Author Topic: In search of the goldilocks bend! (joining abseil ropes)  (Read 20840 times)

agent_smith

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In search of the goldilocks bend! (joining abseil ropes)
« on: July 03, 2011, 03:53:39 PM »
This is a topic that has done the rounds all over the internet and seems to fuel endless campfire debates at climbing areas...

What is the best method of joining 2 climbing ropes together for a retrievable abseil ('Rap' for you Yanks)?

I started a thread on this topic a few years back..but don't recall any definitive commentary from IGKT members (particularly those with climbing experience).

Essential characteristics:
1. Ease of untying after loading;
2. Likelihood of translating around a 90 degree edge from low set anchor;
3. Relative chance of success in tying knot correctly (difficult to quantify);
4. Stability and security, including when joining ropes of different diameters (Note; Strength is not an issue in my view).

So here are some knots to ponder over:

1. The Rosendahl (my personal all-round favourite) - ABoK N/A;
2. The offset double overhand bend - ABoK N/A;
3. The offset overhand bend - ABoK #1410 (aka offset overhand ring bend);
4. Offset stacked double overhand bends;
5. Reef (re-tucked) - ABoK N/A (thought I'd throw this one in as it appears to have some merit) Note: This site wouldn't allow a 5th image...
6. ?
7. ?

I have purposely omitted the Double Fishermans (ABoK #1415) - due to its difficulty in untying and tendency to get stuck at a 90 degree edge from low set anchors.





« Last Edit: July 15, 2011, 06:27:05 AM by agent_smith »

TMCD

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #1 on: July 03, 2011, 04:04:24 PM »
The best bend for climbing IMO, would certainly be the Zeppelin Bend and I don't understand why more climbers don't use it. It's security and strength are legendary, the tails could be taped to the SE's if that's a problem. Another bend I would like to see tested for it's strength and security would be the Tucked Sheet Bend. Most Sheet Bends as we know, simply aren't secure or strong enough for climbing when one's life is on the line. But the TSB seems strong and it's an ideal candidate for testing because of the snagless nature of the knot.

Dan_Lehman

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #2 on: July 05, 2011, 07:25:43 AM »
The best bend for climbing IMO, would certainly be the Zeppelin Bend and
I don't understand why more climbers don't use it.
It's security and strength are legendary,
the tails could be taped to the SE's if that's a problem.

Climbers do well enough with what they have,
and Rosendahl's bend has no good support for your
assertion about strength; security is prima facie suspect
compared with the grapevine bend (aka "dbl.fish." )
which if anything is deemed at times too secure.
"Legendary" is too like "mythical" and "imaginary"; let's see
the facts!

And taping (!) tails to SParts of a knot where those two parts
are at right angles is hardly a winning argument.  (Indeed,
one of the benefits of the fisherman's knot is that its tails
lie alongside the SParts.)  (I'm not aware of rockclimbers doing
any taping of tails; commercial fishers, yes.)

Quote
Another bend I would like to see tested for it's strength and security
would be the Tucked Sheet Bend.  Most Sheet Bends, as we know,
simply aren't secure or strong enough for climbing when one's life is on the line.
But the TSB seems strong and it's an ideal candidate for testing
because of the snagless nature of the knot.

Any knot that is not offset is prone to hanging up on an edge.
(Agent_Smith shows only one of two likely dispositions of
Rosendahl's bend --the better one, for not hanging up.

And pretty much any knot is strong enough,
as the materials are amply strong.  Especially as
the stated criteria don't include strength, but seem
especially aimed at abseil-ropes joining (and one
obvious misssing one:  able to join ropes of different
diameters (at least to 7mm + 11mm).

--dl*
====

Dan_Lehman

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #3 on: July 05, 2011, 07:46:17 AM »
This is a topic that has done the rounds all over the internet
and seems to fuel endless campfire debates at climbing areas...

Fulled by limited attention and wit.  There have been some
inroads made, though, recently (hammering enough times
to make dents).


Quote
What is the best method of joining 2 climbing ropes together for a retrievable abseil ('Rap' for you Yanks)?

"ARJ" ("abseil-ropes joint/joiner/joining...") I call it.


Quote
Essential characteristics:
1. Ease of untying after loading;
2. Likelihood of translating around a 90 degree edge from low set anchor;
3. Relative chance of success in tying knot correctly (difficult to quantify);
4. Stability and security, including when joining ropes of different diameters
 (Note; Strength is not an issue in my view).

Egregious omission : capability of joining 6-7mm and 10-11mm lines!
And, for that matter, lines of differing natures other than diameter
(and possibly in addition to diameter).


