Author Topic: A round turn + U turn jam resistant TIB bowline(not double)  (Read 3182 times)

tsik_lestat

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Combine a round turn (two turns) and a U turn component, which is formed either from the SPart, or the on-going eye leg, in a nipping structure,(that's the tricky part), and you may end up with a decent bowline.

Consider the first photo, which illustrates such a nipping structure,with just one pass of the Working end.You only have to capture the SE to construct the bight component of the bowline, following then the same path of the returning eye leg and completing the knot.I illustrate the loose knot like this for a clear visual of the nipping structure,which, sometimes, is created by diving with the WE through the right holes/loops.

The second and third photo,show the knot tight in its conventional and detail view accordingly, with the tag end inside the eye of the bowline(it could also be outside).Others might describe such a nipping structure as a crossing knot + nipping turn, unlike the description given earlier.However, the key component here, is the 180 degrees U turn of the on going eye leg (black arrow second picture), which functions as a jam blocker, preventing the collar (near the eye) from blocking. The bight component stabilizes the whole nipping structure in a neat way, creating a stable, jam resistant, TIB knot(if the tag end is tucked back through the collar).

If i was to pinpoint some disadvantages of this knot, i would refer to the bulky form of the TIB version, just for the aesthetics,the non-direct first line of defence,which by the way holds and tightens  very well under load, and the more complex nipping structure.

The ring loading profile is fine for me, but there is always the anti-bowline option, shown in fourth picture(loose), for the rigorous knotting minds.

I think this knot might be a good option for an application where heavy load is expected, being less prone to jamming than a round turn (double) bowline.

Considering the acceptable limit of the two turns around the bight component of a bowline,there are quite a lot (TIB) nipping structures (a bit more complex), that could be stabilized and produce stable,secure,jam resistant bowlines, if anyone feels like investigating in this field.One of the simplest instances of this category of knots is the one presented in this thread,unless someone finds a simpler one and proves me wrong. :)



Dan_Lehman

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Re: A round turn + U turn jam resistant TIB bowline(not double)
« Reply #1 on: June 15, 2019, 04:38:50 PM »
1) It's NoTIB!  (Do you know what "TIB" means?)
(TIe the ends of a slack line to respective anchors,
then try to tie this knot (or, already tied, to UNtie it).)

2) Your touting it as " less prone to jamming " begs some
evidence that the numerous known bowlines are otherwise!?
In many cases, bowlines can be untied after being loaded
to near rupture forces.  The water (clove h.) bowline and its
similarly built mirrored bowline are *bowlines* that
should be robustly resistant to jamming,
where that possibly is a concern.


--dl*
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tsik_lestat

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Re: A round turn + U turn jam resistant TIB bowline(not double)
« Reply #2 on: June 16, 2019, 05:52:49 PM »
With all the respect Dan, i think you might have missed a sentence from my previous initial post!

Quote
creating a stable, jam resistant, TIB knot(if the tag end is tucked back through the collar).

Maybe it is my fault, i should have emphasized the text in brackets.Of course i know what TIB means and i did not illustrated the TIB version of this knot for visual reasons, (for a clear visualization of the nipping structure).I thought that it would be quite obvious for someone to tuck the WE back through the collar and create the TIB version.

I only stated that this knot might be less prone to jamming than a double bowline after being loaded to near rupture forces.I do have a strong preference to jam resistant knots, especially bowlines(the water bowline is no exception,i like it too).

My main goal here, was the incorporation of a U turn component in various nipping structures, which, in some cases, works pretty well and may produce stable, jam resistant bowlines.Nevertheless i have come across with bowlines that do not have the jam resistance property, and i am sure you already knew that.

