Author Topic: Analysis of Bowlines paper uploaded for review and comment (PACI website)  (Read 107943 times)

X1

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I am also intending to include another obvious simple lock - that being a strangled double overhand knot around the eye leg (its simple and it works).
  Although this is, unquestionably, the most naive way one can lock the Tail, it was probably one of the first and the most used - so I think it will not make any harm if you include it in your collection. It is not "simple" in any way, regarding the knot per se : it consumes more rope length, it makes the knot more extended, it requires more tucks of the working end (= it requires more time to be tie and untied), and the path of the working end is more convoluted than in most other secure bowlines. However, conceptually, and for somebody who has not yet understood the working of the bowline in much depth, it is the simplest idea - that, as you say, works.
   The same happens for an even bulkier secure bowline, the Double collar ( two collars) Girth hitch based bowline - the "Mirrored"  bowline. Although it is not "simple" regarding the knot itself, it is simple conceptually : the Tail makes a second U turn, around the eye leg this time, and then returns back, going "upwards", following the same path it had followed going "downwards". Moreover, the base Girth hitch used as its double nipping structure is very easy to tie, and the tucking of the working end is straightforward, because the line penetrates both nipping turns at the same time, in its path "downwards" as well as "upwards". Therefore, I believe that the pink boot it was given in your article, which, in Ashley, denotes a knot that is mainly of a decorative value only, is not fair. The "Mirrored" bowline is a fine knot, very easy to understand, very easy to tie, stable, secure, non jamming  - from the Double collar ( = two collars ) + Double nipping turn bowlines we have, iI think it t is one of the best.
   
« Last Edit: July 24, 2013, 06:35:33 PM by X1 »

Festy

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Would it be fair to say then, at least from how I understand the paper, that the standard bowline is to be avoided in life/injury threatening applications, and is actually inferior to the 'cowboy' bowline?

roo

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    • The Notable Knot Index
I am also intending to include another obvious simple lock - that being a strangled double overhand knot around the eye leg (its simple and it works).
I don't want to discount the fact that this would increase the bowline's security and make for an easily-inspected knot, but the backup double overhand knot around a leg might not be as secure in certain types of line as it might first appear as it lacks some structure to press firmly against to prevent springing open.

Similarly, when people try to make a double fisherman's knot less jam-prone by putting a reef knot in the center, it really reduces overall security.



It also may be a bit irritating to have a lump in the loop, especially in cases where the loop needs to be small.
« Last Edit: July 25, 2013, 03:56:40 AM by roo »
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X1

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About the Reversed Water bowline / Reversed Clove hitch based bowline, Mark Gommers writes, in "Analysis of Bowlies"
" In this variation, the Clove hitch structure has been tied in reverse.The Clove hitch structure may be prone to jamming (testing required to confirm)."
   As shown also in (1), the Clove hitch may look a very simple, very weak hitch, but when tied around compressible materials, as the ropes are, it can clinch very hard, and jam. On the Contrary, the Girth hitch does not jam, so it is a preferable solution in all its uses : As "normal" or "reversed" nipping structure, in a "common" as well as in an "Eskimo" variation (2).

 
   I have tested this bowline a number of times, under moderate but cyclic loading, and I believe I can confirm Gommer s statement : Indeed, this reversed Clove hitch structure jams, and jams badly : Therefore, most probably, it is not suitable as nipping structure for a secure bowline that can be used by rescue workers and climbers.

    We may say that a Reversed Clove hitch works like a non-Reversed Constrictor - and jams for the same reason, at the same place : the "lower" collar, around the eye leg (3). Both hitch structures, when tied around the legs of the bight component, are too tight, so they not suitable as double nipping structures for the bowline, I believe. When we try to improve the security of the bowline, we are walking a fine line : We should use a more complex and a more tight structure, but not beyond some limits : a too complex, bulky and difficult to tie structure, and a too tight one, prone to jamming, should be avoided.
   (See the attached pictures)

1. http://igkt.net/sm/index.php?topic=4347.0
2. http://igkt.net/sm/index.php?topic=4009.0
 
   http://igkt.net/sm/index.php?topic=4009.msg26872#msg26872
3. http://igkt.net/sm/index.php?topic=4507.0
« Last Edit: July 25, 2013, 11:47:09 AM by X1 »

alpineer

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When we try to improve the security of the bowline, we are walking a fine line 

My point has always been it's a matter of finding the right balance between improving security and overly compromising any of the good traits present in ABoK #1010 - simplicity, quickness and ease of tying/untying, PET, TIB ...etc. The multiple-loop Tresse structure intrigues me as it appears to hold that promise.     
« Last Edit: July 31, 2013, 07:10:19 AM by alpineer »

agent_smith

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Hi alpineer,

Have you got any high quality images of your 'Tresse' structure?

