Author Topic: In search of the goldilocks bend! (joining abseil ropes)  (Read 21768 times)

agent_smith

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #30 on: July 07, 2011, 05:29:39 AM »
Quote
But your OOB Variation offers us nothing that we don't already have in the OOB +Stopper. In fact less. It's more bulky, at least from the more important footprint perspective. It's not that it can't work. But why add unnecessary bulk? What do you get for it when considering the bigger picture? Your quoted arguments are understood, but if accepted in their fullness, still leave us no better off than before IMO.  Show me something else.

I have analyzed this problem in detail and can say that I have narrowed down my search for the 'Goldilocks bend'. The 'Bound Offset Overhand bend' works well and is an improvement over the iceman bend discovered 5300 years ago. I hereby proclaim that I have evolved the state-of-the-art further in the past 5300 years! (oh oh, what have I just stated... :)  )

The additional mass added by the binding loop adds insignificant bulk in my view. For the binding loop, you get the following:
1. Three rope diameters encircled by the loops
2. So-called 'internal cushioning' (xarax theory)
3. Increased security and stability up to 3kN force (force divided over 2 rope strands... 1.5kN actual on the joining knot) - tested on wet and dry ropes including icy rope (left short length of 8mm cord in freezer to simulate iced rope conditions).
4. Easy to untie - bounced my 100kg mass during actual field testing the other day on 20m abseil descent - no problem untying knot.
5. These last two are difficult to quantify - 1) the thrill of new invention and discovery brought to you by your humble agent smith :)...and 2) I went one better than the iceman - therefore proof of Darwinian evolution :)

...and no doubt Dan Lehman's forthcoming response to my so-called 'Bound Offset Overhand bend' will either shoot me down in flames or support my theory of Darwinian evolution. Better to go down in a blaze of glory than to have never tried at all :)

Looking for the ejector seat handle now...!

Mark



« Last Edit: July 13, 2011, 10:38:29 AM by agent_smith »

Dan_Lehman

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #31 on: July 07, 2011, 03:53:51 PM »
  Although I have no climbing knowledge or experience whatsoever,
 I think that those two "not-offset"  bends can offer something
 along the lines described in this thread ...

No, being non-offset they are prone to getting hung up on an
edge.  (Try pulling the knot over/around the edge of a table,
e.g., and you'll see this.)  Beyond that, they are in some cases
difficult to tie & untie, relative to the best solution --viz., the
offset water knot + stoppered tail .


--dl*
====

Dan_Lehman

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #32 on: July 07, 2011, 04:22:47 PM »
{{Egadz, there is a lot of *spew* going on above, I think, that
calls urgently for some redressing!!  :o   ::)   :P  }}


NB:  it's not quite so simple as I make it, as the
particular orientation of the knot might help (but
all should work --TWO are shown here!), and the
particular orientation of the thinner (or more flexible)
line AND >>it<< being what is stoppered matter
(matter maybe not in ultimate success, but it should
be better).

--dl*
====

I think that it bears isolating & emphasizing the point made about
this offset water knot & orientation choices
(made knowingly or otherwise, they are manifest!):

1. There is the orientation of the twin parts relative each other
--i.e., what might fall under "properly dress so that parts don't cross ..."
guidance which is often given.

2. There is the orientation --IN RE DIFFERENT ROPES (diameter, flexibility,
smoothness)-- of the ropes vis-a-vis the particular position of each
twin --i.e., which line makes the (initial) "choke" of the SParts at
the entry point (which will be what initially (and only, we hope)
resists being pulled open by loading).

3. [this is the most subtle and unrecognized aspect]
There is the orientation of the tied knot body ("nub",
Dick Chisholm might call it) to the axis of tension !!!

Look (back) at msg.#3 image :
the knots are in a sense >>identical<<, but this knot
can be oriented across a range of about 180 degrees
in relation to the axis of tension, ...;
the knot on the left side shows the orange SPart making
a (backward/upward) loop, and (then) turning around
to bend back and go left-to-right,
while its twin comes from the opposite direction and
makes thus a sort of forward arc to join and run parallel;

but on the right --"identical knot" just *dialed* in rotation
to the axis-- these bendings are reversed, so its the (thicker)
rightside rope that makes the loop, the other the arc.