Thank you for your remarks!
« Last Edit: June 18, 2019, 01:45:42 PM by tsik_lestat »

agent_smith

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Re: A round turn + U turn jam resistant TIB bowline(not double)
« Reply #3 on: June 17, 2019, 04:57:43 PM »
Quote
Nevertheless i have come across with bowlines that do not have the jam resistance property

An interesting remark.
As far as I am aware, all 'Bowlines' are jam resistant.
In my view, what you are describing is likely not a 'Bowline'.
A key component of all 'Bowlines' is the nipping loop (which is loaded at both ends, is 'TIB' and has a particular chirality).
It is the nipping loop that plays a pivotal role in the jam resistance.

I'd like to see a clear and unambiguous photo of an alleged 'Bowline' that is vulnerable to jamming.

It is possible that you might be thinking of a 'Bowline' that is built around an #1188 'constrictor hitch' nipping structure.
#1188 is 'TIB' and it is loaded at both ends - so it qualifies as a 'nipping structure'.
However, it does not take the form of a helical loop - so I do not refer to it as a 'nipping loop'.

I struggled for some time in how to conceptualize a 'Bowline' built from #1188 - because I surmised that it might jam.
I am not sure if anyone has load tested such a structure to see if jamming can be induced?
If it turns out that it does jam - then this would be a smoking gun to exclude it from the title of 'Bowline' - and instead 'virtual Bowline'.
In any case, the jury is still out for me on this one...

...

With regard to your use of the descriptor 'Bowline' to describe your creation - I would hesitate to call it 'a' 'Bowline'.
In my view, it is a virtual Bowline.
The nipping structure is TIB and loaded at both ends, but it does not take the form of a helical loop - so this fact ought to disqualify it from being a 'Bowline'.

I use the descriptor virtual Bowline to denote those eye knots that fulfill all the criteria of a Bowline but fall short on account of the geometry of the nipping structure.
All of the primary Bowlines are built from a helical nipping loop that has a defined chirality (either 'S' or 'Z').

tsik_lestat

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Re: A round turn + U turn jam resistant TIB bowline(not double)
« Reply #4 on: June 18, 2019, 11:10:27 AM »
Thank you Mark, your feedback is all-important and more than welcome as always,especially when it comes to the apply of the theory of bowlines, on various structures and their alleged qualification as bowlines or not.

Now, let's see if i have understood your remarks,since i have some questions that need some sort of clarification.

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I use the descriptor virtual Bowline to denote those eye knots that fulfill all the criteria of a Bowline but fall short on account of the geometry of the nipping structure.

I could accept such a term`virtual bowline`for an eye knot with a nipping structure that deviates from the standard, simple, helical loop, but fullfills all the rest of the criteria, having the jam resistance property at the same time.But i am sure, that you are aware of various eye knots,with nipping structures other than single helical loop, which are vulnerable to jamming, when stabilized as bowlines.Furthermore, if the constrictor bowline that you mentioned in your previous reply, turns out that it does jam (most likely it will), i would hesitate too to add the descriptor `bowline`(even after the adjective virtual) to describe this structure.So, how should we call such knots, virtual bowlines that jam or something else?

To be more specific, the first picture shows an instance of a bowline structure, with a twisted crossing knot nipping component, which i am sure  that you would call it a virtual bowline.To my view, the knot is supersafe, having three direct lines of defence against slippage, but on the other hand, the knot is vulnerable to jamming with this more complex nipping structure (it would be wiser to load the knot in a reverse way, moving the complexity to the collar structure level, and create a less prone to jamming crossing knot based loop). It seems that i have the same problem here, trying to describe and classify this knot.

Quote
As far as I am aware, all 'Bowlines' are jam resistant.
In my view, what you are describing is likely not a 'Bowline'.
A key component of all 'Bowlines' is the nipping loop (which is loaded at both ends, is 'TIB' and has a particular chirality).
It is the nipping loop that plays a pivotal role in the jam resistance.

I'd like to see a clear and unambiguous photo of an alleged 'Bowline' that is vulnerable to jamming.

