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General => New Knot Investigations => Topic started by: tsik_lestat on February 23, 2019, 09:00:19 PM

Title: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on February 23, 2019, 09:00:19 PM
Ashley claims that the harness 1050 loop is not secure under all circumstances and it is not recommended as a midline loop.There are a few ways to secure the harness loop and avoid those slippage issues reported by Ashley, making it a safer and more practical knot.This could be done by retucking the harness loop, which is illustrated for comparison reasons to the left of the photos 1,2 below, from the side where the red arrow is pointing to.The nipping component, is being kept as simple as possible and the collar component is a marlin spike and a figure eight, forming the complete knots shown in photos 1,2 accordingly(right side).These loops could also be tied as end of line loops, keeping the nipping structure in this simple form.

However, there is a more interesting approach shown in photos 3,4 which i think deserves the title enhanced harness midline loop.The knot consists of interwoven crossing knots where the collar and nipping components are equivalent to the unknot and the two ends are facing opposite directions.I believe this is an EEL loopknot and the reverse midline loop is illustrared in photo 4 with the corresponding simple harness loop.Considering this midline loop as the base knot, there are several ways of creating some decent end of line loops,loaded in different ways.There is some difficulty to dress the knot especially in stiff ropes, but once tied right,it is a rock solid,jam resistant,stable midline loop loaded from any of the three directions.I guess there are a lot of ways of tying it and one of them is shown in my next reply.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on February 23, 2019, 09:11:46 PM
Focusing on the midline loops shown in my previous reply, here is a method of tying the enhanced harness loop.
First you form a loop, a bight and second loop as shown in photo 1 from left to right.Then the right loop is placed on the left loop as shown in photo 2 and the bight passes like a toggle between the loops with the following pattern~up,down,up,down.If the left loop is placed on the right and the same steps are followed, then the reverse loop is created.
This is a simple easy to remember method of tying and once mastered it can be tied, dressed and inspected in a rather quick way.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: agent_smith on May 08, 2019, 01:21:15 AM
An interesting 'enhancement' to #1050.
But I'm not entirely sure if this offers anything beyond the performance capability of #1053 Butterfly...
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on May 08, 2019, 09:08:34 PM
Thank you Mark!

I believe there are not so many midline loops in the knotting toolbox are there? :)

The 1053 butterfly, is indeed a stable secure midline loop, but i hear that it is not very easy to untie it,especially after beiing eye loaded,having some blocking issues.

However, an interesting feature of the EHL(enhanced harness loop) midline loop, are the 180 degrees U turns of the SP or the SE (depending on the form of the knot being used) in the core nub.This component,prevents the collar from closing too much and block, when the knot is heavily loaded and one can remove/loosen it rather easily, releasing then the pressure from the SP.

A good question might be, if such a component provides a means of constructing stable, jam resistant,  end of line loops(bowlines or not).I believe it does and to align with the title of this tread, i illustrate four different loading profiles of this knot ,as end termination loops(i am afraid there is no room for back sides or mirrors),which is another advantage of the EHL loop.

The first knot which is TIB, can be tied starting from a TIB 1010 bowline(tail inside eye and tucked back through the bight component of the bowline) and then retuck the eye through the SE to create the bottle/jug sling, which is topologically equivalent to this knot (this is a well known method of tying the bottle sling).Once the bottle sling is being formed, then with two flips downwards of the nipping loop of the bowline  and the upper bight encircling the eye of the bottle sling, we create the final knot.It is an easy transform and i repeat it is just two flips far from the bottle sling.

The same stands for the second knot,also TIB, but the difference is that you start from a reversed TIB bowline and then create a reverse bottle sling(if i may use the term), following the same steps.

The other two knots have different geometry ,but they retain their jam resistance with good ring loading profiles, as end termination loops.I tie them using crossing knots but i guess it is not the only way!!!
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: agent_smith on May 09, 2019, 04:25:28 PM
Quote
I believe there are not so many midline loops in the knotting toolbox are there?

