As Fairlead questions, you don't give enough information re the knot:
are you joining two ropes, or making an eye? In any case, both such
knots are known and used, in angling at least (including giving the
knot one more twist); the bend (ends-joining) is known to anglers as
the Surgeon's Knot, and claimed to be nearly 100% if tied correctly
in not-too-strong (<60*#) line (which enables hand setting). It should
be noted that anglers don't tie the knot in the "follow-through" method,
which is tedious, but in the
in-the-bight manner; this is so for the
bend, as what is joined is a short piece to a long one, so the short
one's end is accessible. (Ashley's tying method seems especially
problematic, re dressing!)
As an answer to your question: The knot reduces the strength of your rope by 50% ... I read this <somewhere>
It's discouraging to see such a remark from someone well read on
this forum.
We have I'd hoped shown the weakness of rumors of knot strength, from the
perspective of not knowing exact geometries, or test method, or materials.
And from a single (dubious?) source.
And as noted here, it's not even clear what knot is at issue!
AND, as with any "followed through" knot, there's the question of which end is
loaded (or, how the knot's oriented).
For a
loopknot in material similar to climbing rope, I expect that the knot has
reasonable strength (~= 65..70%). I think that the
bend will be weaker in such
cases, unless somehow one can bring greater-than-manual force to setting it.
--dl*
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