Author Topic: Bowline transformations  (Read 15373 times)

[Inkanyezi] gone

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Bowline transformations
« on: December 24, 2010, 01:16:55 PM »
Dan Lehman has pointed it out several times, that the bowlines found in the wild are often capsized into a form where the collar is drawn out and wrapped around the knot, where the nipping turn has been drawn out into a stretched-out helix, approaching a straight line. It has been questioned whether bowlines are made like this on purpose, which I think is not the case. http://igkt.net/sm/index.php?topic=2209.msg15733#msg15733

I was curious regarding how this transformation might come about, so I tried to collapse bowlines in various types of rope. My muscle power is not sufficient to put them to real test in anything stronger than fishing line, so I also tried to make the transformations with a spun nylon fishing line.

And the result was that I cannot transform a well dressed bowline into the capsized version once it has got into the TurNip form, provided the legs of the loop are close to parallel. However, if the bowline is tied around a large object, it will be subject to ring loading, and then the transformation will readily take place. No wonder then, that I haven't ever seen one of those heavily transformed bowlines around here, because invariably, those that I have seen have been tied around rather thin objects as rings or similar. It is when you tie to a pile of subsantial thickness that the angle of the loop legs will ring-load the knot and pull the TurNip into a straight line. Then the bowline will still hold, but it is more like a noose, because the collapsed knot can slip along the standing part.

So the knot is not really safe; there are conditions when it will change shape into something that may or may not be sufficiently strong or safe. If the tail is left rather long, it is not likely that the knot will come undone, but it may still deform into the collapsed tangle. Even a collapsed knot will hold till the line breaks, although the well dressed bowline tied around a not too wide object is stronger.

My testing with spun fishing line a few times shows that the bowline when tied around a large object does capsize, while around a narrow object, it will not. When testing them against each other, it is the collapsed bowline that breaks. I did it with a marlingspike at one end and a wider iron tube at the other, jerking repeatedly, first to collapse the knot, then to break it. When it broke, the well dressed bowline around a narrow object (marlingspike) still retained its TurNip.

All the collapsed bowlines in the wild are not explained, but I think that I'm on the track of it. Repeated jerking, as when a boat is tied without resilience in the moorings and there are movements, sometimes there can be really hard jerks on its leash. If the bowline then is tied around one of those large piles, it is highly likely to collapse. Those around here are almost invariably tied to rings, or with a long eye that does not cause ring loading, so they don't get past the TurNip state. So there are at least three factors contributing to the transformation: a loosely applied collar, ring loading around a wide object, and repetitive jerks.
« Last Edit: December 24, 2010, 05:45:35 PM by Inkanyezi »
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Hrungnir

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Re: Bowline transformations
« Reply #1 on: December 24, 2010, 04:54:50 PM »
With a loosely tied bowline, I managed to collapse the knot with little force and just one finger in the loop. This wasn't one in a billion, because I needed just two attempts to repeat it. Like Inkanyezi said, the capsized knot has become a noose, which might be quite dangerous when you wanted a fixed loop for the task.

I knew it was possible to capsize the bowline by pulling the loop apart, but I didn't know it was possible to capsize the knot by pulling the standing part.

I've experienced several times that the bowline will work loose with little tension on the line. Perhaps the knot shouldn't be called ?the king of knots??  ???
« Last Edit: December 24, 2010, 04:55:29 PM by Hrungnir »

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Re: Bowline transformations
« Reply #2 on: December 24, 2010, 08:15:57 PM »
IIRC I never used "king" as epithet for the bowline. It is indeed a good workhorse among knots, and as all knots, care should be taken to use it for suitable tasks. I have spent a few moments to break more of the fishing line with various other loop knots, to see if there is a contender, and the bowline does not fare bad at all.

On the image below, I have tried a well dressed bowline against, from top to bottom:
  • loosely tied bowline (broke at capsized bowline)
  • eskimo bowline (surprise! broke at both knots, one strand at the bowline, two at the eskimo)
  • zeppelin loop (one strand broke at bowline, two at zeppelin)
  • zeppelin in a thinner line (broke at zeppelin)

In all of those, the bowline neither capsized nor slipped. I broke by jerking repeatedly with successively harder jerks. I would say that the bowline, when well dressed and not too widely splayed is a strong and secure knot in this kind of material. Maybe it is surprising that the line breaks at the zeppelin, which often is claimed to be very strong, but it seems as the standard bowline is about as strong, at least in this material.

