International Guild of Knot Tyers Forum

General => Practical Knots => Topic started by: dmacdd on July 25, 2010, 03:09:49 PM

Title: Lapp knot
Post by: dmacdd on July 25, 2010, 03:09:49 PM
What is the Lapp knot (a bend) good for?

A Lapp knot has the same structure as a sheet bend, but the roles of working end and standing part of the cord that wraps around the U cord are interchanged.

video here (45 seconds) : [1. Sorry, url now corrected]:

         http://www.youtube.com/watch?v=AF_8VKLo2W8

[2. Note added after the exchanges below: I believe the above video is either simply incorrect, or that it shows an extremely unreliable version of the Lapp knot. Contrary to the video, the two working ends must come out of the knot on the same side.]

I just load tested it in 1/16" / 1.6 mm nylon braid.  It slipped to failure under moderately heavy load.

It is very easy to tie quickly, whether slipped or unslipped.  A slipped Lapp knot is particularly easy to tie when the two working ends are too long for easy reeving through the knot.

So, a light duty bend?, especially for tying slipped with long ends?
Title: Re: Lapp knot
Post by: roo on July 25, 2010, 08:13:57 PM
video here: http://www.youtube.com/watch?v=6EyfYyJkZss
Better re-check your link.

Then again, wouldn't a clean, small, illustration suffice?  Is the attached image the form you have in mind?
Title: Re: Lapp knot
Post by: knot4u on July 25, 2010, 09:07:20 PM
What is the Lapp knot (a bend) good for?

A Lapp knot has the same structure as a sheet bend, but the roles of working end and standing part of the cord that wraps around the U cord are interchanged.

video here: http://www.youtube.com/watch?v=6EyfYyJkZss

I just load tested it in 1/16" / 1.6 mm nylon braid.  It slipped to failure under moderately heavy load.

It is very easy to tie quickly, whether slipped or unslipped.  A slipped Lapp knot is particularly easy to tie when the two working ends are too long for easy reeving through the knot.

So, a light duty bend?, especially for tying slipped with long ends?

Yeah, that link is for "New Rescue Knot, for Fire, Rescue, Mountaineers", which would be interesting if I could figure out all the knots he's tying.

Also, what do you mean by "slipped to failure".  That's a bad thing, right?
Title: Re: Lapp knot
Post by: dmacdd on July 25, 2010, 09:21:48 PM
What is the Lapp knot (a bend) good for?

A Lapp knot has the same structure as a sheet bend, but the roles of working end and standing part of the cord that wraps around the U cord are interchanged.


video here (45 seconds) : [Sorry, now corrected]

             http://www.youtube.com/watch?v=AF_8VKLo2W8
Quote
Also, what do you mean by "slipped to failure".  That's a bad thing, right?

A working end slipped progressively right out of the knot. Yes, it's a bad thing. But there can be useful applications for less than perfectly secure knots if they have other useful attributes.
Title: Re: Lapp knot
Post by: dmacdd on July 25, 2010, 09:30:13 PM

Better re-check your link.

Thanks. Sorry. I just modified the original post to correct the link error:

      (45 seconds):       http://www.youtube.com/watch?v=AF_8VKLo2W8

Quote
Then again, wouldn't a clean, small, illustration suffice?  Is the attached image the form you have in mind?

Yes, that's it,  but I couldn't find one. Did you make this one you posted?
(http://igkt.net/sm/index.php?action=dlattach;topic=1955.0;attach=1547;image)

I suppose I could have made a photo.
Title: Re: Lapp knot
Post by: dmacdd on July 25, 2010, 10:04:44 PM

Then again, wouldn't a clean, small, illustration suffice?  Is the attached image the form you have in mind?

