Author Topic: Agent Smith's Challenge  (Read 7541 times)

roo

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Agent Smith's Challenge
« on: May 06, 2015, 01:42:51 AM »
Quote
Ok, what about this: The middle climber of 3 is tied-in with a Butterfly Loop.
[...]
A challenge I will throw to this forum is to devise a tying method of attaching the Butterfly knot connective eye directly to the harness without need for carabiners.
You've lost your last carabiner and need to tie in on the bight?  I hate when that happens.   ;)

A few different solutions come to mind.  They're not perfect, but:

1)  Push a big bight through your harness loop and then step through the bight.  When you shrink things down, you'll have a lark's head on your harness loop.  Alternately, you could take off your harness and have it step through.   It could also make a Bull Hitch, but that can get a bit jammy.

2)  Use a Midspan Sheet Bend (center diagram) to pinch off a loop around the harness loop.  The bight you were treating as a free end becomes a little leftover loop.   Although this leftover loop's bulbous shape helps prevent slippage back through the knot body, a paranoid person could expand it, put a leg/thigh through it, and shrink it back down if they were concerned about gremlins allowing the bight "end" coming undone while they weren't looking.   The same procedure applies to a little chunkier Timber Hitch on the Bight or some variation.  A Gnat Hitch tied with a bight is another option.
« Last Edit: May 18, 2015, 05:26:40 AM by roo »
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agent_smith

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Re: Agent Smith's Challenge
« Reply #1 on: May 06, 2015, 01:49:06 PM »
Quote
Alternately, you could take off your harness

I should have specified that taking one's harness off isn't an option (in climbing/mountaineering applications) - as it violates the number 1 rule of 'safety first'. The knot must have easy/quick on-off tying capability (that is attaching the rope and also detaching the rope).

Otherwise, interesting ideas. Will play around and confirm. However, I don't think the 'larks head' (girth hitch) option is viable - it might slip under load (eg loading caused by a fall event) - and cause friction damage to the harness.

The middle climber - third person - on the rope has always presented technical issues to overcome. Most sources advise a Butterfly connective eye knot with dual carabiner clip-in. My contention has always been that carabiners can rotate and/or become misaligned due to cyclic loading / slack shaking. That's why lead climbers always tie the rope directly to their harness - meaning a direct rope-to-harness interface with no connectors. This reduces risk since the knot can withstand multiple loading profiles/angles - and connector misalignment is eliminated.


knot rigger

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Re: Agent Smith's Challenge
« Reply #2 on: May 12, 2015, 09:29:35 AM »
Begin by loosely tying a butterfly loop knot with a long enough loop to pass over yourself, maybe 4 feet.  Pass the loop through the tie-in point of your harness: Pass the bight of the loop (I'll call this the "Working Bight") such that both legs of the loop go through your tie-in point.  Now pass the working bight back through the nipping turns of the knot.  Next, in the same manner as finishing a double figure 8 "bunny knot", pass the working bight over your head, behind you, under you feet, and back to the body of the knot. Dress the knot by pulling the slack back out to the two loops you have passing through your tie in point.  If you began with an original 4 foot loop, you should end up with a double ABK version with two, 2 foot, loops tied through your harness.  You could then work the slack in the knot to make the 2 loops smaller, if desired.

 I consider the face of the ABK with the two collars the "front" and the other face the "back".  To dress this knot the best, start with loop of the loose (single) ABK facing you and the "front" side facing up.  Pass the working bight down through your tie in point, then back through the nipping turns in the body of the knot, under the two original legs of the original loop.  Pass the working bight over your head, around your body, under your feet, and back to the body of the knot (same capsize-the-working-bight move as the bunny knot). Pull the slack out to the two loops passing through your harness and dress the working bight into the body of the knot such that it parallels the collars on the front face, and snugs in next to the nipping turns on the back face.

It's very similar to the ABK larks head hitched to the harness idea, but wouldn't cinch down on your tie in point like the larks head would, avoiding the frictions hazards involved in hard loading of the larks head.

This way of tying a double ABK seems very convenient in general, but it has a crucial difference from a normally tied double ABK (tied in the hand wrap style, but with 4 initial wraps, the center two of which become the loops)  A normal double ABK, the loops form the same way as a single ABK: the rope of the loop "flows" from one collar, to the loop, to the other collar.  In this "poke-the-bight-through" version of a double ABK, each loop flows from one collar, to the loop, and back to the same collar! 

