@Dan Lehman I am soory but can you please make some photos of the knot tied loosely.
I have no idea, how to tie it.
@Roo I will try it the next weeks 
And the zeppelin with stoppers will also be testet
Let me endorse Roo's
dbl.zep. recommendation; that one
looks pretty good for better slack-security, while retaining
ease of untying.
As for my like-a-
sheet bend recommenation, you have
all you need :: just tie the " backwards (i.e., load the
ends vice its SParts --which both, respectively, lie on the
same side (i.e., don't use the opp-side version)),
AND THEN
make a 2nd or 3rd wrap & tuck of the hitching line's
tail.
In other words, one might call this series the
"multiple
Lapp bends series --where the fairly well publicized
Lapp bend is what could be called the
reverse(d)
sheet bend. For security, for many purposes, though,
it is essential to take the "hitching" line's (i.e., the end
NOT forming the U-shape, but the one that is tying TO
this U shaped end) end around the opposed SParts and
tucked back through again (& again).
These wraps resemble those of the
grapevine/blood knotwith similar effect :: slack-security. But, unlike these
knots, there is a fairly effective method to loosen &
untie the knot after loading :: pull the ends (tail vs.
SPart) of the U-part appart, to pry out some bit of
hitching-line SPart --enough to then work the knot
loose. (I suppose that this might become less than
all so "effective", at least manually, but I think that
in many reasonable circumstances of materials & force,
the method will lead to success.)
--dl*
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