Yes, that's it,  .... Did you make this one you posted?
(http://igkt.net/sm/index.php?action=dlattach;topic=1955.0;attach=1547;image)

Or is it? (Should it be?) The video shows the RH standing part coming out of the knot on the same side of the knot as the LH working end, which is consistent with the description of the Lapp Knot as having the structure of the sheet bend with the roles of the RH WE and SP exchanged.
Title: Re: Lapp knot
Post by: roo on July 25, 2010, 10:09:44 PM
Yes, that's it,  but I couldn't find one. Did you make this one you posted?
I just cropped and darkened an internet image.

I'm not a big fan of the Lapp Knot (either form).  Sometimes it holds OK, but then sometimes it settles a different way and allows the U shape to straighten and slip out, as you noted.  It's probably instructive to play with different rope types and combinations.

Another thing that makes me uneasy is that it's so close to the Sheet Bend that it may cause people to get muddled on their tying or recognition of the Sheet Bend if they become familiar with both knots.  

I'm not ruling out the possibility that someone may have some use for it, but I can live without it.
Title: Re: Lapp knot
Post by: dmacdd on July 25, 2010, 10:40:39 PM

Yes, that's it,  .... ?
(http://igkt.net/sm/index.php?action=dlattach;topic=1955.0;attach=1547;image)

Or is it? (Should it be?) The video shows the RH standing part coming out of the knot on the same side of the knot as the LH working end, which is consistent with the description of the Lapp Knot as having the structure of the sheet bend with the roles of the RH WE and SP exchanged.

I just tested the two configurations 4 times each, with 1/16" braided nylon, with startling results.

When tied as in the video, with the RH SP coming out of the knot on the same side as the LH WE, the knot is completely unreliable in my test rig. (Slips to failure every time.)

When tied as in the above diagram, with the RH SP coming out of the knot on the side opposite the LH WE, the knot is completely reliable in my test rig.  (And easy to untie after heavy load, by the way.)

This means that the Lapp knot should not be characterized (as perhaps no one but me ever did) as having the structure of the sheet bend with the roles of the RH WE and SP exchanged.

It also means that that video is hazardous.
Title: Re: Lapp knot
Post by: dmacdd on July 25, 2010, 11:02:18 PM
So, like the sheet bend, the two working ends (or the two standing parts) of a Lapp knot should come out of the the same side of the knot.   But it's much more important for the Lapp knot -- essential, in fact.
Title: Re: Lapp knot
Post by: dmacdd on July 25, 2010, 11:53:05 PM
Here's a (trivial)  application for the Lapp knot for which I will try the Lapp knot. I carry a shoulder bag with a long shoulder strap, because I like to carry the bag right down on my hip.  The strap is too long to use to suspend the bag from most chairs, and using it to tie the bag onto the chair is often not practical. The bag has no other built-in means of hanging it from a restaurant chair.  I keep an 24 inch length of cord cow-hitched to the strap anchor to fasten the bag to restaurant chairs.  Sometimes I need the whole length of the cord and sometimes not, depending on the structure of the restaurant chair.   The slipped Lapp knot seems to me to be a good knot to close the cord into a loop around a suitable part of the chair. It is very fast, and if tied slipped, which is entirely appropriate anyway for the application, nothing needs to be reeved through the knot if I only need, say, eight inches of the 24 inch cord -- wherever I need to grip the two WEs relative to their bitter ends to make the knot, I can tie the knot with equal convenience, (and always the same way) and this would be true no matter how long the WEs were.
Title: Re: Lapp knot
Post by: roo on July 26, 2010, 12:11:39 AM
When tied as in the above diagram, with the RH SP coming out of the knot on the side opposite the LH WE, the knot is completely reliable in my test rig.  (And easy to untie after heavy load, by the way.)
One form may be less stable than the other, but I have observed slippage in both forms, even when the correct side of the U is loaded.  The slippage doesn't always occur by the same mode, either.
Title: Re: Lapp knot
Post by: Dan_Lehman on July 26, 2010, 08:50:27 PM
What is the Lapp knot (a bend) good for?

Many things.  It's the base of a fine set of bight hitches (in which
category I include the Sheet bend, and maybe should include
the SquaREef knot(!).

