CAPSIZING / COLLAPSING of REEF KNOT (square knot) Identical
diameter
for each cordage in it.
(Aparte note :
capsize / collapse / roll / walk / collapse/ become
undone / flip / invert / slip /
slide / pull out.... so many words I
have seen used - unclear, really unclear to me!)
"Every one knows" -a good way to start to state an 'unexamined'
affirmation- that a square
knot or reef knot can be
made
into another knot , a lark's head, by
forcibly pulling at the
same time on its tail and SPart .
(
more later about what seems to me
- either some condition akin to frenetic delayed echolalia
or involuntary parrotlike repetition (echoing)
of a word
or phrase just spoken { little me : in the case in point it
is 'written
by another person'. - though
it remains to be seen if the involuntary trait is verified or it is is
wanton.}
- or it could be a lower order phenomena : medullary
reflexive arc unlinked to any descending inhibitory
tract or
may
be "mental rheumatism" causing limping ( may be limp too)
thinking, leading to sternly
echo dire warnings
about it without probably
having ever made any investigation
and experimentation
whatsoever before going
on auto pilot with this litany)
Can you tell, without fail, what happen to the "crossings" in such a
transformation ?
Where do they go?
Which one is kept intact in the same place and of same nature ?
Which one is "translated" ?
Which one is "destroyed" ?
Which one is "created" ?
Take a piece of cordage, or paper and pencil and try to write an answer
before going
to see
what indeed happen.
Learned something ?
Well I did when doing that little experiment.
Shame should not be felt for not knowing but for not accepting to learn.
" never, never, under any circumstance use
this knot as a
bend , it is only a
binding.... " and so forth.
A forceful
unsubstantiated
affirmation stated with a strength of conviction inversely
proportional
to the
documentation offered.
Stating opinion or even knowledge about "a knot" without clearly
telling to which specific
use it was put , the material(s) in which the
cordage is made, the diameter of the cordage ,
the nature of
the cordage 'making' : laid, solid braid, braided sheath with 3S core,
braided
sheath with parallel fibres core, hollow braid, number of braiding (
4,6,8,12,16...)...is
relatively meaningless.
Some knots that were paragons of virtues in the hemp / manilla / flax
/ cotton days
are not
to be 'automatically' taken as such in nylon, or polypropylene
or any post 1950 material.
If the reef knot has one big default it is its jamming potential.
It is
easy to get an unloaded reef/square
to capsize, easy in term of force but not of
specific actual circumstances
in
real
life.
There is only need to overcome what remain of the
tension that was
put into the knot when
setting it.
This is why it is useful in sailing : there is
-there
should not
be any tension applied to -
'no tension' in a reef knot that is why it
can be undone so easily with
one hand.
If you do not apply -directly or indirectly- equal tension on both the
WEnd and the SPart
of the same cordage in the reef knot it will not
come undone.
--------
If you use a reef bend :
- - - be sure to dress it and set it with the very maximum
of force you can give before
using it. (not fully setting
some
knots
may be deliberately used to keep that as a braking
or shock
absorbing
"reserve" but make sure that their tails are longs and/or 'secured')
- - - for my part I do not forget to follow the rule I
was taught so many years ago, in
Brittany by people earning their bread
on
the sea all year long :
always leave long tails (6 to 10 times the diameter or even more : the
bigger the rope the
higher the
multiplying factor)
Please try to refrain a few seconds from immediately thinking
that
this is the
sign of a
bad knotter, - that
would just be prevention and a priori judgment -, may be it is the
sign of
experienced ones ! Even if it is a 'bad knotter' way and
mean, I have
always, till now, seen it serve in good stead.
Just take a look at what can be seen in fishermen's
harbours, not in the Sunday, leisure
cruisers harbours, but in
commercial fishermen's.
Of course there are some times when long tails are
impractical so just secure the tail in
another way.
The worst thing -
beyond urgency time - is to fall back on pre-set response ; always
stop, think and adapt to the local ( space and time and opportunities )
conditions,
diving just reinforced my professional training in that
direction.
Tailored suits are generally better adapted than ready made one!
Very often a knot will slip a bit to begin with when getting
under
its actual load and then
will settle and then fully set, this can be seen
even if it has been set manually.
This do not happen to an identical degree with small or large
diameters of cordage
but I find that the bigger
the diameter the longer the slip may be.
( This question of "size" is something often forgotten in many
discussions :
'scaling'.
