Zeppelin Bend: Security and Strength

[Dan_Lehman]

... using 7mm Edelweiss rope which seems to be stretchy.

Interestingly, Zeppelin bend seems to capsize in the test.

I concur in both of your observations.  Indeed, that rope
seems to do a LOT LOT LOT of moving in the knots !!! !?

Roo will defend the capsizing Thrun's Joints (aka "zep")
as having been poorly dressed --after all, we're dealing
with folks not always able to pronounce the knots!
Still, though, the capsizing surprised me I think in
one of those not-so-bad dressings!?  --eh, maybe
there was yet some good bit of SETTING to get it
into shape.  (It does got against Xarax's assertion
that the knot naturally sets on loading --not in THIS
material, at least!)

.:.  One might need to anticipate the action of such
elastic & slick material with harder setting.  Again,
there seemed to be a LOT of rope movement in
those tests!


--dl*
====

[mcjtom]

Again,there seemed to be a LOT of rope movement inthose tests!

Is that unusual when the load is so substantial?  The cord seems to be the regular kermantle nylon, with untwisted core - nylon kind-of-stretchy but not deliberately enhanced.


Does it seem to you to be extraordinarily slippery?


http://www.edelweiss-ropes.com/en/cordelette-7mm.html

[jarnos]

Using additional turns might be a working solution in such applications.

[agent_smith]

I found this video where they test security of several knots including Zeppelin bend and Zeppelin loop (latter of which only with added security, though) using 7mm Edelweiss rope which seems to be stretchy.

Its full of mistakes with several poorly tied (and incorrectly tied) knots.
Camera moves too quickly to provide any chance of verifying exactly what they tied...

Interestingly, Zeppelin bend seems to capsize in the test.

At 12:14 in the video it appears they are testing a Zeppelin bend (formed as a round sling).
I wouldn't place too much importance on their tests - the camera angle is low and its hard to verify precisely what they tied.
If you look closely (which is hard given the camera angles and speed of movement (even when you pause the video) - you'll see several tying errors.
For example, the #1415 Double Fisherman bends are incorrectly tied, the Sheet bends are incorrectly tied and the #1411 F8 bends have sloppy and varying geometry.
In one of the #1053 derived Butterfly bend tests, you can see quite sloppy tying/setting geometry (one collar is very loose while the other is somewhat tighter).
They add what they call a 'backup' knot to some knot specimens - and also refer to it as a 'barrel' knot - which is incorrect.
Its not a double overhand strangle around the SPart - and in some cases they also tried to use 'whipping' to secure tail ends (which in my view defeats the opportunity to observe rope movement and tail slippage).

It wouldn't surprise me if they tied, then untied, and then retied the knot specimens (or altered the geometry) for the tests. There is no way to be 100% certain...
The camera is positioned too low in several tests - making it very difficult to verify the knot geometry and starting (pre-load) dressing/setting...

The rope is reported to be Edelweiss 7mm accessory cord - EN564 standard - MBS 9.8kN
Link: http://www.edelweiss-ropes.com/en/cordelette-7mm.html
Cord is polyamide (the chemical name for the brand name 'nylon').

[Dan_Lehman]

... you'll see several tying errors.
For example, the #1415 Double Fisherman bends are incorrectly tied,

They are discordant, which is generally not prescribed
and sometime expressly proscribed, yes.  But those "incorrect"
knots did NOT break --not once.  They recorded the highest
forces, but soon enough then the rope broke at the 'biners.

It wouldn't surprise me if they tied, then untied, and then retied the knot specimens
 (or altered the geometry) for the tests. There is no way to be 100% certain...

Huh?  What would be the point --and the risk-- of this?!
They tested what we saw being stressed and breaking
--and, yes, the "seeing" is not always easy & sure,
but otherwise it's adequate.

But, um, knots aren't their greatest skill, we'll hope!

Given how liberal they were with the rope,
I wish they'd thought to tie ends joints in both
side of the stressed sling, to balance the material
feed into the side(s) with the knot(s); then, maybe
we'd have surviving AND broken grapevine joints.


 

[agent_smith]

In reply to Dan Lehman (per his post at reply #64...

Dan - I think you entirely miss the point.

This is somewhat off topic - but...

