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.

[Anton B]

Brion,

how does Otto's sling work? Do you hook the different openings onto something? Is he using the diamond knot like I am, like the Soft Halyard?

Also, I do not seem to be allowed to post attachments, thus the Flickr {ics. Is there a way to do it that I am missing?

Thanks,

Anton

[allene]

First, to insert an image, you click on the insert image icon and give a web address where the picture is. It has to be a web address ending in jpg so I don't think you can use a flicker image. Google plus images work if you open them in a new tab and then use that url.

The issue Brion and I have with your reported results is that they are so far from our experience. Roughly a soft shackle is about line strength. Well, it may be higher than that and probably is but not double. Since the load is shared with two sides of the loop, that means that the strength of each end is somewhat above 1/2 of line strength. But you are seeing something close to line strength and breaking the line to prove it. That would mean that the string of diamond knots that are beyond the knot under load are increasing the strength considerably. Possible and if true something we want to understand as it may have implications for making soft shackles stronger. So we want to see pictures of your setup to see if anything pops out. You may have discovered something significant.

[Anton B]

O.K., here it is!
Here is the Soft Halyard with extra Diamond Knots. It might not be clear, but the tails on the loop with stop knots end just out of the picture, and the other end of the line with the eye splice/shackle ("connector line") is about a foot long and has another eye splice on the other end. One end of the connector line gets put over a stop knot, the other goes to the hook on the scale, so as to pull it with the come-along.



Here is the test rig. Note that the "connector line" has been hooked to the s-hook on the scale, and the eye/shackle has been put on the last stop knot on the luggage tag which is attached to a bolt on the table.



Here are the results



Here's what they look like



Basically, out of 7 tests, 6 of them broke at the end of the bury in the splice and one of them reached almost 100%. After doing 20 splices in a row, they get much quicker, and I was making more of an effort on the taper, so they got better. Because I am lazy, and I was doing a lot of splices in order to just break them, I did not do any sewing or whipping on any of the splices. They would have to be sewed to stay in place under light loads.

On the first pull, the first diamond knot broke, at about 375Lbs, not sure why, but the rest of them lasted, all the way up to 500Lbs, and it was the first knot, rather than any of the ones closer to the loop. It may be that that particular diamond knot was not well made, or that it had suffered wear and tear from the last 10 test pulls wherein other parts of the assembly broke

I am convinced that the diamond knots farther from the loop are as strong as the ones closer to the loop, which is what I hoped to prove.

It occurs to me that I could build a soft shackle with multiple diamond knots to make it of adjustable size.