Author Topic: Mirrored Girth hitch bowline  (Read 9291 times)

X1

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Mirrored Girth hitch bowline
« on: July 24, 2012, 05:19:34 PM »
   A most secure form of a double nipping loop / double collar bowline, that can be considered an alternative of the fig. 8 loop.
   There is a minor - probably - detail in the dressing of this bowline, that I want to point out in this thread. When we have three rope segments penetrating through a nipping loop, they can be arranged in two geometrically different configurations. (The triangle, formed by the cross section centres of the three rope diameters, can be rotated inside the ring of the nipping loop, relatively to the crossing point of the nipping loop.) So, after we have already passed the working end through the nipping loop two times, in order to pass it for the third time we can chose the opening at the one or at the other side of the already placed pair of segments, relatively to the position of the crossing point. I believe that we should pay some attention here, and chose to pass the working end through the side where it is nipped more effectively - and this is the opposite side from where the crossing point is located. I have seen that , when the third rope segment penetrates the nipping loop passing near the crossing point, it can slip through more easily than the other two segments. And it is important to place the final, third leg of the two collars in a position inside the nipping loop s ring where it is nipped as effectively as possible, because this position is the final line of defence of the knot. A third leg that can slip through the nipping loop more easily than the other two does not make any sense - it is a line of defence that either would remain unused and useless, or will be defeated easily, if and when the other two line of defence will have already been defeated. As a general rule, in knots as well as in life/war, the last line of defence should always be the stronger one.  :)
   I have noticed that in the most complete, beautiful compilation of bowlines we have,(1), the Mirrored girth hitch bowline is dressed in the "wrong" way - the third rope segment is situated near the crossing points of the two nipping loops, from where it can slip through more easily than the other two. Compare the mirrored girth hitch bowlines dressed in the one or the other way, at the attached pictures.

1) http://www.paci.com.au/downloads_public/knots/Bowlines_Analysis.pdf
« Last Edit: July 24, 2012, 05:23:36 PM by X1 »

Dan_Lehman

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Re: Mirrored (aka Girth hitch) bowline
« Reply #1 on: July 24, 2012, 06:33:55 PM »
"mirrored girth hitch" is wrong/misleading : it is the bowline
aspect that is *mirrored*, which is equal to a girth hitch
--which is not (itself) mirrored!

I disagree with the reasoning relating to security --it is amply
secure (and one might prefer sooner vs. "last" defence for strength).
Also, the security for which I sought in presenting this knot
is one in which there is no tension on the SPart --"slack security",
the ability to stay tied in unloaded jostling, et cetera.

But I find the positioning that's here advocated to be what
I favor in some conjectured belief about *strength* --that
with the loaded SPart bearing in upon the tail at this point,
the tail will deform per pressure of the SPart more than would
a tensioned part, and this I think will give  improved strength
--a guess!

Moreover, I'll note that I also have tied a version of this in
which the tail skips collaring the eye leg and instead just
"EBDB"-like loops around the 2nd nipping turn to tuck ONLY
into the initial nipping turn, where the 3 diameters might
matter, for strength and improved curvature.  Here, one
needs to re-think things vis-a-vis the tail-tuck-position
issue, as the natural tuck comes at a different place.

Also, Mark's (blue rope) images show the knot too tightly
drawn up; I would leave the collar around the SPart less
tight.  (He was constrained by depth of image space
(given how large-scale his knots are).)

This eye knot seems to be pretty good at staying tied,
although plenty *open* in setting ; it remains easily
untied after loading, which is of value to rockclimbers.


--dl*
====
« Last Edit: March 08, 2013, 05:35:40 PM by Dan_Lehman »

knot4u

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Re: Mirrored (aka Girth hitch) bowline
« Reply #2 on: July 24, 2012, 08:32:09 PM »
This eye knot seems to be pretty good as staying tied,
although plenty *open* in setting ; it remains easily
untied after loading, which is of value to rockclimbers.

