Author Topic: Zeppelin-X bend  (Read 582 times)

Harold Kahl

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Zeppelin-X bend
« on: July 31, 2018, 04:36:39 PM »
In another thread, I did some "backyard" knot jam testing of the Rigger-X Bend (aka Infinity). The Rigger-X is a modification of the Rigger's bend (aka Hunter's) where the tails are crossed inside the knot. The Rigger-X did seem to have better jam resistance than the basic Rigger. Perhaps it is even on a par with the venerable Zeppelin Bend, which, as far as I know, is the gold standard for jam resistant bend knots.

It occurred to me that we could do something similar with the Zeppelin Bend. I may not be the first person to think of this. Here is a video of how I tie these knots.
https://youtu.be/-ZBsGj4yMWc

Some preliminary backyard testing was somewhat promising. I tested two Rigger-X knots against two Zeppelin-X. (3/16" diamond braid polypropylene, loaded to 180 lb.) with the result that both zeppelin-X knots came loose in a minute or less, one Rig-X came untied in under a minute, and one Rig-X was jammed, even with use of pliers. In another trial, I tested two standard Zeppelin bends vs two Zep-X. All the knots came untied without tools, but I had to struggle a few minutes with one of the standard Zeppelins.

Take these results with a grain of salt, because my thumb nails are starting to crack and split from all this knot untying.

Given the variability of the results, I think it will take a lot more testing to prove whether the Zep-X is an improvement to the Zep, but it may be worth pursuing.

roo

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Re: Zeppelin-X bend
« Reply #1 on: July 31, 2018, 06:49:24 PM »
Dr. Asher described a version of the Zeppelin Bend called the Eastern Zeppelin, if I recall correctly.  It employed a similar or perhaps the same tail crossing. 

Book link.

I was never able to detect any benefit for the added complexity.  And as it never seemed to catch on over all these years, I don't think I'm alone.

update:  Eastern Zeppelin Bend diagram from another post:
« Last Edit: July 31, 2018, 09:31:26 PM by roo »
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agent_smith

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Re: Zeppelin-X bend
« Reply #2 on: August 01, 2018, 12:45:26 AM »
per Harold:
Quote
Given the variability of the results, I think it will take a lot more testing to prove whether the Zep-X is an improvement to the Zep, but it may be worth pursuing.

I would concur with roo in that the Zeppelin X bend offers nothing over the original geometry.
I disagree with Harry Asher's term 'eastern' - which I believe to be a direction that is arbitrary.
Direction is always relative to a reference frame.
One could easily flip Harry Asher's drawing 'upside down' - and now it becomes 'west'.

I prefer to use 'X' to denote crossing of the tails - because it is directionless.

I also think you should quietly drop the use of the term 'infinity' - it is not known by this name. The crossing of the tails is simply a modification - and does not constitute an entirely new class of knot deserving of its own unique name.

Harold, it would be good to build a little more momentum in nailing down the jamming threshold of the Riggers X bend.
We also need to test #1425A Riggers bend as a 'control'. I have a suspicion that the cord diameter may be playing a role in how difficult it is to untie a knot after loading...in that, very thin cords are hard for fingers to grasp. Obviously, the smaller the diameter, the less room there is for your fingers to grasp and pull on a segment. Is there any chance of scaling up to a some material that is of a larger diameter (eg 8.0mm)? Consider that by changing your cord/rope material, it gives you an opportunity to see if you still obtaining the same relative results...

Are you able to scale up your testing by using larger diameter cord (eg 8.0mm) and also increasing the tension force to induce jamming?
« Last Edit: August 02, 2018, 12:58:57 AM by agent_smith »

Harold Kahl

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Re: Zeppelin-X bend
« Reply #3 on: August 01, 2018, 01:51:51 AM »


Harold, it would be good to build a little more momentum in nailing down the jamming threshold of the Riggers X bend.
We also need to test #1425A Riggers bend as a 'control'.

Are you able to scale up your testing by increasing the tension force to induce jamming?
I did test the Rigger 1425A against the Rigger X as reported in post 21 of the knot jam test thread. Two 1425A were in the test sample and both needed pliers to untie. That would count as jammed by your criteria. One of the Rigger X also required pliers, so that is certainly not the last word. I'll do more testing, but I have to let my thumb nails grow back in first.

