Author Topic: Knots secure enough to trust with my life  (Read 8190 times)

erizo1

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Knots secure enough to trust with my life
« on: February 29, 2012, 03:56:33 PM »
I'm new to knot tying and eager to learn. After a question on a thread about the security of the Zeppelin bend and loop (http://igkt.net/sm/index.php?topic=1902.45), I got a reply that made me want to pursue this topic more.

I'm very new to knot tying. I'm interested in loops at the moment, and in the zeppelin loop in particular. 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?
...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*
====

So here are the follow-up questions to start this thread:

In abseiling, what bend(s) would be preferred and why? What are the reasons not to use a zeppelin bend? I'm interested in what makes a knot worthy of trust with a person's life, as well as in the practicalities of a knot designed for that particular use.

Taking into account ease of both tying and untying, what are a couple of other good eye knots secure enough for tying in? I find the standard rethreaded figure-eight bothersome - takes too long to tie and dress properly. I'd love to know a few of the lesser-known knots you have in mind, and I'm also curious which bowline variations are secure enough for use in climbing. Is the round-turn bowline secure enough for this, as I've seen asserted on one page?
« Last Edit: February 29, 2012, 04:00:32 PM by erizo1 »

xarax

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Re: Knots secure enough to trust with my life
« Reply #1 on: February 29, 2012, 04:30:44 PM »
   Nobody questioned the security of the so-called "Zeppelin loop"...And he could have not done this, without results of properly performed security tests.
   It is is the cleverness of the solution - to just use a secure bend, and transform it to an end-of-line fixed loop knot- that has been questioned. If you really like secure and dumb solutions, the so-called "Zeppelin loop" is fine !
   There is also another reason the so-called "Zeppelin loop" is not-so-clever : It is because the original, authentic Zeppelin knot, the Zeppelin bend,  is SO clever !  :) It is a rope-made hinge, where the pair of tails are used as the pivot. The so-called "Zeppelin loop" is only a pathetic caricature of this, it is just another tangle of ropes that can also work as a knot...The beauty, simplicity, out most symmetry, the even distribution of tensile forces within the knot s nub, the easiness of tying, the easiness of inspecting, all those things so characteristic of the symmetric bends in general, and the Zeppelin bend in particular, are lost in this ugly monster...
   Let us now go one step beyond those obvious facts...In an end-of-line loop knot, the two ends are loaded with approximately 50% of the load, the third with 100%m, and the fourth with 0%.  In a bend, the two ends are loaded with 100%, and the other two with 0%. I guess one should not be a rocket scientist, to see that a fine and clever solution in the later, may be not be so fine and so clever in the former ! A fine and clever loop knot should treat the standing end, with the 100% of the load on its shoulders, DIFFERENTLY than the two ends of the bight - the eye leg of the standing part and the eye leg of the bight - that carry only half of this load. To treat those ends differently,  is not addressing a problem of security, but it might well be a solution of strength - and it is the rational, clever thing one should do.
   
 
« Last Edit: February 29, 2012, 04:35:52 PM by xarax »
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xarax

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Re: Knots secure enough to trust with my life
« Reply #2 on: February 29, 2012, 04:53:15 PM »
I'm also curious which bowline variations are secure enough for use in climbing. Is the round-turn bowline secure enough for this, as I've seen asserted on one page?
  With convoluted enough knots, and not very slippery materials, I guess that any "secure" bowline would be secure enough - and it might also be helped further by an additional 'lock" - i.e. used as one part of a compound knot. Having said that, nobody should trust a knot that is not tested, and tested properly, and repeatedly. There are many "secure" bowlines presented in this Forum, just search posts with the key-word "bowline". However, none of them is tested as it should - simply because we do not have any willing or capable knot tyers to do the dirty job !  :) Until we have tested ALL those knots, one should probably do what most people do : do what most people do ! Tie a retraced fig. 8 or a retraced 2 fig. 9 knot.
« Last Edit: February 29, 2012, 04:54:55 PM by xarax »
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roo

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Re: Knots secure enough to trust with my life
« Reply #3 on: February 29, 2012, 05:39:55 PM »
So here are the follow-up questions to start this thread:

In abseiling, what bend(s) would be preferred and why? What are the reasons not to use a zeppelin bend? I'm interested in what makes a knot worthy of trust with a person's life, as well as in the practicalities of a knot designed for that particular use.