Thanks, I was looking for the practical application.

roo

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Re: Mirrored (aka Girth hitch) bowline
« Reply #3 on: July 24, 2012, 09:38:54 PM »
I was looking for the practical application.
With this monster (as the OP likes to say) taking up around 64 rope diameters for the knot body alone, I think there is little danger of this seeing much use.
« Last Edit: July 25, 2012, 03:08:19 PM by roo »
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TMCD

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Re: Mirrored Girth hitch bowline
« Reply #4 on: July 24, 2012, 10:24:40 PM »
Would this knot really give much more security than say a double bowline with a DOH stopper? This just seems way to complicated unless you're one of us knot tyers.

X1

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Re: Mirrored Girth hitch bowline
« Reply #5 on: July 24, 2012, 10:45:49 PM »
"mirrored girth hitch" is wrong/misleading : it is the bowline aspect that is *mirrored*, which is equal to a girth hitch--which is not (itself) mirrored!

Correct, but tell it to the author of the reference... And propose a better name.

one might prefer sooner vs. "last" defence for strength.

 When the defence is stratified and arranged in many lines, it pays to have the first lines weaker than the last ones. Otherwise, if the first/stronger line is somehow defeated, all the others will be defeated, too, in their turn, one by one - because if the first/stronger line would be proved to be weaker than the enemy forces, the next/weaker lines would not be able to stop them either. On the contrary, weaker first lines consume part of the enemy forces, and if there is a chance of a successful defence, there will be some resistance left and intact at the very end, and the last/stronger line will hold. Every general, from time immemorial, knows this strategy, I believe it is about time for the knot tyers to learn it, too !  :)
   Because I have seen the same thing in knots. If the tail is blocked in more than one points, say, two, it is much better if the resistance it confronts at the first point is weaker than the resistance it confronts at the second point. Otherwise,  if the tension is not enough to overcome the first obstacle, the tail runs the danger to remain slack, at the segment between the first and the second points - or, if the tension is greater, and succeeds in forcing the tail to slip through the first point, it will probably succeed to force it slip through the second point, too. A gradual, progressive absorption of the tensile forces is always preferable - moreover, it will keep the tail tensioned throughout its entire length, so the whole nub of the knot will be kept more compact most of the time. I am not sure that I have been able to describe this fact verbally with my poor wording, but I have tried to offer some points - I believe you have to connect the dots by yourself. 

a version of this in which the tail skips collaring the eye leg and instead just "EBDB"-like loops around the 2nd nipping turn to tuck ONLY into the initial nipping turn, where the 3 diameters might matter, for strength and improved curvature.

   A much more complicated pattern ! ( Much harder to remember how to tie...) Look at this loop with a fresh eye : Just a double nipping loop ( be it of the girth hitch, or of the double nipping loop of the Water bowline), and a second collar, symmetrically positioned ( mirror-ed), at the other end of this double nipping structure. One can not  forget how to tie this bowline - and any possible mistake would be apparent at the spot.

   I have not reached this loop following this line of reasoning. I have just tried to find out which bowlines have a nipping structure that do not need the collar structure to stabilize themselves -or they need it only in a limited degree. A bowline with a self-stabilizing nipping structure, will not capsize as easily as the others, even if the collar is left slack. ( That does not mean that the collar should  deliberately be left slack, as I will argue at my next comment ). A tail that does not bear the role of stabilizing the nipping structure, would probably be better suited to act more successfully in its prime role : to be attached to the standing part, by being part of an effective collar ! The Water bowline and the girt hitch bowline, as well as the double, crossed nipping loops bowline presented at (1), are examples of bowlines with almost self-stabilizing nipping structures. So, the two nipping loops are not needed/utilized to offer a greater sum of friction forces, or a more effective nipping power - although it is possible that they do, indeed, we are not sure that two nipping loops offer a more effective grip on the tail than one ! ( We have to measure  it, some day in the next century...)

I would leave the collar around the SPart less tight.

   On the contrary, I believe that a tightly dressed knot, being more compact at the first place, right from the beginning - that is, even before its loading - is working better as one piece, one integrated whole. The tensile forces running within its elements would have a better chance be distributed into the whole knot s nub, to be absorbed by a greater portion of the rope segment, so  there will be less danger for an isolated small area to bear the full power of the loading, and to become the weak link - a guess !   

