An interesting series of tests. I find it instructive to watch how the rope stretches and slips through most knots when the tension approaches the breaking strength of the rope.
I notice that the Sheet bend that consistently slipped at high tension in the tests was tied with the working ends on the opposite sides of the knot. I vaguely recall that Ashley suggested that the version with ends on the same side is the proper version of sheet bend as it is less likely to do that. Is this correct?
Funny you should mention the question of which side the sheet bend exits, as I was vaguely considering posting on that myself.
I don’t remember, but I probably learned the sheet bend from Geoffrey Budworth’s Hamlyn Book of Knots (1997), in which he writes:
As a general rule, aim to keep both short ends on the same side.And that's how I tie it.
However, I was reading an old Boy Scout book of my father’s a couple of weeks ago (Knotting by ‘Gilcraft’), and that said:
It should be noticed that the two running ends come out on different sides of the knot. This is the best way of tying it; if they come out on the same side the grip of the knot is not so solid.
The edition of the Scouting book that I have is 1956, but it was originally published in 1929.
Mr Budworth’s opinion is not to be dismissed lightly. But there again, I tend to give some weight to history when it comes to the older knots. In 1929 - assuming the same advice was given in the first edition - knots were in practical daily use in many professions, and I assume the Scouts were giving them a good thrashing too. So it’s hard to decide who’s right.
btw, pertinent to your original post, Budworth comments:
Security tests have shown it to spill after an average of 22 tugs out of 100.
In short, I’d call those tests dubious as for relevance
to the materials being knotted today.
I prefer same-side sheet bend,
but I don’t pretend that it’s all so secure!
(-;