Quite clearly, the eskimo bowline stands up better to ring loading. I am inclined to think that it is a better knot.

So, in order to try a contender to the zeppelin loop, which is a bit awkward to tie, I tried to improve the eskimo bowline, that some people think is not secure enough. I tried the knot, but I am not convinced. It is more difficult to untie than the zeppelin loop, and it is not much easier to tie. Maybe for anyone familiar with the eskimo bowline who wants a more secure knot and doesn't care to learn the zeppelin loop. The only advantages I see with the Janus Eskimo Bowline is that it is just an extension of the eskimo bowline, and that as the bowline, it does not need preparation before passing the end around the object where to tie it. There are variations of the Janus eskimo bowline, depending on which way the collars are turned. I like the second image, because it gives a very neat knot that also preserves the TurNip well, and it also seems a bit easier to untie. Of course, the knot shall be dressed before put to work.
« Last Edit: December 24, 2010, 09:14:56 PM by Inkanyezi »
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Hrungnir

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Re: Bowline transformations
« Reply #3 on: December 25, 2010, 03:48:00 AM »
The comment about "king of knots" wasn't meant directly at you, Inkanyezi. I've never seen you label the bowline as "king of knots", but in articles on the web, books and comments on TV, I often hear the bowline called "the king of knots". Anyone new to the knot might think "the king of knots" must be the perfect knot. Safe and usable for almost any task. In fact, it seems like the knot can be quite dangerous.

The bowline has positive sides like fast and simple to tie, not hard to learn, can be tied with one hand and it's easy to untie even after putting the knot under considerable stress. On the downside it capsizes if you pull the loop apart or put the standing part under considerable stress. If there is little tension on the knot, it will work loose. I wouldn't even attach my compass, knife or mug to my backpack with a bowline, because I would be afraid the knot might work loose. I once used a double constrictor around my mobile phone and attached the other end of the twine to the zipper on the pocket of my jacket, to make sure I wouldn't lose my phone when being on the mountain. The knot worked loose and I reattached the twine to the zipper with a zeppelin loop.

Quite interesting the experiment with breaking strength of different loops :)

[Inkanyezi] gone

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Re: Bowline transformations
« Reply #4 on: December 25, 2010, 03:56:05 AM »
I did a bit more of similar testing, now only with the Janus eskimo bowline against the zeppelin loop. Consistently it breaks at the zeppelin, and the Janus eskimo bowline can be untied after the stress test. I was a bit surprised, because so many claim the zeppelin to be the strongest of them all, but evidently, I have found a knot that is stronger.

So I would argue, that it might be worth the while to put the Janus eskimo bowline to further tests, to see whether it is suitable for mountaineering and SAR.
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Dan_Lehman

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Re: Bowline transformations
« Reply #5 on: December 25, 2010, 06:37:54 AM »
I was a bit surprised, because so many claim the zeppelin to be the strongest of them all, but evidently, I have found a knot that is stronger.

But are those claims ever supported by actual data?
--usually not.  And in some other thread, we have shown
some variety of geometry is possible with the RZ knot,
though that was for an end-2-end joiner.

Re strengths, one must keep in mind not only how much
of particular variance can come into play (an unexplored
factor, but possibly significant), but also materials and even
loading (by jerks, by a drop, by various rates of steady pull).

Quote
So I would argue, that it might be worth the while to put the Janus eskimo bowline to further tests, to see whether it is suitable for mountaineering and SAR.

I probably would tie this knot slightly differently, in the positioning
of the parts through the turNip; given your results, I might want to
re-think my tying.  (But I've yet to play with rope and this image.)

The similarity of these retucked "bowlines" extends to their resistance
to loosening, IMO, and give both the claim that if the tail should escape
its last tuck, there is still a decent knot remaining.