1) http://igkt.net/sm/index.php?topic=3951.0
« Last Edit: July 24, 2012, 10:55:11 PM by X1 »

X1

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Re: Mirrored (aka Girth hitch) bowline
« Reply #6 on: July 24, 2012, 11:02:07 PM »
With this monster taking up around 64 rope diameters for the knot body alone, I think there is little danger of this seeing much use.

   How many rope diameters does the fig.8  "monster" take -  the "monster" that is used all over the world, by thousands of climbers ? I propose it as an alternative to the fig.8 knot - not to the overhand knot !  :) And I have to point out that, fortunately, life is more expensive than a few rope diameters...
« Last Edit: July 24, 2012, 11:07:16 PM by X1 »

X1

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Re: Mirrored Girth hitch bowline
« Reply #7 on: July 24, 2012, 11:05:43 PM »
Would this knot really give much more security than say a double bowline with a DOH stopper? This just seems way to complicated unless you're one of us knot tyers.

   We do not know ! We have to start measuring some things some day !  :)
( Personally, I do believe it gives, indeed
...because of the self-stabilizing nipping structure, and of the second collar.)

roo

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Re: Mirrored (aka Girth hitch) bowline
« Reply #8 on: July 24, 2012, 11:27:35 PM »
With this monster taking up around 64 rope diameters for the knot body alone, I think there is little danger of this seeing much use.

   How many rope diameters does the fig.8  "monster" take -  the "monster" that is used all over the world, by thousands of climbers ? I propose it as an alternative to the fig.8 knot - not to the overhand knot !  :) And I have to point out that, fortunately, life is more expensive than a few rope diameters...
About 61 diameters AND it has a much easier and quicker method of tying.  But all that line makes adjustment during or after tying cumbersome besides being a waste of rope and reach for either loop.  "Life" is not at issue with either loop and so is a pointless distraction.
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X1

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Re: Mirrored Girth hitch bowline
« Reply #9 on: July 24, 2012, 11:42:37 PM »
   An argument about a difference of 3 rope diameters ( 5 %), is a pointless distraction, indeed.
   The one end-of-line loop is a bowline, that can be untied in one step, while the other is a topologically complex, two interlocked fig. 8 knots loop, that can not. I know that many people will never appreciate - or even understand- that difference, but I can not do anything about it, I am afraid.
   This thread was not meant to "defend" the one knot and disqualify the other...If we like to discuss which end-of-line loop is more easy to tie and untie, inspect, remember, etc., we can start a new  thread. The reader is kindly requested to read the first post of this  thread, where I had pointed out the two slightly different ways to dress the Mirrored Girth hitch bowline - and the reason I believe the A way is probably preferable from the B.

knot4u

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Re: Mirrored Girth hitch bowline
« Reply #10 on: July 25, 2012, 12:38:50 AM »
If we like to discuss which end-of-line loop is more easy to tie and untie, inspect, remember, etc., we can start a new  thread. The reader is kindly requested to read the first post of this  thread, where I had pointed out the two slightly different ways to dress the Mirrored Girth hitch bowline - and the reason I believe the A way is probably preferable from the B.

You say you don't want people to compare ease of untying, inspecting, and remembering. I say that you're in the wrong forum. A loop isn't practical merely because it's a loop that includes "Bowline" in the name. A loop is practical when it has one or more features that are more desirable than other loops. Thus, the comparison is necessary and welcomed.

So, what are the one or more features here that are more desirable than other loops? Dan hinted at some features. It would be nice to expound on those features. I'm still not convinced it's a practical loop that I should make part of my vocabulary, but I'm open to being convinced otherwise.
« Last Edit: July 25, 2012, 05:26:48 PM by knot4u »

X1

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Re: Mirrored Girth hitch bowline
« Reply #11 on: July 25, 2012, 01:16:47 AM »
You say you don't want people to compare ease of untying, inspecting, and remembering.