Quote
A Lapp knot has the same structure as a sheet bend,
but the roles of working end and standing part of the cord that wraps around the U cord are interchanged.

Exactly -- and as was later remarked, it's the particular structure of
the same-side Sheet Bend : tails on same side.

The origins of being used by Lapplanders or other northern, icey-area folk
is that it was tied in leather *webbing*, we might say -- i.e., a relatively
rigid flat-cross-section material.  Consider the two loadings (Lapp v. Sheet)
in such material, and I think you'll prefer the former.  One can also try
nylon (etc.) woven webbing, but this unlike leather is compressible.
Still, it seems that cord hitched to a webbing bight is better when in
the Lapp vs. Sheet orientation.

Quote
Contrary to the video, the two working ends must come out of the knot on the same side.

YES, spot on.

Quote
I just load tested it in 1/16" / 1.6 mm nylon braid.  It slipped to failure under moderately heavy load.

Dang, you and that measly little cord again.  Even so, I'm not getting that result.
One needs to set the knot carefully, pulling on all ends and being esp. sensitive
to getting the hitching side (i.e. the non-bight (hitched to, you see) side) snug.
BUT, I won't argue in favor of its use in this form, even so (even though I think
it should be holding; I might be missing transformations in the geometry as
load peaks.  Again, this doesn't concern me for I use a variation, anyway, for
anything serious.

NB:  this Lapp orientation is that of a ring-loaded Bowline !  Which is
why the so-called (by Ashley and his echoes) "Left-handed Bowline" is more
secure in such loading.


I use the simple Lapp, w/slipped hitching-side tail, for a quick release knot,
sometimes -- as pulling the slip-tuck spills the knot completely free.


Now, the obvious variation(s):

1) make a turn around the two SParts with the hitching tail and 2nd tuck;
this anchors the structure to remove the dangerous slippage, as
the full turn will bear down on its SPart;

2) repeat this wrapping, and then tuck the hitching tail out under the
initial turn of the hitching SPart (so, parallel to the bight legs);
this becomes ineffective if the bight is much larger than the hitching
line, as the *ravine* between bight legs will be too *roomy* for
nipping the tail.

These knots have the beneficial characteristic of being secure-when-slack
unlike the Sheet bend -- nothing to sneeze at!

NB:  one can make the initial wraps around both bight legs,
but the knot will be difficult to untie; making the wraps around only
the bight's SPart (or, even if loading is in the dangerous-for-Lapp
orientation, then the tail) will allow for some hope of forcible
loosening
-- by pulling the bight tail to pry out some hitching-SPart
material, and enable further loosening.  YMMV with materials & load.

It also strikes me that the structure is more secure when joining two
ends than joining end to eye (what I've called a "closed bight"),
as if the bight legs have equal loading from the setting, the knot
doesn't seem to close (snug up) as securely -- something one can bias
in dressing/setting, to imbalance eye legs to sort of simulate an
end-2-end geometry.


.:.  The Double Lapp knot -- the best unsung new knot!

--dl*
====
Title: Re: Lapp knot
Post by: dmacdd on July 26, 2010, 09:53:17 PM
I have just further tested the Lapp knot and what I will call, for the nonce, the anti-Lapp knot  multiple times with my 1/16 inch 1.6 mm cord and my test rig (foot bar and dowel handle with rings and substantial  rope leads to shorten the test specimen).

The Lapp Knot:
(http://igkt.net/sm/index.php?action=dlattach;topic=1955.0;attach=1548;image)

The anti-Lapp knot is very similar except that the RH standing part comes out of the knot, contrary to the Lapp knot, on the same side of the knot as the LH working end.

In every case I

set the knot carefully, pulling on all ends and being esp. sensitive
to getting the hitching side (i.e. the non-bight (hitched to, you see) side) snug.

I tested the Lapp knot a further 10 times. In no test did it fail. In each test I exerted enough force to stretch the cord substantially, about 25%.  It did not slip _at all_ in any test. It was easy to untie every time.