 - - - - - -

The charge that ring-loading (pulling the eye apart, and so
treating the knot qua end-2-end joining of the eye legs) will make
a (common) bowline capsize I don't think is so right : it can just
see the tail pull out!  --which were the bowline that "cowboy" or
"left-handed" version, it would stay tied (as a Lapp bend )

--dl*
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[Inkanyezi] gone

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Re: Bowline transformations
« Reply #6 on: December 25, 2010, 11:49:32 AM »
I was a bit surprised, because so many claim the zeppelin to be the strongest of them all, but evidently, I have found a knot that is stronger.

/.../ one must keep in mind not only how much
of particular variance can come into play (an unexplored
factor, but possibly significant), but also materials and even
loading (by jerks, by a drop, by various rates of steady pull).
/.../

There is considerable variance, but the steady pull test with increasing load is a rare bird in real life.

Knots must be tried for security, regarding material of tying and knot form; security implies that the knot shall not work loose when idle or flogging with negligible load. I haven't made anu such trials with kernmantle climbing rope.

I did try gradually increasing load as well, with the same result. The twine broke at the Zeppelin. In the real world, I think jerks are more likely to occur, and as jerks also unloads the line in the lulls, also another real world aspects applies by repeated jerks. One single hard jerk may also simulate a fall. I think that for a fall test, one could use a sandbag of about 200 lbs weight lifted the rope length above the attachment point and dropped when tried with real rope. I wouldn't dare to break-test anything larger than fishing line, after once seeing a mooring line for a large vessel part and lash back with tremendous force. Even something as puny as paracord could do considerable damage.
« Last Edit: December 26, 2010, 04:22:21 AM by Inkanyezi »
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[Inkanyezi] gone

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Re: Bowline transformations
« Reply #7 on: December 25, 2010, 07:29:15 PM »
As the blurb goes, the Zeppelin is said to be the strongest of knots, so I also tried it as a bend between two Janus Eskimo Bowlines, to see where the string would break. If the purported "strongness" would be true, it should break at any of the knots at the ends, but alas, it breaks in the Zeppelin.

I might pee on someone's parade now, but it seems as either the Zeppelin is vastly overrated, or the Janus Eskimo Bowline might be an extremely strong knot.
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Dan_Lehman

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Re: Bowline transformations
« Reply #8 on: December 25, 2010, 08:11:35 PM »
As the blurb goes, the Zeppelin is said to be the strongest of knots,
...
 but it seems as either the Zeppelin is vastly overrated ...

It will be an advance in thinking if we can avoid attributing strength
(and some other attributes) to a knot (form), and instead put them
with some actual knot-instance of particular tied material.  This points
to the unresolved question of mine of defining "knot" and such other
terms as fit these distinctions.  (The old e.g. I gave of teacher's raising
concern about the young girl in a class who counted "only" 4 "knots"
when the expected answer was "10" --her response, "there's a bowline,
clove hitch, sheet bend, and figure-8 stopper" where the expected
counting answer was along the lines of "3 are bowlines, 2 are clove
hitches, 3 are sheet bends, and 2 are fig.8s".)  But revamping thinking
will take some deliberate effort.

Re the RZ knot, I don't know about such a "blurb" claiming "strongest",
but I do recall that in some pull-by-truck-vs-tree testing in small stuff
(3/8" PP laid rope, I think was the thickest), the Rosendahl's Z. bend
was middle-of-the-road along with Ashley's 1408, 1452, SmitHunter's,
and under #1425; all of these were weaker than the Grapevine, and
the winner Blood knot; and in no case did the anchoring Fig.8 eyeknots
ever fail --always, one of the A-vs-B-tested end-2-end joiners !!  Then,
tested in some heavier line --kermantle low-elongation, I think--, the
RZ eye-knot was found stronger than some Fig.8 version.  (And none
of these tests ran to the extent desired by a statistician.)

--dl*
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Re: Bowline transformations
« Reply #9 on: December 25, 2010, 08:35:06 PM »
Maybe leaving the field of bowlines now, but I couldn't resist to try the Zeppelin against the Carrick Bend, which I in fact have named "King" on my webpage. As the Zeppelin also has been named so by others, it would be rather fair to try them against each other.

I don't know of course, how these knots would fare in other types of cordage, but it seems as the Zeppelin is indeed over-rated by those that think it is close to the strength of the rope itself.