No, I said that the thread was about the two ways one can dress the Mirrored Girth hitch bowline. I suppose that the bowlines that are included in the article I was referring to, are practical knots, indeed. Now, if one wishes to argue that the bowlines, in general, or this bowline, in particular, are not practical knots, I suggest he starts a new thread -  where I would love to participate !  :) The present thread is about the comparison of the two ways a ( supposedly) practical knot can be tied, the reasoning and the comparison between them.

A loop isn't practical merely because it's a loop that includes "Bowline" in the name.

   Oh yes !  :) A simple loop that is a bowline ( not because it is named and called  "bowline", of course), is a practical knot ! I have tried to point out a ( possibly minor) detail of one such a knot, which happens to be one of the most secure bowlines I know. I have given the main reasons for my conviction that this knot is a most secure bowline, indeed : the fact that its nipping structure is almost self-stabilizing, and the existence of a second collar. And one should also appreciate the simple pattern of this knot, that makes it hard, or impossible, to forget how to tie it !

I'm still not convinced it's a practical loop that I should make part of my vocabulary, but I'm open to being convinced otherwise.

   What of the two ? That "it s a practical loop", or that you "should make it part of your vocabulary" ? To my view, any  simple knot that is stable and secure, is a potentially practical knot -  and it will become a practical knot, if the knot tyers learn to tie and use it  :) - but this is a matter we can discuss in another thread. I also believe that, if you really appreciate the great convenience of an end-of-line loop that can be untied in one step, as all bowlines can, you will also appreciate this particular bowline. The girth hitch nipping structure can be formed in a fraction of a second, then all you have to do is to pass the working end through this structure ( the co-axial pair of nipping loops) three times, making two collars, one after the first and one after the second pass. Do not be confused by the image of this knot - tie it a number of times, and you will discover that it is  far simpler than it looks:)
« Last Edit: July 25, 2012, 01:26:19 AM by X1 »

roo

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Re: Mirrored Girth hitch bowline
« Reply #12 on: July 25, 2012, 05:50:17 AM »
   An argument about a difference of 3 rope diameters ( 5 %), is a pointless distraction, indeed.
In case you missed it, I was condemning the Figure 8 Loop for its use of rope.  It's odd that you bring this Mirrored Girth Hitch Bowline as an alternative to the Figure 8 Loop when it uses slightly more rope.  This doesn't help improve adjustability.  This doesn't help improve reach. 

You never pass up an opportunity to say how terrible it is that the Zeppelin Loop takes three untuck passes to reduce to a knotless line, but let's count how many untuck passes it takes with the Mirrored Girth Hitch Bowline:  One, two, THREE!   ;D  Oh, how terrible!

While I'm sure both loops have excellent security and jam resistance, the Zeppelin Loop accomplishes it with only 34 diameters which makes adjustment and inspection a pleasure compared to the Mirrored Girth Hitch Bowline's 64 diameters (both measuring the knot body).
« Last Edit: July 25, 2012, 05:53:58 AM by roo »
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X1

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Re: Mirrored Girth hitch bowline
« Reply #13 on: July 25, 2012, 09:48:00 AM »
Quote from: roo link=topic=3994.msg23782#msg23782 date=1343191817[/quote
In case you missed it, I was condemning the Figure 8 Loop for its use of rope.

   Not only for its use of rope! You say a number of other things, that are generally correct. Do not underestimate your own critic. I am not allowed to "condemn" the fig.8 knot, such a beautiful secure knot that is used by thousands of people that hang their lives on it...Most people will consider the fig. 8 knot as the first or the second best bend we have, and they do it for a reason. Again, I have to repeat that this thread was not meant to compare the Mirrored Girt hitch bowline with the fig. 8 loop - not even the Mirrored Girth hitch bowline with any other double nipping loop / double collar bowline ! It was meant to compare the two slightly different ways of dressing the Mirrored girth hitch bowline - and to offer some arguments in favour of the A over the B.

 
While I'm sure both loops have excellent security and jam resistance, the Zeppelin Loop accomplishes it with only 34 diameters which makes adjustment and inspection a pleasure compared to the Mirrored Girth Hitch Bowline's 64 diameters (both measuring the knot body).