At the extremes of the range of rotation of this knot nub
(what is shown), the tails will exit roughly perpendicular to
the axis of tension --pointing one or the opposite direction--;
and in the middle of the range (the two SParts sort of
*colliding* and bending at equal right angle to the axis...),
the tails will be roughly parallel.  (They could thus
serve as the needle on a guage of nub rotation.    ;)  )

Yes, this orientation differences endure tension; there is no
sort of *ultimate* state that heavy loading will shift all to
(not in my experience, and once set there is less ease to
shifting), except perhaps some small adjustment at one
extreme to slightly less extreme (YMMV).

How does this affect vulnerability to flyping?  I'm not sure.
I think that ALL of the possibilities, well set, will hold any
expected abseil load (NOT something to be proved ONLY by
a test device's much greater force; one need only load to about
double expected load, in single strand, hence a rough four-times
the twin-rope abseil loading).

But it's certainly an aspect that should be considered, so that
when one reads the typical, too-spare-on-details test report,
one realizes that some questions are NOT answered.

--dl*
====
« Last Edit: July 09, 2011, 04:29:08 AM by Dan_Lehman »

Morgoroth

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #33 on: July 07, 2011, 04:48:37 PM »
Whatever you guys decide, I think I might need a tutorial.
I tried tying it based off the picture and came up with several variations, but have yet to produce the actual knot.

Dan_Lehman

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #34 on: July 07, 2011, 05:22:27 PM »
Quote
But your OOB Variation offers us nothing that we don't already have in the OOB +Stopper.
In fact less. ...  

I have analyzed this problem in detail and can say that
I think my search for the 'Goldilocks bend' is finally over.

The 'Bound Offset Overhand bend' works well and is an improvement over the iceman bend ...

//

I think that the 'binding loop' that I have added to ABoK #1410 increases its security and stability
(I'm not sure what term Dan Lehman will want to give to this structure).


I'm more sure :  "bunk".  And "offset oh-9" is the name
(nomenclature rule :  "<choking structure ><other line's structure>").

This knot's added bulk might marginally increase security of
the (should be (as shown)) thicker tail, but at the cost of yielding
if anything a more loose overall structure esp. vis-a-vis the crucial
choking (thinner) line.  That is a dubious deal at best, and I think
it's worse.

In regard to ...

Quote
The additional mass added by the binding loop adds insignificant bulk in my view.
For the binding loop, you get the following:
1. Three rope diameters encircled by the loops
2. So-called 'internal cushioning' (xarax theory)
3. Increased security and stability up to 3kN force (force divided over 2 rope strands... 1.5kN actual on the joining knot) - tested on wet and dry ropes including icy rope (left short length of 8mm cord in freezer to simulate iced rope conditions).
4. Easy to untie - bounced my 100kg mass during actual field testing
the other day on 20m abseil descent - no problem untying knot.
5. These last two are difficult to quantify - 1) the thrill of new invention and discovery brought to you by your humble agent smith :)...and 2) I went one better than the iceman - therefore proof of Darwinian evolution :)

...and no doubt Dan Lehman's forthcoming response to my so-called 'Bound Offset Overhand bend'
will either shoot me down in flames or support my theory of Darwinian evolution.
Better to go down in a blaze of glory than to have never tried at all :)

Looking for the ejector seat handle now...!

Better to try and to see the downside before shooting off
fireworks in celebration (and maybe inducing others to dangerous
foolishness).

I don't find this structure at all reassuring in my stress testing
(pulley loading) of 11mm + 8mm; it held, but left me with
concerns in how ... .

One might say that you're "close"; but you're going wild on
the selection criteria and evaluation, methinks.

The attributes you enumerate above are irrelevant to the
job this knot is to do:  strength is irrelevant, and any
"cushioning" must raise a suspicious eye as to how this
is bought (and in any case it's not needed) --it implies
a movement that is not wanted!

You have left the weakness of the OWK --i.e., its choking
strand's end being unsecured-- and added a turn where none
was needed, really.
JUST REVERSE THIS, putting the additional turn where it
will (a) improve significantly the *choke*" and (b) reduce
slippage of the critical tail.  .:.  your "oh-9" => "9-oh".

Voici (attached).

Also shown in my photo is an offset 8-oh.  Note that in this
knot, as the oh-8-9-10-11 ... series runs (with asymmetric forms
were possibe (9 & >9)), using adjacent forms means that the
tail exit in opposite directions; this has a benefit to resisting
flyping, I think.  So, whereas in the offset 9-oh one makes one
full wrap with the choking (should be thinner, or more flexible) line,
going just one half-wrap around (getting an "8" vice "9") will also
benefit things.  (Don't assign *guilt by association* with problems
with the offset fig.8 bend.)

