[Brion Toss]

Hi again,
Ohi, it has been way too long. Sorry to have kept you waiting. Here are some details from the TreeStuff tests:

I'll orient these notes around Allen's samples, since he so bravely offered them for public scrutiny. He sent in 2 conventional (lanyard) shackles that broke at 122 and 116% of rated strength. This puts the average at about the same 120% that we had seen at NER and elsewhere. It is less than the, as I recall, up-to-150% breaks that Evans Starzinger had recorded with the same knot with 1/8" rope, but I now more than suspect that efficiency just doesn't scale reliably with rope that is larger.
We had a total of 8 lanyard knots submitted. Some of them were clearly low-quality -- you could tell just by looking at them -- and sure enough they broke weaker than all the others. Nevertheless, we got an average of 106%, with 105% at the low end, and 135% at the top. Sure enough, the knots with the highest average were also visually superior; they were symmetrical, and drawn up well. Remember this when you are buying soft shackles. One other variable: the testing machine ran at a faster rate than in previous tests, and I had thought that might have given lower results. But I now believe that operator skill was the deciding factor.
By the way, one of this group was a variation of mine, designed to function as a hank for a stays'l. It broke at 130%.
Allen also sent in an 880 button variation, that broke at 214%, which puts it towards the high end of the samples tested. In this group, the weakest was 175%, and the strongest was 225%.Again, quality of finish resulted in higher break strengths. But I'll note that even the weakest, least handsome of the bunch tested much stronger than any of the lanyard variety. The only way I managed to get a weaker result was by making an eye that was intentionally too tight. When I did that, I got a break of 109%. For those of you who might have been making tight eyes to prevent the shackle from opening under flogging loads and such, here is a good reason not to. Another reason is that, in my experience so far, even relatively big-eyed shackles simply do not come apart until you want them to. Don't get intentionally loose-eyed, but don't strangle the poor things, either.
I also submitted three "filled" variations, in which I inserted a short bit of smaller line into the eye of the shackle, to provide more mass. One of these broke at an impressive 275%,but another only reached 232%, and the third only got to 162%. This configuration shows promise, but we need to figure out how to do it right.
One more variation, from an idea courtesy of Mr. Gardner, essentially combines two shackles into one: you make eyes in two pieces of rope, then tie their ends into a 4-strand version of Ashley's 880, and then bury them as usual. The first two samples I submitted broke at 339 and 319%, and a third one I sent as a follow-up was just yesterday reported as breaking at 343%. While this configuration does break the 300% barrier, it is rather labor-intensive to make, and awkward to button and unbutton, as you are dealing with two eyes instead of one. Still, it might be useful in applications where space is at a minimum, but loads are high.
I also submitted one more variation in which the two eyes were combined into one. This would get rid of the awkwardness. Unfortunately, this broke at a mere 230%, and it did so with a surprising failure at the button. This looks like another promising configuration that needs more work.
Short form: the button variation, properly-tied, is reliably at least 50% stronger than the lanyard version. Because previous tests tend to show that efficiency lessens with increase in diameter, it seems preferable to go with the button version in a smaller diameter when the loads go up, rather than making a lanyard version in larger rope. The smaller rope also produces a shackle that fits into much tighter spaces. This had proven valuable in joining rope anchor rodes to chain.
I'm ongoing sorry about being so slow in getting all this down. Thank you for your patience.
Fair leads,
Brion Toss