Knot "implants"

[xarax]

  1a. While the nub of the knot is still loose, insert into it a "knot implant"  : the Tail End of this same knot, or a small piece of another rope.
  1b. Doing this, the bulk/volume of the final, compact knot, increases - the knot becomes "inflated".
 
  2a. Before you untie the knot, pull this implant out of the nub. A straight segment of a rope can always be pulled out of the nub quite easily, even if the knot itself is woven around it very tightly.
  2b. Doing this, the nub becomes less dense and/so more loose. Now you can untie the knot more easily.

  We can apply this trick in many cases we need to facilitate the untiabilty of a knot - simply because we always have one, at least, available Tail End...

   See the attached picture, for such a "knot implant" in the case of a fig.8 eyeknot.
 
 ( I had chosen to make it penetrate the nub along the axis of symmetry of this knot, so the shape of the "implant" itself remains almost straight - and so it can easily pulled out -, and the shape of the surrounding nub remains symmetric - and so it can easily be inspected ( : in general, symmetric forms are more easily inspected than asymmetric ones ). However, due to the fact that, even when the shape of one of the many forms/variations of the fig.8 eyeknot is symmetric, its loading is not ( and its loaded, final, compact form does not remain symmetric ), we can be sure that this is not the optimal, for this purpose, path. The interested reader should try his hand, and find the optimal path through the nub for such an implant, so, when it will be pulled out and removed, the knot will be able to "breath" and to be untied more easily.

[Ruby]

http://www.canyoneeringusa.com/techtips/the-stone-knot-a-canyoneering-secret-weapon/

[xarax]

   I believe you mean that a "knot implant" resembles a " fiddlestick" :
   http://www.canyoneeringusa.com/techtips/fiddlestick/
   However, I think that this use of a marlin spike is meant to facilitate tying a knot ( and improving its security regarding slippage ), not untying it ! My idea is more modest, but also more general : it can be implemented in any tight, difficult to untie knot : Just insert a segment of rope ( a Tail End or any other short piece of rope ) into the core of the knot when it is still loose, which segment will increase its bulk when it will become compact. If, when afterwards you want to untie the knot, you pull this segment out, the knot will become less dense, and so more easy to untie. And it is always relatively easy to pull out of a knot a straight piece of rope that penetrates its nub.

[alpineer]

Climbers will sometimes place a carabiner into the unloaded knot to facilitate its eventual untying.

[xarax]

Climbers will sometimes place a carabiner into the unloaded knot to facilitate its eventual untying.

  I was not aware of that... Yes, an "implanted" carabiner ( just as the "fiddlestick" ) can serve the same purpose, but its diameter/ cross sectional area is much smaller than the diameter of the rope, so I guess the effect will be less pronounced ? ?

[Dan_Lehman]

Climbers will sometimes place a carabiner into the unloaded knot to facilitate its eventual untying.

  I was not aware of that...
 Yes, an "implanted" carabiner ( just as the "fiddlestick" ) can serve the same purpose,
but its diameter/ cross sectional area is much smaller than the diameter of the rope,
so I guess the effect will be less pronounced ? ?

You are wrong : climbing ropes are getting smaller
(and --egadz-- sized now in fractions of mm (!!)),
and common sizes of "single" ropes are from 9.5? .. 10.5mm
which is also the diameter of a 'biner; moreover, a 'biner
is a sure/rigid diameter, not compressible (by rope).

Which point re compression shows how very wrong you are about

A straight segment of a rope can always be pulled out of the nub quite easily,
even if the knot itself is woven around it very tightly.

!!!
I can't believe you wrote this!  Especially considering
to what extent you have gone to assert that the Lehman8
is UNeasily untied (though one might somehow manage
to untie it, nevertheless)!  Being compressible and esp.
so in being untensioned, rope that is crunched upon by
surrounding knot parts is not going to be pulled out
easily, as it might need to go through cross-sectional
transformations/distortions in trying to fit through the
various nip points, and will likely not be all so "straight"
once other parts bear upon it.

YMMV.  And this is where readers would like to know
on what basis --i.p., on what testing-- you make such
an assertion : in what cordage (& knots) and under
what loading have you ever found this to be true?
Even something so little as "100kg" in 3mm line! "[sic]"


--dl*
====

[xarax]

  You are wrong : climbing ropes are getting smaller
  a 'biner is a sure/rigid diameter, not compressible (by rope).