I can increase the tension a little bit, but the rope I've been using will break at the knot at about 200 lb which I tested before I did any jamming tests.

Harold Kahl

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Re: Zeppelin-X bend
« Reply #4 on: August 11, 2018, 10:51:12 PM »
Here are the results of some additional backyard jam testing of the Rigger, RiggerX, Zeppelin, and ZeppelinX bends.
Objective: test comparative jam resistance of the listed knots
Date of test: 8/11/2018
Type of rope: "Everbilt" brand Diamond braid polypropylene, 3/16 inch {4.7 mm), working load limit 60 lb.(27.2 kg)
Test equipment: Mini crane scale, Model SF-918, capacity 300 kg.; cable hoist
Knots tested: The following knots were tied in a string, with bowline knots at each end for connection to the test equipment:
1. Rigger's bend ABOK 1425A
2. RiggerX
3. Zeppelin bend
4 ZeppelinX
5 Rigger
6 RiggerX
7 Zeppelin
8 ZeppelinX
Method: The string of knots was loaded to successively higher tension and the knots loosened after each loading. Time was recorded to completely loosen the knot, but the knots were not necessarily taken apart. The knots were re-dressed or re-tied if necessary each time. In the final trial, loading was increased until the rope broke. In this case it broke at knot 8 at about 220 lb.

Results
120 lb: knot 1 30 sec; knot 2 31 sec, knot 3 29 sec; knot 4 20 sec, knot 5 50 sec; knot 6 22 sec; knot 7 17 sec; knot 8 16 sec
140 lb.: (1) 35; (2) 26; (3)30; (4) 59; (5) 39; (6) 40; (7) 35; (8) 27
160 lb.: (1) 30; (2) 16; (3)20; (4) 30; (5) 78; (6) 28; (7) 16; (8) 35
180 lb.: (1) 48; (2) 18; (3)22; (4) 16; (5) 60; (6) 20; (7) 21; (8) 23
220 lb.: (1) JAM; (2) 62 (pliers); (3)30; (4) 240 (pliers); (5) JAM; (6) 34; (7) 30; (8) broken

Conclusions: Up to 180 lb, which is 3 times the rated working limit, none of the knots jammed, though one of the two riggers was a little bit difficult. These knots are all pretty jam resistant if they are not extremely overloaded.
At 220 lb., both Riggers were jammed solid. Based on this test, it appears that the basic 1425A Rigger loses out to the other three knots tested. One might be tempted to conclude that the ZeppelinX is inferior to the RiggerX and base Zeppelin bends. However, in a previous test of the same type of rope at 180 lb, one RiggerX jammed while another RiggerX and two ZeppelinX did not jam. Therefore I will not declare a winner or loser among the RiggerX, Zeppelin, or ZeppelinX.

One take-away from my testing is that nothing much can be concluded from any single data point. Lots of trials have to be done to develop any kind of trend.

agent_smith

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Re: Zeppelin-X bend
« Reply #5 on: August 12, 2018, 02:51:13 PM »
Thanks, and nice work Harold.

Some clarifications please...

Although not clearly written as such, it is presumed #1 and #5 are the same?
Same issue with #3 and #7.
Best to be absolutely clear with your naming conventions.

The 2 instances of jamming occurred at 220 lbs (0.97kN).
Were these jams 'initial/threshold' jamming or 'maximal jamming'?

Maximal jamming means that not even tools will not loosen the knot.

You didn't indicate if one collar or the other was easier or more difficult to loosen.
Was there a tendency for the collar facing the force generating machine to jam? (or not?)

In terms of #1425A Riggers bend versus Riggers X bend:
[ ] did #1425A  have a significantly lower initial/threshold jamming level compared to Riggers X bend?
Or;
[ ] was there no significant difference?

Full disclosure... in my tests, I found Riggers X bend to have a higher resistance to jamming compared to #1425A Riggers bend.

EDIT NOTE: A new topic category for knot test reports has been created. Maybe you should post your test report there?
« Last Edit: August 13, 2018, 12:42:57 AM by agent_smith »