correct, I have 2nd editions of both texts.
If you'd like me to scan and send you the pertinent pages of Life on a Line
I would be happy to.
Thanks for confirmation & offer. I have the latter,
but might ask particular questions re
On Rope, 2nd ed..
10 %-points" or purely "10%".
I agree that Merchant is could be more specific here. He just says 10%
As do so many others, alas.
Given that he states this can be difficult to show with breaking tests,
I am dubious=>[doubtful] of performing these tests, but I may proceed anyway
if I feel I may obtain meaningful results.
It would be an interesting challenge, if nothing else.
I would tie specimen knots in both ends. For this test,
since you have a seemingly well-calibrated device, you
could make them same-orientation,
or otherwise you have --in addition to what the device
might record, in absolute values-- A-vs-B testing. In
either case, with eye knots at both ends, you get one
that survives intact, for examination. Now, were the
results so pure that dressing-XYZ was always breaking
and leaving dressing-PQR the survivor, you might feel
that you'd found a pattern, BUT would want to get a
surviving weaker dressing and so need to double up
on that, at least for this point of record.
And given your relatively not-so-strong material (if you
are indeed continuing to use something like that),
you should be able to get a good firm set as I specify
with pulling on tails, to try for that, *baked-in*, twin-part
path-shaping for the SPart to bear against. At least, this
is my theory and the best sense I can make of how that
"stronger form" (my label) could in fact be stronger
(for the turn around the eye legs seems rather sharp,
arguably worse than using the other end qua SPart).
But, another aspect of this "perfect form" (not the
Layhands form, mind)
fig.8 is that maybe with
the "weak form" one gets less hard constriction of
the eye legs and therefore they bring more gripping
effect where they collar the SPart and
that is
what gives strength --some frictional off-loading of
force at the entry point!? --Theory-2, which, note,
puts significance to effects coming before any hard
radius of turning is encountered.
(In any case, it is interesting to note that the eye knots
are often found stronger than the end-2-end knot!?
(E.g., one fellow used a truck to do A-vs-B end-2-end knot
testing, and all specimens were anchored w/
fig.8 eyeknotsnone of which ever broke (even vs. a case where effectively
the same structure was there, in the
"twin fig.8s" joint
which is essentially two eyes sharing the eye strands!?).)
(CMC 3rd ed. has end-2-end & eyes equally at 80-81%.)
Do you have [Neil Montgomery's Single Rope Techniques]?
Not yet, I ordered a copy on Amazon. I'll share what I find.
Great, thanks much!
Indeed, it may be common ignorance.. but ignorance by persons,
who as a group, trust this knot with their lives, and the lives of others.
Which could be a point to worry about!
I recall Tom Moyer lamenting that despite his efforts to warn
some group about the dangers of the
offset fig.8 end-2-end knot(aka "fig.8 EDK"), they seemed unconcerned about it.
Now you scare me : how can CMC come out with such
nonsense?!!! I mean that in the sense that LOTS of
testing has put its strength well higher than 50% !!
It seems clear to me that CMC revised there assertions based on the presence of new data.
Yes, fine, but also
in the face of solid other data--or did they admit to having indulged "youthful indiscretions"
at prior data gathering/interpreting/recording?!?
If anyone could provide me Mr. Richards testing, I would appreciate it.
Ah, it came out nicely, via Agent_Smith's hosting --voici
www.paci.com.au/downloads_public/knots/03_Cordage_Institute_Tests.pdfAnd here are remarks about the mistakes in the labeling
of data --a simple case of A vice B & vice versa : soooo
simply noted (even w/o correction), but Smith it seems
has found levels of "embeddiing" of error upon error,
sadly w/o a sane reviewer to set straight. And, so it has
languished in Purgatory of non-presented status, waiting
for Godot. Thanks again to Agent_Smith for doing better.
www.forums.caves.org/viewtopic.php?f=5&t=12907NB : knots are identified nominally; we do NOT see images
asserted to show geometry!
I could suggest Outdoor Knots by Clyde Soles
(and w/help from ... 
) as a fresh, different treatment.
Thanks for the tip, I'll pick up a copy
NB: the
"square fisherman's" got mis-represented in the
photo --it there is actually a, um,
"thief fisherman's" : yeah,
tied a
thief knot backed with
strangles (not how the
climbing community names things, but ... . (Clyde protested
that it couldn't be, for he doesn't know how to tie the
thief;
I infer that, yes, he doesn't, but tied what he intended (and
missed) by flipping his ropes around to tie off with the
strangleand --these being short pieces-- confused tail w/SPart !
OTOH, arguably, this
shown is better, easier to untie
(just make sure that the
strangles stay tied --which,
if they're set snug to the
thief, they have grounds to
be more secure, as slippage will snug them up further!)
.:. a play in double-edgedness!
(I saw photos too late for corrections to be made.)
Okay, "birdcage" is a terms usually applied to a deformation of wire rope,
usually due to shock loading, where the strands gain a permanent deformation,
or twist, that allows you to see daylight through the lay of the line.
It looks like a little metal birdcage.
That was my surmise, except I've trouble with ...
I used the term to describe a similar deformation, or bump,
in the 12 strand core of the rope I describe.
... how one sees ANYthing
in the core?!?!
What's happening with the sheath, to enable this?
(If it's in postmortem cut-&-see, well, okay; but it
still seems odd for the core to have such strength
to birdcage within a close-fit sheath, IMO.
--and more problems with Vectran, hmmm.
(Used on one of rockclimbing gear-seller's hi-mod
lines (5.5mm) and discontinued, for dubious results.)
The guy line rope is constructed of a vectran core, with a polyester jacket. The guy lines had spliced terminations on each end. The original construction of the guy lines (the ones that birdcaged) was that the jacket was stretched equally tight as the core during fabrication.
//
I then fabricated a new set of line, but with the jacket very slack. Even under tension, the jacket could be easily milked along the line.
I'm struck by "fabricated" : implying one's own making,
and not a (complete) "store-bought" product. !?
I'm stumped for an explanation, other than musing that
somehow there was a segment (or few) where the original
sheath was less married to core and slipped back'n'forth
over it, and the Vectan suffered not the polyester (though
the former is much better with heat, but not so, abrasion?!)!?
With a relatively tight sheath, it could be load bearing.
But with a slack sheath, the core didn't have such *oppression*.
And the failure was incomplete, not catastrophic --the sheath
was working, the guy still stabilized , the problem was seen
(before the hourglass ran out of time). --and yet, in just
some few days (or was it a longer period per line, and that
each of the quartet of guys came to grief in short order?)!
--dl*
====
