If you take away the extra coils, this looks to be the Oysterman's Knot or the Ashley Stopper Knot.
When seriously strained, the core mechanism of the knot pulls through the coils and becomes difficult to untie.
(Not sure why SS469 was quoted --just a fer-sure *this* reference?)
As for its likeness to
Ashley's Stopper, there is the general structure
of a noose-hitch clamping its own tail --and that works for any
number of noose-hitches to become stopper knots, pretty well.
By this time of forum discussion we should not be making assertions
about the *knot* but, if we've actually done some *testing*, about
some particularly knotted material! And I see some at my feet
where the thought of the tail being pulled through is hard to raise
--some
theoretical possibility but not one likely in practice, IMO.
I've fiddled it in a couple 5/8" laid ropes (a firm, stiff, soft-laid
CoEx PP/PE one, and a soft-laid (and darn *shedding* of fibre bits)
manila one, and a small single-braided (nylon?) cord). In setting
the knot, the S.Part-end loop is first tightened, and the coils can
then be drawn tight with the tail, before tightening the tail-end
loop upon it --so there should be no room to pull the tail through
these tightened coils. But that is a risk of poorly set such knots,
and the
Ashley's stopper in particular (esp. as that knot is
so poorly presented with regard to tying).
The knot is bulky, but I don't find the consumption of material
to be all so beneficial, to be so well disposed. It's halfway or
further to being a decent heaving-line knot! The double-nipping
(or -noosing) construct is fun idea to explore further, for those
keen to fiddle.
Thanks,
--dl*
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