These directions would be so much better with a few pictures, and I'll try and get some good ones up to this post for clarity soon.
« Last Edit: May 12, 2015, 07:17:16 PM by knot rigger »

knot rigger

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Re: Agent Smith's Challenge
« Reply #3 on: May 12, 2015, 07:52:00 PM »
here are the pics

[1] start with a single ABK, loop towards you, "front" face up
[2] pass the working bight down through your tie in point (and the working bight magically turns red :) ) and poke it back through the nipping turns, under the original loop legs
[3] begin to capsize the working bight over your head

knot rigger

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Re: Agent Smith's Challenge
« Reply #4 on: May 12, 2015, 07:54:53 PM »
more pics

[4] finish passing the working bight under your feet and back to the body of the knot
[5] set the knot with the working bight paralleling the two collars
[6] and next to the nipping turns on the back face

Dan_Lehman

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Re: Agent Smith's Challenge
« Reply #5 on: May 13, 2015, 05:38:06 AM »
[1] start with a single ABK, loop towards you, "front" face up
[2] pass the working bight down through your tie in point
 (and the working bight magically turns red :) )  [--embarrassment  ;D ]
and poke it back through the nipping turns, ...
AND THEN ...
[3] tie off the bight end with an overhand stopper
(which you might reasonably have enough rope to do!   ;)  )


--dl*
====

xarax

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Double Butterfly loop
« Reply #6 on: May 13, 2015, 10:09:46 AM »
   I can not comment on the use of this knot in climbing - perhaps because the only things I had ever climbed, were stairs and ( rarely...) ladders...
   However, I see this knot as what it is per se, a double loop, TIB ( as most of the numerous double loops we already have, and the many more we can imagine...) but also tiable easily and quickly in a straightforward, conceptually simple way, starting from the great Burtterfly loop. As such, I believe it has merit, and it would be fair to be named Double Butterfly loop - I can not imagine any other knot with this name simpler than this loop. Of course, we can always divide the one eye/bight of any single loop in two, and reave each one of the two new eyes/bights through the same or through a different opening of the nub, to turn the single into a double loop - but this "haltering" of the tip of the eye/bight of the Butterfly loop through its central opening is simple, clever, neat, and it generates a very secure double loop, with not-directly-communicating eyes/bights. I had tied the Butterfly loop many times, and with many different ways, but I had never tied this double version of it. 
This is not a knot.

enhaut

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Re: Agent Smith's Challenge
« Reply #7 on: May 13, 2015, 01:24:24 PM »
@ knot rigger
Here is a rhetorical question;
Since this butterfly here is intend to the middle climber it will be loaded oftentimes by both side , if we admit that the AB has a "week" (maybe) side, should it be better to begin the double loop with a Figure 8 butterfly?
« Last Edit: May 13, 2015, 01:32:03 PM by enhaut »

roo

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Re: Agent Smith's Challenge
« Reply #8 on: May 13, 2015, 02:56:05 PM »

1)  Push a big bight through your harness loop and then step through the bight.  When you shrink things down, you'll have a lark's head on your harness loop.  Alternately, you could take off your harness and have it step through.   It could also make a Bull Hitch, but that can get a bit jammy.
P.S.  If you're willing to repeat the step-throughs, a Cat's Paw can also be had with the Tumbling Ring Method.  It should offer more friction than a Lark's Head/Cow Hitch without the jamming of the the Bull Hitch.

A Klemheist knot or the like could also be had via step-through, although it may be a hassle to tame and dress for some people in this case.
« Last Edit: May 13, 2015, 04:44:33 PM by roo »
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knot rigger

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Re: Agent Smith's Challenge
« Reply #9 on: May 17, 2015, 10:57:02 PM »
Quote
Quote from: knot rigger on May 12, 2015, 07:52:00 PM
[1] start with a single ABK, loop towards you, "front" face up
[2] pass the working bight down through your tie in point
 (and the working bight magically turns red :) )  [--embarrassment  ;D ]
and poke it back through the nipping turns, ...
AND THEN ...
[3] tie off the bight end with an overhand stopper
(which you might reasonably have enough rope to do!   ;)  )

DL you (humorously) point out the main drawback in the doubling method I proposed: passing the whole bight around the climber!  This is fairly cumbersome in practice, and would lead to difficulties should the tie-in need to be escaped. I think your stopper knot is an interesting solution, but I find that instinctually I don't trust it enough to fall on it!  It doesn't feel "locked" to me, and isn't "bombproof" the Knot may work loose a little while climbing, and then upon falling the stopper may slip through the nipping turns.  This seems unlikely, but the slim chance that it might happen would cause me to not trust it.

 I first proposed this double ABK method as an interesting solution to the puzzle proposed.  It's better than the larks head solution.  I've thought about it some more, and you (DL) have inspired an improvement in what I originally proposed: add a carabiner!

