International Guild of Knot Tyers Forum
General => New Knot Investigations => Topic started by: X1 on June 30, 2012, 07:51:24 PM
What happens in a bowline if, intentionally or by accident, one of its two essential elements, the collar, cease to exist altogether ? Will this half-bowline still be capable to hold some loading ?
In the standard, common bowline, without the presence of the collar, the nipping loop will open up, and it will degenerate, from a closed loop to an open helix, in no time. However, there are some double bowlines where this will not happen - at least not immediately - because the two nipping loops are stabilized, to a large degree, by the the continuation of the tensioned eye-leg-of-the-bight ( the "first" leg of the collar) that penetrates both of them, the one after the other. I believe that the Water bowline and the Girth-hitched bowline are utilizing the stabilizing action of the collar only a little bit, so they will be capable to bear some loading indeed, even if the bight of their collar is cut in two.
I have tried to figure out a bowline which, at the moment the brave knot experimentalist will dare to cut the bight of the collar with a razor, when the loop is still under load, NOTHING will happen - or, at least, nothing really catastrophic. I have started from a very stable double nipping loop, where the two coils are crossed - and I weaved the working end through this knot along a path that will ensure that two ccrossed oils will remain crossed, under any circumstances ( so the advantage of their mutual self-stabilizing entanglement will remain at all times) . The result is shown at the attached pictures. Under loading, the two crossed nipping loops do not run the danger to open up, because they encircle and stabilize the one the other, without much help from the collar. The situation is similar with the cases of the Water bowline and the Girth-hitched bowline, only this time the two nipping loops are interlocked, and so they can not move apart from each other.
( Note : To form the collar, the working end can go around the standing end passing from the one or the other side - following a clockwise or a counter-clockwise path. ( If we watch the loop from " above" , the one shown here is the clockwise path. In relation to the direction the working end itself is heading to, it is the counter-clockwise path). As far as all the rest of the route is the same, this makes no difference - either path is O.K, so we do not have to remember or to pay any attention which one we should trace with the working end.)
I understand that this bowline might appear complicated to one that has not tied it, but has only seen its 2D drawing - and so, at a first glance, this knot might not receive the attention I believe it deserves.
The truth is that this bowline is exactly as easy to tie as the common double bowline ! The same number of tucks, the same attention to the path the working end should follow.
Just tie a double nipping loop, but when you form the second turn, place it in between the first turn and the standing end - not at the other side, as you do when you tie the common double bowline. Then, when you are going to pass the working end through the nipping structure for the second time, pass it though only one of the two turns of the nipping loop, the first one, and not through the second. That simple !
That is a disadvantage of the 2D drawings. They do not show the actual sequence of the moves we have to follow to tie a knot - so, they may sometimes be a little misleading, as a measure of the real simplicity of the knot. The double, crossed coils bowline shown in this thread is much simpler than it looks - and much more secure than what we would have expected from such a simple loop.
Are you sure this structure is to be properly regarded as a Bowline?
I admit that I have possibly made an error with "ABoK #1033" (Carrick loop) - after reassessing the criteria and Dan's comments, I am willing to revise my initial position and agree that it contains the components and structure necessary to be regarded as a Bowline variant.
However in comparing "ABoK #1033" to your presented structure, I admit that I am struggling.
Here are some photos to draw comparisons...
Thank you Mark,
I have made a somehow arbitrary choice, with two purposes :
a ; to reduce the number of loops we will call by the name "bowline"
b : to name as "bowlines" loops that do look like the standard bowline.
So, I had decided that, in order to call an end-of-line loop a bowline, it should better have a "proper" collar, i.e. a collar just like the collar of the standard common bowline. (The ABoK#1033 has not such a "proper" collar, so I do not call it a bowline.)
However, I have also decided that I would not kill myself if there is a different consensus by the knot tyers community... :) It is not so important a matter, I believe.