It is possible that you might be thinking of a 'Bowline' that is built around an #1188 'constrictor hitch' nipping structure

Actually no! I was thinking about a bowline which i have tied recently, and has puzzled me a lot, shown in photos 2,3,4 in a loose conventional and detail view accordingly.It has a simple helical loop nipping component,which is loaded at both ends and it should rather be caregorised as a link TIB bowline (Xarax or Alan Lee probably have tied this).I see a problem in the upper section of the collar structure (near the eye), although the knot has nothing suspicious in it, and i believe that it will block in that point there, or being very difficult to untie after heavy loading!

So how should i call the previous knot, if it has not the jam resistance property?Should i exclude it from the title bowline?

It appears, that the collar structure, plays an important role  to the overall resistance of a bowline knot to jamming, along with the geometry of the nipping structure and the co-operation of those two components.

« Last Edit: June 18, 2019, 01:36:57 PM by tsik_lestat »

agent_smith

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Re: A round turn + U turn jam resistant TIB bowline(not double)
« Reply #5 on: June 18, 2019, 02:53:00 PM »
Quote
It has a simple helical loop nipping component,which is loaded at both ends and it should rather be categorized as a link TIB bowline (Xarax or Alan Lee probably have tied this).

I am not sure why you wish to attach the name 'link bowline' to this structure?
Lees link Bowline is derived from the Lee zep Bowline, which is based on a 'Myrtle'.

Lees link Bowline is (in my view) a marvelous creation. It has no sharp turns - all rope segments turn around at least 2 rope diameters. It also has 3 rope diameters inside the nipping loop.
Your creation has the final reversal tuck going back through the collar - which is a sharp turn around a single rope diameter (which converts it to a TIB knot).

In my view, it is jam resistant - and remain so right up to its MBS yield point.

Quote
if the constrictor bowline that you mentioned in your previous reply, turns out that it does jam (most likely it will), I would hesitate too to add the descriptor `bowline`(even after the adjective virtual) to describe this structure.So, how should we call such knots, virtual bowlines that jam or something else?

Jam resistance is a property inherent to all 'Bowlines' - at least that is the theory.
I did state that I have had difficulties with the so called #1188 Constrictor 'Bowline' - the jury is still out for me.
#1188 constrictor hitch is TIB, loaded at both ends but does not have the geometry of a simple helical loop.
A constrictor is known to jam - and so using it as a nipping structure might violate the principal of jam resistance.

I believe that an eye knot built around a constrictor hitch would qualify as a 'virtual Bowline'.
Using that term removes it from the primary Bowlines family - which all have a helical nipping loop (or double loop per #1013).
So (for me) calling it a Virtual Constrictor Bowline is a safer bet.
And therefore, 'virtual Bowlines' might (in some instances) be vulnerable to jamming.
In contrast, all of the 'primary' Bowlines are jam resistant.

I originally devised the term 'virtual' to describe those eye knots that have nipping structures that are TIB and loaded at both ends - and essentially fulfill all the criteria but for the geometry failing to be a simple helical loop. So for example, an eye knot built around a marlinspike hitch or a crossing hitch (ie Munter hitch) also trigger the use of the descriptor 'virtual Bowline'.

Quote
So how should i call the previous knot, if it has not the jam resistance property?Should i exclude it from the title bowline?
If I have understood you correctly and am viewing the knot images you refer to, then it is jam resistant and it qualifies as a 'Bowline'. If you remove the tail from the collar, it becomes more easy to visualize the 'bight structure' (which consists of the collar and its 2 legs). And indeed, both legs of the collar are fully encircled and clamped by the nipping loop.

Quote
It appears, that the collar structure, plays an important role  to the overall resistance of a bowline knot to jamming, along with the geometry of the nipping structure and the co-operation of those two components.
Xarax has written extensively about the role of the collar in 'Bowlines'.
The collar and its 2 'legs' play an important role in all 'Bowlines'.
In my view, it is the nipping loop that plays a key role in avoiding jamming.
The collar is braced upon the SPart - that is, the SPart acts as a 'bracing post' - which stabilizes the overall bight structure.
To summarize, yes - both the collar (+ both legs) and the nipping loop are the key components of all 'Bowlines'. They are co-dependent.
If there is no nipping loop - this automatically disqualifies an eye knot from being a 'Bowline'.
If there is no collar and/or the 2 legs of the collar are not fully encircled and clamped by the nipping loop, then it is disqualified from being a 'Bowline'.

