Author Topic: Zeppelin Bend: Security and Strength  (Read 38868 times)

Dan_Lehman

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Re: Zeppelin Bend: Security and Strength
« Reply #45 on: February 29, 2012, 07:46:07 AM »
I'm very new to knot tying. I'm interested in loops at the moment, and in the zeppelin loop in particular. We have xarax's opinion; I'm wondering what others think about the effect of loading one of the ends of the zeppelin bend in forming the loop. Does that make it a less-secure knot than the bend?
I don't recall X. opining this, but simply that
the symmetry of the end-2-end knot's loading
is lost in the eye knot (as one overhand part
is loaded on both ends, the other not).

Quote
I'm also wondering how the zeppelin bend and loop compare in security
to bends and loops typically used in rock climbing.  Is there evidence to say definitively
that the zeppelin bend and loop are or are not to be trusted with my life?

Rockclimbers use end-2-end knots in just a couple of
cirucumstances : joining ends of a small line or tape
to form a closed-loop sling; joining abseil ropes together.
In neither of these cases would one have good reason
to favor the zeppelin bend.

Eye knots are used for tying in, and the zeppelin eye knot
will suffice, as will many many others.  Its ease of UNtying
after being loaded is one attractive aspect --but one shared
by numerous bowlines and other lesser known knots.

--dl*
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erizo1

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Re: Zeppelin Bend: Security and Strength
« Reply #46 on: February 29, 2012, 03:58:22 PM »
Dan_Lehman, I have a number of follow-up questions to your reply, but they go outside the topic of this thread. I'd be grateful is you'd reply to a new thread I started: http://igkt.net/sm/index.php?topic=3810.0.

xarax

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Re: Zeppelin Bend: Security and Strength
« Reply #47 on: February 29, 2012, 04:41:45 PM »
I don't recall X. opining this

As memory is helped by repetition, I will repeat the same things I have written in this forum MANY times ( but have been read only a FEW times, if any, I am afraid...), once again...See :
http://igkt.net/sm/index.php?topic=3810.msg22458#msg22458
This is not a knot.

roo

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Re: Zeppelin Bend: Security and Strength
« Reply #48 on: February 29, 2012, 05:26:15 PM »
... I'm wondering what others think about the effect of loading one of the ends of the zeppelin bend in forming the loop. Does that make it a less-secure knot than the bend?
Actually, the loop is more secure.  Just as the bowline is more secure than the parent sheet bend, most loop knots are more secure than their parent bend.  In a loop, one more part of rope is imparting tension into the knot form which usually keeps things more snug.  In some loops this may contribute to making the knot harder to untie, but in the Zeppelin Loop, ease of untying is maintained.

Quote
I'm also wondering how the zeppelin bend and loop compare in security to bends and loops typically used in rock climbing. Is there evidence to say definitively that the zeppelin bend and loop are or are not to be trusted with my life?
The Zeppelin Bend and Zeppelin Loop can be trusted with life.  In fact they or their double form would be my first choices.  And I've gotten positive feedback from people who use them in such capacity. 

The Zeppelin Loop is also quite nice in handling oddball loading configuration, such as accidental pulling of the free end, or loading the legs in opposite directions (the latter being something a Figure 8 Loop can have problems with).  I also like the distinctive, symmetric knot form makes the Zeppelin Loop (and bend) very easy to check for errors, even from a distance.

I do think that the double/triple fisherman knots are the gold standard of security, it's just unfortunate that they're also horribly jam-prone.

The most important thing is that you are testing knots yourself in the material that you will be using.  There is no substitute for this.  It will give you a feel for the properties of knots that no amount of reading will do.
« Last Edit: February 29, 2012, 05:51:30 PM by roo »
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erizo1

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Re: Zeppelin Bend: Security and Strength
« Reply #49 on: February 29, 2012, 06:13:56 PM »
Very grateful for the replies. Thanks!

xarax

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Re: Zeppelin Bend: Security and Strength
« Reply #50 on: February 29, 2012, 06:57:48 PM »
the bowline is more secure than the parent sheet bend

1. The Sheet bend IS NOT the parent of the bowline ! In fact, it has a very limited relation with the bowline, if any. Read the thread "What defines a bowline" (1), about what the bowline is...