At first I thought it was the Carrick bend that stood the test, but dissecting the remaining knot reveals it to be the Zeppelin, severely distorted.
« Last Edit: December 25, 2010, 08:42:55 PM by Inkanyezi »
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Dan_Lehman

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Re: Bowline transformations
« Reply #10 on: December 25, 2010, 09:03:45 PM »
Dan Lehman has pointed it out several times, that the bowlines found in the wild are often capsized into a form where the collar is drawn out and wrapped around the knot, where the nipping turn has been drawn out into a stretched-out helix, approaching a straight line. It has been questioned whether bowlines are made like this on purpose, which I think is not the case. http://igkt.net/sm/index.php?topic=2209.msg15733#msg15733

I was curious regarding how this transformation might come about, ...

And your discovery with larger-dia eye-hitched objects might be
the or at least *a* clue.  I wonder at the actual diameter being
something, too (though one would think this behavior scaled
with diameter), along with roughness of fibres (worn, i.e.) ?!
And I also wonder about tying method inducing some particular
torsion favorable to the transformation --alas, I have not
made note of how the knots might be tied.

And I still wonder about the movement *laterally* putting a
biased loading on the knot, to slacken the tail-eye-leg and
tension the SPart's turNip, thereby giving some impetus to
capsizing?

Because many of the mooring lines I see don't seem to have
unusual stiffness, inflexibility, such as might make tying a
more snugly set bowline difficult; can the users be indifferent
to the knot's later disposition?  I've wondered if one dock's
more frequent "cowboy" bowlines are a response to what
was found --a better structure to resist capsizing?!

I have seen plenty of photographs of yachting bowlines with
rather ample collars, yet uncollapsed.

--dl*
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Re: Bowline transformations
« Reply #11 on: December 26, 2010, 04:14:38 AM »
And I tried it again, with well dressed knots, with a gradually increasing pull, and this time the Carrick Bend remained intact and the twine broke at the Zeppelin. Quite clearly, these Janus Eskimo Bowlines are strong enough; the rope breaks at the bend, and the difference in strength between the Carrick Bend and the Zeppelin bend is not significant. They are both very good utility bends, secure and perhaps also "strong".
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[Inkanyezi] gone

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Re: Bowline transformations
« Reply #12 on: December 26, 2010, 04:58:06 AM »
I did another run of tests with the Janus eskimo bowline against the fig8 loop, and invariably, the Janus eskimo bowline breaks. The fig8 indeed is stronger. Both with jerks and steady pull, the result is the same. A curiosity is that when it is dressed in the neatest way, nothing remains of the knot once it is broken.
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knot4u

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Re: Bowline transformations
« Reply #13 on: December 28, 2010, 02:26:13 AM »
If the bowline then is tied around one of those large piles, it is highly likely to collapse. Those around here are almost invariably tied to rings, or with a long eye that does not cause ring loading, so they don't get past the TurNip state. So there are at least three factors contributing to the transformation: a loosely applied collar, ring loading around a wide object, and repetitive jerks.

A simple Bowline around a large pile seems like bad form.  How do we fix those problems if we still want to use a Bowline somehow?

I propose a Bowline on a Cow.  Another option is a Bowline on a Pile.

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Re: Bowline transformations
« Reply #14 on: December 28, 2010, 11:58:33 AM »
We were into it when the tree felling was discussed; two round turns around the pile, a backhand turn, and then two half hitches is a method that is proven. However, it seems as many of these eyes are used permanently and just dropped over the bollard. The eskimo bowline is worth considering, as it stands up better to ring loading and does not capsize as the standard bowline. It is very easy to tie with the hand-twist method; not very different from the standard bowline. Instead of laying the end over the standing part, lay it under the standing part and make the twist in the same way, whereupon the end takes a u-turn around the other leg of the loop instead of around the standing part and goes back from whence it came through the TurNip. If that seems awkward, you can just make a loop and tie the end like a sheet bend to the other leg of the loop; i.e. pick the TurNip from the loop leg instead of from the standing part.
« Last Edit: December 28, 2010, 12:46:39 PM by Inkanyezi »
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