."
Dan Lehman replied that :
"There is a noticeable difference of geometry if one orients the knot's tails in a certain way. In the simple and commonly presented geometry, they align adjacent on the axis of tension, SParts making a 1-diameter turn around them; but in the version I intend, the Sparts turn more broadly, and that is what leads me to conjecture "greater strength". Getting this orientation takes some careful placing of the ends and then careful setting --dressing AND setting are mindful acts."
" In the disposition of the knots' tails, I see a trio [at least] of orientations for Rosendahl's bend ."
To which you might have taken your fingers off of the keyboard and endeavored
to discover these geometric variations (and maybe offer additional assessment as
to their *durability* over a range of loading/force). Or do you think I made them up?
Schematically, the principal differences can be shown (font surviving
--oh, what we lose in non-ASCII! ) as below, the upper one showing SParts
surrounding cross-sections of tails oriented adjacent & parallel to tension,
with the lower one showing the tails oriented about 45deg to this, and so
giving the more gradual, stronger(?) curvature.
======\\
O O
\\======
=====\\
O\\
\\ O
\\======
Now, it could be that the issue is more subject to fine aspects of material,
and that what might look good at setting time will, when push comes to shove
towards a rupture force, be converted to the upper orientation.
I notice the telling absence of any mention to an erroneous previous claim
( that the Zeppelin bend feeds "generously" on its tails while it is been tightened ...
Which is hardly surprising (the absence, i.e.), as that wasn't the point of discussion (strength).
But, it is certainly the case that the result of tying can vary per setting method,
and esp. in some materials more so than others it is necessary to pull the ends
to draw the knot up properly --otherwise, one has what might be referred to as
some kind of "opposed
Bowlines " structure, each SPart leaning firmily
into one
side of its collar vs. passing less firmly across its center.
I can not help but to pay attention to the results of other peoples keyboard,
I have to say, ...
But showing this attention by mere regurgitation of those results gets us
nowhere --we have the original instance, after all. (Though in some other
forums full copy-repetition is sometimes useful to preserve what is later
deleted --we don't suffer that problem (deletion) here.)
My theory is that, in the case of Zeppelin bend, the two tails (acting together, as a unified entity)
and the two loops of the overhand knots, function as a pivot hinge . Any subtle geometric
difference in this arrangement does not results in any noticeable difference of the bend s strength at all.
But that's a non-responsive theory given the presented fact of geometric variance:
either you have to demonstrate that the variance doesn't exist (or, as I suggest above,
exists in a sort of temporary & tenuous way only),
or you need to explain a theory of knot strength that makes the variance irrelevant.
Most of us are yet holding to some notion that curvature plays a role in strength
(though it might be less than we suspect, material variant (e.g., super slick stuff
not so much helped)), and so observations of effects on curvature rate at least
a worthy conjecture to the question. Just saying "I don't think so" doesn't help.
Pulling the standing ends would do the job, and the Zeppelin bend will dress itself to some
stable geometric form, that has nothing to do with the knot s strength.
This is demonstrably false. I suspect that in your moderately slick, firm, round
kernmantle ropes it is much true; but there are other ropes, and perhaps especially
laid ropes (having their surface groves for friction) well *seasoned* in the field
will behave differently, as will stiff ropes. This is readily seen with material in hand.
--dl*
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