I apply a strict definition of what a 'Mid-line TIB knot is... and yes, in this context, there aren't so many.

Characteristics:
1. Can be tied without access to either end (ie 'TIB'); and
2. Remain stable and secure when bi-axially loaded (through loaded).

For example, the #1047 F8 is 'TIB' but, it is not stable when through loaded.
The #1047 F8 therefore fails to be categorised as Mid-line TIB, and instead is categorised as a fixed eye (loop) knot.

The concept of bi-axial loading refers to a state where load is aligned from SPart to SPart in a straight line (axially).
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on May 10, 2019, 04:25:34 PM
The artillery, man-harness loop, was primarily designed and used for eye loading applications and i think it is not suitable for bi-axially loading.The loop presented here, as an improvement,supports multidirectional loading and meets the characteristics of your strict definition of a midline loop.It even can be loaded as an end of line loop as i've showed in my previous reply,unlike F8,which you correctly stated and illustrated that it fails to be categorised as a midline loop.Few knots can do both,Span loop comes to mind along with Xarax great work on this loop.

Since you have mentioned the butterfly which can be tied as a bend, I thought to apply this technique to the EHL midline loop and create an asymmetrical bend.The tying method is the same,the eye is just replaced by the two ends, so there is no need of posting a photo about this structure.However, to overcome the weaknesses of an asymmetrical bend,(if there are any) and turning it to a symmetrical one, i ended up with this beautifull ,symmetrical, Zeppelin-like,Hugo bend A, tied by Xarax,presented in the following thread,in reply 50, https://igkt.net/sm/index.php?topic=4090.45 (https://igkt.net/sm/index.php?topic=4090.45), using the famous 69 method of tying :). I have not seen so far the transformation of this bend to a loop,illustrated in the following photos,which is a compact Zeppelin-like loop with the benefit of having no overhands in its structure,but non-TIB.I see some connections to all these knots and it should be expected, since they share some resemblance to each other.

Edit .....

1: An indicative asymmetrical bend that corresponds to the Enhanced harness loop has been added, as mentioned previously (third image).

2: If we shrink the eye of the EHL2 end termination loop by pulling each strand, starting from the on going eye leg, a noose or a one wrap hitch is being created, as shown in fourth image. The resulting knot, which can also be tied independently in the end method, retains the tibness and the jam resistance properties.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on January 30, 2020, 08:27:01 PM
One other application of the main knot presented in this thread, would be  a double Spanish-like, either end loadable (EEL), bowline knot.

Verily, we should firstly tie an EHL midline loop following the previous steps, with a quite large eye, and then fold it over the  main nub, as illustated in first image. The next step, is to pull the two eye legs of the initial eye, as the black arrows indicate, and create the two loops by working out all the slack and cinching the knot.

It looks good enough for an anchor system if tied in the end method, but this is probably the easiest method of tying in the middle of the rope, same as in double lineman's knot that corresponds to the single butterfly 1053 midline loop.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: SS369 on January 30, 2020, 08:40:51 PM
Hi tsik_lestat.

"It looks good enough for an anchor system if tied in the end method."

Please explain this further.

SS
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on January 30, 2020, 09:04:24 PM
Sorry for the incorrect wording SS369, what i meant was that it looks good enough for an anchor system generally. But if you have not access to the fixed anchor points (like two tall trees for instance), you have to tie the knot in the end method, which is not difficult afterall, at least for me.

However, the easiest method to tie it in the bight, i believe it is the one described previously, at least until now.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: DerekSmith on May 03, 2020, 09:01:54 PM
I like the EHL, it is indeed a nice stable knot and so far seems to be jam resistant with its large 'fold away' collar.

Here is another method to form it :-

Tie a slipped OH, then with the slipped end, cast a half hitch over the loop...

The only thing to watch out for is that the OH and the HH must be opposite chirality.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on May 04, 2020, 02:46:26 AM
Hello Derek, it's nice to hear from you again.