Dan_Lehman

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Re: A round turn + U turn jam resistant TIB bowline(not double)
« Reply #6 on: June 18, 2019, 10:13:30 PM »
To summarize, yes - both the collar (+ both legs) and the nipping loop are the key components of all 'Bowlines'. They are co-dependent.
If there is no nipping loop, this automatically disqualifies an eye knot from being a 'Bowline'.
If there is no collar and/or the 2 legs of the collar are not fully encircled and clamped by the nipping loop, then it is disqualified from being a 'Bowline'.
This is not MY idea of *bowline*, for the record;
I'm more generous, just wanting the central nipping
loop.  But even then, there come issues with some
of the things such as the water (=>clove h.) bowline
where one can quibble about "nipping loop" as the
outgoing eye leg is now a bit removed from the SPart.

Then come the problematic cases where *loop* seems
to go too far into a *helix*, with increased forces --a change
in identity per loading?  --well, capsizing surely does that!
(And bowlines [#1010[ have capsized, yielding a sort
of noose-hitch w/pile hitch geometry.

<sigh>

--dl*
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tsik_lestat

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Re: A round turn + U turn jam resistant TIB bowline(not double)
« Reply #7 on: June 18, 2019, 11:59:07 PM »
I think, i am in a position to say, that i have fully understood your concept of virtual bowlines, due to your in depth analysis in your previous replies, and i see no problem of using that descriptor, for a structure that fulfills all the criteria.

However, in regard to the second knot presented in my previous reply(4), i have a couple of things to clarify ........

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I am not sure why you wish to attach the name 'link bowline' to this structure?

The choice of the name `link`, was not arbitrary. In this particular knot, the link, passes under the SP, collars the on going eye leg, encircling the crossing point of the nipping loop before entering into it. The concept of `link`, has been defined in this forum by Xarax, and i comprehend it as an internal interface, a bridge, between the returning eye leg and the  bight structure of such bowlines, named as link bowlines.

Quote
Lees link Bowline is (in my view) a marvelous creation. It has no sharp turns - all rope segments turn around at least 2 rope diameters. It also has 3 rope diameters inside the nipping loop.

I strongly agree with that statement, and i was not intending to make a comparison.Lee's link bowline, has a different kind of link, (a good one), involving a turn to a certain point of the nipping loop, which retains the jam resistance of the knot.

Quote
If I have understood you correctly and am viewing the knot images you refer to, then it is jam resistant and it qualifies as a 'Bowline'.

Yes, you are refering to the right knot images. My poor evaluation tests, show to me that my link is not so good, it will close too much around the crossing point of the nipping loop, will propably jam, or will be very difficult to untie, while the collar appears to have no such problem.Since i have no scientific evidence to support my claim, i am not putting my arms into fire for this.However, if it turns out that you are right and the knot is jam resistant, when maximally loaded, I have been shooting my own legs regarding this. :) :) :(

To be seen.......................

Thank you for this constructive debate!!!!!

« Last Edit: June 19, 2019, 10:05:20 PM by tsik_lestat »

agent_smith

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Re: A round turn + U turn jam resistant TIB bowline(not double)
« Reply #8 on: June 19, 2019, 02:38:08 PM »
Quote
This is not MY idea of *bowline*, for the record;
I'm more generous, just wanting the central nipping
loop.

As you surely must be aware, Xarax has discussed and debated the role of the Collar with you in substantial detail.
Xarax theories cannot be easily dismissed - as he is usually proven to be correct with the passage of time.

Xarax sees the 'bight component' as a composite structure consisting of a collar and its 2 legs. The 'legs' of the collar must be fully encircled and clamped by the nipping loop.

The nipping loop is the key component of all 'Bowlines' - the absence of which triggers automatic disqualification from the title of 'Bowline'. A nipping loop must be TIB, loaded at both ends and has a defined chirality (either S or Z).