I tested the anti-Lapp knot a further 8 times.  It slipped to failure every time in a load considerably less than I am able to exert with my test rig,  with relatively little stretching of the cord.

I believe these results condemn the anti-Lapp knot as unsuitable for a great many applications.

Title: Re: Lapp knot
Post by: roo on July 26, 2010, 10:50:06 PM
I believe these results condemn the anti-Lapp knot as unsuitable for a great many applications.
Another evil impostor scenario, although I think users should be cautioned not to expect a lot from the Lapp Knot anyway.  It's a step down in performance from the general utility Sheet Bend.

As an aside, it's good to properly set knots, as Dan mentions, but that does rapidly become more difficult as rope diameter increases.   
Title: Re: Lapp knot
Post by: roo on July 27, 2010, 03:48:53 AM
One attempted justification for using the Lapp Knot is using the slipped version as a quick release bend, as mentioned before.  Now, I can see not having end access to the rope for the knot on one side, since you may want to release it from a distance, possibly, but it seems unlikely for this to be the case on both sides.

In the likely event that we have end access for the future "U" shaped rope, then the slipped version of the Sheet Bend becomes an easy and familiar solution.

One way of doing this is tying and collapsing a Halter Hitch around the rope with end access to force it to assume that "U" shape.

http://notableknotindex.webs.com/haltersiberian.html

Don't try this with the Siberian Hitch, by the way.  Anyway, other less gimmicky, more standard sheet bend/bowline methods with a draw loop would work as well.

P.S.  This can be done without any end access, as shown by the new image at the bottom of the Halter Hitch page, but at the cost of some simplicity.
Title: Re: Lapp knot
Post by: Dan_Lehman on July 27, 2010, 05:54:24 AM
I have just further tested the Lapp knot and what I will call, for the nonce, the anti-Lapp knot  multiple times with my 1/16 inch 1.6 mm cord and my test rig (foot bar and dowel handle with rings and substantial  rope leads to shorten the test specimen).

The Lapp Knot:
(http://igkt.net/sm/index.php?action=dlattach;topic=1955.0;attach=1548;image)

The anti-Lapp knot is very similar except that the RH standing part comes out of the knot, contrary to the Lapp knot, on the same side of the knot as the LH working end.

Whoa, this is an easy change to state :
the LH SPart is the upper strand instead of the lower
(and thus the two tails are on opposite sides).  The reader
can SEE this at once -- just loading the other end.  Your
words coerce a re-tying of the "RH" side to be seen.

As for Roo's limited vision on value, he should read my post to its end,
and realize the considerable value of the simple, "obvious" extensions
(neverminding whether someone has put them in a book or on-line
(well, they are on-line now)).  And lapp it up!

.:.  The Extended (or "Multiple") Lapp Bend -- the best of new knots!


--dl*
====
Title: Re: Lapp knot
Post by: roo on July 27, 2010, 03:03:29 PM
As for Roo's limited vision on value, he should read my post to its end,
and realize the considerable value of the simple, "obvious" extensions
(neverminding whether someone has put them in a book or on-line
(well, they are on-line now)).  And lapp it up!

.:.  The Extended (or "Multiple") Lapp Bend -- the best of new knots!

If the justification is some double version or versions (yet to be diagrammed) of the Lapp Knot, it had better have some very good justification beyond novelty or modest increase in security/stability.  Otherwise you'll end up unwittingly promoting the single version to a whole host of people who may not realize its problems.
Title: Re: Lapp knot
Post by: dmacdd on July 27, 2010, 03:33:15 PM
The Lapp Knot:
(http://igkt.net/sm/index.php?action=dlattach;topic=1955.0;attach=1548;image)

The anti-Lapp knot is very similar except that the RH standing part comes out of the knot, contrary to the Lapp knot, on the same side of the knot as the LH working end.