2. I have seen no tests of the security or strength of any of the two forms of the Sheet bend, in comparison with any of the two forms of the bowline - tied with/on the same material. While this claim sounds reasonable, I would never trust another person s life on something that, although reasonable, is not tested experimentally.

1) http://igkt.net/sm/index.php?topic=3233.0

The Zeppelin bend and Zeppelin Loop can be trusted with life.

No, they can not, and they should not ! - until they are tested, and proven to be more secure and strong than any other similar knots that can possibly be used for the same purpose. Of course, I am speaking about other people s lives, ( OPL), because, if anybody actually believes in this, he can always put his own life into test - falling from a increasingly dangerous height above the ground.

I've gotten positive feedback from people who use them in such capacity.
I hope that the absence any negative feedback is not a consequence of a sufficiently dangerous height... :)

I also like the distinctive, symmetric knot form makes the Zeppelin Loop (and bend) very easy to check for errors, even from a distance.

   For the so-called "Zeppelin loop", such a distance is a prerequisite...The more the distance, the more 'distinct, symmetric form" this ugly monster acquires. At a sufficient distance, this tangle will be transformed into a perfect circle. However, as a knot, it always remains a zero.

« Last Edit: February 29, 2012, 06:59:33 PM by xarax »
This is not a knot.

roo

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Re: Zeppelin Bend: Security and Strength
« Reply #51 on: February 29, 2012, 07:02:03 PM »
1. The Sheet bend IS NOT the parent of the bowline ! In fact, it has a very limited relation with the bowline, if any.
:o :o :o :o :o

Lay a sheet bend besides a bowline and cover up all but the central knot form.  Notice anything?

Or tie a bowline and only load the standing part and the one leg belonging to the "U" shape.  Notice anything?

I probably shouldn't even bother responding to this. :-\
« Last Edit: February 29, 2012, 07:06:52 PM by roo »
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xarax

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Re: Zeppelin Bend: Security and Strength
« Reply #52 on: February 29, 2012, 07:06:00 PM »
1. The Sheet bend IS NOT the parent of the bowline ! In fact, it has a very limited relation with the bowline, if any.
:o :o :o :o :o

Lay a sheet bend besides a bowline and cover up all but the central knot form.  Notice anything?

I probably shouldn't even bother responding to this. :-\

I agree 100% !  :) You should not, because you do not understand that the Sheet bend has no nipping loop as the bowline...and you have not read the relevant thread in order to start trying to learn it.
This is not a knot.

roo

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Re: Zeppelin Bend: Security and Strength
« Reply #53 on: February 29, 2012, 07:17:46 PM »
the Sheet bend has no nipping loop as the bowline.
The loop or coil of the Sheet bend most certainly "nips" the U shape of the rope.  The distal part of the U shape helps anchor that coil so that it can provide nip.

Or would you like to claim that a bowline ceases to be a bowline as soon a rotating, high-friction load causes only the leg belonging to the U shape to be loaded?
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xarax

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Re: Zeppelin Bend: Security and Strength
« Reply #54 on: February 29, 2012, 07:34:02 PM »
The loop or coil of the Sheet bend most certainly "nips" the U shape of the rope.  The distal part of the U shape helps anchor that coil so that it can provide nip.
Or would you like to claim that a bowline ceases to be a bowline as soon a rotating, high-friction load causes only the leg belonging to the U shape to be loaded?

   We have been talking about all those things, and then some, on the thread about bowlines (1). The question about the relation of the Sheet bend and the bowline, if any, has been discussed by an exchange of different views between Derek Smith and me. I have to remind you that you have vigorously insisted that this was not a "practical" matter, and you orchestrated the head to be removed from the "Practical knots" Forum, to the now extinct "Knot Theory"(!?) Forum..
  I would be glad if you have made up your mind by now, wish to read what was written there, and reply THERE.
( Many things "nip"other things, but they are not nipping loops !  :) )

1. http://igkt.net/sm/index.php?topic=3233.0
« Last Edit: February 29, 2012, 07:34:59 PM by xarax »
This is not a knot.

roo

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Re: Zeppelin Bend: Security and Strength
« Reply #55 on: February 29, 2012, 07:39:07 PM »
The loop or coil of the Sheet bend most certainly "nips" the U shape of the rope.  The distal part of the U shape helps anchor that coil so that it can provide nip.
Or would you like to claim that a bowline ceases to be a bowline as soon a rotating, high-friction load causes only the leg belonging to the U shape to be loaded?

