Soft Halyard or Line Shackle

[Brion Toss]

Hello,
Great fun. This is similar to the work of rigger Matthew Otto, though he uses a series of locked Brummels. As for relative strengths, first quibble: I believe Lash-It has an average break of 500lbs.
Next, your pictures appear to show the line doubled on the scale, or nearly so (slight angle). If so, the scale will read about twice the load on the rope. Did you take this into account?
Next, there is no question that the Diamond weakens the rope severely. On the other hand the material is doubled in this configuration. Still it is intriguing that the attached eye piece broke. One question: what do you mean by an adjustable eye? I can't picture it, or how a whipping is involved.
With a clearer idea of the configuration we could conduct more formal tests.
Fair leads,
Brion Toss

[Anton B]

First: Yes, Lash-It has a breaking strength of 500 Lbs. I got the 400 number from somewhere on the web which was not the Samson website. Careless Googling...

Basically, this is what allene on L-36 is calling a line shackle or a soft halyard, only with more diamond knots in line so as to be able to attach the eye at various points to make an adjustable assembly. What I am erroneously referring to as the "adjustable end" is the eye that you can enlarge to put over the diamond knot. I am not sure what the name for that part of the assembly is, just "eye"? The soft shackle eye? Retractible eye? Please tell me what I should be calling it so as to make myself better understood. I am going to go with soft halyard for the assembly, even though I plan to use this attachment on a small boat for the shrouds and forestay, hence the need for at least a gross method of adjustment. But what do you call the spliced eye which can be enlarged temporarily to insert the diamond knot? I know I am doing this against the advice and good sense of people smarter than I, but will do it anyway ;-)

In any case, I whipped the soft shackle eye in place, as opposed to sewing it, only out of laziness, as I couldn't find a needle at the time. I figured it didn't matter as long as it held the splice in place so the eye size wouldn't change when opening and closing it to put it on the diamond knot, and since the whipping is not what makes the splice stick, it didn't really matter that I did that instead of sewing. Correct me if I am wrong.

As for the pulling rig, I have the stainless flat bar arranged so the mechanical advantage is 3:1, with the scale reading 1/3 of the load on the line being tested. The scale was reading between 100 and 140 or so, but it is hard to certain since it is bouncing around, and the come-along is a ways away from the scale face. I plan to rearrange it to get an easier read. I also plan to make a holder for my cell phone so I can take video, which will make it very easy to ascertain the maximum reading. The scale goes up to 550Lbs, but I did the lever so I could test higher strength lines. I will probably re-do these tests with the scale pulling directly as I think that will be more accurate.

I too was a bit surprised that the one eye broke, and am not sure why that happened. Could have been bad workmanship; eye too small? At this point, I can do all the splices quickly and easily, so further testing will be easy. Pulling straight with the scale, and getting the break on video will make the test easier to do, more accurate, and I can watch the line break instead of trying to watch the scale while it happens, which is less fun.

I don't have a theory as to why the line is breaking at 400 or so at the end of the taper in the bury, as opposed to the stated breaking strength of Lash-It at 500. I too will try to make better tapers, and also make more accurate sized eyes, etc.

As some point, I will pull the larger lines and see if the testing with the big line is proportional to the little ones.

But again, the main thing I was interested was whether the multiple diamond knots would break before the rest of the assembly. The soft halyard with luggage tag loop with a single diamond knot is well tested, but I could not find anything written up about using multiple diamond knots, nor could I get anyone to venture an opinion on it.

I will always do the right thing, but only after trying everything else ;-)

Anton

PS: many thanks to allene for putting all that great info up on the L-36 site, it has been very interesting and useful to me.

[Anton B]

Oh, also, please tell me more about Watthew Otto's work.

Did he make something similar in function to what I am trying to do, only with locked brummels, or are you saying that he was testing locked burmmels in a similar manner?

Anton

PS Maybe Opening eye? Openable eye? Was that my third eye? Was it blind?

PPS I guess allene is just calling it a shackle, but that is what I was using as the name for a soft shackle, the whole assembly. Hm.

[allene]

I would encourage you to use either a brummel or stitch, not a whipping.

If I understand what you are doing, I do not think the multiple diamond knots will hurt the strength of the assembly. The weak point will be the joint at the diamond knot and the eye of the line shackle.

These things typically break at the knot. You should have a strength of about 1/2 line strength but if your setup is doubled as Brion says, then getting about line strength would be right. It should not break at the splice so that is a huge mystery. You should have close to line strength there. Perhaps I am not understanding the setup.

[Brion Toss]

Hello again,
First, a picture of Otto's adjustable sling. Kind of a reverse version of yours, with no adjustable eye needed. We don't have confirmed break numbers for this one, either. Your configuration shows promise, but your enthusiasm and creativity is somewhat offset, at the moment, by a lot of variables and approximations; we just can't get meaningful numbers based on the setup you show. For that matter, we can't even comprehend what that setup is. I urge you to make friends with someone who can do some formal breaks.
Fair leads,
Brion Toss

[allene]

I looked at the flicker pictures again and my guess is that you are pulling on line that goes around one of your pins and then breaks after the pin. My thought is that you are getting friction at that pin so not all the force on the line goes to the DUT. But I can't really know for sure because the setup is not clear from the pictures.

Allen

[Anton B]

I attached the one end in several different ways, only in order to get the length right, not having taken any care in the length of the connecting line. None of which affected how they broke.

They broke at the end of the bury in the spliced line for the most part. The eye and the knot breaking were anomalies.

I will re-do the test with more care, and better pictures and I hope I will confirm that the breaking point will consistently be the bury and not the knot, and not the eye, but we shall see.

I am pretty sure I have already proved that it will break at close to line strength, in the application the tension is probably less than 20% of breaking strength even at peak loads, I just wanted to make sure that there wouldn't be some freak situation at the diamond knot that would give me less than 50% strength.

What I am doing is exactly like Allen's Soft Halyard, only with more diamond knots. In 9 test pulls, it never broke at the diamond knot closest to the loop, only at the last knot, the one the eye was pulling on, and seemed to break at about 80% of line strength.

I'm pretty happy with that.