Example : length goes by power of one, surface by the power of 2 and
volume by
the power of 3, that is why gigantic ants are a 'no go'.
Scaling and the nature of the material the cordage is made of are of
great importance)
You tested a 8mm cordage with 40 kg, to test 'to scale' a 2 mm cordage
you should
load it with 2.5kg and not 10kg.
Weight
is applied by 'surface of section" so if you
divide the
diameter
by 4 your divide the section by 4x4=16 so you must divide the
weight by
16 and not by 4. )
If you have not left enough tail length to 'pay' for the slipping you
will run
the risk to
be bank routed.
-------
Just go take a hemp or manilla 6 to 8 mm of
diameter cordage. ( Nylon , PE, PP...
will have different behaviours )
Suspend one extremity to a secure fixed point.
At the other
extremity put (knot fully set by hand and no shock
loading) a 50
kilograms
weight.
50 kg translate to 7.8 stone or about 17.5 % or 11 %
of the
strength for these diameters
as the reef knot leave remaining 50% of
the maximum strength of the unknotted cordage
that is about safe.
Go ask your friendly car mechanics to help you with his elevating
platform or his
'cranking' block of pulley.
Now use your best hand and pull one of the tail of the reef knot to
make it capsize.
Please try again.
Harder please !
Not SO easy to get the capsizing, is it ? My own
Simple
explanation.
Well you had to overcome the setting put in the knot plus about 70% of
the
load
on it
when pulling at a 45° angle.
That will be more that 106 kg for a load of 150 kg.
Do you really think that you can easily spill it with a flick of a
finger, or "the brush of a
shroud" ?
-------
Some 'muscular physiology' facts showing that most people will not
capsize a reef knot
put under a 80 kg load :
Muscular strength ( untrained, naive, proverbial "average" individual)
is very much under
most rope breaking point.
Most would not even begin to really strain a plaited cotton mason chalk
rope with a
32 kg (70.5 pounds if I am not
mistaken)
breaking
limit.
In a French survey of 92 young men aged 19-20 randomly taken from the
general
population the maximum force for elbow flexion in the dominant
upper member show
that 95% of population is roughly between 212 N and 353 N
that
is that is less than
22kg / 48lb at lowest
- 36kg
/80 lbf at upper limit. ( mean being 283N)
Another study give for upper member *forearm totally extended from the
arm*,
held 30° under the horizontal and at 45°
ABDuction (arm
opening away from the
body axis, and in the body plane) give :
47kg pulling towards the body axis
27 kg pulling upwards and 26 kg pulling downward
24 kg when closing the angle coming toward the body axis
15 kg opening the angle away from the body axis.
I have no notion of
repartition of age classes age and size of sample : only that
was in
a study on muscles and skeleton disorders afflicting
workers used to
heavy and/or repetitive loads in their working hours.
--------
Ever thought about the cycling stress your shoes laces 'binding' is
subjected to in
a day of walking ?
If someone own a
gauge please do your shoes laces as usual and measure the
"pull"
applied when you walk.
I would be curious to know the result.
Think 80
paces a minutes in brisk walking that is 80 x 60 = 4800 in an hour of
walking.
I really cannot remember the last time I have had to "re-do" my lacing
in the last
50 years, and I walked quite a lot in my life and
get
up and down quite a number
of steps in my medical life, doing "home
visits", well the reef bend was performing
quite well I can tell you.
I have some questions and remarks :
- where are the statistics about " all the deaths"? Never found one.
- where is an 'actual' verified, testimony ?
- where are the official reports about such a death ?
- where are the "tests" done on reef knot in all manner of cordage ?
- there was a time (hemp / manilla cordages) when it was used in
mountaineering.
If it had been "an assurance of death" I think that
there would have been less
enthusiasts "à la belle
époque".
- it is used to join two cordage that will served as tow line
by
professional fishermen. ( I have seen it )
- it is used
( I met a man
who learnt it from his grand father who
had had it from his own father who....)
in Brittany to
join two length
of 'line'
(name is ' de la ligne' / that is a cordage
designated by the label of 'line' to
be differentiated from
the 'piece of rope' that is 'une ligne' / a line
-
nowadays it is thin braided nylon, coloured as a
tarred cordage , before it was hemp or the lesser quality
cordage made
of manilla )
to make the piece of cordage joining the pot to the float that allow
to know where it is.
Well they have yet to lose a pot because
the knot capsized.
