Whether the alleged percentages for breaking strength are correct or incorrect,
I can't tell and also have my doubts about them.
I was trying to point out though that retained breaking strength of one
knot may be high, it does not necessarily mean higher overall security of that knot.
In particular the sheet bend seems to slip before it breaks, but the zeppelin rather
breaks before it slips, at least in my experience.
In this case, I disagree: we can tell -- the knots at issue are ancient,
and if they had anywhere near this alleged breaking strength we
wouldn't be learning about it all of a sudden only in the 21st century!
Moreover, one can't posit the knot as insecure and accept a high
breaking strength -- it has to hold in order to break. And fishing
line does not make for greater, rather lesser, security.
Have a look here.
http://www.versus.com/fishing/videos/#browser (type: "knot wars" in the search bar)
They did not show a close up of the tied knot, but they showed how each knot is properly tied,
they tried it with 3 common types of fishing line and repeated each test several times.
They also seem to know what they are doing and you expect them to tie the knots they present correctly.
Do I have ultimate proof of that? No.
Thanks. As for knowing what they're doing, well, hmmm,
that impression is given at times by some hilariously botched
presentations, but I'll hope that they do.
Those who might use such end-2-end knots in that case would do so
with Strangle knots tying off the ends; the main knot would be
chosen for ease of untying (and possibly for different-diameter ropes).
Does not make sense to me. 1. why not use a better knot in the first place (that has the quality of being secure AND ease of untying) like the zeppelin e.g. ?
2. If you use a sheet bend for ease of untying and then back it up with strangle knots (which jam so hard that a marlins pike runs home crying) the ease of untying is gone.
Your supposed "better" knot isn't proven to be all so secure
in the case of contact w/rock and wouldn't be trusted.
(Here is a good cue for Agent_Smith to re-surface and tell
of his further adventures at promoting that e2e joint to the
SAR/climbing world!). And the
Strangles would hardly be
so tight as you fear (!! --indeed, I've heard of folks having
them come loose, even (!?)), as they are only loaded by hand
in setting, and secure the
Sheet bend's tails, that's all; ease
of untying is present.
Except that in the "gel-spun" (HMPE) line, the Palomar isn't so strong;
Then I would use the Uni instead of the Palomar, which is also good for that purpose.
Hmmm, I don't see the
Uni in Geoff Wilson's small pamphlet on
tying Gel-spun lines; but I do see his note that the
Blood knot broke
as such low loads (40%) that he stopped further testing/listing of it
in an appendix of various results: the
Uni seems rather like the
Blood in geometry. And the bump in strength from the
Palomarto
Triple P. of about 12%-pt.s came from the triple-turns on
the ring; he uses a similar thing with the
Uni --although names
the structure
"Collar & Capstan", and makes no comment about
it being tantamount to a
Uni, and ties it directly into
Strangleform using a helper eye to pull tail up through wraps--
and boasts about an 85% or better strength.
It really is irritating to have authors present knots that are
--though not clearly stated, but by apparent presentation--
the same as others, but the similarity isn't remarked/confirmed!?
(Were it confirmed, the image from one knot could help in
guiding the tying of the other; it could further inform the reader.)
As I think Knot4U remarked, he'd never guess that the Palomar
would be so strong; I've had the same puzzlement, if not for
absolute strength, then, for relative strengths --i.e., I cannot
figure why one knot is stronger than this other, and so on,
given appearances. Partly this must be due to the failure of
the presentation to show even the final image, or what the
geometry becomes on loading --though we can note that
with angling knots, one is often setting them to a fairly
high percentage of tensile strength (I think Barnes, who got
to test the new-fangled at that time nylon monofilament,
opined that about 60% tensile loading was needed for
optimal results): which means that the
set geometry
should be pretty near the
at-rupture geometry.
(In contrast, we meager humans setting even skinny climbing
ropes come nowhere near to full-load force, let alone breaking
forces.)
Here's such a mystery: an end-2-end joint recommended as
very strong, for gel-spun line, is joining two
Bimini Twistsin a
"Cat's Paw Splice" --which is just the repeated making
of a sort of "Girth hitch" around-&-through-&<repeat> weaving
of eye-&-eye. With ten such interweavings, who would think
that the eyes would be where the break would occur? --after all,
those eye strands individually need share only 50% of the force,
whereas the eyeknots have 100% on a single strand! But, as
per Wilson, increasing from ten can gain strength, so it must be
in the wraps that the break occurs. And this is at about 90%
of listed break strength (which is typically understated).
--dl*
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