Whoa, this is an easy change to state :
the LH SPart is the upper strand instead of the lower
(and thus the two tails are on opposite sides).  The reader
can SEE this at once -- just loading the other end.  Your
words coerce a re-tying of the "RH" side to be seen.

I agree. My description of the anti-Lapp knot, while correct, was not as kind to the reader as yours above.   An alternative reformulation: "The anti-Lapp knot is similar, except that the horizontal U of the LH cord is turned upside down, so that the standing parts come out of the knot on opposite sides."

And a drawing or photograph would have been even better.  So see the attachment.
Title: Re: Lapp knot
Post by: jarnos on July 08, 2021, 02:05:16 PM
Mark Gommers tells in his Bowline Analysis (version 3.0 thereof) when talking about ABoK #1034 1⁄2 what he calls Tail outside Bowline:
Quote
Point of interest: Geoffrey Budworth, in his book ?The Complete Book of Knots? referred to
this particular structure as a Lapp knot (at page 35). The history of the
?Lapp knot? was described in the April 1996 edition of ?Knotting Matters?
where it was apparently used in Lapland for tasks such as hitching reindeer
to sledges and suspending sheath knives. Budworth also comments that
this knot was often called a ?false sheet bend?.

Title: Re: Lapp knot
Post by: KC on July 16, 2021, 09:34:09 AM
Any of the simple end connection forms where one side is simplest bight, is as family to me
that starts with SquaREef(?*) family, that have the primary lock force dialed down to Zer0 and with 2 bights/host, no locks/hitches or such actions with PRIMARY force, only deflected.
>>so should NOT be used on a linear pull, only against radial swell, where the PRIMARY force can then power the locking factor agaisnt host.
.
The rest of larger family to me form a locking hitch around the bight host, with primary force side
>>except this Lapp
>>in any mixed Bend (thus not Square sub-family that is not Bend and needs matching rope/s)the locking side would always be the smaller/tighter; to impose it's tension X rigidity divided by size(so smaller is greater) against the host bight side.
>>bight side is the free escapee side, the other the lock, Square by this measure has 2 escapees w/o lock against Linear pull.
Another thing about the Lapp, in shorthand to self, i reference when tying in a binary of weave vs. pass in crossings.
>>rest are weave, turn, weave.
>>Lapp does a pass, turn, tuck(counter-intuitive to years of weave, turn, weave)
.
You do want the tails on same side, so don't pit primary force vs. secondary force (after arc) as hold
>>but rather secondary vs. secondary for the stop, not on primary side of SPart vs. Spart, but rather after arc by each side.
i think of primary as 220v and secondary as 110v, and say not to try to control 220v w/110v (SquaREef as Bend)
.
Lapp Knot never scored with me as a working class knot;
but, have seen it's weakness , be a strength in a breakaway/fuse context if set to fail right, perhaps w/falsie; not sure, too long ago.
Also, a knot-part that doesn't 100% stop force, then doesn't concentrate the stop/ wear in that position, if setting up the next force catch for follow up buddy to shut down flow entirely, but spread out.  Like RT rather than Turn on smaller host to share the wear.
In working knots i consider RT as a Real Turn, choice to use just single Turn a purpose full downgrade to perhaps pass more force to the next position(or quickie, or short rope; but purposeful downgrade).
.
One of the reasons i evaluate Linear inputs of termination(Hitch) or continuance (Bend) , things w/SParts:
first by Primary Hook of SPart of linear input converted to radial control thru Primary Arc as the ruling primary Hook ruling rest of structure in tension and rigidity;
Is because can't escape that model even in these simplest beginning lessons, with everything else stripped away to minimum, Hook model logically persists, as primary, even if only , conversion point to radial control the whole mechanix rides on for control/stop.