Make it "offset water knot", perhaps : "ring bend" by some
conventional/historical senses ought to be a hitch,
not an end-2-end knot; and "ring" has a good sense as
a type of object.  (But this "ORB" should nevertheless
get the point across in the rockclimbing world, once
"offset" is understood.)

And that's clearly --by the same simple nomenclature--
"offset grapevine bend".

Nothing "stacked" really, just an EDK (OWK (ORB)) with the
ends stoppered with an overhand.

Here is the simplest and likely best (partly for the
simplicity, using well-known knotting movements)
--the offset water knot with the thin tail stoppered.
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*
====

xarax

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #4 on: July 05, 2011, 12:53:22 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 :
   1. The double line / double overhand bend ( See (1), and first attached picture).
   2. The Salty Cracker / ABoK#1031 bend ( See (2), and second-third attached pictures)
   Now, if we insist on using an "offset" bend, why we do not just tie an one-sided double overhand bend ? ( See fourth attached picture)

1) http://igkt.net/sm/index.php?topic=2804.msg18471#msg18471
2) http://igkt.net/sm/index.php?topic=2804.msg16650#msg16650

« Last Edit: July 05, 2011, 01:35:40 PM by xarax »
This is not a knot.

Morgoroth

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #5 on: July 05, 2011, 05:30:31 PM »
Sorry, I'm confused, which is the Offset Grapevine Bend?

TMCD

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #6 on: July 05, 2011, 07:10:59 PM »
The best bend for climbing IMO, would certainly be the Zeppelin Bend and
I don't understand why more climbers don't use it.
It's security and strength are legendary,
the tails could be taped to the SE's if that's a problem.

Climbers do well enough with what they have,
and Rosendahl's bend has no good support for your
assertion about strength; security is prima facie suspect
compared with the grapevine bend (aka "dbl.fish." )
which if anything is deemed at times too secure.
"Legendary" is too like "mythical" and "imaginary"; let's see
the facts!

And taping (!) tails to SParts of a knot where those two parts
are at right angles is hardly a winning argument.  (Indeed,
one of the benefits of the fisherman's knot is that its tails
lie alongside the SParts.)  (I'm not aware of rockclimbers doing
any taping of tails; commercial fishers, yes.)

Quote
Another bend I would like to see tested for it's strength and security
would be the Tucked Sheet Bend.  Most Sheet Bends, as we know,
simply aren't secure or strong enough for climbing when one's life is on the line.
But the TSB seems strong and it's an ideal candidate for testing
because of the snagless nature of the knot.

Any knot that is not offset is prone to hanging up on an edge.
(Agent_Smith shows only one of two likely dispositions of
Rosendahl's bend --the better one, for not hanging up.

And pretty much any knot is strong enough,
as the materials are amply strong.  Especially as
the stated criteria don't include strength, but seem
especially aimed at abseil-ropes joining (and one
obvious misssing one:  able to join ropes of different
diameters (at least to 7mm + 11mm).

--dl*
====
I have real life working experiences  with the Zeppielin Bend, pulling out Ford F250 vans mired in a foot of mud on more than one occasion. The bend didn't slip an inch, and held beautifully under extreme load and torque pressures that were experienced in wet, sloppy, heavy caked mud. Rest assured, the Zeppelin Bend is a fine all around bend that is arguably the best bend we have today.

Dan_Lehman

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #7 on: July 05, 2011, 09:13:46 PM »

[unneeded text omitted! ]



I have real life working experiences  with the Zeppielin Bend,
pulling out Ford F250 vans mired in a foot of mud on more than one occasion.
The bend didn't slip an inch, and held beautifully under extreme load
and torque pressures that were experienced in wet, sloppy, heavy caked mud.
Rest assured, the Zeppelin Bend is a fine all around bend that is arguably the best bend we have today.

I rest assured that one could've had the same experience
with Ashley's #1408, 1452, 1425, the carrick bend, and
many others.  (But I don't understand "torque pressures"
for an end-2-end joiner --the line was seriously twisting
at the knot?)

--dl*
====

alpineer

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #8 on: July 05, 2011, 09:26:55 PM »
I have real life working experiences  with the Zeppielin Bend, pulling out Ford F250 vans mired in a foot of mud on more than one occasion. The bend didn't slip an inch, and held beautifully under extreme load and torque pressures that were experienced in wet, sloppy, heavy caked mud. Rest assured, the Zeppelin Bend is a fine all around bend that is arguably the best bend we have today.

