KnottyGirl (be careful how you pronouce that! :o ),
let’s assume that knot names will get us nowhere but confusion fast;
so thank’s for pointing to a commonly reviewable site, by Grog
http://www.animatedknots.com/rollinghitchscouting/index.php?LogoImage=LogoGrog.jpg&Website=www.animatedknots.com
Although, frankly , Grog is far from unconfusing in his presentation!
The knot shown by him in white w/black-stripes rope, lower right side,
and referred to as being incorrect (inferior), IS WHAT THE BSA NAME
the “Taut Line Hitch”–as per my The Boy Scout Handbook,
10th ed., 1990, p.138. As to the efficacy of this version vs. the one where
the 2nd turn is jammed up into the initial turn, YMMV–I seem to recall one
IGKTer’s casual testing in which he found some mixed results, but overall
better for what Grog rails against.
For a surer securing, you can compromise: make the initial hitching as per Grog
–i.e., a jammed 2nd turn–; but then follow this not with a closing HHitch, but
at a little remove, tying the other version, presented by the BSA.
These friction hitches can be tricky: they might be slipping until you set them
tigher intially, then their grip begets ever tighter grip on increased loading
–until they might reach some untenable point (though it is known also that
they can hold until rupture in some cases).
The BSA form should prove more easily adjusted, and adequate to holding
when in natural-fibre cordage; in slipperier (nylon, polyester, polypropylene/-ethylene)
cordage, some additional structure might be needed–e.g. a full/round turn on the
object (not really practical around a large one, like a tree; fine around a tent stake),
or the guard structure I presented above (the combination; maybe just a leading
turn/HHitch, say). Adjusting tension w/compound hitches will be additional hassle,
but okay. An advantage to the compound version is that under greater tying tension
(i.e., the tyer faces greater pull on the working end which will make tying difficult)
making a quick “guard” structure (the HHitch) is easy and relieves the force on
the working end for tying the full & closing knot.
And around that pole, I hope that you can see that the closing HHitch is by no means
all so sure of staying put–putting an Overhand stopper in the end to prevent it from
loosening makes good sense (ditto for the Clove h. & 2HHs as well). You can find
on-line references to something called the “Tarbuck Knot” (or T. Hitch), which amounts
to a Rolling H. w/extra turn in the gripping coil and a more secure (and harder to tie)
closure; its better form might be that in which the knot more resembles a Cow Hitch
(Larkshead/Girth Hitch) than a Clove hitch, re the orientation of the finishing part);
the Tarbuck thus is an alternative to finishing with a stopper knot. (And I just now see
that Ashley has somewhat anticipated Tarbuck’s “invention” in his own exploration to
see what might be more resistant to torsion & loosening.)