   We have been talking about all those things, and then some, on the thread about bowlines (1).
I'm not going to sift through some protracted theoretical word fight to get an answer.   If you want to avoid the question, that is fine.  It's off topic, and you won't change your mind anyway.
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xarax

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Re: Zeppelin Bend: Security and Strength
« Reply #56 on: February 29, 2012, 07:46:03 PM »
you won't change your mind anyway.

  Is this, at last, an admission by you that I, too, have a mind - as, presumably, you do? Thank you, doctor ! :)
« Last Edit: February 29, 2012, 09:56:50 PM by xarax »
This is not a knot.

Dan_Lehman

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Re: Zeppelin Bend: Security and Strength
« Reply #57 on: February 29, 2012, 08:23:30 PM »
the Sheet bend has no nipping loop as the bowline.
The loop or coil of the Sheet bend most certainly "nips" the U shape of the rope.
The distal part of the U shape helps anchor that coil so that it can provide nip.

It is more or less, resp., of opposite-side or same-side (recommended)
sheet bends, in that the mechanics of the "loop" here
are of loading-from-one-direction and not of both ends
(of the loop) being pulled upon (50% & 100%, with friction
leading to equalization at some point, in normal cordage).
One can suggest that the same-side ("proper") sheet bend
is just a tucked version of the thief knot , to put it in
perspective --of more nearly, in effect, U-2-U workings rather
than U-2-loop.  But this is getting awfully picky.

As for security and testing,
some arborist did test the zeppelin eyeknot in a kernmantle
("static", low-elongation something or other, 8-11mm, IIRC)
rope, and found it stronger than some fig.8 he also tested
("some" meaning that the exact orientation wasn't obvious).
It held to a high rupture value, so obviously didn't slip.
Meanwhile, we have the Dave Richards testing of various
kernmantle cordage (7mm accessory, 10.2? mm dynamic,
and 12.7mm low-elongation) to show that the sheet bends
(single & double) were weaker and less secure --sometimes
needing stopper knots!-- than bowlines.


Quote
Or would you like to claim that a bowline ceases to be a bowline
as soon a rotating, high-friction load causes only the leg belonging to the U shape to be loaded?

Well, this certainly points to issues in defining "knot",
and why I use ' *knot* ' often, to alert one to some
problematic definitions.  For, surely, in the loading above,
one has an effectively different physical structure and
should expect associated behavior if so!  And I do wonder
if by such effective loadings those trawler hawser bowlines
get capsized; the capsized forms are undeniable, but
the path TO them is unknown to me, up for inference.


--dl*
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xarax

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Re: Zeppelin Bend: Security and Strength
« Reply #58 on: February 29, 2012, 09:31:20 PM »
...we have the Dave Richards testing of various kernmantle cordage (7mm accessory, 10.2? mm dynamic, and 12.7mm low-elongation) to show that the sheet bends (single & double) were weaker and less secure --sometimes
needing stopper knots!-- than bowlines.

Thanks for this information. Would it be too difficult for you to cite links ? 
 
  All those "tests" you refer to, are unique, once-happened phenomena ( should we better say "miracles" ? ), or they have been verified by reasonable repetition ? Because most of the 'knot tests" I read could not have attracted any attention, if done in any field of modern science and technology... ( And, yes, I know, middle ages were different in this requirement for "plenty" of numbers... :))

the path TO [the capsized forms of bowlines] is unknown to me

I believe we should first explore the ultimum strength of the many forms of "secure" bowline-like loops, before we would attempt to follow closely any - rare or not - collapse of those knots under extreme loading.
« Last Edit: February 29, 2012, 09:57:32 PM by xarax »
This is not a knot.