If you are going to test some knots and them publish those tests to the world - the tester should do 'his' homework first.
The 'How Not 2" YouTube channel is likely seen by a substantial number of viewers - and it is 'holding itself out' as possessing some level of expertise.
That is, most lay people would form the view that their test results hold some sort of credence.

If you are going to test #1415 Double Fishermans - why not at least make an attempt to tie it as per its correct geometry?
Note that you could use #1415 as a 'control' in an experiment to compare against a discordant #1415 (where the chirality of one of the strangled double overhand knots has been reversed).
Note however this is not what they purported to do!

Same goes for #1431 Sheet bend.
If you are going to test a Sheet bend - why not do your home work and tie it correctly?
Again, you could use #1431 as a 'control' to compare against a 'discordant' (left hand) Sheet bend (#1432) - but this is not what they purported to do.

They are effectively holding themselves out to possess a certain a level of expertise - but cant even tie their knot specimens correctly!

With regard to my point that it wouldn't surprise me if they re-tied or fiddled with their knot specimens between the elapsed time of the opening sequence and the actual load test ...
I stand by that remark. It wouldn't surprise me at all.
Thats not to denigrate them - its simply a statement that I wouldn't be surprised.
If you think about it - there is no way for the viewer to be 100% certain of anything.
There are many things in life where I am "not surprised".

Here is a statement of fact for you:
The video contains clear evidence of numerous/several errors.
Several knot specimens were incorrectly tied.
Voice over commentary also contained errors.

[Dan_Lehman]

If you are going to test some knots and them publish those tests to the world - the tester should do 'his' homework first.

Doing one's homework might be what you should ascribe
to knot-book authors, too : what they do is parrot prior
books, sometimes to the degree of copying text/images!!

What counts as "homework"?

If you are going to test #1415 Double Fishermans,
 why not at least make an attempt to tie it as per its correct geometry?

Whose idea of "correct" is this?  IF they scanned many sources
--and "many" here I think would be 4-5--,
they'd likely have found no more than one discordant version
of the Grapevine bend.  Well, I don't know their source, but
maybe it was a "trusted" one, and ... so we got the discordant
version --and for us, maybe a bit of a boon because otherwise
I think that testing has deprived us of seeing that (to know
how snooty we should get over "proper" forms, e.g.!).

Same goes for #1431 Sheet bend.

I've been seeing that in some older mountaineering books
showing up opp-sided; and I recall a quite-aware Rob
Chisnall reporting quick'n'dirty testing of the knot versions
in KM arriving at a conclusion that the "bad/left-handed"
form was slightly better --or better in some ropes.
(IMO, it appears maybe better, in drawing up more
like the *rounded* geometry of the BWL, BUT THEN
I think when high forces, at least, come to play,
things go worse for it.
(It might be the better version to START with, and then
to add some securing extension to.)

They are effectively holding themselves out to possess a certain a level of expertise
-- but cant even tie their knot specimens correctly!

I concur in this.  Recall the testing of a couple Fig.8
EKs with the guy claiming (a) that he'd tied them the
best that he could (we should hope not!) --though they
were differently loaded vis-a-vis interior/exterior S.Part--
and (b) that nevermind for the knots will "dress themselves"!
That was a set of bloopers at the comedy level!

With regard to my point that it wouldn't surprise me if they re-tied or fiddled with their knot specimens between the elapsed time of the opening sequence and the actual load test ...

I don't follow this, for had they done so, they MIGHT've
been able to rescue those capsizing Thrun joints(aka Zep) !

I stand by that remark. It wouldn't surprise me at all.

You're beneath a lone tree in an electrical storm.
You deny them the wit to get things right, but posit
that by some assessment of what IS right they go
to shenanigans of faking their already lambasted results!

And all that aside,
there seemed to be IMO a LOT of rope movement
--gives me the willies!

Also, for the most part, we DO NOT SEE THE ACTUAL
KNOTTED GEOMETRY MEETING THE TEST (start) AND
NIGH RUPTURE (pre-break but close), ANYWHERE!!!

And we DO see both Dave Richards, under auspices
of Cordage Institute?, and CMC Rope Rescue having
Fig.8 EK in both reeved ("re-woven") and "in the bight"
tying forms, as though ... the knot will care!!
(In one rope of Richards's testing though avg. of the
two were close, one (re-threaded, IIRC) had double
or more the Stnd. Dev. !?)


