  For a nipping loop to function, all that is required is for one end to be secured, the round turn frictional amplification is then sufficient to transfer the applied load into the nipped core.

Well, I've echoed, reiterated, concurred in this point.

--dl*
====

I had the distinct impression that Xarax required both ends of the nipping loop (ie a closed helix structure) to be loaded - and this requirement narrows the range of knots that could fit within the definition of a Bowline. Xarax also required a collar structure (which acts as a 'capstan' to a certain extent). Therefore, the presence of a nipping loop and a collar structure is what enables a structure to be classified as a Bowline.

Where this gets murky - in my view - is when we start to examine more complex nipping loops (nipping structures).

For example, the so-called 'Karash loop' has a nipping structure based on a crossing/munter hitch. The question for me is whether the munter hitch component actually functions as a nipping structure. That is, is it loaded at both ends and does it create a compression zone? There is indeed a collar structure... so it is down to the nipping structure.

And then there are the double nipping loops as with #1013 (Double Bowline) - again, both ends are loaded and there is a compression zone. There is also a collar structure. So #1013 is definitely a Bowline.

In my new and revised Bowline Analysis paper - I will be attempting to arrange and classify Bowlines based on their nipping structures..eg;
[ ] single nipping loop based on a closed helix
[ ] double nipping loops based on a closed helix
[ ] crossing/munter hitch
[ ] overlapped double nipping loops (as with #1012)
and so on...

DerekSmith

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #282 on: January 03, 2016, 01:13:04 PM »
I am starting to get quite worried here.

Not only has Constant not waded in on this discussion, but you are all talking about him in the past tense.

What has happened?

Derek
« Last Edit: January 03, 2016, 02:07:55 PM by DerekSmith »

agent_smith

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #283 on: January 03, 2016, 03:11:28 PM »
He is alive and well...but for reasons unknown to me, he no longer visits the IGKT forum.

Xarax is a passionate man - and he certainly pushed out the IGKT horizon further than most.

His theories on knots and in particular - Bowlines - broke new ground.

You either loved or disliked him - and whichever camp you were in, you would have to admit that he did make significant contributions to our understanding of knots.

...

It would be good to get a summary of his position re the structure and definition of a Bowline... seeking clarification on his theories about the following:

1. The collar structure and the 'capstan effect' created as the collar performs a U turn around the SPart (I recall Xarax adding a pulley substitute for the SPart to illustrate his theory)
2. The 'proper' collar (what exactly did Xarax mean by this?)?
3. The nipping loop loaded at both ends (and not just one end) - a few things come to mind here... this narrows the range of eye knots that could be classified as belonging to the Bowline family (which is better than a wider definition in my opinion). It also makes the definition of a nipping loop stricter. Need verification of Xarax's position on this.
4. The nipping loop and its compression zone contained within the helix. Need further expansion on this.
5. Complex nipping structures such as the 'Karash double eye knot' - per Mike Karash - instead of a simple helix it is now a more complex crossing/munter hitch - does this still fall within the definition of a nipping loop according to Xarax?
6. Tight radius turns and pathways - forcing the working end to wind around single rope diameters/cross-sections - instead of more gentle curvatures - what is his views on this (although this one is not Bowline specific)?
7. Anti-Bowlines - what is Xarax's position on this? - ie Where the collar does not form around the SPart but, instead, forms around the returning eye leg. And according to Xarax - there are 4 anti-Bowline structures (chirality?). And is he in support of the 'anti-Bowline' term?
8. The nipping structure of #1012 (water Bowline) - I see this as 2 nipping loops functioning as a clove hitch (when united) but which can also be spread apart to break the clove hitch structure and instead function as 2 independent nipping loops - symmetry breaking?? And a Bowline based on a 'constrictor hitch' nipping structure - I see this as 2 interlinked nipping loops - but in this case, the nipping loops cannot be separated. I think Xarax and Dan debated these structures at length...but what was the outcome?

I would like some very clear and very concise (ie clarity) on these points.

Edited: Grammar corrections and added further points
« Last Edit: January 04, 2016, 06:12:38 AM by agent_smith »

Dan_Lehman

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Re: Analysis of Bowlines paper uploaded for review and comment (PACI website)
« Reply #284 on: January 04, 2016, 07:25:55 AM »
Quote
Quote

    I would agree with you on this one were it not for the fact that a nipping loop does not have to be externally loaded on both ends in order to function.  For a nipping loop to function, all that is required is for one end to be secured, the round turn frictional amplification is then sufficient to transfer the applied load into the nipped core.

Well, I've echoed, reiterated, concurred in this point.

--dl*
====

I had the distinct impression that Xarax required both ends of the nipping loop (ie a closed helix structure) to be loaded - and this requirement narrows the range of knots that could fit within the definition of a Bowline. Xarax also required a collar structure (which acts as a 'capstan' to a certain extent). Therefore, the presence of a nipping loop and a collar structure is what enables a structure to be classified as a Bowline.
As noted above, X's position wasn't everyonElse's --did you
miss my remarks about his rejection of the sheet bend
as having a nipping loop (something he I think began mostly
challenging Derek about, ad nauseam)?!  My point to this
comparison was to show --concurring w/Derek's view--
that the apparent "loop" can be effected, can exist,
without its continuation being loaded --it might be a free
tail!  And where it somewhat IS loaded, that loading can
vary by quite some amount, it would seem, enough to
raise the question of making its loading a criterion.
But there is some appeal for that, still ... .
(And one can think that although there might not be
such extended loading of it where it is the crossing
part of a clove-/cow-hitch-like component (e.g. water
bowline
).

I'm reminded that I choose to take a view of what is
a noose based on purely *apparent* structure
irrespective of behavior --which behavior can be so
contingent upon materials & forces : I don't want
knots to be jumping from one class to another based
on a change of materials!  (Now, in more practical
vs. theoretical terms, I would treat "noose" in the
way it's commonly understood, and where just such
particular, sliding-until-tightly-closed behavior occurs.)


Quote
For example, the so-called 'Karash loop' has a nipping structure based on a crossing/munter hitch. The question for me is whether the munter hitch component actually functions as a nipping structure. That is, is it loaded at both ends and does it create a compression zone? There is indeed a collar structure... so it is down to the nipping structure.
Here I disagree (but "feel your pain") : I see that very
crossing-knot structure to have a collar(-ing effect)
--the S.Part bears into the turn around it, after all.
It certainly functions to nip : the knot wouldn't hold
the "proper collar" otherwise!  (Mind, I don't give a hoot
about having this particular propriety, but ... .)


Quote
And then there are the double nipping loops as with #1013 (Double Bowline) - again, both ends are loaded and there is a compression zone. There is also a collar structure. So #1013 is definitely a Bowline.
One can question how much such a coil is related
to the turNip --examining the forces along the strand,
and so on.  But if that isn't part of the group, then woe be
unto us; but we've gone beyond the 360degree turn, now
--as with the mirrored & water bowlines not seeing the
nipping turn's "end" lead (directly) into the eye.

One might consider Ashley's #1016 --which I'm thinking
is one of the many knotting mistakes echoed for ages--,
which concludes with a knot whose apparent turNip
is loaded on one end only, the other held in resistance.
(But consider #1074, at which there is explicit rationale
given for the cryptic advice of the former (and #1882)
--whose images and final knots contradict the advice
(for "double bearing") !!  Methinks Ashely quite sloppy,
in this, alas.)

As for
Quote
you would have to admit that he did make significant contributions to our understanding of knots.
I can agree with "significant" if only measured by volume
(as in "quantity" not "noise").


--dl*
====