Author Topic: Bend: Square Knot with Secured Working Ends  (Read 11118 times)

knot4u

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Bend: Square Knot with Secured Working Ends
« on: November 07, 2010, 04:43:00 PM »
(There's a thread out there discussing this, but I can't find it...)

The bend is a square knot with secured working ends.  Many webpages on the Internet quote Ashley who said, "There have probably been more lives lost as a result of using a square knot as a bend (to tie two ropes together) than from the failure of any other half dozen knots combined."  That's where I believe the bad reputation of this bend originates.

HOWEVER, I think Ashley was talking about a square knot WITHOUT secured working ends.  I'm essentially talking about a different knot.  According to my brief testing, this bend is good for ropes of different diameters (and ropes of the same diameter of course).  Thoughts?


Square Bend with Working Ends Secured by using Zeppelin Knots
(aka, Zeppelin Loops Interlocked)
« Last Edit: November 07, 2010, 05:49:54 PM by knot4u »

SS369

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Re: Bend: Square Knot with Secured Working Ends
« Reply #1 on: November 07, 2010, 05:12:43 PM »
It became good or better because of the change in the loading, now shared. In my humble opinion that is.
You've effectively changed the original bend into another by the loading (now) of both the working and standing parts.
So is it still a Square knot?
Could do the same thing with many other tie off/ loop knots, ie, Bowline, etc.
Putting a large stopper in both lines would keep it secure to a point as well.

This does beg the question: When does a knot become another and stop being the original?

SS

Sweeney

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Re: Bend: Square Knot with Secured Working Ends
« Reply #2 on: November 07, 2010, 07:01:33 PM »
In effect this is 2 loops interlocked - you could achieve this by using any 2 loops as long as you have access to at least one end by simply reeving one loop through the other (a bale sling hitch/cow hitch etc) rather than tying a reef/square knot and securing the ends. One could tie a reef knot and then simply half hitch the ends close to the knot to stop slippage.

Accepting that the knot in the middle is a reef/square knot no matter how formed then to me there are 3 separate knots not one - not least because they are clearly separated from each other. Perhaps we could call an arrangement like this a "compound bend"? I have see similar shown for joining two markedly different ropes by interlocking 2 bowlines avoiding some of the chafe caused if the 2 bowlines are simply tied one through the loop of the other.

Sweeney

DerekSmith

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Re: Bend: Square Knot with Secured Working Ends
« Reply #3 on: November 07, 2010, 07:42:31 PM »
 That's where I believe the bad reputation of this bend originates.


My personal opinion is that the reputation of the Reef Knot stems from its near obligate insistence under use, to transform into a Cow Hitch on a straight cord, and for the straight cord to then proceed to work out through the Cow hitch.  I believe that this propensity is in no way engendered by Ashley's documentation of it - it rightfully earned its reputation all by itself.

I agree that securing the 'ends' prevents failure, even if the Reef manages to transform itself - but herein lays the challenge posed by Scott - when is a secured Reef knot not a Reef knot?

By definition, in securing the ends, it is no longer the Reef Knot - it is now a "Reef with secured ends" - or if it has responded to differential cord stiffness in use, it will soon be one loop Cow hitched to another.  Then you have decomposed your bend into two interlocked loops, each with the weaknesses inherent in the respective loop knots.

If you are going to bend two cords together, why antagonise the problem by making two knots instead of one?  But then we are only a stroll away from asking when is a 'complex' knot an assembly of knots?

Derek

knot4u

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Re: Bend: Square Knot with Secured Working Ends
« Reply #4 on: November 07, 2010, 08:04:42 PM »
It's titled the way it is for identification purposes.  I understand the equivalence to loops interlocked with Cow Hitches, but for me this contraption is easier to explain and visualize if you say it's a Square knot with secured working ends.

As to the purpose, here are some advantages...