Taking into account ease of both tying and untying, what are a couple of other good eye knots secure enough for tying in? I find the standard rethreaded figure-eight bothersome - takes too long to tie and dress properly. I'd love to know a few of the lesser-known knots you have in mind, and I'm also curious which bowline variations are secure enough for use in climbing. Is the round-turn bowline secure enough for this, as I've seen asserted on one page?
I've replied to some of this in the other thread, so I'll try not to re-hash stuff too much here.  The only reason I can think of for not using the Zeppelin Bend is unfamiliarity.  Just as with any other bend, if you're not comfortable with execution and inspection yet, you should hold off until you have it mastered.

As for loops other than the Zeppelin Loop for alternatives to the Figure Eight Loop, I would have you consider the Water Bowline.  It should be a natural extension for anyone familiar with the quick-tie method of the bowline.  It's more secure than the Double Bowline, although the Double Bowline isn't horrible, either.

Test them all in the material and conditions that you expect to see, and go with what you are comfortable.
« Last Edit: October 12, 2014, 05:58:09 PM by roo »
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erizo1

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Re: Knots secure enough to trust with my life
« Reply #4 on: February 29, 2012, 06:15:12 PM »
Thanks very much!

Dan_Lehman

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Re: Knots secure enough to trust with my life
« Reply #5 on: February 29, 2012, 07:18:18 PM »
In abseiling, what bend(s) would be preferred and why?
What are the reasons not to use a zeppelin bend?
I'm interested in what makes a knot worthy of trust with a person's life,
as well as in the practicalities of a knot designed for that particular use.

Discussion of abseil-ropes-joining knots can be found (with
images) here:
www.rockclimbing.com/cgi-bin/forum/gforum.cgi?post=2091962;search_string=offset%20fig.9;#2091962

The zeppelin bend can be faulted for two reasons:
1) it is not *offset* and so will not flow over rough surfaces & edges;
2) it is rather *open* in structure --not a compact-tight knot-- and so
suggests vulnerability to further loosening and snagging to be pulled open.

The principal quality for an ARJ knot is security, and then beyond that
are ease of tying (correctly), ability to avoid getting snagged or caught
up on edges, and ease of untying.

Quote
Taking into account ease of both tying and untying,
what are a couple of other good eye knots secure enough for tying in?
I find the standard rethreaded figure-eight bothersome - takes too long to tie and dress properly.
I'd love to know a few of the lesser-known knots you have in mind,
and I'm also curious which bowline variations are secure enough for use in climbing.
Is the round-turn bowline secure enough for this, as I've seen asserted on one page?

One can take the fig.8 start (i.e., tie an 8 in the SPart)
and finish it in ways that are both simpler, definite (almost
nowhere does anyone give express dressing guidance!),
secure, and easy to untie.  I'll attach photos to this post of what
I proudly name the "Lehman8" and --hmmm-- "Collared8"
(to which knots' common mid-state of completion lies what I
call the "Quick8" and then "tucked Quick8" in which the
tail is left, respectively, as-is after its initial insertion & tuck, or else
taken from there and tucked out between the eye legs (by which
one might gain some slack-security in this loop's nipping of the
fig.8's body)).  The design goal of the Lehman8 was to
get the apparently stronger fig.8 "padded-path(tm)" geometry
with the bowline's easy-to-loosen *collar* closure;
I think it meets this pretty well, but have no insight as to actual
strength (but will assert that any difference is likely small &
insignificant, practically!).

(In urethane-coated 5/16" 12-strand Dyneema rope, the
Quick8 proved relatively weaker among a few tested knots,
but did not slip --though it appears that the "tucked" finish
was necessary to prevent slippage (but, hey, that base has only
a 2-nip, pretty straight-through-passage of the tail!).  Please note
that this material is an extraordinary one, unlike common cordage!)

