Why wouldn't you use either an eye knot with
a properly, tight-sized (unsnagging, i.e.) eye;
or simply a noose-hitch, which will cinch up snug
to the bumper's grommet? (E.g., the poacher's
noose (a strangle knot tied to the noose SPart)
I'd think would give you what was wanted.)
--dl*
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I think C. Kirk is using the stopper knot at the other end of the rope, not the attachment to the grommet.