It depends on the application, and we're talking climbing knots here, specifically the best knot for tying and retrieving abseil ropes. Climbers are efficiency minded, but with safety as the overriding factor when choosing a knot and it's properties (in this particular case, for tying two ropes together quickly for abseiling and being able to retrieve them with a minimum of effort). The two knots shown by Dan Lehman are Quick to tie, Simple to tie, Easy to tie, Easy to untie, Easy to Remember and Ample Strong, Safe, Secure, and Stable for this job. You'd get less than this from another knot.

alpineer
« Last Edit: July 05, 2011, 09:33:15 PM by alpineer »

xarax

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #9 on: July 05, 2011, 10:02:47 PM »
You'd get less than this from another knot.

   How are you so sure about this ? Do you know all the possible bends that could serve that purpose, and have compared those two knots with each one of them ?  :) I like myths, too, but not myths about climbing knots.
This is not a knot.

alpineer

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #10 on: July 05, 2011, 11:40:22 PM »
You'd get less than this from another knot.

   How are you so sure about this ? Do you know all the possible bends that could serve that purpose, and have compared those two knots with each one of them ?  :) I like myths, too, but not myths about climbing knots.
Allow me to ask you this Xarax, what is the simplest knot structure that can be tied(and maintained) in the end of a single piece of cordage and with a minimum of hand movement and mental focus. The answer is the same for two ropes (pair them together and tie them as one). It's the Overhand form. The two knots shown in Dan Lehman's post are based on the Overhand structure, and simply "paired" Overhand Knots with a single Overhand Stopper round one strand. Anything fancier has to be justified in light of it's intended use. Please note also that an abseil knot is a temporary means of fixing two ropes (not intended to be permanent).
Climbers need also to consider worst case scenarios. Imagine you are on a mountain and you need to abseil to retreat quickly due to injuries, storms, lightning, impending darkness, what have you. And let's say you(others) are in a state of shock or have difficulty focusing on self-rescue. Simplicity is appreciated most at these times. There is no myth here. Anything simpler would necessarily be a single rope of 2 x length (no knot needed).
alpineer  
« Last Edit: July 06, 2011, 12:28:33 AM by alpineer »

xarax

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #11 on: July 06, 2011, 12:21:54 AM »
    Thank you, alpineer,

  I have not been able to quantify what we mean by "simplicity" in the field of practical knots. Of course, it is something very different from simplicity of mathematical knots, where, again, there are problems if we go further than the naive enumerating of knot crossings. In practical knots, we have to take into account the simplicity of the mental picture we start with when we tie a knot, the simplicity of the required dexterity of the hand and finger moves, etc.. In general, we must be very careful when we speak about simplicity...There are some attempts to measure simplicity by enumerating the number of steps that a Turing machine executing an algorithm will need to describe a phenomenon, but this has not gone beyond measuring the simplicity of simple mathematical formulas.
   The two knots posted by Dan Lehman are not simple overhand bends ! They are contraptions based on the one-sided overhand bend, more or less clever than many others we could imagine. ( I myself have proposed the one-sided double overhand bend, for example. ) What I found a little unbalanced/annoying in your reply was not the essence, but the tone : You seemed too sure about the uniqueness of the particular solution, so sure that you have used capital letters to show it !  :) Of course, I am in no position to lecture to you about climbing knots ( and to nobody else, I am afraid...) , but I felt the obligation to put a small question mark alongside the big exclamation mark !  :) Again, I had no intention to criticize the essence of your suggestions.
« Last Edit: July 06, 2011, 12:24:57 AM by xarax »
This is not a knot.

alpineer

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #12 on: July 06, 2011, 12:45:40 AM »
Xarax,
Capital letters were used to highlight the words, not to inflict tone.
Btw, you must be hovering over your keyboard. I came back to my post to add something and you'd already responded. You're are obviously a faster typist than myself. Please, give a slow typist a chance. 

xarax

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #13 on: July 06, 2011, 12:56:36 AM »
Please, give a slow typist a chance.  

 :) And you should also take into account the fact that I was, simultaneously, responding to the other thread, too !
    Do you consider the one-sided double overhand knot a "fancier" solution ?  I would say that it is "simpler" than the two overhand+the stopper knots mentioned above. What about the Salty Crackers -ABoK#1031 alternative to the fisherman s knot?
« Last Edit: July 06, 2011, 12:58:03 AM by xarax »
This is not a knot.

alpineer

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Re: In search of the goldilocks bend! (joining ropes)
« Reply #14 on: July 06, 2011, 01:10:59 AM »
The Offset Double Overhand Bend uses more rope than is necessary and is unnecessarily bulkier (and is therefor more likely to get caught On or In some natural terrain feature) than the Offset Water Bend (a.k.a. EDK). So why would you use it? Because it's prettier? Not a good enough reason. It also takes more hand gymnastics to tie. It's not that it couldn't work Xarax, but it's not the better choice for this one very specific job (i.e. abseiling).

alpineer