* if us Americanos would have renamed Reef to about anything but Square; i would always call Reef in respects, but also the reminder and flavor of where much came from of these things, the work, sweat comrade etc. of what was l-earned to pass on. 
BUT, i say Square, because it is so important to have knot framework SQUARE geometry to purpose, and pulling out of square on same axis in Thief, or cross axis in Granny, or both as rollout in Grief, is the real lesson. 
.
And this is a beginner's knot of passage it seems, and the focus should be on the key geometry (squareness etc.), even if not shown as geometry to get on the truest track from the word go.  That is much of reason for my trying to show definition of pivotal principles is to steer towards them from start, never conflict to give truest consistent view over growth.  Working it backwards, making more sure evolves to destination.  Another reason for comparison's of Ancient stories like Samson, Achille's Heel, Greek/Roman Column and other 'heritage' and story lessons framing at times.
.
Many, many unspoken lessons in SqReef family!
Title: Re: Lapp knot
Post by: KC on August 04, 2021, 01:02:55 PM
This is how i look at any bight based knot/Bend, chasing the forces in electrical pressure, rather than tension pressure imagery.  Naming them as High, Low and No voltages, w/arc and nip as conversion points/boundaries.  i find this key to viewing Square family, Sheet Bends, Lapps, Surgeon's etc.
(https://upload.wikimedia.org/wikipedia/commons/f/fd/Tension-rigidity-changes-viewed-in-knot-bight-base.png)
.
Applied to Sheet Bend tail in or out:
(https://upload.wikimedia.org/wikipedia/commons/a/a6/Tension-rigidity-changes-viewed-in-knot-bight-sheetbends.png)
.
Then to the Lapp Knot here:
(https://upload.wikimedia.org/wikipedia/commons/2/2b/Tension-rigidity-changes-viewed-in-knot-bight-lapp.png)
These show similar 'voltage' patterns to Sheets, but then also bring forth the view by comparison of weave or not.
i assume when tying i want WE(Working End) to weave into and out of arc Turns as a default mnemonic shorthand.  Meaning i don't note if i am supposed to weave, just assume and simply note the exceptions that don't.  This lowers the tying memory overhead, but also gives a different view of the funcionality.
.
Sheet Bends weave into and out of the arc/Turn of a passive bight with the active lock side.
About matching Lapp, does not weave, but rather pass other rope parts until serves around arc and then passes rope parts again, until a final single tuck to secure.
A tuck is as WE serves under an existing , therefore greater tension AND thus also greater rigidity rope part to me.
A weave is more of where WE pass over an existing rope part on host, that has tucks on either side.
>>Kind of like a linear answer to RT of 3arcs listed radially on host
>>weave gives a more 3arc rappel rack function, as a linear listed gauntlet of arcs
But still, to the same 3arc sciences have tried to show.
.
With everything the same between tails same side forms of Sheet Bends and Lapps;
To weave or not, seems to be the single binary coin flip of determinant change defining between.
.
Lapp proper not as secure, but not then locking as hard as Lapp.
Tail in or out argued as best or not for Sheet Bend;
BUT Round Turn (RT) instead of simple Turn for lock side is a game changer for both problems.


In case the skull and cross bones as like ABoK w/Danger Will Robinson warning is unfamiliar or forgotten:
60's "Lost in Space" series, kinda about others that left the safety of the ground for whatever dangers
voice by famous announcer Dick Tufeld, Bill Mummy as Will, plagued by dangers and the Eddie Haskell-ish Dr. Smith
Title: Re: Lapp knot
Post by: Dan_Lehman on August 05, 2021, 12:08:19 AM
This is how i look at any bight based knot/Bend,
"Bight hitches", I call 'em --using "open" (just
one bight end loaced) or "closed" (load both ; an eye).

You need to run this experiment to the next leve
--to "double" versions.  There, the sheet bend gains
not so much (though one has other variations for this
(ABoK #488, i.p.!)), and the Lapp, plenty : slack security
and stability, and with forcible loosening by pulling the
tails apart to prise out some SPart, enuff to loosen further!