  Which point re compression shows how very wrong you are 

  My impression was that the average diameter of a carabiner is smaller than 9.5 - 10.5 mm (*). Even one mm makes a big difference, because what we need and use is the cross-sectional area, so the diameter squared, not the diameter itself.
  Re "compressibility" :
  The fact that ( climbing ) ropes are not rigid and "compressible", does not mean that the area of their cross section becomes smaller ( and so the volume of a rope-made "knot implant" shrinks... ). "Compressibility" simply means that the ropes can be "flattened", their circular cross-section becoming elliptical, not that they become thinner. That may be the case in hollow/single braided ropes, indeed, but not in kermantle climbing ropes.
  ( Which point shows how very wrong you are each time you wish/imagine/pray that it was me who was very wrong...  I suggest that, after all those years with no much success, it is time to re-consider your strategy. )

   I can't believe you wrote this!

   Coincidence ! ! Me too ! 
   Either you have not read/understood my point about a "straight" rope segment, or you have not tried a "knot implant" inserted into a fig.8 eyeknot as shown in the picture.  Why ? Was it sooo difficult ?  I did, in fig.8 eyeknots tied on more than a dozen different ropes, from 5.5 ( paracord), 9.5 to 11mm static climbing and caving ropes, to a 13mm braided marine rope. Although it is difficult, indeed, to measure how easy or difficult a knot can be untied, my "feeling" was that the trick worked, and it worked well each and every time ! The "hole" that remains after the "knot implant" is pulled out, enables all the adjacent segments to "breath", and reduces the inner "pressure" of a tightly woven nub, allowing its easier untying. The only difficulty I had experienced was when the end of the "knot implant" happened to be melted, so hardened and somehow flattened... ( I had also "implanted" the Tail End through other openings of the fig.8 eyeknot, but I had not been able to notice any major difference, so I decided to refer only to the symmetric case ).
   And this is where YOU should explain how you become convinced about the seemingly "reasonable", but completely fictitious "description"/"explanation" of something that, unfortunately for you, does NOT happen ! 
   Being compressible and esp. so in being untensioned, rope that is crunched upon by surrounding knot parts is not going to be pulled out easily, as it might need to go through cross-sectional transformations/distortions in trying to fit through the various nip points, and will likely not be all so "straight" once other parts bear upon it.
   Nevertheless, as a piece of underground knotting literature, it is a good try : a well-written long sentence - considering that you had only imagined all those things...
   
   I am trying to figure out gripping / nipping structures which could immobilize/secure more or less straight rope segments for years now - and I had found a few, only, knots which are able to achieve this... Therefore, I have much experience of the fact that a tensioned straight segment which penetrates a nub woven around it, slips like an eel - and even in the case the nub is tensioned by its one or both ends, the situation does not improve much. Yes, if your knot is a Pretzel loop, and as a "knot implant" you use its slipped tail, you will not be able to pull it out easily - IF THE KNOT IS STILL UNDER TENSION. I had not claimed that, using a "knot implant", it would be easier to untie a TENSIONED, by the one or both its ends, knot, had I ? 

(*) This estimation is based on my very limited knowledge, and almost null experience, of climbing carabiners - there are hundreds of different types ! I do not doubt that some of them, made of light alloys, may be as thick as the climbing ropes, indeed.
    http://www.climbing.com/blog/24-innovative-carabiners/

[Dan_Lehman]

  You are wrong : climbing ropes are getting smaller
  a 'biner is a sure/rigid diameter, not compressible (by rope).

