Soft Halyard or Line Shackle

[allene]

Originally Posted by Brion Toss

Hi,
Actually, in the shackle, the standing part of the eye is doubled, while in the new configuration it isn't. That makes the single standing part weaker than the doubled-but-stress-risen Diamond knot side.
Fair leads,
Brion

In the shackle think of two sides. One is just straight doubled amsteel and carries half the load. The other side has the eye and the diamond knot. Each side has half the load of the shackle. If the shackle has 150% of line strength, each side has 75%. His setup is exactly the same as the half with the eye and the knot, except that he has more knots.

Another way to look at is that in the shackle the strength should be 400% but it is 150% and breaks at the knot so the knot is 37% efficient strength wise. In his setup, the knot has two strands so it should be .37 x 200% = 75% and should break before the end with the eye in it.

There is something else interesting going on here.

Allen

[Brion Toss]

His setup is most definitely not exactly the same. In the shackle configuration, the eye side is twice as strong as in his version, because there are two standing parts in the shackle, thus 200% strength there. It would seem that the lanyard knot parts in both versions are stronger than a single part, but I would think not by much. If the knot didn't degrade the strength of the rope so much, the shackle would be much stronger, but as it is, the knot side of the new configuration is -- or should be, properly tied -- stronger than the single standing part of the spliced eye.
This would be easy to test, by making the eye of larger rope than the lanyard knot side, and measuring the break point of the latter.
I would also note that Anton deserves better test equipment to assess his innovation. Regarding this, please see accompanying new thread on the break test extravaganza.
Fair leads,
Brion Toss

[allene]

Agreed that the eye part is not as strong as in the half shackle but it is still as strong as line strength, or at least it should be close. But then again, it has a taper so perhaps it is an especially abrupt taper. I still contend that the knot should be 75% of line strength but if his tapers are abrupt and weaken the line more than to 75% and his calibration is off so that makes us think it is breaking at line strength.

Off to read the new thread... (can't find it, maybe it will show up later).

[Anton B]

I was taking care to make long tapered splices, and got up to line strength on at least one break, and 90% on a lot of them. I was getting 75% when I wasn't taking much care of the tapers.

I bought that scale for $25, how could it be inaccurate? ;-)

I have a new idea; using something like a whoopee sling to make a cascading adjustable shroud with those new fangled friction rings, which would allow the whoppe sling splice part of it to only carry half the load, and use a bungee cord in the same way as the Constrictor jam cleat.

I will mock one up with my tiny line ('cause I'm too cheap to use big line) and break a couple of them and see what happens there.

If you are interested, I could try to do another test of the luggage tag with extra diamond knots using a stronger shackle to see what it takes to break it.

Anton

PS, please link to the new thread...

[allene]

Originally Posted by Anton B

I was taking care to make long tapered splices, and got up to line strength on at least one break, and 90% on a lot of them. I was getting 75% when I wasn't taking much care of the tapers.

I bought that scale for $25, how could it be inaccurate? ;-)

I have a new idea; using something like a whoopee sling to make a cascading adjustable shroud with those new fangled friction rings, which would allow the whoppe sling splice part of it to only carry half the load, and use a bungee cord in the same way as the Constrictor jam cleat.

I will mock one up with my tiny line ('cause I'm too cheap to use big line) and break a couple of them and see what happens there.

If you are interested, I could try to do another test of the luggage tag with extra diamond knots using a stronger shackle to see what it takes to break it.

Anton

PS, please link to the new thread...

Is it possible for you to make a conventional soft shackle and break it to see if your results are calibrated to others? It should break at 125% of line strength plus or minus. If it is breaking at 200% of line strength, then we know what is going on.

[Anton B]

Yes, next time I am doing some testing, I will make up a soft shackle with only one knot and see what I get. I will also pull the one I already made and see if I can make it break. I could also make another one with multiple knots and see if that is the same too.

But you will also have ot take a look at mey new idea and tell me what you think ;-)

Anton

[Brion Toss]

Hi again,
Let's just back up a bit. We have a lovely new configuration, which I will tentatively call an Inverse Otto, that wants testing. So far, our intrepid inventor has, with a minimum of equipment and a lot of enthusiasm, demonstrated that it shows promise. There are variables to be dealt with: multiple vs. single lanyard knots; tapers in the splices; actual strength of the materials; how much load comes where; and maybe especially how accurate the machinery is. So I urge you to send some samples in, configured any way you like, for our Extravaganza. You get free breaks, courtesy of Treestuff, plus enduring fame.
Fair leads,
Brion Toss