In my view, only requiring a nipping loop is too wide a definition - and has potential to allow many 'ambiguous' eye knots to claim the title of 'Bowline'.

I prefer a more narrow definition - which restricts the number of eye knots that can make a claim to the title of 'Bowline'.
In my view, the collar (and its 2 legs) and the nipping loop are co-dependent and essential components.

Quote
But even then, there come issues with some
of the things such as the water (=>clove h.) bowline
where one can quibble about "nipping loop" as the
outgoing eye leg is now a bit removed from the SPart.

I would posit that a 'Bowline' built around a constrictor hitch is a structure that needs to be assessed - particularly if significant loading can trigger jamming. A constrictor hitch is TIB and loaded at both ends - but, it has a propensity to jam.

Dan_Lehman

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Re: A round turn + U turn jam resistant TIB bowline(not double)
« Reply #9 on: June 19, 2019, 07:56:15 PM »
Quote
This is not MY idea of *bowline*, for the record;
I'm more generous, just wanting the central nipping
loop.

As you surely must be aware, Xarax has discussed and debated the role of the Collar with you in substantial detail.
Xarax theories cannot be easily dismissed - as he is usually proven to be correct with the passage of time.
:o
How on earth does one "prove" a definition to be "correct"?!!
--it is just a way of seeing/grouping things, after all.
If someone excluded what I include (or otherwise has
a different set of things), by what ground is it at all
to be judged for correctness?

(Btw, has time proved his "capstan effect" over your
 pulley'd attempt to test for it?  --or of a sheepshank! ::)  )

Quote
Xarax sees the 'bight component' as a composite structure consisting of a collar and its 2 legs.
What is a "collar" without two legs (or, from the
other side, What are two "legs" absent a collar?!
I.e., the essence of the one implies the other,
so I don't see compositeness to it!

Quote
The 'legs' of the collar must be fully encircled and clamped by the nipping loop.
#1033, is it?, --carrick bwl-- in the returning eye
leg's swinging from turning around the SPart to then
avoid the nipping loop so to turn around an eye leg
begs a question about the above --which can be seen
to come only in an indirect way, and challlenging that
"bight" definition.

Quote
A nipping loop must be TIB, loaded at both ends and has a defined chirality (either S or Z).
Again, these are just from-out-of-the-blue
constraints --and for what point?  One of the
more beautiful *bowlines* has a "cloverhand"
base --though, of course, per that base, NOT
in your set; but firmly in mine.
Note that "TIB" aspect can appear on an extension
to a knot :: so how odd if that then puts in one of
two kin where the other's excluded --but I'm thinking
now of an entire knot and not the component.

Quote
In my view, only requiring a nipping loop is too wide a definition - and has potential to allow many 'ambiguous' eye knots to claim the title of 'Bowline'.
I prefer a more narrow definition - which restricts the number of eye knots that can make a claim to the title of 'Bowline'.
Is this claim such a valuable thing in your mind, in some
kind of *marketing* terms?  --a prize to be closely guarded?!


Quote
Quote
But even then, there come issues with some
of the things such as the water (=>clove h.) bowline
where one can quibble about "nipping loop" as the
outgoing eye leg is now a bit removed from the SPart.

I would posit that a 'Bowline' built around a constrictor hitch is a structure that needs to be assessed - particularly if significant loading can trigger jamming. A constrictor hitch is TIB and loaded at both ends - but, it has a propensity to jam.
But "both ends" are that of the base, which is going
somewhat astray from a "nipping loop".  I was just
able to pull out slack in the middle of the constrictor
and load the knot WITHOUT putting tension through
to this loosened part --challenging the "on both ends"
claim.  And I know that one can do this with the
mirrored bowline (possibly with a purpose to the
pulled-out mid-knot eye!?), rendering it in loading
like mirrored/opposed sheet bends !

