ropes and cordages

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ROPES & CORDAGES

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TWO VERY INTERESTING ARTICLES FOUND ON THE NET

MOVEMENTS OF FIBERS IN ASSEMBLIES
by J.W.S. HEARLE and A.H. WILKINS

SNAPPING OF ROPES UNDER STRESS
by L.CONTRI , S. SECCHI

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Follow-on on TREES THEY KNOW

This time instead of the usual 'Z' laid you will see some 'S' laid : fallen pine and vine in
FONTAINEBLEAU ( 60 km forml Paris - France ) forest.

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S-LAY TREE IN DORDOGNE
A photo of its trunk ( fruit tree )

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Added 2012 Jan 6th

USING 'S' and 'Z' TO CHARACTERISE LAID-UP
CORDAGES

or A MISTAKEN (IMO) CORDAGE CODE

or ARCHAEOLOGIST MYSTIFIED BY A CORDAGE CODING ( he is using
NOT the language of ropesùmaking but the language of textliles which makes
for a lot of misunderstanding when speaking about ropes and not texiles yarns!)

or, but that is doubtful, at least to me ;-D : A MISTAKEN NAUTILE

Early 2006 I found a publication and ever since I have hesitated and postponed
the demolition of an archaeologist 's writing about one of the illustration shown which
to me shows the author is lacking in education about 'traditional' laid-up cordage.

-----------------------------------------------------------------
A cordage is a succession of 'structures' assembled by "axial torsion applied'.

*** FIBRES when they have a natural orientation make the decision for the orientation of
the YARNS (FIL de CARET) made with them.
As fibres and yarn are of the same orientation it is usual to code (reading from left to right
1 2 3 4 5) for the YARN only. It is always best to avoid ambiguity and always state the
way you coding is written. In my case it is yarn / strand / hawser
to which if the need arise are added / cable / super-cable

*** yarns are twisted in groups to make STRANDS or SUB-ROPES (TORONS )

*** Several strands are LAID-UP ( sont COMMIS) to make HAWSER , the cordage (HAUSSIERE
ou AUSSIERE). Les (h)aussières sont des cordage commis UNE fois ;
hawser are cordage laid-up ONCE. Curioulsy this laid up once stage when speaking about
'thread' is called 'cable" which for ropes is in fact a laid-up twice cordage. There is a lot less
ambiguity in French were hawser==aussière and (marine) cable is grelin. so in French the
cable of textile is the Fil câblé == cabled thread in textile : single yarns are spun with an
S-twist then several single yarns are plied together a Z-twist, then several plied yarns are
laid up together with an S-twist to make a 'cabled yarn' which is not ambigous as 'cable' is.
See how ambiguous this is because cabled yarn of textiles is in factthe hawser of ropes and
cordage : NEVER NEVER NEVER be ignorant enough of ropemaking to speak of 'cable'
and intent 'cabled yarn', always say the full "cabled yarn" to avoid the confusion with the
cable which is a twice laid-up cordage and not a once laid-up one.

*** Three hawsers are LAID-UP into a CABLE ( GRELIN). Les grelins sont des cordage
commis DEUX fois ; cables are cordage laid-up TWICE.

***Three CABLES are LAID-UP into a SUPER-CABLE ( SUPER-GRELIN)
Les super grelins sont des cordage commis TROIS fois ; super cables are cordage laid-up
THRICE..

The laying-up or 'commettage' in French is a twsiting like the one preceding it BUT it warrant
a special name due to teh very specific events ( physics) happening at this stage that are
wildly different from what followed the other twisting procedures in rope making.
( see DUHAMEL DU MONCEAU )
--------------------------------------------------------------------

The code S or Z is allowed ONLY if it refers to a TWISTING procedure in the
making of the cordage ; that is so if one wants that the coding stays 'homogeneous'.

One character in an identification code MUST be in correspondence with one and only one
characteristic (and reciprocally) that is being coded for :
for example one MAY NOT use the same sign to code for say a square and a cube.

It is very important to realise that the  S or Z stands for the result of an axial torque on
the orientation of a structure and stands for nothing else as a coiling for example.

caveat : it is for commodity and expediency that I here use the words 'helix/helices"
when it would more appropriate to consider that it is really helical torus(es) that exist
in 3D rather that a line deploying in 3D as for a proper helix - a consideraton of
"helicoid' was quicly pushed aside-.