  • It's good to have options.
  • The value of a knot is not always apparent.  I have used some knots that are not on my Favorites that were best for the job.  For example, I never thought I would use the Slippery Eight Loop until one day it was about the best knot for the application.
  • This contraption is easy to remember.  If a person can only remember a Square and a Bowline, then the person could still make a good (or great) bend for many situations.  That is, if this contraption is actually a good bend.  Is it?  I don't know.
  • For certain applications, this contraption may be stronger or securer than some other bends that people love.  For example, I may tie this contraption if I'm joining ropes of vastly different diameters or different materials.  I've tested the Zeppelin Bend, the Carrick Bend and other bends.  They don't work too well in these situations, or at least I wouldn't use them.
  • Unlike plain interlocked loops (without the Square in the middle), this contraption prevents rope rubbing and damage.
  • Unlike a plain Square knot for binding, this contraption has not jammed on me.
« Last Edit: November 07, 2010, 09:46:15 PM by knot4u »

Sweeney

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Re: Bend: Square Knot with Secured Working Ends
« Reply #5 on: November 07, 2010, 10:17:11 PM »


  • For certain applications, this contraption may be stronger or securer than some other bends that people love.  For example, I may tie this contraption if I'm joining ropes of vastly different diameters or different materials.  I've tested the Zeppelin Bend, the Carrick Bend and other bends.  They don't work too well in these situations, or at least I wouldn't use them.
  • Unlike plain interlocked loops (without the Square in the middle), this contraption prevents rope rubbing and damage.


I would agree with these 2 points in particular. When posting earlier I had in mind that I had seen a similar configuration before and in fact it was a double fisherman's knot (or grinner knot) where the 2 double overhand knots were separated by a reef knot thus preventing them from jamming too tightly (if I remember correctly Owen Nuttall came up with this).
« Last Edit: November 07, 2010, 10:17:50 PM by Sweeney »

DDK

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Re: Bend: Square Knot with Secured Working Ends
« Reply #6 on: November 08, 2010, 02:40:36 AM »
...  So is it still a Square knot? ...
... This does beg the question: When does a knot become another and stop being the original? ...

I wonder as well if this isn't more aptly described as a modified Zeppelin Loop Bend.

As far as is it still a Square/Reef Knot, I think I have a definitive answer ... that answer is No.  My reasoning is that, since it started as a Thief Knot, how could it "stay" a Square/Reef Knot?  ;)

DDK

knot4u

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Re: Bend: Square Knot with Secured Working Ends
« Reply #7 on: November 08, 2010, 04:08:29 AM »
My reasoning is that, since it started as a Thief Knot, how could it "stay" a Square/Reef Knot?

Keen observation... If you untie the Zeppelins, yes, you would have a Thief Knot.  Performance-wise, it doesn't seem to matter if the middle knot is a Thief or a Square, unless you need the working ends to be on the same side.  Aesthetically, I do like a Thief better here.  ;)
« Last Edit: November 08, 2010, 04:37:33 AM by knot4u »

DDK

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Re: Bend: Square Knot with Secured Working Ends
« Reply #8 on: November 08, 2010, 05:49:14 AM »
... Aesthetically, I do like a Thief better here.  ;)

Absolutely.  No doubt it was the striking appearance of the central inversion symmetry which gave its presence away.

e.g. central inversion symmetry - http://igkt.net/sm/index.php?topic=1992.msg14579#msg14579

...  Performance-wise, it doesn't seem to matter if the middle knot is a Thief or a Square, unless you need the working ends to be on the same side. ...

I wonder if under load the middle structure will behave partly or mostly "Thief-like" and will distort as such with the associated constructive cogging.  A question which may be difficult to answer is how much does the middle structure bring to the party as far as security is concerned.  If the behavior is exactly "Thief-like", it may not be that much.  That is, the bend may be only slightly more secure than an unmodified Zeppelin Loop Bend.  The one caveat I would add is that the larger radii of curvatures found in the middle structure which tend to increase break strength are usually to be favored to those found in the unmodified Zeppelin Loop Bend.  This may not be of major concern given that the tension in the loop is already half of the total load.

e.g. constructive cogging - http://igkt.net/sm/index.php?topic=1597.msg10962;topicseen#msg10962

As an aside, one could replace the Thief Knot middle structure with a Figure Eight Bend and maintain the central inversion symmetry.   :o
 
DDK
« Last Edit: November 08, 2010, 06:34:27 AM by DDK »

knot4u

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Re: Bend: Square Knot with Secured Working Ends
« Reply #9 on: November 08, 2010, 07:14:41 AM »
I wonder if under load the middle structure will behave partly or mostly "Thief-like" and will distort as such with the associated constructive cogging.