Here is another method to form it :-

Tie a slipped OH, then with the slipped end, cast a half hitch over the loop...

The only thing to watch out for is that the OH and the HH must be opposite chirality.

I can not justify a slipped overhand's mere existence in the structure, unless it is used as a starting point, as part of a tib tying process to form a TIB 1010 bowline, or a harness loop. Anyhow, and provided that i am no good in " words can work situations" , it would be very helpful to provide a diagram/image of your method. I have made available previously a quite simplified method of tying. Note that we need to tie it in the middle of the rope, without having access to either ends, so a TIB tying method is essential, at least for the midline instances.

The feasibility of multidirectional loading, along with the option of various loading profiles and the ease of untying, make up a versatile knot, whose origin might be traced to a TIB 1010 Bowline, according to the following knotting sequence transitions.....

1. TIB 1010 bowline ==> bottle sling ==> EHL1 end of line ==> EHL midline.

2. TIB reversed bowline ==> reversed bottle sling ==> EHL2 end of line ==> EHL midline.

3. Tying directly a 1050 midline harness and retuck it to get the midline EHL.

4. TIB tying method shown at reply#1 to form the midline EHL.

All the aforementioned methods/transforms are TIB tying methods, they utilize no ends for EHL midline formation.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: DerekSmith on May 04, 2020, 03:32:01 PM
Hi tsik_lestat,

I see now that I have tied a different knot to the one you have posted.

I had assumed you had passed the loop bight through the center of the two loops, but you did not...  you passed the bight loop over, under, over, under - forming a stunningly stable construction.  I am even more impressed by this knot than I was by the one I thought you were tying.

I am intrigued - how did you invent it?

Derek
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: siriuso on May 05, 2020, 07:10:17 AM
Hi tsik_lestat

I think you have got the best midline loop. The EHL is better than Alpine Buttterfly Knot, for it is more secure and non jamming.

The tying method is the same as ABOK#1142 Jar Sling Knot. With a different dressing, EHL is using the Sling's handle as the EHL loop, where as the ABK is using its center nub to hold object.

Happy Knotting
yChan

Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: agent_smith on May 05, 2020, 09:51:05 AM
Hello tsik_lestat,

I see that you breathed new life into this thread at reply #6 .
Looking specifically at your double eye Bowline presentation - just clarifying if this a claim of originality? I presume yes?
Its definitely an improvement over other double eye Bowlines that employ a communicating segment to enable adjustment of the size of the eyes.

As with #1087 Spanish Bowline, the communicating segment is the collar.
In your presentation, it is more efficient because it is indeed EEL.
In comparison, the Spanish Bowline is not suitable for 'EEL' loading profiles.

The outgoing eye legs from each eye are adjacent, rather than splayed as with #1087.
As with any knot, with practice, should be fairly easy to tie from memory.

I haven't read all of your other posts in detail but, are you also suggesting that this Bowline is bi-axially loadable (ie through loadable from SPart-to-SPart)?

Note: You are likely aware that there is a known vulnerability with #1080 Bowline on-a-bight when used for anchor systems.
I have not fully investigated if your presentation has a similar vulnerability...
Link: https://ukcaving.com/board/index.php?topic=14602.0
Its an amusing video with not a lot of scientific rigor....but, you can see the vulnerability the presenter is trying to warn of.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on May 05, 2020, 07:18:23 PM
@ DerekSmith

Hi tsik_lestat,

I see now that I have tied a different knot to the one I have posted.

I had assumed you had passed the loop bight through the center of the two loops, but you did not...  you passed the bight loop over, under, over, under - forming a stunningly stable construction.  I am even more impressed by this knot than I was by the one I thought you were tying.

I am intrigued - how did you invent it?