Quote
Comments please...

By the way, I'm not convinced of the criteria "relative ease of tying"...a climber by definition is already competent in tying a range of knots (eg Prusik hitch, Double Fishermans, Clove hitch, Tape knot / Ring bend, Figure 8 loop and rethreaded method of tying, Bowline variant (eg my EBSB variant), French Prusik, Double figure 8 loop (AB0K #1085), etc etc. Some of these knots are arguably 'difficult' to tie. It comes down to practice, practice and practice. Anything is hard at first (eg learning to drive a manual car) - but over time and with practice, it becomes 'easy'.

This is worrying:  you should be well familiar, by reading rockclimbing
forums, with the difficulties knots pose for many,
in addition (perhaps) some aggravation in the popularity of
the indoor "sport" climbing and its bringing some relatively
inexperienced and ill-trained climbers to situations that really
call for better preparation.  The assertion that climbers can tie
all those knots you list (and esp. the EBSB deviation from better
knotting of the EBDB  :P ) is readily evidenced to be wrong.

Quote
Statistically, more climbing is done on nice sunny crags with easy access in comparison to high altitude mountaineering in gales force winds, subzero temp and with oxygen starved brains...in any case, the high altitude mountaineer still had to tie and use some knots just to reach the summit.

I'll take this as a counter argument to my point about ease of
tying benefiting some trying circumstances.  Irrespective of
weather, there can be unseen delays and aggravated fatigue
resulting in a delayed-until-late retreat by abseil, and the history
of climbing injuries I think will support the assertion that in
such cases complexity of actions increases the risks of injury
--simplicity helps.  The de facto easy-simple-quick tying of
an "EDK" (with long tails) is an order of magnitude simpler
than most alternatives --which I must concede includes my
suggested improvement, as my knot (with dissimilar ropes)
depends upon making two particular orientation choices:
how to position the different ropes; which tail gets tied off
(tying back-2-back "EDK"s in contrast IS simpler).


Quote
As it is a one piece knot, I like it more than the compound knots proposed by Dan Lehman...

And so one must note that this aspect goes directly against
e.g. Xarax's disdain for "compound" knots in favor of those
with some added parts in a single *unit*.  It is simpler to
make a sequence of simple actions than one complex one
--recall the rage back in the day over "RISC" architectures
(computers) and their efficiencies.


--dl*
====

[Edited to add the final note, so that the immediate following
duplication of this msg. can be **near-deleted** --reduced to
an editing note but preserved so as not to disturb msg. count,
and to show source of Xarax's quote.
(I don't know how I managed to duplicate this post;
I apologize for that & its clean-up mess.) ]
« Last Edit: July 08, 2011, 03:45:26 AM by Dan_Lehman »

Dan_Lehman

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #35 on: July 07, 2011, 05:49:35 PM »

[ This post #35 was a (near) duplicate of my post #34 --I don't
know how it came to be--, and so I am here deleting the contents
and preserving the fact of the post & total post counts & #s. ]
.
.
.

--dl*
====
« Last Edit: July 08, 2011, 03:48:37 AM by Dan_Lehman »

xarax

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #36 on: July 07, 2011, 07:17:10 PM »
  It is simpler to make a sequence of simple actions than one complex one...

   The problem is that we have no "measure" of the simplicity of a knot, we can not quantify "simplicity". Are two overhand knots, the one after the other, "simpler" than one double overhand knot ? Than a figure 8 knot ? Is the two strand MatthewWalker bend too simple a knot to be tied very easily ? Is a knot simple-to-tie because it is easier memorized by the human mind, "simpler" than a knot simple-to-tie because it is easier manipulated by the human fingers ? "Emerging" entities are complex structures, not mere collections of their simpler elements. Is the universe a simple collection of elementary particles and forces, the living animals a simple collection of cells, the society a simple collection of individuals, the house a simple collection of bricks ? Is a certain sequence of simple numbers, just a simple succession of those numbers and nothing else, or there is a unknown law there that could be somehow deciphered ? It is easy to overemphasize simplicity, and it is difficult to implement ii in the degree it deserves, but no more.   
This is not a knot.

alpineer

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #37 on: July 07, 2011, 07:25:01 PM »
http://en.wikipedia.org/wiki/Euro_death-knot
 
According to the article's description the smaller dia. striped green rope in the upper right photo should be at the bottom of the knot, or one has to assume that the red green rope is of a stiffer nature (article good,picture bad).