.:.  And where have WE gotten in typing into e-sharable
printed guidance HOW TO TEST KNOTS ?!  --specifying
source work and showing photos of tied specimens at
start and under medium then high stress (and ruptured
knot, perhaps --sometimes revealing, sometimes blasted
out of sight).  !?


--dl*
====

[We are knot crazy]

What's up knerds, just chiming in here. In my experience the Zeppelin bend is one of the finest out there- and I'm proud to say I discovered it through experimentation before ever reading about it in an external source (so I'm a little biased). It is strong and stable in different kinds of rope, resists jamming, and ties and unties easily, even after heavy loading. What more do you want from a bend? A double sheet bend can slip out in slick synthetic rope- a zeppelin, or even better, a double zeppelin, will hold up under the same conditions. I'm all for using it.

[Dan_Lehman]

It is strong and stable in different kinds of rope,

By what basis do you claim this?

The revelations of the testing video cited above are rather
disturbing, albeit also themselves in some question.  Would
that they'd tried Ashley's jointS #1452 & #1408.

(-;

[agent_smith]

Response to reply #68 (per Dan Lehman).

The revelations of the testing video cited above are rather
disturbing,

Wow - I wonder what level of "disturbance" you are experiencing
For me personally - I am experiencing zero disturbance in the force.

Rules of life:
1. Don't place any emphasis on a tiny test samples using only one type of rope (eg a test sample of 3).
That's a very small sample to draw any conclusions that lead to emotional 'disturbances'.
I would be more disturbed by people who get disturbed by reaching conclusions from tiny sample sizes of 3 tests.

2. In this day and age, its not impossible to obtain the same cordage and attempt to repeat the tiny population sample size tests of 3.
Go to internet, tap on your keyboard, provide credit card details and postal address, and wait for delivery of product (Edelweiss 7.0mm EN564 cord).
Run tiny sample size tests to see if instability can be reproduced by own tests...
What if you can't repeat the 'How not 2' results? What would that mean?
Or, maybe the 'How not 2' Zeppelin bend test need a particular dressing state or geometry to trigger the results seen in their video?
(eg maybe it is necessary to have a looser dressing state on one collar of the Zeppelin bend - with the opposite collar dressed tightly? Or, maybe
you need to configure the sample as a round sling with only 1 Zeppelin bend - not two Zeppelins in a round sling configuration?).
The rope movement that occurred in their test (visible on the right side carabiner anchor point) indicates some kind of anomaly - possibly due to a dressing/setting issue?

3. Use a camera - ideally a video - and try to get continuous footage (rather than swift camera movements
with missing video frames - avoid jumping ahead in time continuum - and let viewers see precisely whats taking place in your tests.).

Would that they'd tried Ashley's jointS #1452 & #1408.

Why?

More relevant would be to repeat the Zeppelin bend tests using different cordage materials / rope materials.
Also configure test sample differently with dual zeppelin bends formed as a round sling (rather than single Zeppelin bend tied within a round sling).

Commentary on How Not 2 video:  https://www.youtube.com/watch?v=dagg2-If4h8
1. At exactly 11:49 in the video - look closely at their Zeppelin bend knot dressing. What do you see? (note the dressing state).
2. At exactly 11:58, note the sudden time shift going to 12:00 (missing footage). Note also that at 11:58, the viewing angle is side-on, making it hard to see the exact geometry and dressing state.
3. Note the relative movement of rope on the right carabiner versus the left carabiner (there is no net rope movement of left side - and what does that suggest?).
4. At 12:12 in the video, look at the relative rope movement on the carabiner on right side... (left carabiner is out of camera view).

...

The following is off-topic:

With regard to earlier comments re #1415 Double Fishermans bend:

Whose idea of "correct" is this? 

#1415 is depicted in a particular geometry.
Its formed as S/S or Z/Z chirality.
That is, each strangled double overhand knot is either 'S' chirality or 'Z' chirality.
It is not a 'true' #1415 if the double overhand knots are discordant (ie of opposite chirality).
Knots that are known and published have a particular geometric form. They don't have random forms, otherwise we could not recognize the distinctive form/geometry that is attributed to a particular knot species. That is to say, our ability to recognize any given knot is down to its particular geometry/form (its uniqueness which distinguishes it from another knot).

IF they scanned many sources
--and "many" here I think would be 4-5--,
they'd likely have found no more than one discordant version
of the Grapevine bend. 