  Which point re compression shows how very wrong you are 

  My impression was that the average diameter of a carabiner is smaller than 9.5 - 10.5 mm (*). Even one mm makes a big difference, because what we need and use is the cross-sectional area, so the diameter squared, not the diameter itself.
  Re "compressibility" :
  The fact that ( climbing ) ropes are not rigid and "compressible", does not mean that the area of their cross section becomes smaller ( and so the volume of a rope-made "knot implant" shrinks... ). "Compressibility" simply means that the ropes can be "flattened", their circular cross-section becoming elliptical, not that they become thinner. That may be the case in hollow/single braided ropes, indeed, but not in kermantle climbing ropes.
  ( Which point shows how very wrong you are each time you wish/imagine/pray that it was me who was very wrong...  I suggest that, after all those years with no much success, it is time to re-consider your strategy. )

Climbing ropes compress under pressure --their
multiples of twisted kern/core strands re-align
laterally in compensation--, and that makes
less of a deflection in the rope going around
and compressing them, and it changes effective
diameter in assessing a bend-radius of the rope
bending around ... ,
and it makes pulling out the deformed rope
difficult (as its shape is no longer *straight*).

I have much experience of the fact that a tensioned straight segment
which penetrates a nub woven around it, slips like an eel --and even
in the case the nub is tensioned by its one or both ends,
the situation does not improve much.

Talk about moving goal posts --now it's "tensioned"
(somehow, magically)?!  Even so, I have some doubt
about e.g. my favored multiple Lapp bend end-2-end
knot being all so easily loosened with exactly this case
of straightness --of the very highest tensioned S.Part--,
in serious rope & forces (and by only manual untying)!
But the image you present shows a knot with an "implant"
that were it the rope's tail would be untensioned.  And I
have no trouble realizing how tightly such an inserted
part can be held (esp. in non-new cordage).


--dl*
====

[xarax]

Climbing ropes compress under pressure --their multiples of twisted kern/core strands re-align
laterally in compensation--

   This re-alignment does not mean that their cross sectional area becomes smaller - only that it changes shape, it becomes elliptical. In order to shrink, and become thinner, the rigid material should either
1. "flow" along the rope ( which does not happen in a rope, of course, by definition )
2. "swallow" some portion of the voids which exists in between the strands, and become denser. This is very difficult, and, even if it happens, it happens in a very small scale, because parallel strands, like the ones inside the bundles of fibres in the kern, arranged the one next to the other, do not leave much empty space between them. That is why the kermantle ropes are so stiff, and, even if they can be flattened, they are  not-compressible.
   What you think as a "compression" around a bend, is compression along one direction, perpendicular to the path of the curve which the rope follows. It is very easy ( and, with your new pair of glasses, you, too, can do it ...  ) to see that where the rope is "compressed" ( in the sense you mean ) it is also flattened - and so its cross-sectional area remains the same, and so the volume which the "knot implant" occupies inside the nub remain the same, too. I do not doubt that the shape of cross section does not remain circular, because, along its path through the nub, the rope is squeezed by other segments, from different directions, but this effect plays a minor, only, role in how easily "straight" segment be pulled out. ( "Straight", re its axis, not "cylindrical", re its surface ).  We can imagine the shape of the rope as a solid generated by the translation, along its axis, of a more or less elliptical cross section ( because the rope is everywhere squeezed by adjacent segments ) - but of a "wobbling" elliptical cross section, whose axes rotate, but its area remains constant. )

I have much experience of the fact that a tensioned straight segment which penetrates a nub woven around it, slips like an eel

Talk about moving goal posts --now it's "tensioned" (somehow, magically)?! 

   You do not follow my advice, to re-consider your strategy against me !  You lose ! 
   When you insist to suppose that me and everybody else except you is so dumb, you look, at least, less clever...
   TENSIONED BY THE KNOT TYER HIMSELF, WHO PULLS THE F..."KNOT IMPLANT" OUT, YOUR BRIGHTNESS !
   What part of the this sentence you do not understand, Watson ? 

   What would had made the "knot implant" more difficult to pull out of the nub, would had been the tensioning of the nub itself, by one or by both its ends - but I believe no climber would wish to untie the fig.8 eyeknot by which he remains attached on the main line, and test the law of gravity... However, as I had mentioned in my previous post, even in the case of tensioned nubs, a "knot implant" can be pulled out of most of them with ease - simply because there are so FEW nubs which can withstand a pull of a penetrating straight segment out of them. If the segment offers a "handle" = if its path through the nub follows an L-shaped turn, so it is not straight any more, things change a lot - but when the path is more or less straight, and if the surrounding nub is not one of the FEW, only, nubs which are able to effectively grip / nip a penetrating line ( as the climbing friction hitches are, with their long, helical "nipping tubes", or the nubs of the few tight adjustable loops ), a tensioned straight line can slip like an eel, indeed.
   In a sense, this idea tries to turn a disadvantage of most knots, in relation to their security ( the difficulty of securing a tensioned straight line ), into an advantage, in relation to their untiability. Myself, I had tried this idea in practice, on a variety of materials, and my impression / understanding is that it works. Of course, the only way one can prove it, is by testing it - but one can NOT disprove it, I am afraid, by keyboarding !       
 