(-;
Title: Re: Lapp knot
Post by: KC on August 05, 2021, 11:09:07 AM
For me 'Bight Hitches' (guess we should not use any contractual form..) start with Bight_Hitch_0 of non-hitch of the SqauREef fam; where neither is a lock/hitch both are just the bight of matching forces, so no primary force not applied in lock of added hitch.  To me the bight is as a locked slip, bight is the escapee and hitch the jailer.  SquaREef has no jailer/lock, just 2 potential escapees.
.
The solution is to use SquaREef as in Round Binding, so turns the pull from flat linear to 90degrees around half arc, changing the direction of the lock that is not working 90 degrees as do to accommodate  antiBowline.  And as with the changed direction of loading and lock in antiBowline, the SquaREef now locks with primary 220v raw alpha force where did not before.  But is not greater over lesser, is of matching/matching locks to each other.  In Sheet for unmatched Bend, we would always make the smaller/denser/stiffer side the lock.  With SuaREef must be matching, so there is neither advantage nor disadvantage as each half locks.
.
The all around clamping of RT 3arcs cures many things for us i think.  Don't need to worry about tail in or out of Sheet Bend/Bowlines and is not just a sincere arc pull with just minimal force back from SPart side to perform grab.  RT upgrade gives real, compounding grip by comparison.  For me corrects Lapp and Sheet/Bowl shortcomings when 1 Turn used in the lock.  i mostly consider a single arc as a get by or purposeful pass of less buffered force to the next position.  As from a VERY key lesson (again TYSM) of
ABoK Lesson#1669: "If the rope is weak and the hoist is heavy, a Round Turn on the Standing Part adds materially to the strength of the knot"
>>can be diminished by overly spiderly pre-fixxing to subsequent lower tension for performing this #1669 utility , if the pre-fix is of
ABoK Lesson#1720: "If a spar is small a RT is preferable to a single turn. It makes a stronger knot and dissipates the wear.".
Drops the usable tension for the RT around SPart trick.  So reduces the RT grip around SPart that performs more of a pull along SPart, that shearing across the support column of the SPart.
.

i prefer Sheets w/RT lock, slipped for ease and the slip crosses self for extra bulk, similar if ever use Lapp.
i like grooming the RT lock long, pulling to set from BE backwards to maintain more of a long gauntlet of 3 arcs as like short rappel rack , like a linear RT theory, buffering to harshest deformity of the arc of change.  And when really concerned even kinda extrude the 3arc longer linear into the bight side as well, setting backwards so it too locks down to gauntlet of 3 linear arc list pf softer deformity before the major deformity of the arc of conversion U back around.  Only done that in a Sheet Bend actually, but would faithfully mirror 'down' to lesser Lapp.  The Linear list of 3arcs also comes into play to upgrade SquaREef not in Sheet Bend direction, but rather to Surgeon's etc.
.
(https://upload.wikimedia.org/wikipedia/commons/f/f8/Grooming-and-dressing-knots-to-cleaner-structural-form.png)
i kinda call this Sheet version with RT each end for gauntlet of 3 arcs rappel rack effect buffering force to the harsher 180 U turn radial arc from each end of pull a Slipped Double Bull Sheet(careful how you say that, but still more polite than bight hitch contraction..), because we came to call the twist to short 2 arc gauntlet of Bull Hitch a Bull nose if theory applied farther than Bull Hitch.  This fully weaves into and out of the 180 U turn arc too. Extra swell arc from crossing of the BE slip is very purposeful and in fact might use it as a tightening crank to the 'off'/Omega/secondary/post arc/110v side of that arc of conversion.  This gives more deformity so more grip, after the first 2 pre-fixing arcs list, as then presents the greatest deformity of the arc in continued progression.
.
But anyway, Lapp study is not isolated to Lapp for me, but is piece of puzzle position to this whole 'fam' .  Just as SquaREef is puzzle piece that shows with neither side as lock, so is a 'Bight Hitch' of value:0 and appropriately in the list of these at array position _0 on that list..when not wearing horse blinders to limit peripheral range depth to myopic scope.