This one was given to me by the guy, Jean-Paul
Lemoigne, who make these beautiful
half-hull . Jean-Paul refuse to use digitally driven machines
and do
it all the hard
old way.
The 2 dark brown ones are made of wengé wood
specially
for me (he dislikes working
very hard wood which 'destroy' the edge of
his tools ) as a friendship gesture after so
many years of
'going
there".
His father was a fisherman on "Notre-Dame de Rocamadour, a
lobster boat that was
fishing off Mauritania, which you will
see on
the
slideshow about Douarnenez museum
harbour.
One guy on a quay in Camaret (
Prequ'île de
Crozon, South of Brest in Brittany just
try http://geoportail.fr/
to visit
France by proxy) had a good laugh at me when I
said
" this knot
which is not.... is not to be use...if one had to follow the opinion
of some."
He was laughing shaking his head in disbelief and calling guys around
to witness before
I had reached the '...' part in my sentence.
Had to win back his respect before going on about bowlines (see
next topic) which got
more head shakes.
After that little innocent question the guy was taking me for an ass
(the
donkey sort!) till I
decided to
take him up on
the use of the brand new fid he was holding in hand and
passed on to him a
trick or two on the Swedish fid. They were not liking this fid at all
but
the 'coopérative' had no normal fid left.
By the way : if you roll a splice under your foot over there you
are done for :
for them it is THE landlubber tell tale sign , a splice done in the
correct
manner at
each
move does not have to be 'rolled' under foot.
The goal of a correct setting is to maximise the surface of
contact between
different parts of the cordage inside the knot. This
in a stable disposition while
simultaneously making sure that the
disposition will maximize the 'pressure'
applied on these surfaces of
contact when the load is applied.
Must be done in such a way that the more load is
applied, the
more friction is generated,
all the while making sure to give the best
D/d ratio to the fibres in the cordage.
- even with a cheap highly springy and sleek fibrillated polypropylene
8mm
3S laid
cordage (I wonder why they produce this sort of junk ?
, even
the Constrictor does
not hold a cyclic loading with it! May be it is an
experimental testing material for
knotters ? ;-) ) it can be
made staying put : just dress perfectly and
maintain it
under tension all the time.
I would certainly not go over my balcony
with it though!
In that polypropylene if setting is not absolutely top then the knot
readily
slides and
separates
at the least loading.
If tension is relaxed a small bit and then re-applied then it readily
slides as the
"springiness" make it 'undress'.
Just show that when one discuss a knot one had better say what sort of
cordage
was used.
- in 16mm Nylon (braid sheath, parallel fibres core) it held nice and
well,
setting
was quite easy. Suspend my full weight on it with no
particular precaution several
time. Perfect behaviour.
- in 3mm braided polypropylene cordage :
* 50 shock loading ( 20 kilogram free falling for
10 centimetres ) : quite unaffected.
* My best pulling ( ouch it is cutting in the
skin!) left it quite unaffected
* doing the experiment I proposed at the
beginning of this paragraph with only
20 kilogram load :
capsize when
the angle was still a bit less than 45° but
immediately lock
in the
new
disposition. ( 6 times out of 6 )
(I will leave you experiment - always taking great care to avoid any
bodily harm to
anyone- beyond laid hemp, braided polypropylene
and
these diameters I used
because the 'behaviour of a knot' is
not
independent of the nature of the material,
the nature of the
"making" ( lay - braid...), the diameter, steady progressive and
continuous load or shock load, unique or multiple....)
-in 2 mm, 3 strand laid nylon with the knot soaked in WD40 in the hope
of making
it slippery : I suspended my
little 73.7kg self (have no fear I may be a
stark raving
mad French lunatic who holds the Reef as being a true bend , a
fool in short,
I am not stupid, my feet were safely some centimetres
above the floor ).
I did not wait and used it immediately after soaking
it as I was not
all that sure that WD 40
agree with nylon after a few
moments .
Did this 9 times without any progressiveness in putting my weight on it
though not
trying to shock load it.
I am still waiting to see the reef knot slip or capsize.
In spite of the heavy
duty gloves I had done I finished with angry purple welts on
my
fingers.
Must have been a fluke surely !
Nylon was given for 120 kg so 73.7:120 = 61% so the reef must
be
much better
than the 40%-50% remaining strength, another fluke surely
or
within the statistical
variation (standard deviation was not given)
When making use of a reef knot (any knot in fact) I always make sure
it is
"freshly done"
by myself.