[alpineer]

Of course, the only way one can prove it, is by testing it - but one can NOT disprove it, I am afraid, by keyboarding !       

Nor, for that matter, CAN one prove it by keyboarding !   

[xarax]

  I had not proved it - but I had thought about it, and I had tried it.
  Now, your turn, one-liner-guru !  ( I mean, try to do something MORE than write just another of your "clever", "wise" one-liners : try it, and report your findings. That would be a constructive comment ( and criticism ). A hint : Try it also in the case of the Water bend, which also becomes very tightly woven and difficult to untie.
   
 

[Dan_Lehman]

 - - - - -  [argh, prior Reply apparently left at Preview
              but thought Posted, and ... lost, grrrr ] - - - - - - - -

Climbing ropes compress under pressure --their multiples of twisted kern/core strands re-align
laterally in compensation--

   This re-alignment does not mean that their cross sectional area becomes smaller
--only that it changes shape, it becomes elliptical.

Now we are differing on the meaning of "compression":
I mean that the pressure is there and changes shape of
the compressed item.

What you think as a "compression" around a bend,
is compression along one direction, perpendicular
to the path of the curve which the rope follows.
It is very easy ( and, with your new pair of glasses, you, too, can do it ...  )
to see that where the rope is "compressed" ( in the sense you mean )
it is also flattened
--and so its cross-sectional area remains the same,
[/quote]
I've not said nor meant to imply otherwise, re volume
--just shape.  And I submit that forcing a rope to change
its shape will require effort in addition to what is otherwise
required --that it increases resistance to movement.

... rope is squeezed by other segments, from different directions,
but this effect plays a minor, only, role in how easily "straight" segment
[can] be pulled out. ( "Straight", re its axis, not "cylindrical", re its surface ).

Let me remind you that I have long disparaged the
common assertion that merely *slipping* a finishing
tuck (i.e., tucking out a "slip bight" vs. unfolded tail)
makes it thus easily untied : I maintain that many
such structures are hard to move (and then that the
bight tip's U-turn adds resistance because in most
cordage it's very hard to double back perfectly, without
much bending resistance!).

I have much experience of the fact that a tensioned straight segment [that] penetrates
a nub woven around it, slips like an eel

I have one childhood experience with an eel
--and the effects of eel-slime on one's t-shirt!

Talk about moving goal posts --now it's "tensioned" (somehow, magically)?! 

   You do not follow my advice, to re-consider your strategy against me !  You lose ! 
   When you insist to suppose that me and everybody else except you is so dumb, you look, at least, less clever...
   TENSIONED BY THE KNOT TYER HIMSELF, WHO PULLS THE F..."KNOT IMPLANT" OUT, YOUR BRIGHTNESS !
   What part of the this sentence you do not understand, Watson ? 

--the entire part, which is what was not
previously stated.
Beyond that, I have trouble seeing this tensioning
going so well & easily, with force transmitted through
tight nips so as to render the implant entirely tensioned.

 - - - - - - - TEST REPORT - - - - - - - - - - - - - -

I did a quick test of the implanted fig.8 as pictured by X.
above, using a 1/4" 3-strand fibrillated PP/PE? mixture
(waxy feel) that is NOT new, and fairly firm.  I tested the
knot once for each end being loaded (and opposite being
the eye); another part of the same rope was *implanted*
as X. shows, splitting the twin parts in three points.

I loaded the knot with 65# on a lousy 5:1 pulley;
the effect on a trio of 'biners --one starting to lock but
the others easily opened-- suggests that the actual
load might be approx. 100kg (heard that number before?  ).

As a loosening force on the implant, I used 15#,
and cradled the nub in a girth hitch w/webbing.

