Author Topic: Double Dragon Loop trumps the Bowline Family?  (Read 11739 times)

Festy

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Double Dragon Loop trumps the Bowline Family?
« on: June 02, 2014, 06:52:39 PM »
That is my query.

The DDL is easy to tie, is easy to remember, and is a safe knot (or so it seems to this amateur knotter).

There is no multitude of ways to tie it, lock it and whatnot like there is with the bowline.

So, for someone who just wants to remember how to tie enough knot types to get by, is the DDL a good way to go?

cheers


roo

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Re: Double Dragon Loop trumps the Bowline Family?
« Reply #1 on: June 02, 2014, 07:33:03 PM »
That is my query.

The DDL is easy to tie, is easy to remember, and is a safe knot (or so it seems to this amateur knotter).

There is no multitude of ways to tie it, lock it and whatnot like there is with the bowline.

So, for someone who just wants to remember how to tie enough knot types to get by, is the DDL a good way to go?

cheers
There are a few ways of tying the double dragon loop, but the simple way has a fundamental problem in that you cannot thread the rope around or through an object before closing.  That's somewhat important for an end loop. 

The loop isn't suitable for on-the-bight use as it can jam in that configuration unless one side of the parent line is unloaded.

In stiffer rope, the security of the double dragon isn't as much as one would expect from a loop with such complexity.  A water bowline does better:

http://notableknotindex.webs.com/waterbowline.html
Update:  related: http://notableknotindex.webs.com/monsoonbowline.html

The double dragon loop also has some problems with stability when the two legs of the loop are pulled in opposite directions.
« Last Edit: June 21, 2014, 10:47:49 PM by roo »
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Festy

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Re: Double Dragon Loop trumps the Bowline Family?
« Reply #2 on: June 02, 2014, 08:13:31 PM »

There are a few ways of tying the double dragon loop, but the simple way has a fundamental problem in that you cannot thread the rope around or through an object before closing.  That's somewhat important for an end loop. 



http://www.southee.com/Knots/Knots_SingleLoops.htm

see no. 5, Method #2

Maybe I'm wrong, but this seems to do what you describe above?


roo

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Re: Double Dragon Loop trumps the Bowline Family?
« Reply #3 on: June 02, 2014, 08:53:57 PM »

There are a few ways of tying the double dragon loop, but the simple way has a fundamental problem in that you cannot thread the rope around or through an object before closing.  That's somewhat important for an end loop. 



http://www.southee.com/Knots/Knots_SingleLoops.htm

see no. 5, Method #2

Maybe I'm wrong, but this seems to do what you describe above?
That's why I specified the "simple" method.  The alternate method is very prone to misremembering and error.
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Festy

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Re: Double Dragon Loop trumps the Bowline Family?
« Reply #4 on: June 02, 2014, 09:02:40 PM »
That's why I specified the "simple" method.  The alternate method is very prone to misremembering and error.

copy that

xarax

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Re: Double Dragon Loop trumps the Bowline Family?
« Reply #5 on: June 02, 2014, 09:11:21 PM »
   The Double Dragon is a fine loop - provided it is double ! :) I mean, it is the doubled version of the Tugboat A loop, shown at :
   http://daveroot.atspace.cc/knots/Knots_SingleLoops.htm#PerfectionLoop
   http://daveroot.atspace.cc/knots/Knots_SingleLoops.htm#DoubleDragon
   The main problem with the single version, the Tugboat A, is that the positions of the continuations of the eye legs may be swapped inside the nipping loop, resulting in an unstable knot, which can be severely deformed under heavy loading. I say " they may be swapped", because/although this had never happened to the few, only, Tugboat A loops I had tied and tried in my life - but as it can happen, I have to suppose that, eventually, obeying Murphy s Law, it will happen...
   The "doubled" version is supposed to address this problem, because the nub of the Double Dragon s eye-knot is more voluminous, spherical and compact than the nub of the Tugboat A, and the positions of the corresponding segments of the rope inside it are now more stable : they can not swap positions very easily. Also, the second wrap of the collar structure keeps the nipping structure "closed", and, with the help of the friction and the stiffness of the rope, it retains its integrity and prevents any severe deformation. However, the problem of the two possible dressing forms, of which the one is much better, stable and good-looking than the other, remains - in theory, at least, the knot can be either dressed or settle in the "wrong"/ "inferior"/ "ugly" form - and, although in the doubled, dragon version, due to the presence of the second wrap, this will not lead to a catastrophic deformation, in my mind it is a point of concern nevertheless. It is not just a "bistable knot" ; it is a knot where the one "stable" form is based on a nipping structure which is depending upon the services offered by the collar structure too much - so, in theory, at least, it is a knot where the one stable form is much less stable than the other !  :)
   Moreover, as it happens to many of the TIB crossing knot-based eye-knots (1), the nipping loop forms a tight collar around the eye legs, and that is a disadvantage regarding ring loading.
   Another possible disadvantage, regarding strength, is that the Standing Part s first curve is narrow, because it encircles the two eye-legs only, so two, only, rope diameters.
   However, what bothers me more is that it is a doubled version of something that is not good enough as a single... I would had preferred a doubling that would duplicate something already very good:)