Comment: Assuming proper dressing and tightening with long tails, I'm not convinced of the need for a stopper knot for the EDK/OOB/OWK/ORB (irrespective of orientations, natures). It might help as a backup to a poorly tied knot? My understanding is that if the knot does flip, it will roll only once before tightening up and reverse the relative positions of the two lines. This may preclude the concern over which line does the initial choking. That being said, I simply don't know. I'm just not convinced. It would be nice to know that one could safely reduce the knot to it's essential simplicity.

It bears repeating and emphasizing that we are (or should be) discussing these knots in the context of abseiling/rappeling only.
Quote
What is the best method of joining 2 climbing ropes together for a retrievable abseil ('Rap' for you Yanks)
« Last Edit: July 07, 2011, 08:34:02 PM by alpineer »

Dan_Lehman

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #38 on: July 07, 2011, 07:52:45 PM »
http://en.wikipedia.org/wiki/Euro_death-knot
 
According to the article's description, the smaller dia. striped green rope
in the upper right photo should be at the bottom of the knot,
or one has to assume that the red rope is of a stiffer nature (article good,picture bad).

The image on the left margin is correct re this aspect;
that on the right, not, as you note.  But I don't follow
your final clause --"stiffer" = "thicker", re this aspect,
so your critique remains valid even then.

Quote
Assuming proper dressing and tightening with long tails,
 I'm not convinced of the need for a stopper knot for the EDK/OOB/OWK/ORB (irrespective of orientations, natures).
It might help as a backup to a poorly tied knot? My understanding is that if the knot does flip,
it will roll only once before ... . This may preclude the concern over which line does the initial choking.
...

Such assertions have been made, and the common practice is to
employ the offset water knot (EDK) with long tails.
But, to my mind, the common practice/advice falls way short
of precluding concern --rather, it seems like telling someone
"Oh, that way is safe, just wear body armor and carry a gun" !!

I'd rather DO something with those long tails than just HAVE them
--so, tie a stopper.  Which stopper might help secure the stopped-to
thicker line, as well as stopping the draw of its own tail out and
opening the choke.
And I would NOT have any long tail (beyond length needed to stopper).

.:.  I want a knot that works for sure, and not one supposed
to have only some limited non-working.  (For I darn well know
that testing of myriad combinations of factors has NOT been
done.  But, yes, there IS a lonnnng history of usage, and I only
know of one not-well-presented supposed failure.)

 - - - - - - - - - - - - -

Quote
The problem is that we have no "measure" of the simplicity of a knot,
we can not quantify "simplicity".  Are two overhand knots, the one after the other,
"simpler" than one double overhand knot ? Than a figure 8 knot ?
...
Is a knot simple-to-tie because it is easier memorized by the human mind,
"simpler" than a knot simple-to-tie because it is easier manipulated by the human fingers ?

There is much we don't know yet we pursue it with some belief,
backed by analysis & reasoning.  Yes, I submit it's simpler to repeat
simple actions than do a complicated one, generally.  One knows
the simple act, and only adds to that the repetition; in contrast to
having to engage more mentally & physically to e.g. make some
careful reeving and then dressing & setting.  This should be easy
enough to give a casual check of, in hand.  In the case of tying
overhands, one has simplicity conceptually/mentally and physically
(and very easily seen correct/wrong when so).

NOW, might there be some cordage in which the physical/structural
simplicity of the overhand is inadequate to provide frictional security?
Yes, that seems so, too.  And so we have some ideas beyond that,
ready to bring into play (one might be tying off the thinner tail with
a strangle knot to be the point of surety!?).


Incidentally, I should allow that in some rockclimbing-forum debates
about ARJ knots, some long-time climbers have claimed DECADES of
use of non-offset knots without the supposed issues of snagging.
Well, maybe it's just a matter of small frequency : how big a deal
(risk) is it to encounter this, at only 1-in-500 cases?  The believed
solution ("EDK") is surely no big problem, though.


--dl*
====

alpineer

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #39 on: July 07, 2011, 08:54:24 PM »
Quote
But I don't follow your final clause --"stiffer" = "thicker"
Thanks for noting that Dan. My error, meant green rope. Post edited, if that's OK.
Quote
rather, it seems like telling someone "Oh, that way is safe, just wear body armor and carry a gun" !
 ;D
Quote
how big a deal(risk) is it to encounter this, at only 1-in-500 cases?
Agreed. It's the knot's simplicity which is of primary interest.
 