Quote
The knot must have easy/quick on-off tying capability (that is attaching the rope and also detaching the rope).

The middle climber - third person - on the rope has always presented technical issues to overcome. Most sources advise a Butterfly connective eye knot with dual carabiner clip-in. My contention has always been that carabiners can rotate and/or become misaligned due to cyclic loading / slack shaking. That's why lead climbers always tie the rope directly to their harness - meaning a direct rope-to-harness interface with no connectors. This reduces risk since the knot can withstand multiple loading profiles/angles - and connector misalignment is eliminated.


A_S identifies two needs for this tye in method (1) it must be easy on, easy off and (2) that it should be "bombproof" like the lead climber tying directly in with a re-threaded fig 8 loop.  Falling on a loop cliped to your harness with a 'biner isn't as bombproof as tying in directly, but that doesn't mean that one doesn't have any carabiners with them!

So I propose this modification, after [2] (see above) poking the bight through the nipping turns, clip a 'biner through both collars of the ABK, and the working bight, as shown in [11] (where the working bight is still shown in red, as in the first round of pictures)

now this leaves the gate of the carabiner flapping around to bang into stuff, or possible to turn around such that the gate is loaded by the collars or working bight (rather than the spine of the 'biner as shown)  So I've taken the further step of clipping the 'biner through the two tye-in loops, to help dress the overall knot, and keep the kont compact and the biner loaded on the (strong) spine.  as shown in [12]

the last picture [13] is of the same knot (DABK locked with 'biner) with 11mm static kernmantle and a 7/16" locking modified D 'biner.

So, last thoughts:  I approached this problem as an interesting puzzle, and have now perhaps come up with what could be a real-life solution. ( I'm not a sport climber, but I do ropes access work, which is a similar skill set)  I see that this DABK w/ biner lock method COULD safely improve the middle climber tie in method which A_S is (rightly) dissatisfied with.  I think my proposed solution should be tested further by experienced climbers to see if it has merit.  One drawback of this method is that it could involve side-loading a carabiner gate, and i've attempted to address the issue with the [12] dressing.  I'm not sure if this solution is adequate or successful at addressing the risks of a gate loading event. (this problem of gate loading, or side-loading is what A_S is dissatisfied with in the first place)  I have intentionally used locking carabiners, as I think this application warrants it.

PS
Quote
Since this butterfly here is intend to the middle climber it will be loaded oftentimes by both side , if we admit that the AB has a "week" (maybe) side, should it be better to begin the double loop with a Figure 8 butterfly?

enhaut, I'm not sure what you mean by "a double loop with a figure 8 butterfly"  what's a "figure 8 butterfy"?  Also, I'm convinced with 95% certainty that the difference in strength between legs of the ABK loop is less that 6.5% (i just need to make time to update my break testing analysis conclusions with the new data analysis Tex helped me with)
« Last Edit: May 18, 2015, 03:00:22 AM by knot rigger »

enhaut

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Re: Agent Smith's Challenge
« Reply #10 on: May 18, 2015, 12:16:01 AM »
what's a "figure 8 butterfy"?
you can see the bend here;
http://igkt.net/sm/index.php?topic=3251.msg19544#msg19544
and the loop is just below.
I was thinking that maybe if there is more material involved the "robustness" might improve as well...
« Last Edit: May 18, 2015, 01:25:42 AM by enhaut »

agent_smith

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Re: Agent Smith's Challenge
« Reply #11 on: May 18, 2015, 01:51:49 AM »
Quote
Since this butterfly here is intend to the middle climber it will be loaded oftentimes by both side , if we admit that the AB has a "week" (maybe) side, should it be better to begin the double loop with a Figure 8 butterfly?

Yes, the Butterfly eye knot could be loaded axially from either side of the connective eye.
The notion of a 'weaker' side and a 'stronger' side in my personal view is trivial as we are talking about small % points in ultimate strength. I would not be alarmed or cry foul of imminent death simply because the Butterfly was to be axially loaded from one side or the opposite side. To me, its the same argument re the strong Vs weak version of the Figure 8 connective eye knot (#1047). In the scenario of a falling climber, the risk of catastrophic knot failure is the least of your worries - of far greater concern is sharp edges (eg the rope being loaded over a sharp edge) and or the risk of hitting something during the fall. Also, in the scenario of a climber tied in the middle of a rope - while crossing a glacier - another risk is dragging your buddies towards you if you fall down a 'slot' (ie crevasse). If they cant self-arrest on the ice/snow, they too will be dragged perilously close to the edge...
Furthermore, I dont know of any documented and verified report of a correctly tied and secure knot catastrophically failing on account of a falling climber. There are lots of incidents of rope failure due to falling over sharp edges or rocks being dropped by a lead climber onto a rope and cutting it and/or catastrophic failure caused by chemical damage (ie exposure to acids).