1.  http://igkt.net/sm/index.php?topic=4354.0
     http://igkt.net/sm/index.php?topic=4354.msg29708#msg29708
This is not a knot.

Dan_Lehman

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Re: Double Dragon Loop trumps the Bowline Family?
« Reply #6 on: June 03, 2014, 06:17:36 PM »
   The Double Dragon is a fine loop - provided it is double ! :) I mean, it is the doubled version of the Tugboat A loop, shown at :
...
what bothers me more is that it is a doubled version of something that is not good enough as a single... I would had preferred a doubling that would duplicate something already very good:)

Were the tail to go in the opposite direction in
its wrappings, you do get something better in
the single version, which can be dressed and
set to have an appealing-looking gradual curve
of the SPart (to what extent this has actual
practical benefit, we don't know --though I think
it does help keep the knot more easily untied).

I found this knot in the Wild some years ago
at Cape May Point; beyond the find, I had no
further information about its use / user.
(The tail is (un)raveling as it exits rightwards.)


--dl*
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xarax

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Re: Double Dragon Loop trumps the Bowline Family?
« Reply #7 on: June 03, 2014, 09:02:58 PM »
I found this knot in the Wild some years ago at Cape May Point;

  It looks like the Tugboat B to me...
  http://igkt.net/sm/index.php?topic=112.0

  The deflexion of the Standing Part  before its first curve is significant, indeed. Moreover, the swap of the eye legs into the "lower collar" seems less possible ( the one path of the returning eye leg towards the "higher collar" is much straighter and shorter than the other ), and, even if it does take place, it leads to an equally stable eye-knot.
This is not a knot.

xarax

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Re: Double Dragon Loop trumps the Bowline Family?
« Reply #8 on: June 04, 2014, 04:04:49 AM »
  The "reversed" eyeknot of the Tugboat B loop  ( i.e., a "transformed" eye-knot, where the Standing + Tail Ends pair and the eyelegs pair of the initial one have been swapped ), is shown at (1), and at the attached pictures. As a reversed form of a TIB eyeknot, this eye-knot is also a TIB eye-knot - although, by this transformation, the initial TIB crossing-knot Tugboat B loop is now turned into a (secure/locked) TIB bowline ( as simple as the Lehman s TIB bowline).
   As I had mentioned at (1), the doubled version of this TIB bowline is identical to a modification, by JP, of the ( already modified initial one :) ) Tresse bowline, tied by Alpineer (2). So, to compare apples to apples, the interested reader should compare the Double Dragon to the "reversed" TIB Tresse bowline. Good luck !  :)

1. http://igkt.net/sm/index.php?topic=4695.msg30330#msg30330
2. http://igkt.net/sm/index.php?topic=4595.0
« Last Edit: June 04, 2014, 04:16:50 AM by xarax »
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xarax

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Re: Double Dragon Loop trumps the Bowline Family?
« Reply #9 on: June 04, 2014, 04:06:38 PM »
   I seize the opportunity to illustrate the similarities between the "correctly dressed" forms of those two eye-knots : the reversed Tugboat A loop and the Samisen 4 bowline ( shown at (1)). As one might have expected, the "wrongly dressed" forms of those eye-knots suffer from the same problem, to the same degree : their unbalanced nipping structures may "open up" and disintegrate, if their eyelegs are loaded in a certain uneven and unfavourable way. 
   I had noticed that this deceivingly compact and good-looking Samisen 4 bowline :

can also be dressed in a more unstable form than the shown one, which might be considered as a serious disadvantage
 
 , but I had not realized, till now, that ( as I should had expected...), the cause of the problem is the similarity of its form to the form of the reversed Tugboat A bowline ( which also suffers from the same problem ).
   