« Last Edit: July 07, 2011, 08:56:53 PM by alpineer »

alpineer

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #40 on: July 07, 2011, 09:01:49 PM »
Secure and stable up to 3kN (tested by load cell today - as a double strand to duplicate double rope abseil descent - since force would be split between 2 rope strands)
If that's the case it certainly performs no better than a properly tied OWK, re:strength.

agent_smith

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #41 on: July 08, 2011, 03:32:20 AM »
Thank you for your critical analysis Dan.

Quote
Better to try and to see the downside before shooting off
fireworks in celebration (and maybe inducing others to dangerous
foolishness).

I wouldn't go that far in my remarks... I did try various combinations of how the binding loop is formed. The photo I chose to post is one possible variation - and the form I found to cinch up well and create the smallest profile. I would not assess it to be 'dangerous' nor categorize it as 'foolish'. I performed an abseil descent on the original structure photographed with my bouncing/cyclic 100kg mass. The knot held - there was no discernible slippage of tails. I admit that I have not loaded the knot up to failure - as it costs me money every time I break ropes/cords.


Quote
I don't find this structure at all reassuring in my stress testing
(pulley loading) of 11mm + 8mm; it held, but left me with
concerns in how ... .

When I read this comment, I was concerned so I pulled out a range of different ropes/cords from my vast arsenal of climbing and abseiling ropes. I tried:
[ ] 6mm + 11mm
[ ] 7mm + 11mm
[ ] 8mm + 11mm
[ ] 7mm + 9.1mm
[ ] 8mm + 9.1mm

I also tried a few static + dynamic rope combinations - with older and stiffer bluewater static ropes tied to newer edelrid dynamic ropes. Again, no discernible problems.

In each case, I cinched the knot up as tight as I could using hand strength. I clipped the joined ropes to ceiling anchors and then bounced my 100kg mass repeatedly over about 30 seconds.
I then repeated the process but this time deliberately tying the above knots loosely and also undressed (deliberately trying to be sloppy). Again, the structure held with my bouncing 100kg mass.

I admit again, I did not pull the combinations to failure with the load cell (money is an issue - and I didn't want to destroy my precious ropes - as I run a climbing school I need the ropes :)  )


Quote
One might say that you're "close"; but you're going wild on
the selection criteria and evaluation, methinks.

Am trying not to be too wild! My criteria are nearly the same as the 'icemans was' - keep it simple, but effective. I just wanted to demonstrate that humans today have evolved the state-of-the-art some way in the past 5300 years! Like I said, maybe the iceman WAS a lot smarter than we may give him credit for... In any case, I really cant see how my tactic of adding one simple 'binding loop' is really complex. I really don't think you need a university degree to perform this simple procedure.


Quote
The attributes you enumerate above are irrelevant to the
job this knot is to do:  strength is irrelevant, and any
"cushioning" must raise a suspicious eye as to how this
is bought (and in any case it's not needed) --it implies
a movement that is not wanted!

I agree that strength is not an issue. I have always stated as such... in my view, security and stability are more important characteristics. Slow pull tests to failure do however provide us with insight into how the structure behaves under increasing load - and we can draw certain conclusions from those tests and perhaps make improvements. In my view, cyclic load testing - and dynamic load testing would yield more useful test data. Both are more difficult to achieve though...and cost more.

The 'internal cushioning' theory was from xarax - it started in one of his thread topics a while back... my real point is that the binding maneuver adds another rope diameter to the structure. I am still trying to assess the value of internal cushioning.


Quote
You have left the weakness of the OWK --i.e., its choking
strand's end being unsecured-- and added a turn where none
was needed, really.
JUST REVERSE THIS, putting the additional turn where it
will (a) improve significantly the *choke*" and (b) reduce
slippage of the critical tail.  .:.  your "oh-9" => "9-oh".

Now this is the interesting bit..you're making a suggestion to improve my binding loop concept. I did try this but didn't photograph it and post it.

I like the concept you elude to...re analyzing this variation of where to make the binding loop. But when I first experimented with forming the binding loop in the opposite direction, I found it didn't cinch up as easily and took more effort to 'set and dress' the knot. At the end of the day, I am seeking your counsel and guidance... with the ultimate goal of seeking your endorsement.

I re-photographed what I am referring to a 'bound offset overhand loop' - with the binding loop shown in opposite and original directions for comparison.