Another thing to realise is that

if fibres/yarns make FIRST-ORDER HELICES then

a strand is SECOND-ORDER HELIX ( an helix of helices of first-order, and helix
of helices)

a hawser is a THIRD ORDER HELIX ( an helix of strands) ( cordage UNE fois commis
that is cordage laid-up ONCE)

a cable is a FOURTH ORDER HELIX ( an helix of hawsers) ( cordage DEUX fois commis
that is cordage laid-up TWICE)

a super-cable is a FIFTH ORDER HELIX ( an helix of cables) ( cordage TROIS fois
commis that is cordage laid-up THRICE)

You must immediately note that to go from one (N) order helix to the (N+1) order helix you
MUST ADD material to the "starting" order.
ONE STRAND is a second order helix but one MUST ADD AT LEAST ANOTHER
STRAND to go to the third order helix by TWISTing the regrouping of strands.

illustration 1    illustration 2
illustration 1 is a modelisation of one yarn helix made into a single strand helix made into a
single hawser helix

IF you make a third order helix without adding material, say using a single strand to be
strained into making an helix ( this will be a serialized hockles) then this new helix is not
of the same type as the third order helix it is a SUPER-COILING of ONE strand.

You must NOT confuse a SUPER-COILING and a (N+1) order helix made by addition
by a twisting procedure of several (N) helices.

Super-coiling (cylindrical snarling) is readily seen in rubber bands used as 'motor'
for model air planes.
This super coil is the result of excessive torsion and this is something that ropemakers of old
avoided at "all prices" as it is something that destroy a lot of fibres and so weakens the
cordage.

Using those two ZS signs you can give the identification code of a cordage

by a triplet such as ZSZ for hawser ((h)aussière ou cordage une fois commis or once
laid-up cordage)

or a quadruplet such as ZSZS ( cable or grelin in French, a twice laid-up cordage, un
cordage deux fois commis)

or a quintuplet as ZSZSZ ( super-grelin ; cable, cordage TROIS fois commis or thrice
laid-up cordage )

Using those two ZS signs IMPLIES THAT EACH LETTER STANDS FOR A TWISTING PROCEDURE :
operative word here is TWIST.
So writing in a scientific article, for an archaeologist such as the author of the article, that
the cordage in Fig 18

[open quote] zS2[S2] cable made of palm (BE95/96-6.004 1375-h-0447); another piece
is (BE99-31.007 2383-h-3122) (S-spun soft fibre yarns). Fragment (BE96/…-10.001
0572-h-1314) is slightly different but with a comparable appearance. Here, the ply is wound
around itself resulting in the same pattern of curling but around a core. The curling of cordage
like this is not a result of post-depositional processes and seems to be intentional. It might be
the curl of a wig.[61] The cordage originates from a late fourth to early fifth century CE
context.
Courtesy of the University of Delaware/Leiden University/UCLA Berenike Project.
[end quote]
or
[open quote]1.3.4. Kinks
Kinks are curls, crossings or curvings in cordage which are not parts of knots, and which are
not due to post-depositional circumstances. Kinks are not necessarily accidental (figure 18).
[end quote]
is tantamount to saying that it was made with THREE twisting procedures the third being the
first laying-up or 'commettage'

The second quote I have much difficulties to understand and in my time as a reader for a
'reading committee prior to publication' in scientific domain I would never have accept this
manner of witting.
If that person realised that it was CURLS AND NOT THE RESULT OF ANOTHER TWISTING
PROCEDURE THEN HE IS DOUBLY FAULTY TO HAVE USED ZSS as this is ABUSING THE CODE !
LETTERS ARE TOI BE USED ONLMY FOR TWISTING PROCEDURE WITH ADDITION OF MATERIAL
AND NOT FOR SUPER COILING BY CYLINDRICAL SNARLING!
I don't find those remarks very bright !
Why is he speaking of knots I cannot even begin to understand as try as I may I cannot see
any knot in Fig 18.
I can NOT SEE ANY KINK in that Fig 18
cordage.( A kink is an abrupt bend or loop in a rope which is a result of an unbalanced
twist relationship in the rope structure.
Strand kinks are also termed as cockles, or knuckles. )
and kinks are certainly NOT crossings !
Kinks are avoided by all reasonnable persons using cordage and are ALWAYS ACCIDENTAL
and due to a mistaken manipulation. Here lie kinks and their damaging influence, as you can
see this is quite a long way away from anything in Fig 18.
Here the curl / coils are evidently so regular and in series that I am hard put considering
them "accidentals".

The author speaking of Fig 18 seems to me quite unable to really make a much needed
distinction between COIL/ COILED and CURL/CURLED about yarns.