Derek

The EHL1 end of line eye knot, was the first instance i had tied, when i was fiddling with crossing knot nipping structures, about a year and a half ago. Then, it was delivered directly to Xarax, and after some evaluation/discussion we had, it found its way to publicity, gaining almost instantly, the green light for posting.

I have feautured its versatility, by gradually tying and presenting, most of its corresponding equivalent profiles. Indeed, it is a very stable construction that resists to jamming, and all one has to do, is to press sequentially the two collars to release the pressure and untie the knot.

I guess, i won't be able to get it over with some other potential equivalent invention  :( :).

@Siriuso

Hi tsik_lestat

I think you have got the best midline loop. The EHL is better than Alpine Buttterfly Knot, for it is more secure and non jamming.

The tying method is the same as ABOK#1142 Jar Sling Knot. With a different dressing, EHL is using the Sling's handle as the EHL loop, where as the ABK is using its center nub to hold object.

Happy Knotting
yChan

it certainly is a good knot, but let us not forget that the alpine butterfly has intensively been tested and used in the field, without reported failures so far. The OP's structure features no such background, but i guess, time will tell if it will gain more attention. The omens are promising :).

Trully, the EHL functions more effectively when eye loaded, using whatever profile, with no jamming issues. Believe it or not, i had not seen its relation to the jug knot in the first place.

I understand you have your own TIB method of tying this knot. Feel free to post it, for further evaluation, it would be much appreciated.

@Agent_smith

Hello tsik_lestat,

I see that you breathed new life into this thread at reply #6 .
Looking specifically at your double eye Bowline presentation - just clarifying if this a claim of originality? I presume yes?
Its definitely an improvement over other double eye Bowlines that employ a communicating segment to enable adjustment of the size of the eyes.

As with #1087 Spanish Bowline, the communicating segment is the collar.
In your presentation, it is more efficient because it is indeed EEL.
In comparison, the Spanish Bowline is not suitable for 'EEL' loading profiles.

The outgoing eye legs from each eye are adjacent, rather than splayed as with #1087.
As with any knot, with practice, should be fairly easy to tie from memory.

I haven't read all of your other posts in detail but, are you also suggesting that this Bowline is bi-axially loadable (ie through loadable from SPart-to-SPart)?

Note: You are likely aware that there is a known vulnerability with #1080 Bowline on-a-bight when used for anchor systems.
I have not fully investigated if your presentation has a similar vulnerability...
Link: https://ukcaving.com/board/index.php?topic=14602.0
Its an amusing video with not a lot of scientific rigor....but, you can see the vulnerability the presenter is trying to warn of.

You might say, that there was some sort of refreshment, by planting this double tangle into the thread. i don't think that it has been tied before, but you never know. The fixed eye segments of the knot, are certainly an improvement, compared to the communicating portuguese-like double eye anchor systems.

It has some complexity when tied in the end method,  but practice usually improves knotting skills for anyone willing to go for it, as you correctly point out.

I do not recommend it for biaxial loading. Why bother, when there is always the flexibility of forming a powerfull midline geometrical profile, with a configuration of an opposite two end direction, that can be bi-axially or tri-axially loaded?

Thanks for sharing this video, i had no time to study it, but i shall do it later on. I wouldn't have thought to use a bowline on a bight, for an anchor system, plus i have never tested the OP's double loop for such vulnerabilities.

I guess we know the drill, perform intensive tests before using any knot.

I provide some visual reviveness injection, with some midline stuff, analyzed in this thread, in better quality i hope  :). The knots are in a loose form, and their eye segments, have been kept purposely small, in order to demonstrate all the nub details (overs and unders).
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: alpineer on May 07, 2020, 08:41:50 AM
Focusing on the midline loops shown in my previous reply, here is a method of tying the enhanced harness loop.
First you form a loop, a bight and second loop as shown in photo 1 from left to right.Then the right loop is placed on the left loop as shown in photo 2 and the bight passes like a toggle between the loops with the following pattern~up,down,up,down.If the left loop is placed on the right and the same steps are followed, then the reverse loop is created.
This is a simple easy to remember method of tying and once mastered it can be tied, dressed and inspected in a rather quick way.