I must confess that I am not a believer in the notion of adding a simple overhand (strangled?) knot (#515) to one of the tails as a security device. Overhand knots can work loose - particularly if the rope if stiff. For example, I never use a simple overhand knot (ABoK #515) as a stopper knot in the end of my abseil ropes...I always use a double overhand knot (ABoK #516), because I know from experience that it is more secure.

At the end of the day, anyone can come up with a bunch of reasons to discredit my offset overhand bend variation. If the motivation behind resisting this new variation is to ensure public safety (and climbing community safety) - I would say that such persons are incorrect. My variation is not dangerous - this i have empirically proved via real-world field testing. If the motivation behind the resistance is something else - I would not understand resistance merely on the basis of resisting change.

However, I do enjoy serious analysis - particularly where critique is evidence-based or derived from structured testing. This type of analysis drives further invention and innovation.

Again I make the point, (and an open challenge) - can we go one better than the iceman?

My binding innovation increases the radius around which the loops tighten against - we know this is sound science. The addition of the binding loop adds security in my view - testing over the past few days has shown me that this is correct - since the binding loop is a further structure that must unravel to lead to catastrophic failure. The addition of the binding loop does not significantly increase the knots profile (it does a bit - but the point is not significantly).

Quote
The assertion that climbers can tie
all those knots you list (and esp. the EBSB deviation from better
knotting of the EBDB  Tongue ) is readily evidenced to be wrong

That's a personal view and I'll take it is such...I has used my EBSB Bowline variation for 2 years in the field - and use it exclusively (don't use the F8 #1047 anymore). I have taught the EBSB variant to many people - they learned it and now use it. The tail is held very securely and does not work loose - it is very secure and stable in all loading profiles (including ring loading). In your EBDB variation, I can work the tail loose through cyclic loading (just did it then on Bluewater static 11mm while typing this post). But that's another topic of discussion.


« Last Edit: July 08, 2011, 09:30:16 AM by agent_smith »

alpineer

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #42 on: July 08, 2011, 09:34:59 AM »
    I have used my EBSB Bowline variation for 2 years in the field - and use it exclusively (don't use the F8 #1047 anymore). I have taught the EBSB variant to many people - they learned it and now use it. The tail is held very securely and does not work loose - it is very secure and stable and in all loading profiles.

agent smith, I've been using an ABoK #1034.5 Cowboy Bowline variant(EBCB) for tying into a climbing harness that:
>doesn't require a pre-tied knot
>requires only 1 nipping loop
>has the end binding encircling 3 rope diameters
>has the nipping loop encircling 3 rope diameters
>has the tail exiting alongside the S.Part
>is relatively easy to learn and remember (just a Half-Hitch nipping loop married to a Figure-Eight)
>makes a strong, secure, stable knot even if the tail is re-tucked through another part of the nipping loop
>is easy to untie

It merits inclusion into your Bowlines article on the PACI website. Btw nice job on the photos.

Here's the link to some photos.
http://igkt.net/sm/index.php?topic=1202.135 (Replies #145 & 146)

 

agent_smith

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #43 on: July 08, 2011, 10:03:00 AM »
Nice one alpineer,

I need time to properly analyze your Bowline variant...will endeavor to take some high quality photos tomorrow and then we'll see if I can add it to my Bowlines paper and upload it to the net for the world to see. Naturally, I'm sold on my EBSB varant, Dan Lehman's EBDB has merit, but I honestly dont find the tail to be as secure as in my version. I can make the tail slip in Dan's EBDB by cyclic loading the knot. I'll post back in that Bowline thread when the photos are done...

This is off topic though...

I am still determined to move forward with more vigorous testing this weekend of my 'Bound Offset Overhand bend' (# 1410 variant). I will try descending with ropes soaking wet Vs dry and I will also perform a cyclic load test on icy ropes pulled out of my freezer to see if I can induce a failure mode.

As stated though, I cant test to destruction of the ropes at thisstage - the budget wont allow it...however, I might see if I can find some really old 5mm or 6mm accessory cord lying around. I guess I should do some slow pull tests with the trusty load cell to compare behaviour of the bound offset verses ordinary offset overhand bend - we'll see what effect the 3 rope diameters has.

I should even try to weave some coloured thread into the sheath (like Dan Lehman once asked me to do a few years ago). Oh dear...how I hate needle and yarn work!

Mark

alpineer

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #44 on: July 08, 2011, 10:14:41 AM »
Apologies for the thread drift Mark.
alpineer