Loop with interlocking slipknots, anyone seen this before?

[elplatt]

Wondering if this is a known knot.

[Luca]

Hello elplatt,

Your images are much more beautiful than the image I post below (my first ugly photo! ), but they are not very clear with respect to how the loop that you show us is built: my picture below attempts to show an exploded version of what seems to me to be the loop in question.
If the loop is that, here the merits and the flaws that it seems to me that it has (for the record: I personally do not seem to have ever seen):

Merits:
-Compared to as appear the final result,is relatively easy and quick to execute.
-Hey, it seems to work!
-Despite there in the middle is an Overhand noose,seems to be pretty easy to untie after being subjected to a certain load. (for how it loaded (if it is oriented as I show),the standing part (the strand of white rope on the right in the image below) is the "strangler",and is 100% loaded, vs. the first leg of the loop (the strand of white rope on the left) 50% loaded;then, given also the fact that it is not used as a stopper knot, I would be more inclined to classify it as an Overhand noose rather than as a Slipknot(I do not see a second Slipknot/noose in the blue rope if the knot is constructed as in the image below(?))).

Flaws:
-Bulky.
-Ehm..Ugly .
-This loop is based on the fact that the noose,and the continuation of the second leg of the loop(??) are blocked by the bight passing through the noose: this may be suspicious about its safety and stability when subjected to heavy loads (you also block the bight that blocks the noose, but maybe you act in this way to avoid the dangers of a slipped knot (?)). I do not know if,and how much,it can be more secure than the simple ,not "overkilled" and "harmonic" to look at,loops like these:

http://igkt.net/sm/index.php?topic=3924.msg23274#msg23274
http://igkt.net/sm/index.php?topic=4367.msg27386#msg27386
http://igkt.net/sm/index.php?topic=4560.msg29521#msg29521

                                                                                                                      Bye!

[xarax]

   The use of the slipped overhand knot as a bowline s nipping structure was attempted also by Alan Lee, at :
 
   http://igkt.net/sm/index.php?topic=4125.msg27023#msg27023
   http://igkt.net/sm/index.php?topic=4125.msg27024#msg27024

   A "simplified" implementation of this idea is shown at the attached picture.

[elplatt]

Thanks Luca, very helpful info!

You pretty much reproduced it exactly, although my version did not have the extra twist in the loop of the slip knot, so the blue rope would go in the other side.  It's a little less bulky and ugly that way.

Here's a video of me tying it: https://www.youtube.com/watch?v=FLRB1hbHr7k

The other merit (the main one, for me) is that after unblocking the final bight, pulling on the end completely unties it all.

Also, very helpful reference to the overhand noose.  The "second slipknot" was where the bight is passed through the loop of the first slip knot.  I wasn't really sure what to call that.

Thanks again!

[Dan_Lehman]

   The use of the slipped overhand knot as a bowline s nipping structure was attempted also by Alan Lee, at :

You've used this, yes,
but the OP really is using what we can
differentiate by calling it the overhand noose
--the SPart is what moves (and so, nips) for
the OP; whereas your knot will likely fall apart,
being the common mid-line eyeknot of the
trucker's hitch !

There have also been instantiations of this general
nipping idea w/o any not, just the turNip --where
the similarity is in the *choking* of that nipping
structure and tucking material through it.

--dl*
====

[xarax]

your knot will likely fall apart

  I do not believe that "likely" is the right word here - something like "perhaps", perhaps, would be more appropriate. Notice that the Tail End of the "white" link is nipped by a mid-line implementation of the opposed bights locking mechanism (1) ( which is always surprisingly efficient.
   The single nipping loop of the "White" link can be replaced by a double one ( = this half-hitch-looking knot can be replaced by a Clove or Girth hitch-looking one ). In that case, the tensile forces which would be able to reach the "white" Tail end would be greatly reduced.

1.  http://igkt.net/sm/index.php?topic=4906.0

...being the common mid-line eyeknot of thetrucker's hitch !

   I had not realized this particular "similarity" till now - which points to the same enhancement of the mechanism described above : just pass the "white" Standing Part through the "orange" slipped bight once more, as we do in the Trucker s hitch.
   Anyway, this knot was only meant to be a simplification of the knot shown by Alan Lee - and a demonstration of his idea, of replacing the simple crossing knot-based nipping structure of a PET eyeknot by a slipped-overhand-knot based, more complex but also more stable one.
     

[elplatt]

I'm a bit new to knots, are "nip," "block," and "choke" standard terminology?  I've seen them used, mostly on this forum, but am not entirely sure what they mean.

Dan_Lehman, the "turnip" sounds interesting, any info on it online?

The discussion here gave me some good leads, and it appears that the knot is a "mooring hitch" or "tugboat hitch" tied on an overhand noose instead of a bight (which makes it a loop rather than a hitch).

http://www.animatedknots.com/mooring/

[Luca]

Hi elplatt,

You pretty much reproduced it exactly, although my version did not have the extra twist in the loop of the slip knot, so the blue rope would go in the other side.  It's a little less bulky and ugly that way.

Here's a video of me tying it: https://www.youtube.com/watch?v=FLRB1hbHr7k

The other merit (the main one, for me) is that after unblocking the final bight, pulling on the end completely unties it all.

Thank you for the video!
Yes,the loop that you show on YouTube is different(but still I'm not sure it's the same as what you show in your first post):the main difference  is that the noose in your video is oriented differently, with the "strangler part" that becomes the first leg of the loop,not the standing end as is instead the case in the image that I show above.
You are right, in the way you show the loop has a better look, and perhaps the forces inside also act in a more balanced way with respect to the maintenance of the stability of the knot when subjected to a heavy load.
But the problem arises when, after submitting the loop to a load not so heavy, it's time to slip away the noose as it is oriented in your video: you have slipped it away easily,but because in the video you have not loaded the loop.
I have loaded it not very heavily, using my 9 mm. white rope, not so much stiff, but surely not soft, and it took at least three minutes to be able to loosen what (in the photo below) also in your video indeed takes at least the geometry of a Slipknot.
So unfortunately the forces inside seem to act in a way that the Slipknot component(which basically plays the same functions as the nipping turn (or turnip) of the common Bowline) tends to jam:The "other version",with the  noose oriented in the other way, is maybe more unstable,but is more much easy to completely untie.
The loop you show in your video is classifiable both as a PET and TIB loop: the acronym PET (which refers to the kind of knots that are fixed loops) means "post eye tiable ": this means that the first link of the loop (ie the portion of rope which is between the standing end and the first leg of the loop, as for example the nipping turn of a common Bowline) is topologically equivalent to an un-knot (= absence of a real knot, ie the  possibility to tie/untie this portion of rope without the  use in any way of the ends of the rope,(ie just like you does when you execute an Overhand noose/Slipknot...).
TIB means "tiable in the bight":it refers to any knot that has the possibility to be performed without the use in any way of the ends of the rope (ie the whole knot actually is topologically equivalent to an un-knot ...).
So, a common Bowline is a PET loop, because its simple nipping turn is an un-knot,a not knot, but the whole knot is not a TIB knot, because when you  finished to execute it,you will realize that you have made a topologically real knot (you can not untie it without the use of the ends of the rope).
A retraced Figure 8 loop, in contrast, is a TIB knot, because it has the possibility of being tied/untied ​​entirely without the use of the ends of the rope, but it is not a PET loop, because,if you decide to execute the loop using the working end of the rope, you will be forced to perform what is topologically a real knot (a Figure 8 knot in this case..) BEFORE the formation of the "eye" around the object that will to be hooked.

                                                                                                                          Bye!