...

Some interesting solutions from various contributors.

I tend to think that passing a large bight/loop of rope over your head is cumbersome - I'm not saying impossible - I'm using the word 'cumbersome'. In the context of mountaineering - it wont be a realistic proposition on account of 1) crampons strapped to plastic boots, wearing a large backpack, wearing bulky clothing, wearing gloves/mitts which reduces some dexterity. All of these factors would combine to potentially make the process of feeding a large bight/loop over all of these items difficult (but not impossible).

My stated solution (in original post) was to simply tie #1047 into the bight (the enlarged eye of the Butterfly that was fed back through the central nub) and then clip it to secure it to the harness belay loop. Although this requires a spare carabiner.

And knot rigger's solution and stated risks:
Quote
I think my proposed solution should be tested further by experienced climbers to see if it has merit.  One drawback of this method is that it could involve side-loading a carabiner gate, and i've attempted to address the issue with the [12] dressing.  I'm not sure if this solution is adequate or successful at addressing the risks of a gate loading event.

Hmmm - interesting but is reliant upon the connector staying in the proper alignment - Will have to think about that issue a bit more...

« Last Edit: May 18, 2015, 01:53:21 AM by agent_smith »

knot rigger

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Re: Agent Smith's Challenge
« Reply #12 on: May 18, 2015, 02:59:01 AM »
A_S... I never went back and found the original post that prompted Roo to start this thread, untill now:

Quote
A challenge I will throw to this forum is to devise a tying method of attaching the Butterfly knot connective eye directly to the harness without need for carabiners.

Now I have indeed devised a method - but it involves making the eye of the Butterfly elongated (sort of into a long bight segment) and then 'retracing' that bight back through the central nub and then terminating it with a figure 8 eye knot and clipping that eye to the harness. It works well and isn't all that complicated. It retains the bi-axial loading capability of the knot.

However, I'd like to discover a method that does not require carabiners and retains the simplicity of the original Butterfly connective eye knot.


I see now that you preceeded me with the idea of tucking back the bight through the nub of the ABK. :) Your solution seems very good to me, the only drawback being that it could be a bit bulky I suppose.  And you're OP clearly states that you'd prefer not to use a carabiner at all, so my DABK with a 'biner is out of bounds there.  And I agree that passing a bight around a climber is too cumbesome to be of much use, but it does yeild a "bombproof" tie-in for a middle climber without a carabiner. 

Honestly,  I think if that I first saw my DABK locked with a carabiner in use by a middle climber as a tie-in my first reaction would be "what the @#$!".  A single ABK clipped with redundant 'biners (I assume you mean locking 'biners) would provide a good balance of security, and efficiency, with-out much risk (but yes, some risk) of catastrophy due to 'biner side-loading.  The DABK step through would be the most secure, but least efficient solution.  And your DABK with a fig 8 finish is easy to tie and inspect, an improvement in security, but perhaps at the trade off of it being bulkier than other solutions.

Enhaut, thanks for posting the Figure 8 butterfly (loop and bend)  It's new to me and I look forward to exploring it.  I haven't read all the posts yet, but I gather that you propose it as a more secure, or maybe stronger alternative to the ABK?

roo

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Re: Agent Smith's Challenge
« Reply #13 on: May 18, 2015, 03:21:54 AM »
  And I agree that passing a bight around a climber is too cumbesome to be of much use, but it does yeild a "bombproof" tie-in for a middle climber without a carabiner. 
I think this would be a last-ditch and at least conceptually simple approach if you lost all your carabiners.  But maybe putting a leg/thigh through the leftover loop of a Midspan Sheet Bend and adjusting it down to an appropriate size wouldn't be too cumbersome.  It should be "bombproof" and fairly trim.
« Last Edit: May 18, 2015, 03:26:38 AM by roo »
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alpineer

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Re: Agent Smith's Challenge
« Reply #14 on: May 18, 2015, 03:49:54 AM »
My preferred way of tying onto the middle of the rope for glacier travel has been to connect the Eye of a long loop Butterfly to the biner with a clove hitch. I took this lesson from arborists who are required to tie onto the rope with a cinching knot on the carabiner to guard against cross-loading it's gate. The long Eye of the Butterfly helps isolate you from tension on the main portion of the rope caused by inattentive end climbers.

To address Agent Smith's Challenge, tie a Fisherman's Loop directly onto to the harness with the ABK's Eye .     
« Last Edit: May 18, 2015, 04:30:48 AM by alpineer »