No need to wonder, test it out!  :)  According to my testing, it makes no difference if it's a Thief or a Square in the middle.  Anyway, it may be advantageous for the middle structure to act like a Thief Knot if it could.  That way, I think the tension would tend to be naturally balanced on each leg of each loop.  What I'm saying is that it may be good for the middle structure NOT to hold super securely.  The securing knots are where most of the security is and should be.

I wonder if under load the middle structure will behave partly or mostly "Thief-like" and will distort as such with the associated constructive cogging.  A question which may be difficult to answer is how much does the middle structure bring to the party as far as security is concerned.  If the behavior is exactly "Thief-like", it may not be that much.  That is, the bend may be only slightly more secure than an unmodified Zeppelin Loop Bend.  The one caveat I would add is that the larger radii of curvatures found in the middle structure which tend to increase break strength are usually to be favored to those found in the unmodified Zeppelin Loop Bend.  This may not be of major concern given that the tension in the loop is already half of the total load.

The tension at the point of contact with the other loop is the full load, but the tension on each leg of loop would be half the load.  In other words, half plus half equals full tension at point of contact (and full tension at each Zeppelin Knot).

As an aside, one could replace the Thief Knot middle structure with a Figure Eight Bend and maintain the central inversion symmetry.

That's a different concept.  The working ends would end on the other side of the knot such that each working end would NOT be secured to the standing end of its own rope.

In contrast, in the original post, each working end is secured to the standing end of it's own rope.  Don't forget that a big advantage here is that the contraption in the original post can be used with vastly different diameters.  I'm talking about something crazy like bending a bootlace with a thick 300 lb rated rope from Home Depot.  I've tested the contraption in the original post to bend such a rope difference.  It works fine, but using a Figure 8 in the middle would NOT work well for bending such a rope difference.
« Last Edit: November 08, 2010, 08:45:35 AM by knot4u »

Transminator

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Re: Bend: Square Knot with Secured Working Ends
« Reply #10 on: November 08, 2010, 09:16:10 AM »
HOWEVER, I think Ashley was talking about a square knot WITHOUT secured working ends.  I'm essentially talking about a different knot.  According to my brief testing, this bend is good for ropes of different diameters (and ropes of the same diameter of course).  Thoughts?

My initial thought was: why bother?

why bother tying a knot that needs backup instead of using a better one in the first place?
This looks like a knot that is rather awkward to tie (first a reef knot and then two zeppelins to secure the ends)
> why not use a zeppelin to bend the ropes and you are done!

greetings

Sweeney

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Re: Bend: Square Knot with Secured Working Ends
« Reply #11 on: November 08, 2010, 09:55:28 AM »
I don't see any value in this arrangement (2 loops linked via a reef knot) as a means of securing a reef knot - indeed why bother. But it does have merit when joining a very heavy line to a very light or thin one to avoid chafe at the point of contact of the 2 loops as has already been said a couple of times. Looked at only fulfilling this need there is some value in remembering it.

Sweeney

DerekSmith

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Re: Bend: Square Knot with Secured Working Ends
« Reply #12 on: November 08, 2010, 11:37:12 AM »
HOWEVER, I think Ashley was talking about a square knot WITHOUT secured working ends.  I'm essentially talking about a different knot.  According to my brief testing, this bend is good for ropes of different diameters (and ropes of the same diameter of course).  Thoughts?