You write about the 100%-v-50% difference between
the SPart & outgoing eye leg.  But what is it in the BoaB?!
--by simple-observation math, 100-v-25.  It is then
easy to suggest the climber's old tie-in, bowline on a coil,
and the like Portuguese bwl. as making an even greater imbalance,
and the "tensioned at both ends" claim banks its validity
on little actual tension.
.:. These are problematic things!!

Jamming, as you know, is much material-/load-dependent
(though you have some ideas about calibrating the
load aspect).

In sum, the definition of *bowline* is a choice of how
to speak of things, of what to denote/connote (where
the definition invites/greets newly discovered members).
I find the nipping-loop structure to be a simple aspect
to enable a vast number of ways to use it in making
an eye knot.  You are uncomfortable with the fastness,
and I think want to ascribe also some behavioral aspects
(non-jamming, PETiable?) to it.  One can define things
one way or another, going more general and then having
qualifiers to pick out subsets, or be more particular but
then need ways of combining the narrowly defined things.

I can see myself backing off with "bowline" more to a
stricter "nipping loop"  rule (but I feel no compunction
for "collar") and pushing the more complex bases
(my cloverhand e.g.) into some orbiting set of
associated entities.  Should I do more organizing of
the myriad knots-sketches I have, another way to
group things might come to mind.

My "bowline" vs. "anti-bowline" were already a way
to try to indicate subsets, based on the re-entry of the
returning eye leg --an aspect that at times seemed
unconvincing, where it came in more roundabout
than direct ways (myrtle & my "anti-bwl" being
simple, direct contrasts which give credence to the split).


--dl*
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agent_smith

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Re: A round turn + U turn jam resistant TIB bowline(not double)
« Reply #10 on: June 20, 2019, 02:16:55 AM »
At this point i would interject and declare that we are now drifting away from Mr tsik_lestat original post.

We are now entering the complex topic of defining what a 'Bowline' is.

But...

Quote
How on earth does one "prove" a definition to be "correct"?!
How does one prove the Earth is spherical (ie not flat)?
How did Einstein prove that gravity isn't a 'force' per se - but, simply the result of curved space (geometry)?

You 'prove' a theory by testing it. If your test finds fault in the theory - you go back to the drawing board and figure out a better theory to explain the findings.

Quote
Btw, has time proved his "capstan effect" over your
 pulley'd attempt to test for it?
I did state that Xarax is usually proven to be correct (usually does not mean 100% of the time).
Even you (Dan) have not been correct 100% of the time.
We all make mistakes or we posit theories which may not be entirely correct.

Xarax devised a clever experiment to 'neutralize' the nipping loop.
Did you see it?
The power of the nipping loop wins over any 'capstan effect'.
The clamping force generated by the nipping loop overshadows any effect of the collar braced upon the SPart.
When the nipping loop is neutralized, we get an opportunity to see the tail segment slip and slide around the SPart (assuming the baseline #1010 Simple Bowline structure).
In devising his experiment, Xarax inadvertently demonstrated the power of the nipping loop.

Quote
What is a "collar" without two legs (or, from the
other side, What are two "legs" absent a collar?!
I.e., the essence of the one implies the other,
so I don't see compositeness to it!

I concur that my use of the word 'composite' was hasty - Xarax did not specifically use that word.
Xarax - as far as I am aware - was the first person to direct attention to the role of the collar, and its 2 'legs'.
I don't recall you (Dan) conceptualizing it in this way?
I intended the word 'composite' to mean 'conglomerate' or 'amalgam' or 'constituent'.
The concept of the 'legs of the collar' assists with identifying if a structure is a 'Bowline' - and yes, #1033 was a useful test vehicle.
The 'legs' of the collar in #1033 have a different geometry compared to the #1010 Simple Bowline.
Ashley appeared to conceptualize 'Bowlines' as having parallel legs of the collar entering through the central nipping loop.
Although Ashley does not appear to specifically use terms such as collar, of legs of the collar - basing his analysis on physical appearance.
In #1033, the legs of the collar enter the nipping loop from opposite directions - but, both legs of the collar are fully encircled and clamped by the nipping loop.
For me, this is one of the key requirements of all 'Bowlines'.
In my view, #1033 is a Bowline - although Ashley did not recognize it as such.
He mistakenly labelled it is a 'carrick' - when in fact if you look closely, it is close but not quite a carrick mat form.
The #1439 derived carrick eye knot is the true carrick 'loop' (not #1033).
But #1439 derived carrick eye knot isn't a 'Bowline' because only one of the legs of the collar is encircled and clamped by the nipping loop.
In #1033, both legs are encircled and clamped by the collar.

