... because of the friction in the drawstring seam, instead of the entire loop moving when tightened, the hitch moves,
But this is given your particular tightening method--of pulling the end UPWARDS
through the wood--; can you pull more
in line with the circumference,
holding the knot in place and pulling the end to/through it? --that could have
a lesser problem, perhaps, of the end's movement drawing the hem towards
the knot with it; but can this disturbance be countered by some iterative
fiddling with the stuff?
As for material, you cite chemical composition, but that's only part of the story
(and IIRC, nylon's pure coef. friction is lower than PP's), another being structure
of the cordage. The cord in your photo looks to be a sort of diamond braid, which
has a relatively rough surface; "solid braid" nylon would be smoother (and not all
so stretchy, though I'd think that your braid wasn't so much either).
I've mused over having a 2nd rope in which the hitches would be formed, through
which one would equally draw the two ends of the tensioning rope, but in practice
I think one will find that things don't work out to their
theoretical niceness
--one end would pull through whilst the other just thought about it.
(I tried Rolling H. with a
Prusik orientation, 1/2 turns; loaded on both ends,
when pulling down against the 2 turns, the one turn pushes the knot and prevents
it from gripping--this would be the tightening mode--; going the other way, it
grips. (This idea arose from a mistake in the revision of
On Rope for
its 2nd edition, where presumably a layout person inverted images and changed one
word of text to match, yielding sliding hitches that will do ONLY that--slide!))
--dl*
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