((rupture analysis of Tucked Quick8
The white marker threads were sewn in at points where the rope
parts exited/entered the knot, so to show the degree of knot
compaction/compression or slippage as they are drawn away
(or, for the unloaded tail, sucked in).  The pink thread was sewn
at the point I deemed probable for rupture, AS SET; the gold
was the point  ... probable to come into rupture position, if
not an alternative point.  In this case, we see some compaction
of the knot, with white threads of loaded strands pulled away;
note the slight difference between eye legs (the lower and more
pulled-away leg is that of the tail).

The upper knot equals the ruptured lower knot, and was at the
opposite end of the test speciemen, subjected to equal tension
--hence, it's our insight into geometry changes/effects!

The apparent break point came a little inside the knot, as the
SPart bent around other parts --though the rupture segment
is not all so pointpoint precise, and it COULD be that rupture
began farther *into* the knot (more around the eye leg(s)),
and then got distributed thereafter.  In this photo, the tails
are coming at us and it's hard to gauge how much they
might've been "sucked in;" but other perspectives show that
it was not much (and, I think, to some extent, the turn of
the SPart is working to come back over them!)
))


--dl*
====
« Last Edit: February 29, 2012, 07:28:29 PM by Dan_Lehman »

xarax

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Re: Knots secure enough to trust with my life
« Reply #6 on: February 29, 2012, 07:19:19 PM »
   Do not let the misleading name of the so-called "Zeppelin loop" confuse you, and succeed in making you believe that the quality of the superb Zeppelin knot, the Zeppelin bend, can somehow be "transported" to this ugly dumb monster, the so-called "Zeppelin loop", by sympathetic magic !  :) Because this is a cunning strategy that attempts to sell this end-of-line loop knot, and hide the many other knots we already have. There are many bowline-like loops offering the same, and even superior, security and strength than any eyeknot that needs an overhand knot tied on the standing part before the tip of the bight.
This is not a knot.

roo

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Re: Knots secure enough to trust with my life
« Reply #7 on: February 29, 2012, 07:26:00 PM »
There are many bowline-like loops offering the same, and even superior, security
Name one.

It had better not be an "ugly dumb monster".  You should also let us know what testing you did to determine this, since one of your most common phrases is "I have not tested this".
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roo

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Re: Knots secure enough to trust with my life
« Reply #8 on: February 29, 2012, 07:45:56 PM »
Quote from: Dan_Lehman link=topic=3810.msg22474#msg22474
The [i
zeppelin bend[/i] can be faulted for two reasons:
1) it is not *offset* and so will not flow over rough surfaces & edges;
2) it is rather *open* in structure --not a compact-tight knot-- and so
suggests vulnerability to further loosening and snagging to be pulled open.
Point 1 is based largely on conjecture.  A European Death Knot that is "supposed" to not get caught on sharp edges may get caught in crevices or other narrowings (branches) due to its bulk which exceeds the Zeppelin Bend.

I don't really see the openness of a properly-set Zeppelin bend (with or without asterisks).  Can you produce any hard evidence of a snag pulling a Zeppelin Bend open?  I doubt it.
« Last Edit: February 29, 2012, 07:50:39 PM by roo »
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Dan_Lehman

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Re: Knots secure enough to trust with my life
« Reply #9 on: February 29, 2012, 08:39:17 PM »
Quote from: Dan_Lehman link=topic=3810.msg22474#msg22474
The [i
zeppelin bend[/i] can be faulted for two reasons:
1) it is not *offset* and so will not flow over rough surfaces & edges;
2) it is rather *open* in structure --not a compact-tight knot-- and so
suggests vulnerability to further loosening and snagging to be pulled open.
Point 1 is based largely on conjecture.  A European Death Knot that is "supposed"
to not get caught on sharp edges may get caught in crevices or other narrowings
(branches) due to its bulk which exceeds the Zeppelin Bend.

There is no conjecture about the flow over surfaces,
which is readily demonstrable to any who care to look
--the edge of a desk is often an immediate structure
for testing that.  As for some "V" narrowing, that could
catch any knot, yes.  The "bulk" of the EDK/ORB hardly
much exceeds the zeppelin's --and with parallel tails,
it lacks the poking out of them, as well.