I have load tested #1033 and it remains jam resistant right up to its MBS yield point.

per 'TIB' requirement for a nipping loop:
Quote
Again, these are just from-out-of-the-blue
constraints --and for what point?
Nothing out-of-the-blue here at all.
The concept of the 'TIB' requirement for a 'nipping loop' was my attempt to narrow the definition of what a 'nipping loop' is.
I further qualified TIB with the requirement that the 'nipping loop' must be loaded at both ends and will have a defined chirality (either S or Z).

Its about having a set of 'rules' to draw boundaries.
I began with the premise of the simple overhand knot (#514).
I needed a set of rules to distinguish #514 from a nipping loop. And this would enable me to test out the theory.
And this is where I devised the requirement for TIB.
#514 is not TIB - so it is automatically disqualified as being a 'nipping loop'.

In my mind, stipulating a TIB requirement is a simple and elegant way of ruling out a whole cohort of structures which might otherwise be considered as a 'nipping loop'.
But of course this opens the way for #559 Marlinspike hitch and #1195 / #1818 Crossing hitch (Munter hitch).
Eye knots built around #559 or #1818 therefore also must be considered.
And so the 'proper' nipping loop had to take the form of a helical loop - because they both fulfilled the 'chirality' requirement (Munter hitch and Marlinspike hitches both have either S or Z chirality).

But opening up 'Bowlines' to #559 and/or #1818 would also cause difficulties...
And so it seems appropriate to introduce the subset 'Virtual Bowline' - to describe those eye knots which meet all of the requirements for the title of 'Bowline' - but fall just short on account of the geometry of the nipping structure. And here the term 'nipping structure' is used instead of 'nipping loop'.

Quote
You write about the 100%-v-50% difference between
the SPart & outgoing eye leg.  But what is it in the BoaB?!
--by simple-observation math, 100-v-25.

I would caution here that you need to be specific about the loading profile of #1080.
You realize of course that #1080 can be loaded only via  one SPart - where the knot is tied end-of-line - and there is a tail.
In such a case, there is only one (1) functional nipping loop.
The alternative loading profile is where #1080 is tied mid-line and there are now two (2) SParts and two (2) functional nipping loops.

Your math may be affected by loading profile.
Depending on tiny and subtle tying variations, an end-of-line #1080 with only one SPart and one functional nipping loop may have loading bias on just one of the 'eye's. In other words, it is possible that load is biased on just the primary eye (loop) and the secondary eye (loop) has comparatively less load (and if poorly tied - maybe minimal load).

In contrast, if #1080 is tied mid-line and there are two SParts and two functional nipping loops, then you could more confidently state that both the primary and secondary eye share load.
« Last Edit: June 20, 2019, 04:21:48 AM by agent_smith »

tsik_lestat

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Re: A round turn + U turn jam resistant TIB bowline(not double)
« Reply #11 on: June 20, 2019, 05:30:15 PM »
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At this point i would interject and declare that we are now drifting away from Mr tsik_lestat original post.

We are now entering the complex topic of defining what a 'Bowline' is.

No worries at all, Mr agent_smith, i don't consider it as a deviation from the norm, or drifting away from my original post. Afterall, when someone uses the word bowline, he should expect such dynamic shifts in the course of the discussion, which i find entirely meaningful and relevant to the initial post, and most of the times equally important, as a presentation of a new structure.

