the "mirrored bowline" is presented, which I think is a good
candidate for use not only for rockclimbers
wanting durable, when-slack security, but
for HMPE needing when-loaded security.
I tested the mirrored bowline against the bowline I presented.
To be sure : the
m.bwl. has collars around both
the S.Part (the usual) and an eye leg (and with the
cow hitch/ larkshead base, hence the moniker
"mirrored"
).
Just to be sure, for Brion Toss managed to omit the
latter tuck, and what's in that on-line video is thus
a compromise, nipping 2 vs 3 diameters (but it held).
(And noting that EStar has presented an extra wrap
in what he's called "
triple"
fisherman's knot--as I note in the thread here on end-2-end knots
(3-2 ought to yield 1 ; "triple" less "double =>"single").
... just some minding of details!
There was no slippage in either knot. The line broke where it entered my bowline.
The mirrored bowline does not look stronger by inspection
so I would not draw a conclusion about which is stronger from this, only that neither slipped.
Allen, IMO, the inspected aspect that should/could
suggest a bump in strength is the curvature of the
S.Part in its initial turn, which with the
m.bwl.turns around 50% more material --which doesn't
ensure such a difference in geometry, but might
be oriented to do so, with care (YMMV and all).
That said, I know that even with moderate loading
--what I can do is load w/5:1 lousy pulley and thus
get some "serious" forces--
what one thinks will be, from simple image & tying,
changes to something unexpected with the heavy
forces (and maybe stretch --but HMPE should limit
that).
OTOH, the case of the
blood knot (in nylon fishline)
shows that other structures can be strong --there,
the binding/pressure/gripping of the overwraps.
I recall one person's testing of the
strangle noose(a "half-a-dbl.fisherman's tied around line making a noose)
in 3/8" Bluewater low-elongation caving rope around
a standard-size (about 10mm dia) carabiner breaking
at the S.Part of the noose --i.e., where
the line was initially
constricted, not bent !!
(And I think that some similar testing of the knot
in thicker, arborist rope, had the break in the turn
around the anchor, or maybe in the knot.)
After seeing the slippage of HMPE, I opted to test
not the
fig.9 eye knot but this
in reverse,
to try for a broader, more gentle curvature. It in
fact did best of the five I tested, slightly. More
interestingly, it
seems to have broken beyond
the initial U-turn of the S.Part, where eye legs bore
across the continuation of that loaded part!?
(Hard to tell, I sewed into the line some marker
threads --one at an expected weak point, and another
some measure past that, anticipating movement
of the line in loading (and markers at all ends at
the boundary of the knot, to show movement of
material --and any slippage-- out of the knot during
compression.)
BTW, insofar as I've been able to judge where the
breaks in knots come, it seems to be that material
on the
inside of a turn is crushed and ruptured
--NOT as has been sometimes suspected that the
outer fibres bear all the load and rupture. This
assessment comes in looking at 3-strand/laid rope
where often 1 strand breaks and the test is stopped
and the broken strand can be traced back to a point
in the knot where rupture likely occurred. In braided
rope, that's another challenge ... . Just to the point
of a general
location of the break, using some
marker (I use bright threads) and photo of the knot
at high load showing location of the marked points
then can be a help, though the ruptured line
is often an explosion of material, defying easy
examination.
--dl*
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