   It seems you do not understand that a pattern  is a different thing from a quantity, like the total length, or the number of crossing points. A pattern can be simple, and easy to remember and inspect, while it uses a lot, even an infinite amount of line, of knot crossing points, etc.. A certain knot can be hard to remember how to tie or to inspect, even if it uses less line, and fewer crossing points, than another. The ugly dumb so-called "Zeppelin loop", is not only a disgrace for the best, most symmetric and beautiful knot we have, the genuine Zeppelin bend, but it also is hard to remember how to tie, and hard to inspect if it is tied correctly. The Mirrored Girth hitch bowline is a piece of cake compared to your beloved monster. And I have to remark that a monster is still a monster, and will be a monster for ever, even if it loses 5% of its weight ! :)

   Anyway, this thread was obviously not about the so-called "Zeppelin loop" monster, but about two different ways to dress the Mirrored girth hitch bowline. I do not compare a bowline-like loop with a two-interlinked overhand knots loop, as I have explained over and aver again, because I believe I understand the difference between them. Irrespectively of the fact that this particular two interlinked overhand knots loop is so hard to remember how to tie and so hard to inspect if it is tied correctly, AND it is a disgrace of one of the most beautiful knots we have - that is, irrespectively of the fact that the so-called "Zeppelin loop", is,after all, nothing but a monster ! :)
   I have a theory about why people do not seem to understand the difference between the Zeppelin bend and all the other bends : They do not understand how the Zeppelin bend works ! This unique, most remarkable bend is a rope-made hinge, and I believe that this fact explains why it does not jam, why it does not consume its tails while it is tied as well as while it is loaded, and why it is such a secure knot. The standing parts do not embrace directly each other ( as it happens in the Hunter s bend, for example), but they are revolving around a central common axis, the pivot of the hinge. The pair of tails that act as this pivot are subject mostly to shear forces, a thing we do not have in any other bend. 
   I believe that this thread was about the two forms one can dress  the Mirrored girth hitch bowline, but some people prefer to discuss other things. I am not a fan of any "stay-on-the-subject !"  puritanism, but I would much appreciate if we will continue to discuss something that has an even remote relation with the initial subject of the thread- and a certain two-interlinked knots end-of-line loop, be it a monster or not, has no relation with the two ways one can dress a certain secure bowline. 

P.S. The "monster" adjective was not introduced into the thread by me...I do not believe that the so-called "Zeppelin loop" is a monster - it is just one more dumb and ugly end-of-line loop, among so many others. What I detest is that it is a dumb and ugly exploitative user / parasite of the most clever and beautiful bend we have, the beauty we call Zeppelin bend.
« Last Edit: July 25, 2012, 04:10:27 PM by X1 »

X1

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Re: Mirrored Girth hitch bowline
« Reply #14 on: July 25, 2012, 03:58:51 PM »
   Here are two simple schematic drawings of the two ways we can pass the third ( the "3 ") rope segment through a nipping loop .( See the attached pictures). Variation A is the "correct" one, where the third leg is located far from the crossng point, and it is nipped more effectively, and variation B is the "wrong" one, where the third leg is located near the crossing point, and it is nipped less effectively than the other two. I hope that those drawings illustrate the ( incomprehensible, most probably... :) ) following text of the first post: 

   " When we have three rope segments penetrating through a nipping loop, we can arrange them in two geometrically different configurations. (The triangle, formed by the cross section centres of the three rope diameters, can be rotated inside the ring of the nipping loop, relatively to the crossing point of the nipping loop.) So, after we have already passed the working end through the nipping loop two times, in order to pass it for the third time we can chose the opening at the one or at the other side of the already placed pair of segments, relatively to the position of the crossing point. I believe that we should pay some attention here, and chose to pass the working end through the side where it is nipped more effectively - and this is the opposite side from where the crossing point is located. I have seen that , when the third rope segment penetrates the nipping loop passing near the crossing point, it can slip through more easily than the other two segments. "