I would never use one, even one of mine that has been left
alone for
some time.
In fact I abstain from leaving knots in a cordage as this is
quite
detrimental to it.
Do not - just as a precautionary principle as there are better ways to
proceed
- suspend a living creature from it or put a living creature
under a load put on this
knot, or any other knot or load for that
matter.
For each sequence ( successive or consecutive , immediately following
each other
or with a very short interval) of use of a same - as in very
same individual knot
- reef knot
I make sure of its setting.
You will find "le noeud plat" ( that is the Reef K.) in
the official
(
published in 1875
by Minister orders ) Manuel
Du Gabier.
This official French Navy Manual
put it as
something that it was compulsory to know
to get a " gabier"
brevet.
It is Fig 2 on Page 2 with this text :
"Ce noeud sert à réunir deux bouts de filin qui
ne doivent pas faire une grande force.....
Il sert également à terminer un amarrage.
Quand il a forcé, ce noeud est souvent difficile
à défaire"
"This knot is used to join together two ends of rope which are not to
be submitted to
great force...
It is also used to finish a seizing.
When it has been heavily loaded, this knot is often difficult to undo"
I read the warning we find here and there, first of all in
the Manuel du
Gabier, about
not overloading this knot, not as a warning
about not using it because it will slide or spill,
but because it will
be difficult to undo it if it has been heavily loaded.
Hence the
warning do not overload it!
This warning has been , IMO, quite misread or rather mis-interpreted
( not
analyzed at
all IMO) as : "beware, it is no good, it spill". That
is not in the words.
This knot is still :
- taught in fishermen professional schools in France.
- retain in the program of our diving federation (
FFESSM
Fédération Française
d'Exploration et
de Sports
sous-marins ) "pour les cours de matelotage" for seamanship
courses.
Do you really think that it is because they are less intelligent and
informed than all the
"Cassandra" giving external signs of speaking and writing
under
the influence of
"parrot
programming".
Not once have I seen someone taking pain to argument the affirmation
beyond the fallacy
of " argumentum ad baculum" or "appeal to authority"
or "anecdotal or hasty unexamined
generalization" or "bandwagon
consensus" or....
It is not because menacing warning is used (argumentum ad
consequentiam, another fallacy),
or appeal to an
unsubstantiated published assertion is made ( ABOK being a case in
point
on
this particular topic), or just some bad event is known, most often
just by
hearsay ( the
man who knows the man who knows the man who knows the man
who saw the bear -
just happened that too often there never were a bear
in the first place, or a 2 days cub),
or because
the idea has got the
consensus
of
the "followers"
that it makes it to be 'the
incontrovertible truth'.
I could as well out of the blue state something like :
" Sheet Bend is no more secure than Reef Bend".
Beware! this may not be so far from containing some 'truth'.
That will
not hinder people to go on writing or saying " do not use
the Reef,
use a Sheet
instead, marvellous bend the Sheet is ".
Remember : Reef is
for
to equal diameter cordages, Sheet is meant for two different
diameters; but not too different ; just try it with a 2mm on a 30 mm
and we will speak
about it again.
Are you so sure that the Sheet is so much better ?
Or is it just another unexamined credo?
I will retain the noeud plat or noeud droit as
-- a good 'noeud
d'ajut' (bend in English) and not only as a binding though this is its
safest
area of use,
-- to be put to use as any
knot, any tool, as it is meant to be, that
is observing 'indications',
'no-indications',
'contraindications' and possible 'adverse effects'.
Try using a chisel
as a screw driver or a screw driver as a chisel and you will find that
they
are both "useless, good for the junk pile..."
Of course they were
not meant to be used in such a manner.
Would you say that antibiotics are to be discarded because they
are useless in a brain
tumour or that surgery is useless because you
cannot apply it to cure a flu syndrome ?
How about two persons in a heated discussion ,
one saying " no! believe
me,
elephants are much better"
and the other " I tell you: fruit flies any
day it is for me" ?
Well the first one is the manager of a circus and the other is a
geneticist.
It all depends upon perspective.
Nevertheless you better stay safe and retain "
never, never, under any circumstance
use
this knot as a
bend , it is only a binding.... "
A last advice , please take every precaution possible
about going to lie on a bed.
So many people die in a bed!
One of the most unsafe place in the world
it is apparently.
May be we should think about discarding them altogether along with the
reef
knot ! ;-)