knudeNoggin
ArboristSite Lurker
And waiting on that offered post of an image out of Ashley's Book of Knots
--just a # will do for me (I have the book).
Yes, even bowlines can jam, although they can be tested
to rupture (one in each end of a test specimen) without jamming;
YMMV depending upon materials and setting and, if I understand
the OP's case, loading --he loaded the tail as well as the eye.
Which tightens the collar (rabbit path around tree; the bight formed
by the tail) sufficiently that, with elastic material, the load-reduced
diameter will see the tight collar become too tight (jammed) when
tension's off and the main line swells back to original diameter but
cannot squeeze back into the knot.
To answer the How to Untie question, I'll just echo what some others
suggested about using tools, and add that perhaps some salad oil on
the main line at the collar will help it slip back through.
As for a better knot ... ? In the OP's case, loading the tail was the
likely problem (why not put that 2nd loading also into the eye?).
A water bowline (i.e., running the rabbit through a clove hitch)
would add grip to the tail leg and let you leave the collar looser
(without fear of the knot capsizing), and should prove immune to jamming.
Another bowline-like knot is ABOK #1033. Here, one proceeds
as though tying the bowline in the "rabbit out of hole ..." method,
but instead of taking the tail back through the hole immediately,
go around the eye leg that flows from the main line, AND THEN
through the hole in the opposite direction (to the bowline's way)
--looks sort of like the carrick bend's lattice-like weaving
(before that ends-joining knot is capsized into form on setting).
And you'd leave this tail rather loose, at least not pulled as tight
as it could be (which would fold that eye leg back); that should
never be able to be jammed.
*kN*
