This is the first I've heard of stable/unstable forms of the Double Dragon, and I must confess that I'm not seeing why the form described above is more stable. Do these pictures capture the form of the DD which you are saying is more stable?
Dave, in the double version, the instability is diminished to the
extent of perhaps insignificance; in the single version, however,
it's a real concern. Knowing one double version can lead one to its
cognate *single* form (which can seem fine to quick consideration).
.:. Thus, for that "average person" who uses knots infrequently,
one can be concerned about an inadvertent slip or adventure into
the single form, and ... . Perhaps not just average persons:
you have slipped (pardon the pun) into just this case with your
Exploding version--a slipped SINGLE (unstable) Dragon. That knot's
[cf
www.layhands.com/knots/Knots_Hitches.htm#ExplodingDragon]
Fig.5 shows the distortion its instability can yield (more likely in
stiffer ropes, which cannot be so snugly set, and in stretchy
ropes where
distortion is aided by the yield of the material.
BTW, if you spot anything at my knots website which is inaccurate/questionable, I'd appreciate hearing about it!
Okay, though you might be surprised! One big blooper I noticed in
looking over your site is that in the table of knot strengths you
have startlingly different values for a couple testings of the (nominal)
"Figure Eight Knot": that should make one double-check what's what!
This line in the table has mixed data for the loopknot with the stopper,
relying too simply on the fickle name similarity (nomenclature
in knots is a mess!). The two low values are stoppers, others loops.
That was interesting to see, for I was not aware previously of testing
of stoppers. As with hitches, though, one must wonder what sort of
object is associated with the knot (such details weren't revealed).
A major objection I'll make is against the Highwayman's Hitch:
this knot readily capsizes, and that so many knots books present
without a note of serious caution baffles me. You do give the warning
"it doesn't appear to be secure enough to handle a heavy strain on the rope"
which is good. But why bother with it at all? Because someone
--indeed, many someones, have it in THEIR knots collections.
Clyde Soles's
The Outdoor Knots Book has a simple but effective
variation of it, which has been discussed on rec.crafts.knots.
And, hmmm, the Tarbuck Knot: when you read such assertions as
"Do not use this knot as a hitch around a rigid rope or rail to resist
a lengthwise pull (illustrated in at least one manual). It seems
like a good idea, but it should be remembered that the knot relies for
its grip on creating a dog's-leg kink in its own standing part (fig. 4).
This is impossible if the line is tied to a separate and unyielding
foundation." (The Complete Book of Knots, p.67)
why do you repeat it, instead of thinking "Huh?!"
Afterall,
what part of this knot actually does the work of
gripping?
--the coils, as in other friction knots. And how does
this knot differ
from the Rolling Hitch (which carries no such qualification),
or other such hitches? (If that qualification applies to any of
these knots, it's to that "Midshipman's Knot" (p.65), which
you show tied to a rigid object.) Your putting a stopper on the
Tarbuck's nice, but is likely more needed in other knots such as the
Tautline, 2HHitches, Clove, Magnus, & Rolling (i.e., that version
of Clove w/extra turn(s)). Also, the stopper should be tied snug
to the knot body to prevent ANY retreat of the stopped end;
this need shows the unique benefit of the Overhand knot (vs. the
Fig.8, Ashley's (shown w/Tarbuck), etc.--which would require
working the knot to bring the stopper snug).
All for know,
cheers,
--dl*
