This nipping loop in the structure is tensioned only after a full turn around the object,
so that's a strike against its efficacy at providing sure nip.
The turn could be a double turn, which I think will be better than the more complicated additional
two single loops of your variation.
I am sorry but in this you are completely wrong. Increasing the number of turns in the nip loop will
dissipate the tension and results in very poor grip. Multiple loops increase the grip as a linear function.
Two will have twice the grip of one. Three will have three times, etc. But the multiple loops will also
begin to increase the resistance to pulling tighter. As I said with 5 loops it was possible to tie in Glide dental floss.
WELL, "completely" entails the bit about the reach of tensioned ends to the
nipping loop, about which I'm quite right; adding loops in your way will by
force migrate then around the object and so closer to the ends. But my point
is that whereas in e.g. the Constrictor the tensioning of ends pulls directly into
the Overhand crossing (but has the long reach around to tighten the overwrap),
here, in order to tighten the nipping loop force must flow around the object
which is no small order for some sorts of things.
As for the double loop vs. single (my way), I find the opposite -- same materials
as before; at least if I have a structure in which the two turns are rather spaced
in their circumnavigation of the object (in my case, roughly 1.5" opp. dble.loop).
Here, the tensioning was more nearly parallel with object.
In some earlier playing, I found that the workings of the dbl. loop were adding
nips that frustrated tensioning it. argh.
As for mechanical advantage, in many common materials you'll find that the usual Trucker's Hitch is around 1.5:1, way shy of the theoretical 3:1, and friction as well as material resistance to bending eats up a great deal of such supposed advantages in related structures; there is a thread about that on this forum, in which I experimented with some various ropes and
barbell (dead) weights. I really recommend that others employ such testing
to better appreciate the hype that books sell.
Where to start? It would not surprise me if the Truckers Hitch measures out at 1.5 to one Mechanical Advantage,
because theoretically it actually only starts out at 2 to one not the often quoted 3 to one. This is just basic pulley physics.
Just look at this diagram from the Wiki pulley entry for an explanation. [see above]
Here's where to start: with a proper notion of the structure at issue. A Trucker's
Hitch is a mechanism to tension a line tossed (paradigmaticly) over the truck's load
from an anchor side to a hitching side (to coin some terms); there, after working
some impromptu sheave mid-line of the rope (maybe a slip-knot), a turn is made
on one hopes a relatively smooth hook or through a ring --low friction, ideally--
and then taken up through the impromptu sheave, and hauled
downwards -- NB.
Now, by your bassackwards reference, you would have the low bed of the truck
moving up to the impromptu eye
; in fact, it is this eye that moves downwards
towards the hook/ring anchorage. That, as you can see, means that there are
3 parts bearing load (haul end (still not bitter), reeved up to eye part, and first
part brought from eye to hook/ring), to the one S.Part carrying force away: 3:1.
Or, put another way, to close the gap by pulling the rope eye down to the ring
would move this eye X distance and you'd have hauled out 3X rope to do so.
Try your testing experiment with weights and the ropes passing over lubricated pulleys.
For me, at issue is
actual (vs. hyped, and theoretical) advantage.
Seeing as how I am right about the mechanical advantage of the Truckers Hitch,
could you please give me the benefit of the doubt and take a look at this knot with an open mind?
(By the way I am not the first to point this out to you. see: http://igkt.net/sm/index.php?topic=1416.0,
for a recent Noob who tried to discuss this that you shot down.)
My mind is plenty open; I doubt you followed my link there, but only echoed your
mistaken notion of the hitch. I've explained it above; Inkanyezi has done so here,
and perhaps some others will chime in, if you want the *democratic* approach.
But the issue should be clear from above. It's a matter of what moves;
that you
must understand before throwing physics books about, or they'll miss.
If you draw THE LOOSE ENDS in by 4 feet the load will move 1 foot.
This points to an aspect of such binders that goes against their use for tying
up the odds'n'ends of, e.g., gardening for trash: that you loose a lot of cord
(one end or the other). As opposed to some binding such as hauling line
through a Rolling hitch, where the hitch's end is short as can be, and when
tightened the other end can be cut off close to the knot and all remaining
line returned for further use.
And I will note that generally 4:1 is better than 2:1.
You might test this theory in practical circumstances. There can be quite
a diminishing return (of gained tension/force) with each frictional sheave,
and balanced against the complexity of tying and consumption of material,
"better" might go to the structure w/less TMA. YMMV.
... But never the less the issue remains the rope is still in the position to cut itself.
This is going to significantly reduce the breaking strength.
Do you know what will be cut? -- quite to my surprise, it will/could be the
moving rope ! (not the bight one would think it was going to saw through)
At least that's what happened when I tried it in cotton string (supposedly an old
way to cut such stuff). AND in one case where a rockclimber did "StairSteps"
with old climbing rope through a nylon tubular sling -- imagine! (Sling was
not in good shape, but the *winner*.)
In the first place that was not my quote. However I have not found this knot in any of the sources I have looked at.
Given your experience which is obviously vastly superior to mine, I suspect you haven't either, or you would have mentioned it.
As I said, books copy prior books and stick to a pretty narrow repertoire of "knots".
Now, in Hansel&Gretel land, there's no telling what might turn up (!); but, so far,
I've only found this floating binder in my own hands; and it's nice to see others
looking around with new ideas, too.
I don't know about whether there are other new knots, perhaps you can find one yourself.
Done. . . . and, er, *doing*.
--dl*
====