If yes, can I use them (copyright and royalty free) in the paper?

And - I would need some technical content (a few paragraphs) to explain and compare/contrast it with #1010.

Mark

agent_smith

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Hello SS369,

To answer your question, yes - I would be happy to release the 'Analysis of Bowlines' paper to the IGKT.

This would free me up as I am soon to run out of time (unfortunately, I have to work to earn a living and survive). Normally, this time of year is my busiest (work) period but there has been an economic downturn which has slowed me down too (worrying). Whilst I don't have a particular end date in mind per se - each day I spend working on knotty stuff is a day less spent on securing my work / income future.

I feel I have set a reasonable baseline for others to continue this work...

My preference is to upload the source document (which is in Bill Gates Microsoft Office Word format ...'filename.doc' - not the newer 'filename.docx' format). Hopefully, there are a few people in the IGKT that use Microsoft Word software?

The source file is close to 50 MB in size.

One way to do this is for me to upload it to a free 'cloud' storage site such as 'Dropbox'. I could upload it to 'Dropbox' and share the file with a list of IGKT people.


Mark

SS369

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Hello Mark.

Thank you for your response to my inquiry.
I would be interested in being a recipient of the file when you're done with it.
I am not familiar with Dropbox, but if that is what it takes I'll learn about it.
As for the IGKT being the repository for it, I was just asking ahead of time about the possibility.

I think we can all understand the "unfortunate" need to earn a living. So, I would like to publicly thank you for investing so much of your time to this. I personally appreciate the work.

SS

alpineer

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Hi alpineer,

Have you got any high quality images of your 'Tresse' structure?

If yes, can I use them (copyright and royalty free) in the paper?

And - I would need some technical content (a few paragraphs) to explain and compare/contrast it with #1010.

Mark

Hi Mark,
I'll be working on that over the weekend, and of course you may use any images (copyright and royalty free). I must say you've set a high standard with your images.

Dan_Lehman

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I don't want to discount the fact that this would increase the bowline's security and make for an easily-inspected knot, but the backup double overhand knot around a leg might not be as secure in certain types of line as it might first appear as it lacks some structure to press firmly against to prevent springing open.
While one can read of some rockclimbers testifying
to the loosening of a strangle tie-off, such that
I've mused about suggesting a double strangle (as it
will get one full round turn clear of changing direction
in tucking back through the nub), a well-set strangle
should hold.  BUT, (1) it doesn't ensure that the bowline
doesn't itself loosen, all so well --it's not easy to tie
the strangle snug to the bowline, though one
can work it so by means of pulling on the collar, after
the knot is tied (but that will enlarge the eye)--;
and (2) if tied around an eye leg, it fills an area that
might not have much room (the small eye of the
climber's tie-in comes to mind) --in this case,
the tail can be pulled away and tied off to the
SPart.  (A point you make, too.)

Quote
Similarly, when people try to make a double fisherman's knot less jam-prone by putting a reef knot in the center, it really reduces overall security.
???
How can the (so-called) "square fisherman's" be even AS
insecure --let alone more so-- than the squaREef knot itself?!
(I do have some inclination to recommend that the center
knot be the thief, in thought that it will slip until
pulling those back-up "safeties" (i.e., the strangles)
into the nub and getting them greater security, thus;
one needs to have pretty evenly distanced back-ups
so they abut simultaneously the center knot.)


--dl*
====

Dan_Lehman

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I am also intending to include another obvious simple lock - that being a strangled double overhand knot around the eye leg (its simple and it works).
Mark

One can simulate this sort of coiled/wrapped looking
with the tail, tucking back through the turNip for
the finish --the tail's wraps bind the (two, not just
one
eye legs) and it in turn is nipped-gripped by
the turNip, which is effectively a half-hitch in this
function.  --i.e., a sort of strangle knot wrought of
the two parts and not a single strand.  In some cases,
taking the tail back through its own wrapping makes
for the surest looking binding; but it might just run
out the central nipping loop (aka "turNip")  to be
roughly parallel-to/beside the SPart.