IMO this knot bears a stronger association with the False Butterfly Knot than with the Harness Loop, which is how I came across it, trying to secure the FBK for 2-way through loading.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on May 07, 2020, 04:06:24 PM
Good evening Alpineer

i am of the view that EHL, is a retucked version of 1050 harness loopknot, hence the name. You are prompted to tie the knot first and then remove some components, starting from the collar that encircles both eye legs. Then, flip the other collar, rearrange the eye legs, and you have brought the harness into light. Υοu can obviously reverse the process and tie the EHL starting directly from the harness.

I am having trouble to rule out EHL's bowline/harness inherence, and pin down its association with false butterfly that you are reporting. Nonetheless, you have prompted my interest, if you care to feed with more detail, or even illustrate a potential tying method, in order to clear up this traced origin.

I provide an image for your reference, so as to which knot you refer to as false butterfly.

Link : https://www.ropelab.com.au/wp-content/uploads/2015/09/Alpine-Butterfly-errors-1024x534.jpg (https://www.ropelab.com.au/wp-content/uploads/2015/09/Alpine-Butterfly-errors-1024x534.jpg)

Given your climbing and knotting background, as well as your investigations on the midline concept, i can't help asking your estimation about the functionality of OP's midline, EHL, structure, compared to the alpine butterfly.

Thanks.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: alpineer on May 07, 2020, 07:16:57 PM
Good evening Alpineer

i am of the view that EHL, is a retucked version of 1050 harness loopknot, hence the name. You are prompted to tie the knot first and then remove some components, starting from the collar that encircles both eye legs. Then, flip the other collar, rearrange the eye legs, and you have brought the harness into light. Υοu can obviously reverse the process and tie the EHL starting directly from the harness.

I am having trouble to rule out EHL's bowline/harness inherence, and pin down its association with false butterfly that you are reporting. Nonetheless, you have prompted my interest, if you care to feed with more detail, or even illustrate a potential tying method, in order to clear up this traced origin.

I provide an image for your reference, so as to which knot you refer to as false butterfly.

Link : https://www.ropelab.com.au/wp-content/uploads/2015/09/Alpine-Butterfly-errors-1024x534.jpg (https://www.ropelab.com.au/wp-content/uploads/2015/09/Alpine-Butterfly-errors-1024x534.jpg)

Given your climbing and knotting background, as well as your investigations on the midline concept, i can't help asking your estimation about the functionality of OP's midline, EHL, structure, compared to the alpine butterfly.

Thanks.

Hey tsik,
It's #3 in the linked image.

To be clear, there's certainly a transformational relationship between the Harness Loop and your proffered knot. However, I think the FBK (perhaps more correctly referred to as the Half Hitch Loop) relationship is more direct. Starting from your "step 2" image, feeding the bight directly through the two small loops gives you the FBK/HHL.

Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: siriuso on May 07, 2020, 07:59:46 PM
Hi tsik_lestat,

I have made a big mistake in my reply on May 05.

The text should be read as :

"The tying method is the same as ABOK#1142 Jar Sling Knot. With a different dressing, EHL is using the Sling's handle as the EHL loop, where as the JSK is using its center nub to hold object."

It should be JSK instead of ABK.

yChan
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on May 07, 2020, 10:07:46 PM
@Alpineer

I was kind of leery of the structure you were suggesting, but i had to clear it up. Indeed, this maneuver forms the false butterfly, the very same Derek had tied in his first attempt.

However, i am still not seeing any structural propinquity in the core nubs of the two midline knot structures, in a geometrical and functional sense. Besides, the overhand links of the false/half hitch butterfly, are hardly pointing to the bowlinesque descent of EHL, but that's only my interpretation.

@Siriuso

Nothing to worry about, i perfectly understood what you meant in your previous reply.