And?
In my view, this indicates incorrect geometry - and possible ignorance of the correct form.
I note that you yourself have pointed out the many errors of knot book authors and 'sources'.
Also, #1415 has symmetry when tied in S/S or Z/Z geometry.
When tied in S/Z or Z/S geometry, the interpenetrating double overhand knots do not press against each other uniformly.

Well, I don't know their source, but
maybe it was a "trusted" one, and ... so we got the discordant
version --and for us, maybe a bit of a boon because otherwise
I think that testing has deprived us of seeing that (to know
how snooty we should get over "proper" forms, e.g.!).

Are any 'sources' truly trustworthy?
Well - I would answer that a very tiny number of sources can be trusted!

As for testing, #1415 could be tested with a control sample tied discordantly.
I would be looking for effect on jamming thresholds... (not pure MBS break testing).



Note to Dan Lehman: I am not surprised by any of these remarks I have made

[Dan_Lehman]

Response to reply #68 (per Dan Lehman).

The revelations of the testing video cited above are rather
disturbing,

Wow - I wonder what level of "disturbance" you are experiencing
For me personally - I am experiencing zero disturbance in the force.

Rules of life:
1. Don't place any emphasis on a tiny test samples using only one type of rope (eg a test sample of 3).
That's a very small sample to draw any conclusions that lead to emotional 'disturbances'.
I would be more disturbed by people who get disturbed by reaching conclusions from tiny sample sizes of 3 tests.

But what we can SEE in those few tests is behavior that is
--to reasonable assessment-- disturbing : the pull into opposed
nipping loops and their capsizing into helical twists & more.
YES, that perhaps could've been prevented by setting the
knots better.  Recall though, e.g., at one time Xarax proclaimed
dressing & setting UNneeded for this supposed wonder knot
--that it would per loading assume a good form.  Maybe for
some light forces in some materials ... , but not in what we
saw.  And I don't need to see 100 more tests :: if this is
a shown potential, I want to take precautions --re cordage,
setting, or knot.

> Run tiny sample size tests to see if instability can be reproduced by own tests...

Good idea; I'll try some shock cord, which is quite
an exaggeration of stretch, but if that does NOT show the
behavior, ... back to wondering how it came to be for the 7mm!?

> What if you can't repeat the 'How not 2' results? What would that mean?

.:. That I'm a swell guy!  Give me your knots to tie.

Would that they'd tried Ashley's jointS #1452 & #1408.

Why?

To see how those knots perhaps better handled that material
AND relaxed (to be kind) setting --to give good knots their show.

> Also configure test sample differently with dual[] [joints] formed as a round sling

Yes, in general, I think a better plan --avoiding the unhelpful
breaks-at-pin.  (Except, if you want info re slings, which will
not catch on if req'd to have dual knots!, test such slings.)

With regard to earlier comments re #1415 Double Fishermans bend:

Whose idea of "correct" is this? 

#1415 is depicted in a particular geometry.

By Ashley, and much else ; but it's not amazing nor some
huge breach of what-knot-names-denote understanding
for the discordant form to come along, under that name.
(For some I've-never-seen-explained reason, Des Pawson
has ALWAYS shown discordant fisherman's knots (single;
though, hmmm, bet he does CONcordant doubles!?) .

Are any 'sources' truly trustworthy?

I used to think that I was, but recently had to annotate
an annotation in my Hensel&Gretel to say essentially "WTH?"
with that --can only imagine some quite careless reach to
that entry based on "Japanese..." in title from some other
image.  Egadz.  (And where I have a method of tying off
venetian-blinds pull cords --left/center/right-- with, resp.,
OH, F8, & F9 knots to record their position,
I recently found I'd tied F9 in all three !!!  Holy smokes,
I'm losing it!
(fyi : OH EKs qua stoppers in pull cones;
 slipped (!?) strangles stoppering pull cord ends in the
bottom to-be-pulled-up bar's plastic stovepipe-hat-like
plastic plugs.
--and variations, sometimes interesting.)
From Cambodia? or China? (country IDs, but not sure
if for assembling vs. producing materials.)


(-;

ps:

Note to Dan Lehman: I am not surprised by any of these remarks I have made

Sigh, nor I.

[mcjtom]

The great thing about HowNot2 is that they have a question, design a test, actually do it for all to see, reflect on improving the method and comment on results, and move on...  

They replicate tests within reason - others can try to reproduce them (and then move on?)...