1.  http://igkt.net/sm/index.php?topic=4883.msg31900#msg31900
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Festy

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Re: Double Dragon Loop trumps the Bowline Family?
« Reply #10 on: June 05, 2014, 06:50:49 PM »
Can we say that the Yosemite bowline is more secure than the Standard bowline?

xarax

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Re: Double Dragon Loop trumps the Bowline Family?
« Reply #11 on: June 05, 2014, 08:09:15 PM »
   Can we say that the Yosemite bowline is more secure than the Standard bowline ?

   Yes, because a more complex knot can not be less secure than a simpler one. 
   No, because we are not allowed to ask this question in the first place : we should always compare apples to apples.
   { The Yosemite bowline is a "secure" bowline, a two-collar ( = double collar ) bowline, which is a much more complex knot than the "Standard" bowline. Perhaps we can say that one of the four "Eskimo" bowlines is more secure than one of the two "Standard" bowlines, or that the Lee s locked bowline is more secure than the Yosemite bowline(*), because we can compare eye-knots which belong to the same family, regarding complexity.}

   So, there are two ends in this new line of yours - but I believe you should better stretch it as a new thread...

 (*) As mentioned by Mark Gommers in the Analysis of Bowlines : "The "Yosemite" bowline can easily be miss-tied. If the tail is drawn up before the SPart has been tightened (hence also tightening the nipping turn), the tail can be displaced to the extent that the entire bowline structure is compromised." The Lee s locked bowline does not suffer from this.
 
« Last Edit: June 05, 2014, 08:15:09 PM by xarax »
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Dan_Lehman

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Re: Double Dragon Loop trumps the Bowline Family?
« Reply #12 on: June 05, 2014, 09:25:45 PM »
   Can we say that the Yosemite bowline is more secure than the Standard bowline ?

   Yes, because a more complex knot can not be less secure than a simpler one.
Perhaps this should be better restated as
the extension of a knot cannot be less secure
than the (base) knot itself
--although even here,
one might want to be more circumspect!

In tests of abseil-ropes-joints, the offset water knot
(aka "EDK"="Euro Death Knot" ) proves more secure
under load than the "more complex" offset figure 8 bend
--with the irony that the latter might have been chosen
presuming just the opposite.


--dl*
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xarax

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Re: Double Dragon Loop trumps the Bowline Family?
« Reply #13 on: June 05, 2014, 09:59:20 PM »
the offset water knot (aka "EDK"="Euro Death Knot" ) proves more secure under load than the "more complex" offset figure 8 bend

  Good find ! If "security" here is not meant as anything more than just resistance to slippage, this should be the only exception that proves the rule !  :)
  Perhaps the gripping power of the nub on the Tails is "wasted" along the longer and more convoluted paths of the Stranding parts, so the generated friction is distributed and consumed in places it is not needed...  :-\ :-\ :-\
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Festy

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Re: Double Dragon Loop trumps the Bowline Family?
« Reply #14 on: June 06, 2014, 11:18:23 AM »

   Yes, because a more complex knot can not be less secure than a simpler one. 
  No, because we are not allowed to ask this question in the first place : we should always compare apples to apples.
   { The Yosemite bowline is a "secure" bowline, a two-collar ( = double collar ) bowline, which is a much more complex knot than the "Standard" bowline. Perhaps we can say that one of the four "Eskimo" bowlines is more secure than one of the two "Standard" bowlines, or that the Lee s locked bowline is more secure than the Yosemite bowline(*), because we can compare eye-knots which belong to the same family, regarding complexity.}

   So, there are two ends in this new line of yours - but I believe you should better stretch it as a new thread...

 (*) As mentioned by Mark Gommers in the Analysis of Bowlines : "The "Yosemite" bowline can easily be miss-tied. If the tail is drawn up before the SPart has been tightened (hence also tightening the nipping turn), the tail can be displaced to the extent that the entire bowline structure is compromised." The Lee s locked bowline does not suffer from this.

and the Lee's lock is the Yosemite with the bitter end fed back down through the two collars?

now the line in red has me puzzled I must say!