Against the point, though, comes some considerable
user testimony to having successfully used non-offset
knots w/o difficulty, or to having difficulty where an offset
knot wouldn't have helped.

Quote
I don't really see the openness of a properly-set Zeppelin bend (with or without asterisks).
Can you produce any hard evidence of a snag pulling a Zeppelin Bend open?  I doubt it.

(The asterisks indicate a qualified use of the word.)
A zeppelin doesn't get set so snugly as many knots,
and as the ORB ; there are spaces around the collars,
which is why the knot can be untied so easily.  This is
enough to give some concern to me about snagging,
although both unlikely to occur, and then arguably
unlikely IF occurring to be severe?

So, yes, it's more an *apparent* than any confirmed
worry.  But there is no positive quality moving me to
use the knot vice others, for which I haven't even this
concern.


--dl*
====
« Last Edit: December 09, 2013, 06:18:35 AM by Dan_Lehman »

roo

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Re: Knots secure enough to trust with my life
« Reply #10 on: February 29, 2012, 08:46:35 PM »
Quote from: Dan_Lehman link=topic=3810.msg22483#msg22483
   As for some "V" narrowing, that could
catch any knot, yes.  The "bulk" of the EDK/ORB hardly
much exceeds the zeppelin's --and with parallel tails,
it lacks the poking out of them, as well.
Anyone who cares to check (with holes or gaps of various sizes) can see that the European Death Knot gets caught in gaps that the Zeppelin Bend pulls through.  Those tails poking out of the Zeppelin Bend bend back easily.  Throwing a wave down the rope doesn't help much with a size-based interference, compared to a mere sharp edge scenario. 
« Last Edit: March 01, 2012, 09:26:41 PM by roo »
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xarax

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Re: Knots secure enough to trust with my life
« Reply #11 on: March 01, 2012, 12:24:41 AM »
One can take the fig.8 start (i.e., tie an 8 in the SPart)

   Now, what if one does not want to have the fig. 8 knot tied on the standing part, "before" the tip of the loop, but "after" the tip, on the tail ? I believe that what can be done on the standing part, can also be done on the tail... so we get a bowline-like loop. I am personally interested on those loops, because I want knots that can be completely untied before the tail gets out of the ring, or bollard, or waist - so, when the tail is released from its entanglement with the standing part, there is no knot left on the line that can be caught somewhere and cause problems.
   Have you tried the same or similar knots with a shape 8 unknot ? I think that what you seek is already given by the geometry of the 8, and not by the topology, so why use a fig. 8, when you can use a shape 8 ?
   Have you bought your new camera, or just decided is about time to let us have a glimpse on your top-secret archives ?  :) ( By the way, I think that the shades in your pictures are somewhere too dark, and somewhere not dark enough...Anyway, at last we have PICTURES as well as words... I hope this trend will continue.)
   
   
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knot4u

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Re: Knots secure enough to trust with my life
« Reply #12 on: March 01, 2012, 01:54:37 AM »
Videos worth watching about testing the Zeppelin Bend...

http://www.youtube.com/watch?v=Givv9cBB_Hw
http://www.youtube.com/watch?v=_-uQrx7yPYM
« Last Edit: March 01, 2012, 02:48:17 AM by knot4u »

xarax

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Re: Knots secure enough to trust with my life
« Reply #13 on: March 01, 2012, 03:03:09 AM »
Videos worth watching about testing the Zeppelin Bend...

  I wonder why they almost never put the bends to destructive tests, to measure their ultimum strength...the "absolute" number we were talking about. Also, we should know the ultimum strength of the material used... In short, we want more numbers, and fewer pictures of knot tests - just as we want more pictures, and fewer words of knot structures... :)
 
« Last Edit: March 01, 2012, 03:03:45 AM by xarax »
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knot4u

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Re: Knots secure enough to trust with my life
« Reply #14 on: March 01, 2012, 03:35:24 AM »
For this thread, I don't think a destruction test would provide information that's more useful. Also, in the first video, you can see the rope used and the load in precise poundage, which is a lot more experimental data than about 99.79% of the posts on this site.
« Last Edit: March 01, 2012, 03:57:22 AM by knot4u »