I have been following such constructive debates, since they gave birth to an excellent paper, and they always catch my full attention wherever they take place, under my topic or anywhere else in this forum. I have some difficulties in decoding Dan's writing, but a big cup of coffee helps solving that problem. :) :) 8)

There is always the chance that someone might post a structure,(Alan Lee is a usual suspect), which could negate or expand all the known theory on bowlines, advancing new concepts and triggering similar discussions.
« Last Edit: June 20, 2019, 06:00:31 PM by tsik_lestat »

Dan_Lehman

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Re: A round turn + U turn jam resistant TIB bowline(not double)
« Reply #12 on: June 23, 2019, 08:08:33 PM »

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How on earth does one "prove" a definition to be "correct"?!
...
You 'prove' a theory by testing it.

But it's interesting to wonder how you can conceive this
"*bowline*" as a theory and then would seek to prove that!

--dl*
====

agent_smith

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Re: A round turn + U turn jam resistant TIB bowline(not double)
« Reply #13 on: June 23, 2019, 10:19:02 PM »
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But it's interesting to wonder how you can conceive this
"*bowline*" as a theory and then would seek to prove that!
An example of which is that I theorize that all Bowlines are jam resistant.

tsik_lestat has suggested otherwise but, I need to see evidence of such.

I also theorize that all nipping loops / structures are TIB, jam resistant, have a defined chirality (either S or Z) are loaded at both ends and fully encircle and clamp both legs of the collar.
Be that as it may, the #1249 Constrictor hitch may be troublesome if employed as a nipping structure in a 'Bowline' - and so the theory may have to be modified if it causes jamming.
I don't regard #1249 as a 'loop' - rather, it is a structure. All of the primary Bowlines are built from a helical loop (or double loop per #1013).
I am unclear if anyone has load tested a 'Bowline' built from a #1249 Constrictor to see if jamming can be induced?

Virtual Bowlines built from nipping structures should also be jam resistant.
And so i theorize that if #1249 is used, then the knot ought to be regarded as a 'virtual Bowline' (rather than Bowline).
And if it does jam, then this would mean it fails as a virtual Bowline - because according to (my) theory - all Bowlines - including virtual Bowlines are jam resistant.

Another theory is with regard to effect of having 3 rope diameters inside the nipping loop.
I know that Alan Lee has looked at this but the results have been inconclusive in my view.
A 'control' needs to be used and a statistically valid data set is needed to probe this further.
So its still a 'theory' - until it is proved otherwise.

tsik_lestat

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Re: A round turn + U turn jam resistant TIB bowline(not double)
« Reply #14 on: June 25, 2019, 03:52:33 PM »
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An example of which is that I theorize that all Bowlines are jam resistant.

tsik_lestat has suggested otherwise but, I need to see evidence of such.

I do not suggest otherwise, i mainly agree with this theorised axiom, i just think that there might be a few structures, that should be considered as special cases, deviating from the jam resistance property.

In the case of nipping structures other than simple helical loop, one should find those with the appropriate geometry, which retains their jam resistance, when stabilized with bight structures, in order to qualify as virtual bowlines.

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the #1249 Constrictor hitch may be troublesome if employed as a nipping structure in a 'Bowline'

True. I was unable to create a jam resistant bowline knot, using a constrictor hitch as nipping structure with the stantard or the Carrick method.Even if the hitch, is to be used as a collar component, in a simple helical nipping loop, for the creation of the "double collar crossed bight bowline", it seems problematic too, in terms of jam resistance.

However, there is a case the hitch might work well, as a collar structure, shown in photos below.First photo shows a bowline with two rope diameter inside the nipping loop.If you want a third one, you move to photos 2,3,4, which show the knot in its loose, conventional and detail view accordingly. If you isolate the collar structure in both TIB knots, it forms the constrictor hitch.

But does the second knot look familiar?Yes it does, it belongs to the End Bound category, as a variation of your EBSB without the Yosemite finish.Probably you have tied it and have dismissed it as inferior?

Judging from your extensive load tests on EBSB, this knot(s) should also be jam resistant!!!!