Archaeologist are studying cordages made "the old way : by hand" and I find quite
disturbing that they do not have enough sense to list reference else than ASHLEY
or HIMMELFARB ; none of those archaelogists seem to have enough "culture générale" to
know:

*** The French Enlighthement Encyclopedists and their articles on "cordes" (ropes)

*** the 1747 monumental work by Henri-Louis DUHAMEL DU MONCEAU :
TRAITÉ DE LA FABRIQUE DES MANOEUVRES POUR LES VAISSEAUX, ou
L'ART DE LA CORDERIE PERFECTIONNE. (biographie) (PDF of this book )

*** the 1839 book by BOITARD : NOUVEAU MANUEL DU CORDIER.
(PDF of this book)

Those books treat the hand made cordages and not as

1957 HIMMELFARB's THE TECHNOLOGY OF CORDAGE FIBRES AND ROPES
or 2004 McKENNA's HANDBOOK OF FIBRE ROPE TECHNOLOGY
the modern processes.
Archaeologist lacking " culture générale" in cordage will do well reading those old books
if, of course, they have enough 'general culture' to read French.

First this is NOT A CABLE as understood in cordage a cable is three hawsers laid-up together
; the author is confusing the reader knowledgeable in rope making by using an inappropriate
term taken from TEXTILES. He is using ( imporecisely at that : he should have
disambiguated by using "cabled yarn" instead of 'cable". the textile industries nomenclature
and the rope of old nomenclature are not using cable with the same meaning : a marine cable
needs a QUADRUPLET, when a TRIPLET it is HAWSER!

The only other way of using the word 'cabled' 'cable' is not a ropery term but a textile
industry term as in "a cotton cabled thread" which is quite different from what is shown
here.
In textile manufacture 'un fil cablé' , a "cabled thread' is ( strictly defined ) 'coton câblé' are
different from 'coton retors' cabled cotton = re-twisted cotton
Re-twisted cotton =2, 3 or more spun yarns are regrouped and again twisted.
Cabled cotton = re-twisted thread are regrouped and twisted again.

So to make things simpler and clearer than the convoluted formula used in the article I will
say that this zS2[S2] is in fact
a ZSS meaning that
two Z yarns were twisted in an S Strand ( or S sub-rope)
and that two such S stands were TWISTed in a S hawser
but that is NOT an hawser that is shown in Fig 18, nor a cable.

to make the yarn from the fibre == FIRST Twist ( ONE length of 'material is necessary)
to make the yarns into stands == SECOND Twist ( at least TWO lengths are necessary)
to make the strands into hawser == THIRD Twist ( AT least FOUR length are necessary
Just this should have alerted the guy : there are "only TWO lengths' of material in his
cordage so it cannot be ZSS (three successive assembling twists)

Well there is ONLY TWO TWISTS that are necessary to yield a reproduction of the cordage
shown in Fig 18, not three, so the use of three letters, each standing for a twist is
not proper.

If you use three twists then the last two letters in the code are SS and this shows that there
is ABSOLUTELY NO LAYing-UP mechanism possible with two successive twist in the
same orientation, the locking up is impossible ( aucun mécanisme de commettage n'est
possible) and this lead to a "disastrous" hawser.

Just look at the dishevelled double helices in this illustration :
it is the result of THREE twisting procedures building a ZSS cordage that has absolutely no
intrinsic stability and no resemblance to the item shown in Fig 18.

First let us be very wary of what this guy assert and let us do some forensics on his picture.
lets us tweak the picture so let us get some more details
We see
*** a first order helix that is a Z
*** a second order helix that is S
*** and the final structure is S-oriented COILING, NOT TWISTING.
Here is a modelisation of this final structure.

Well thisZSS is mistaken IMO in its meaning "three twisting" as I am going to show it :

See how the structure can be analysed : two helices that are following one another with a
slight phase shift .

I made a 'true" (three twisting with addition of material) ZSS.
I used 3 Z yarns ( FIRST torsion, twisting procedure)
those I assembled to get  S strands ( sub-rope ) ( SECOND torsion, twisting procedure)

IF I assembled by a THIRD torsion, twisting procedure,  S-oriented   2 of those S strands
( illustration ) and then do not forcibly glue of seized the extremity ( this is not necessary with
a 'good" cordage) the whole unstable structure unravel and becomes this loose structure
you see there
This is a real ZSS and yet it does not look like the Fig 18.