I'm surprised to report that Xarax . . .
is a whacko!  No, that ... his thesis was supported;
mine needs higher forces, or ... !?
Still, I remain skeptical of this "implant" notion
in general.
(Slicker cordage will see forces transmitted better
throughout the nub, and I believe that this will
make loosening more difficult --though the same
quality might help parts move in order to loosen.)

After all, consider that the common orientation of
the fig.8 eyeknot is that of loading the *interior*
twin part, which upon its tightening and shrinking
--by extension-- and pulling away from the *exterior*
twin part will leave that latter part loose around the
eye legs, and . . . able to "easily" pull out the tail?!
Didn't we say that the knot is jamming or hard to
untie?!
YMMV?!


--dl*
====

[xarax]

I've not said nor meant to imply otherwise, re volume --just shape.  And I submit that forcing a rope to change
its shape will require effort in addition to what is otherwise required --that it increases resistance to movement.

   OK - I thought you were talking about difficulty in the movement of a ( tensioned, by the pull ) straight segment through the nub, due to a change of its cross-sectional area...
   It WILL require an effort, indeed - but my point is that it requires LESS effort than the effort to untie a tightly woven nub.

Let me remind you that I have long disparaged the common assertion...

Let me remind you that I had NEVER said such a nonsense ! The U-turned tip of a slipped tail can NEVER pass through a "hole" with an area equal to the sum of the cross-sectional areas of its two legs... This would require a very soft rope, able to turn around zero rope diameters... and most of the utility ropes are not like this.

  Your "test report" is a report, but not of a test !  And I would not even comment on the "rope" you had used !  Laid 3-strand cords present as much surface friction as you can get - if that was your main purpose, you had chosen wisely ! 
   Grow up, take a grown-up kernmantle climbing rope, and do a real TEST. 
  ( If you had ever tried to figure out the nub of a decent adjustable loop, you would had understood which my starting point had been, at once. )

   A "knot implant" can be pulled out of most <nubs> with ease - simply because there are so FEW nubs which can withstand a pull of a penetrating straight segment out of them.
...FEW, only, nubs ... are able to effectively grip / nip a penetrating line ( as the nubs of the climbing friction hitches, with their long, helical "nipping tubes", or the nubs of the few tight adjustable loops )
   In a sense, this idea tries to turn a disadvantage of most knots, in relation to their security ( the difficulty of securing a tensioned straight line ), into an advantage, in relation to their untiability.

P.S. 1
I got my BEST results when I used sleek, canyoning ropes... The disadvantage of a slippery rope is that, ceteris paribus, it can be entangled into more tightly woven, so more difficult to untie nubs  - but it seems that its advantage, re. how easy the slippery "knot implant" can be pulled out of the core of those nubs, outweighs the disadvantage.
P.S. 2
When you will perform your next, real test, try to see if there is some other path through the nub of the fig.8 eyeknot ( as I suspect that it will be ), where the "hole" inside the nub, left after the removal of the "knot implant", will enable the adjacent segments to "breath" more easily.

[xarax]

I have much experience of the fact that a tensioned straight segment [that] penetrates a nub woven around it, slips like an eel

I have one childhood experience with an eel
--and the effects of eel-slime on one's t-shirt!

Talk about moving goal posts --now it's "tensioned" (somehow, magically)?! 

--the entire part, which is what was not previously stated.

I DID STATE THE ENTIRE PART. IT IS STILL THERE, FOR EVERYBODY TO CHECK !

I have much experience of the fact that a tensioned straight segment
which penetrates a nub woven around it, slips like an eel --and even
in the case the nub is tensioned by its one or both ends,
the situation does not improve much.

Talk about moving goal posts --now it's "tensioned"
(somehow, magically)?! 

[Dan_Lehman]

  Your "test report" is a report, but not of a test ! 

What would you know of either,
as you present neither?!!
(Your pipe dreams are from a not-a-pipe, even!)

And I would not even comment on the "rope" you had used !
Laid 3-strand cords present as much surface friction as you can get
--if that was your main purpose, you had chosen wisely ! 

Would what not?!
And yet ...
(Not commenting can be done if fewer keystrokes.)
((But maybe that comment ce n'est pas une comment.))