So you are suggesting the jug knot tying method to form the EHL. I found it a bit more complex for my taste, when i came across to it, but that's a subjective matter. I shall have a look again to see if it acommodates any amendment, but I was counting on your ability to ferret out new tying methods  ;).
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: alpineer on May 08, 2020, 05:33:48 AM
Re tying methods for this knot, my hybrid style "loop on the hand w/X-crossing underneath" will get you one tied, dressed and set in 7 secs. Just make the "X" in the opposite direction with the other hanging strand and proceed from there with the appropriate over/under maneuvers. https://youtu.be/DYGdvL9-P30
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on May 08, 2020, 08:11:51 AM
Good day Alpineer

I see that you have attuned your hybrid tying method to form a false butterfly as well. Thanks for bringing this in, the only con i would add, is that is not so straight forward as tying the butterfly, because you have to brake the two loops apart and place one upon the other, continuing with the over, under maneuvers. However, it is more memorable, in the sense that one does not need to remember the chirality of the two small loops, i'll give you that.

Your hybrid method of tying the alpine butterfly is more suitable for me, as i find that you can easily adjust the size of the eye. It resembles with one of my own, but only in the final stage, where you are adjusting the size of the bight you are going to feed through the two loops. This very method, relies on a type of pretzel structure formation, but i think yours is quicker and easy to remember.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: alpineer on May 09, 2020, 09:59:49 PM
@Alpineer
However, i am still not seeing any structural propinquity in the core nubs of the two midline knot structures, in a geometrical and functional sense. Besides, the overhand links of the false/half hitch butterfly, are hardly pointing to the bowlinesque descent of EHL, but that's only my interpretation.

I'm not sure how to interpret what you're saying re "bowlinesque descent". However, performing D.L.'s backflip/halter maneuver on the FBK produces two healthy B'lines; depending on the direction, either twinned or splayed.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on May 09, 2020, 11:52:46 PM
However, performing D.L.'s backflip/halter maneuver on the FBK produces two healthy B'lines; depending on the direction, either twinned or splayed.

Good call Alpineer. I have just tied them and in this initial phase they look healthy to me too. I guess, i prefer the splayed version, but i am not sure about the EEL ability, as i have the sense that i have to load it from the weak link of the FBK for a stable structure development. I wonder, if they have been tied before. If not, they're waiting for your moniker  ;).

I'm not sure how to interpret what you're saying re "bowlinesque descent".

All i am saying is that the parent knot, is a TIB 1010 bowline. Check out how Alan Lee ties the Jug sling knot, starting from the tib 1010 variant. Link : https://www.youtube.com/watch?v=WBDn25h80KU.

All you have  to do to reveal EHL, is to flip the collar that encircles both eye legs, plus the nipping loop of the bowline. That said, even so i am refering to an end of line profile of the knot with this paradigm, the same stands for the midline structure, therefore i am tracing EHL's origin by laying emphasis on this equivalence, not only in a topological but in a functional sense too.

In other words, i have produced a retucked version of a bowline, or a second order bowlinesque type of knot, or a squared bowline, that inherits all its good properties like jam resistance, being simultaneously far more secure and stable than the parent.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: alpineer on May 11, 2020, 09:00:22 PM
I think we've made our points, time to move on.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: agent_smith on May 12, 2020, 03:01:22 AM
Hello tsik_lestat,
I would like your permission to include your bi-axially loadable TIB eye knot ('EHL') in my paper on the Butterfly knot.
If you grant permission - I will need some historical info...eg discovery date, the inspiration that led you to its discovery and your real name, etc.
Also need any test data - ie any load tests that have been conducted in human rated EN ropes (eg EN1891 or Sterling HTP).

Of importance to me would be test data on bi-axial through loading (SPart-to-SPart) and also various types of eye loading.
Jam resistance data is of high importance to me...

You can PM me to let me know...


Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: alpineer on May 12, 2020, 08:01:59 AM

Given your climbing and knotting background, as well as your investigations on the midline concept, i can't help asking your estimation about the functionality of OP's midline, EHL, structure, compared to the alpine butterfly.

Thanks.

Mechanical functionality appears to be good. However, any advantage that it might conceivably have over the ABK re jamming immunity comes at the price of extra complexity. It would have to solve a problem that climbers experience on a regular basis in order to be considered. In situations where the ABK is typically used, I wouldn't think the forces enough to cause a jamming incident. Perhaps rescue loads on low stretch rope could initiate jamming. Agent Smith?

A curiousity of doubled back nipping structures is that they can cause the knot to have more than one possible dressing geometry, which may be of concern.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: alpineer on May 12, 2020, 07:13:55 PM
This fellow managed to jam an ABK in an ill suited towing application.
https://igkt.net/sm/index.php?topic=6150.0
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on May 13, 2020, 08:54:33 AM
@ agent_smith

Undoubtedly, it goes without saying,that you have absolute permission, to deal with this knot, in whatever way you desire, and i personally thank you for your intention to include it in your ABK's upcoming paper. I shall contact you to provide with every additional info i know. Mind you, there's not so much, as official test data conducted in human EN rated ropes, are rather scanty at the moment.

Some further contributions might be added, regarding the tying method of the midline mirrors, as well as a variation of an end termination profile, which adds even more security.

For those interested, the span loop midline structure, appears to accomodate the same tucking as EHL does, generating a bulkier profile, due to its more complex link.

@alpineer

Quote
However, any advantage that it might conceivably have over the ABK re jamming immunity comes at the price of extra complexity.

That's true, stability and jam resistance comes at the price of some bulkyness, along with some difficulty to form on stiff ropes, but nonetheless, i believe it operates on the margin of admissible and balanced complexity. I am of the view, that sometimes you got to go a bit more complex to achieve the desired functionality, but not going too far.

I'd also comment, that the flexibility of loading EHL's eye without observable jamming incidents, adds some extra versatility, in contrast with ABK's eye loading profiles that are likely more prone to jamming, as fellow climbers and testers report.

Quote
A curiousity of doubled back nipping structures is that they can cause the knot to have more than one possible dressing geometry, which may be of concern.


This particular dressing state, appears to be immensely stable, where the eye bight is firmly clamped, enjoying full constriction from both EHL's links, that can hardly deform under high strain.

Thanks for your evaluation, it's much appreciated.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: alpineer on May 13, 2020, 07:44:53 PM
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l wonder if they've been tied before.

Centuries ago, no doubt.
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on May 19, 2020, 03:52:01 PM
Quote
l wonder if they've been tied before.

Centuries ago, no doubt.

That might be the case, but until proven otherwise, a moniker like Double Alpineer's FBK loops, sounds eligible and rather euphonic so far ( aka Double Lineman's ABK loops :)).
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: agent_smith on June 03, 2020, 02:00:36 PM
Requesting load testing to determine jamming resistance in the following loading profiles:

[ ] Bi-axial loading from SPart-to-SPart
[ ] Eye loading (with one SPart anchored)

Alan Lee perhaps?

Or anyone else?
Title: Re: Second order retucked/enhanced harness midline loops and the equivalentEOL loops
Post by: tsik_lestat on July 09, 2020, 03:48:29 PM
                                                                         Mirror tying method

1. Form a Z loop, a bight, and an S loop knotting scheme, like the one illustrated in first image (in contsast with the tying method described at reply#1, where the initial configuration was S loop, bight, Z loop).

2. Place the S loop over the Z loop, (or the Z over the S loop), as shown in second image. Note, that you have to place the S loop, (or the Z loop), on Z loop's segment that is a direct continuation of the bight component, in contrast with the tying method presented at reply#1.

3. Pass the bight through this configuration, in the following order, ~ under, over, under, over ~.

The resulting mirror knot is shown in the next two images, in a loose dressing state, in front and back view.