My initial thought was: why bother?

why bother tying a knot that needs backup instead of using a better one in the first place?
This looks like a knot that is rather awkward to tie (first a reef knot and then two zeppelins to secure the ends)
> why not use a zeppelin to bend the ropes and you are done!

greetings

Why Bother?

Because it is a great way of joining two cords of dissimilar thickness, or two cords with other dissimilarities such as stiffness, slipperiness etc.  Our loop knots are generally well adapted to tying to themselves but bends between different materials are notoriously fickle.  So making a loop of thinner, softer cord and having it 'Cow Hitched' to a thicker, stiffer loop is an excellent way of bending those different cords safely to one another - AND we don't need to remember specialised knots for joining different media.

Having highlighted the solution though, I don't think I would go to the hassle of making the Reef and then making the loop knots - I think I would rather settle for tying an OH loop in a bight on the thicker/stiffer rope (it should not be overloaded because the other cord is lighter - weaker?), then Cow Hitch the lighter cord to the loop and tie a BWL by slipping an OH into the SP of the lighter cord, passing the end through the slipped loop, then making the BWL by drawing back the slipped loop.

Of course, if the application is open to unloaded 'flogging' and the cord is one that doesn't particularly enjoy being in a BWL, then perhaps just tying off the end to the SP with a (double)strangle might be preferable.

Derek

Transminator

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Re: Bend: Square Knot with Secured Working Ends
« Reply #13 on: November 08, 2010, 02:19:06 PM »

Because it is a great way of joining two cords of dissimilar thickness, or two cords with other dissimilarities such as stiffness, slipperiness etc.  Our loop knots are generally well adapted to tying to themselves but bends between different materials are notoriously fickle.  So making a loop of thinner, softer cord and having it 'Cow Hitched' to a thicker, stiffer loop is an excellent way of bending those different cords safely to one another - AND we don't need to remember specialised knots for joining different media.

Good point Derek.
I see how this improves the option to join two sets of dissimilar ropes (different material, different diameter) with two interlinked loop knots by not just interlinking them but reef knotting the loops together.
Therefore not only the zeppelin could be used, but also any form of the bowline or the double dragon or any combination of the secure loop knots.
I did not mean my "why bother" in a disrespectful way, by the way. For the above mentioned situation, it is indeed an option, but not as a general bend (as it is overkill if the ropes are similar and there are easier options).

Other ideas might be:
1. in my tests the zeppelin and the butterfly bend have been surprisingly reliable with completely different types of ropes (both have not failed, whereas the double sheet bend did)
would I abseil from a burning building with this configuration?> probably not  ;D
2. Zeppelin or butterfly bend in which the thinner rope is tucked twice through the two eyes (the double sheet bend principle) before tightening
3. zeppelin bend in which the two ends are bend with another zeppelin as security


DerekSmith

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Re: Bend: Square Knot with Secured Working Ends
« Reply #14 on: November 08, 2010, 02:22:05 PM »
Oh that is a GOOD piece of detailed observation by DDK, spotting that this was a Thief configuration before it was made into meshed loops.  Only after having been given the heads up and a much more detailed examination of the image, did I realise that the picture actually holds this information - Well spotted DDK.



However, as far as this statement is concerned  --


As far as is it still a Square/Reef Knot, I think I have a definitive answer ... that answer is No.  My reasoning is that, since it started as a Thief Knot, how could it "stay" a Square/Reef Knot?  ;)

DDK

Knot4U said that it was a Square knot and made no mention of 'Reef' (I think that was my wrong conclusion) and as a Thief is a Square knot, then the answer does not stand, because "since it started as a Thief Knot" - it ended as a thief knot.

NB  Am I wrong, but in order to tie the Zeppelin Loop, wouldn't an OH have had to have been tied in the SP before making the Square knot (unlike a BWL which can be made without any prior preparation).  Wouldn't this 'pre assembly' spell out that the square knot was only a part of the final construction, adding weight to DDK's suggestion that "I wonder as well if this isn't more aptly described as a modified Zeppelin Loop Bend."

Derek
« Last Edit: November 08, 2010, 03:52:02 PM by DerekSmith »