YET IF I take this ZSS, not letting it relax and tightly COIL IT , NO AXIAL TORSION,
JUST TURNING AROUND A CORE AND SO MAKING A COIL I get an almost
perfect imitation of Fig 18.

The successive twistings are made by applying torque using successive axis that all have
globally the same direction but to apply a COIL I had to use an axis which is almost ( it is
the angle of the coiled helix) perpendicular to the axis of the strands.
It is very much like hairdo waviness made using "bigoudi" or hair-curler.
Here is a comparison.

So as it is not an axial torque that was applied one has NO RIGHT to code it as an S twist
the proper formula is not ZSS (three twist procedures)
but
ZS ( two twist procedures) FOLLOWED by a coiling/curling procedure S-oriented
which is quite different structurally and procedurally.
see ***** below

It is IMPROPER to code ZSS because the coding is NOT-homogeneous:
--- the first S codes for an S-TWIST
---the second S codes for an S-NO-TWIST BUT COILING

Just my two cents.

------------------------------some words----------------------------
in http://www.manilacordage.com/faq.php
[open quote]
What is a Kink? A Cockle? A Knuckle? A Hockle? and a Chinckle? How do they affect a
rope?
A kink is an abrupt bend or loop in a rope which is a result of an unbalanced twist
relationship in the rope structure.
Strand kinks are also termed as cockles, or knuckles.
A hockle is a condition whereby a rope strand twists on itself -- also called a chinckle.
Apart from the effect on the strength of the rope, kinks and cockles are detrimental because
they interfere with the utility of the rope. They will not pass through a block, will not lie
properly, and will chafe more readily.
[end quote]
----------------------------------------------------------------------

PS : to tell all the tale : if you take the two (no addition of material) ZS and apply a wild
excess of torque in the same orientation to make a ZS super- coiled in S while pulling a lot
then you will get "serial cylindrical snarling" - like in the rubber band.
This excess of torsion will break a lot of fibres so nullifying their tendency to reverse
the applied torsion and the structure that is yielded by such a process is again an imitation
of Fig 18.
The precedent imitation was made by coiling around a core and using 'artificial hemp'
(SPLEITEX) this one with over-torsion and serial cylindrical snarling was made with
" first quality hemp".
As you can see 'the central void' is now almost virtual and it was not so easy to push
the metal needle inside. The super coil is quite 'springy' while the first normal coil was soft,
supple.

This super coiling tend to 'crowd" upon itself while the coil was rather "loose' and
supple and all in all the coil resemble the curls in European hairs while the super
coil resemble more the curls in black African hairs.

Here are the results of coiling in false hemp or first quality hemp and of super coiling
induced by excessive torsion leading to serial cylindrical snarling..

***** With super coiling the pai of  ZS ( yarn/strand ) becomes a ZSS^* (S^* is NOT from
a torsion procedure like S is) BUT NOT by assembling several ZS into a 'true' ZSS but by
having its OWN (N)-order helix becoming its OWN (N+1) order helix.
It is entirely born of itself while in a laying-up procedure it participate with its own helix to the
(N+1) order helix WITH OTHER (N)-order helices.

To take some words of my old domain : autologous and heterologous.
A cable is an heterologous (N+1)order helix coming from 3 (N) order helices (hawsers)

bold="">( as in going from 3 hawsers to 1 cable : passage from cordages laid-up
ONCE to cordage laid-upTWICE.)
An helix order is added but sue to the addition of material of the previous order of
helix.
The number of LAYing-UP procedure augment from (x) to( x+1).

AUTOLOGOUS : one helix order is added BUT by the cordage ITSELF which is
supporting the wild excess of torsion
The material used to make the (N+1) order helix is given by the (N)order helix itself with no
external additionof material but by MODIFICATION OF THE SPATIAL
CONFORMATION of the pre-existing.
The number of LAYing-UP procedure is unchanged.

In the case of the pair of ZS becoming a cylindrical snarl it is an autologous
(N+1) order helix born of its own (N) order helix

A SS sequence is not "stopped" , "seized" as with a SZ or ZS.
It is not stable because absolutely no internal forces of counter-torsion make it
stable as happen in a laid-up cordage such as a ZSZ where the SZ is "the lock" that
makes it stable

The super-coiling is a wild excess of torsion that make appear a (N+1) order helix
out of pre-existing, with no adfdition of new cordage material, (N)-order helices so
no new laying-up.

Copyright 2005 Sept - Charles Hamel / Nautile -
Overall rewriting in August 2006 . Copyright renewed. 2007-2012 -(each year)

Url : http://charles.hamel.free.fr/knots-and-cordages/