There are various ways to instantiate this tail-wrapping
tactic, wrapping away and reaching back to tuck,
or reaching and then wrapping back (much as though
tying a strangle).  The former might be best
with the tail tucking back through the wraps,
so that's the more difficult one to tie,
vs. reaching and wrapping back and simply tucking
through the turNip --unless you want to tuck
now back eyewards through those wraps (which
indeed looks good!).


--dl*
====

X1

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One can simulate this sort of coiled/wrapped looking with the tail, tucking back through the turNip for the finish
There are various ways to instantiate this tail-wrapping tactic, wrapping away and reaching back to tuck, or reaching and then wrapping back (much as though tying a strangle). 

   All those things are more complex than any of the simple "locks" we have, to enhance the security re. slippage of the Tail Common bowline - and require a minimum understanding of how the bowline works in the first place, in order to be understood, and not just be tied by parroted tying methods. If one decides to spend some hour to study the bowline, he will not need any such naive lock, as a double or triple or quadruple Strangle on the eye or the Standing end...He will just tie a Janus bowline, for example : much easier, much faster, much simpler - one whole knot, not one compound knot formed by the addition of a naive (  half-clever" = dumb ) thing. on top of a marvellous ( ingenious ) thing !
 
« Last Edit: July 26, 2013, 12:59:06 PM by X1 »

Dan_Lehman

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One can simulate this sort of coiled/wrapped looking with the tail, tucking back through the turNip for the finish
There are various ways to instantiate this tail-wrapping tactic, wrapping away and reaching back to tuck, or reaching and then wrapping back (much as though tying a strangle). 

   All those things are more complex than any of the simple "locks" we have,
to enhance the security re. slippage of the Tail Common bowline ...

I disagree : rather, this tail wrapping (a) is much like
the tying of the back-up strangle knot, but it takes
a different course in (a1) binding the eye legs together
--which effects the locking of the turNip-- and (a2)
incorporates the two parts vs. the single strand (but
the tyer need not consciously remark at this);
and (b) it isn't merely fighting "slippage of the tail,"
but is --as noted above-- securing the turNip against
its loosening --that is the important aspect!


--dl*
====

X1

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 :)
this tail wrapping (a) is much like the tying of the back-up strangle knot, but it takes a different course in
(a1)  binding the eye legs together--which effects the locking of the turNip-- and
(a2)  incorporates the two parts vs. the single strand, and
  (b)  it isn't merely fighting "slippage of the tail," but is ...securing the turNip against its loosening
  a1, a2, b... I wonder how many letters one should had used, in order this "much like" becomes "like", and then "not like" and then "different", and then "much different" - because that is the real relation between the Janus-like lock, on the one hand, and the naive x-turn Strangled overhand knot lock around the eye leg or the Standing end, on the other = they are much different !
 
« Last Edit: July 27, 2013, 04:56:50 PM by X1 »

X1

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   In a previous post (1) I had proposed that we should mention - indeed, we should emphasize - the fact that the Lehman s locked bowline is TIB - but I had not said the same thing for the slight variation of the Scott s locked bowline, shown in the same post, and suggested in (2). Why ? Simply because I had NOT noticed that till now !  :)   :)  I was so sure it offered a slight advantage over the original Scott s locked bowline (3), -due to the fact that the Tail is not forced to make a sharp turn around one rope diameter when it collars the rim of the nipping turn-, that I had not examined any further. As I had said many times, it should be expected that with  stiff ropes, such a sharp turn can work as a spring, and drag the Tail out of the main collar around the Standing end - or, in a less tightened knot, it can be left in place as an "eye wide open", around the nipping turn s rim. However, I had never seen, till now, that this slight variation offers another advantage - which might be considered as MUCH more important than the "no-sharp-turns" one that had made me tie it in the first place !  A locked safe bowline, which is also TI,. is a very versatile knot. We do not have sooo many, that we can ignore the ones we meet, by design or accidentally !
   ( I am very curious how the inventor of the Scott s locked bowline will respond to this property / advantage of his own knot !  :) )
1. http://igkt.net/sm/index.php?topic=4480.msg28525#msg28525 
2. http://igkt.net/sm/index.php?topic=19.msg20616#msg20616
3. http://igkt.net/sm/index.php?topic=19.msg20538#msg20538