Regarding the presence or not of a "proper" collar, and/or of a "proper" nipping loop, read the following comment ( written a long time ago), of how to include all the knots that are really similar in structure to the standard bowline ( the ABoK#1010) in a coherent family of knots :
We have four distinct strategies : The first is to have a broader concept of the collar ... and the second is to have a broader concept of the nipping loop.... The third is to have both, and the fourth is to have none of them... I will not hesitate to adopt the one or the other, or both, or none - provided this will help us study the knots we already know, and the knots we are going to learn if we adopt any one of the those four strategies.
The loop presented in this thread contains all the components and the structure necessary to be regarded as a bowline variant, that is for sure ! In fact, its differences from the standard Double bowline can be regarded as minor ones - yet I believe that they are very important. As I have stressed, this particular form of the double nipping loop is very stable ; it does not need the help -or even the mere presence- of the collar, in order to remain a closed loop when it is loaded. The nipping structures of most of the other bowlines ( with the exception of some double nipping loop bowlines, as the Water bowline and the girth-hitched bowline), the moment they lose their collar, they also lose their necessary stability, and they degenerate into open helices.
Of course, one can further improve the security of this bowline by adding a second collar - just like one does to get the "Janus" or the "mirrored" variants. However, I believe that, before we duplicate the number of the collars of a bowline, we should better try to improve the single collar form, by improving the nipping and the self-stabilizing ability of its nipping structure.
X1, can you re-post your 'double crossed nipping loops' Bowline in the Knotting concepts/exploration forum in the What defines a Bowline thread please?
I would like to compare the way the nipping turn components grip and stabilise the bight component with "ABoK # 1033'.
This suggests that Rothman had attempted to tie his usual bowline but the knot had failed. It is possible Rothman either forgot to tie his bowline after pulling the rope through his harness, or did so only partly or incorrectly. A figure-of-eight knot has been discounted because there was no bight left in the rope. Deputy Gloucestershire coroner David Dooley said: ?Had a stopper knot been used, the rope probably would not have failed.?
Nobody in this Forum had suggested that the simple, common bowline should be used in place of the retraced double eight knot loop, ever !!! In fact, the knowledge that the simple bowline is not sufficiently safe for rescue/climbing purposes was the motive behind the invention of many variants of the original knot, that are as safe as ( in fact, more safe than ) the knots used by rescue personnel and climbers.
The bowline presented in this thread is a one-collar loop knot that can remain functional even if the collar segment of the rope is accidentally cut - in an effort to discover a nipping structure that would not need the collar as much as the standard bowline does, i.e. in an effort to discover a more self-depending effective nipping structure. I have not said that this bowline could be used without its collar ! :) I have said that, if the collar is not needed as much as it does in the standard bowline, this means that the nipping structure itself is more self-stabilizing, so it will not obligate the collar to bear additional forces that those it already has. A less loaded collar is a safer collar in a safer bowline-like loop.
However, the Double, crossed nipping loops bowline is still a one-collar bowline. I believe that a safe bowline that could replace the retraced double eight knot loop should include two collars. So, if one takes the tail of this bowline, drives it around any one of the two legs of the bight, and through the nipping loop for a second time, then he would have a safe bowline that could be considered as a rescue/climbing knot suggestion.
What is the referent to "this", please?
(Your comment comes out of the clear blue sky,
and I don't find sense for it in this thread; however,
I do know of the tragic incident to which you refer.)
that Rothman had attempted to tie his usual bowline but the knot had failed.
It is possible Rothman either forgot to tie his bowline after pulling the rope through his harness,
or did so only partly or incorrectly. A figure-of-eight [eye]knot has been discounted
because there was no bight [not bight, "knot"] left in the rope.
Deputy Gloucestershire coroner David Dooley said: "Had a stopper knot been used,
the rope probably would not have failed."
To which one might have said, "Had any knot been well tied
--be it even a simple bowline--
it probably would not have failed."
One might also ask --but I saw no evidence of this question--
What was the belayer doing while the climber climbed?!
For the belayer's reported statement(s) indicated some
unbecoming lack of attention to the climber.