Soft Halyard or Line Shackle

[allene]

Originally Posted by Brion Toss

Hi all,
Here are a few details from the tests.
First, as noted previously, the best numbers came with shackles that had been cycled at 50% of the average tensile result of shackles that had not been cycled. So if we broke 5 shackles, and they had an average break of 10,000lbs., then they cycled a sample up to 5,000lbs, ten times, before taking it up to break. This added about 20% to the shackle strength for most of the samples we broke.
Next, the smaller shackles did the best, with one notable exception. The average of uncycled breaks for 5/32" was 260% of rated strength, which dropped down to 195% for 3/16" and 141% for 1/4". But the 11mm HSR, New England's heat-treated rope, broke at 166% of rated strength (over 52,000lbs.)
Even the lower numbers were well in excess of numbers we have gotten with conventional soft shackles,. Most heartening.
Most of the tests were done with a lanyard through end of the shackle, and a pin at the other, though some were attached to a lanyard at both ends. The HSR started cutting through the lanyards at high loads, so the testers had to insert thimbles for those. With that exception, then, these numbers were for very tight bends, on the order of 1:1. This means, among other things, that we are safe using them to join rope to chain for anchor lines.
Most of the samples broke at the end of the tail bury, so the taper is one of the things I'll be adjusting in the next batch.
I'll be working with the wonderful tech people at New England Ropes to analyze this data further, and to prepare for future destruction.
Fair leads,
Brion

Hi Brion,

What did you use for a taper?

Very impressive results. It does start to bring up the concern that these loads get high enough you have to start to worry about the soft shackle cutting through any rope it might be securing. I have wondered if you are securing an eye splice in StaSet, what ratio of shackle and strength starts to move the failure mechanism to failure in the StaSet? Obviously not a concern when securing chain.

Allen

[Brion Toss]

Hi,
I used a fairly blunt taper, just cutting a 45 on the ends. That's one of the things I want to change for the next batch. As for the cutting problem, it happened, as I understand it, with a Spectra/Spectra connection, with a shackle of HSR, and a lanyard of the softer SK78. With a Dacron lanyard, it might be a self-solving problem, mostly because the Dacron should be at least 3 times the diameter of the HSR.
Fair leads,
Brion
PS,
You can see a video of a shackle break here:
https://www.facebook.com/brion.toss

[allene]

Originally Posted by Brion Toss

Hi,
I used a fairly blunt taper, just cutting a 45 on the ends. That's one of the things I want to change for the next batch. As for the cutting problem, it happened, as I understand it, with a Spectra/Spectra connection, with a shackle of HSR, and a lanyard of the softer SK78. With a Dacron lanyard, it might be a self-solving problem, mostly because the Dacron should be at least 3 times the diameter of the HSR.
Fair leads,
Brion
PS,
You can see a video of a shackle break here:
https://www.facebook.com/brion.toss

Two things:

1) The Samson taper is strong and easy. 1 fid length back cut e/o pair for total of half the strands. Then taper the very end with a shallow cut or by removing half the remaining strands working away from the end
.
2) The cutting of line I was worried about is as follows. Say you have some 7/16 StaSet at 6600 pounds and want a soft shackle of similar strength. For thin line you have 260% line strength so 1/8 Amsteel is a perfect match. The question is did you just introduce a new failure mode where the 1/8 inch soft shackle cuts through the 7/16 line causing a failure in the splice of the StaSet.

[Brion Toss]

Hi again,
I rather doubt it; the fatter Dacron would provide a bigger radius, thus more surface area. But care to make up some test samples?
Fair leads,
Brion

[Brion Toss]

Hi all,
We are moving into the next phase of shackle destruction, with a batch that will be made by me, and by other riggers. This will take a bit of time, especially as I am shortly heading for Tasmania, but we will post the results here.
Fair leads,
Brion Toss

[Essington]

So, I was playing around with the strong soft shackle yesterday and realized that its design lends itself to a "soft halyard" type construction.

The interesting feature of this shackle design is that the tails exit on the same side of the knot as the standing parts. What's to say that we have to bury the tails into the standing parts?
What happens if we make one tail longer? Maybe significantly longer, then bury the other (short) tail into it?
Well, now we have a soft shackle with a spare long tail that we could do something useful with!

I guess you could do this at the end of a halyard, but it would be mildly annoying to build the button knot with such a long tail (the rest of the halyard), and if the shackle eventually failed for some reason, reconstructing it would shorten the halyard by several feet.

One interesting use would be to thread 72 diameters or more of the tail over another line. This would give us a soft shackle that could be slid to any position on the line, but would stay put as soon as a load is placed on it (something like a whoopie sling)!


This type of construction would yield a strength of somewhere short of 100% (of single line strength), but might be useful for something like a backstay pigtail.

[allene]

Originally Posted by Essington

So, I was playing around with the strong soft shackle yesterday and realized that its design lends itself to a "soft halyard" type construction.

The interesting feature of this shackle design is that the tails exit on the same side of the knot as the standing parts. What's to say that we have to bury the tails into the standing parts?
What happens if we make one tail longer? Maybe significantly longer, then bury the other (short) tail into it?
Well, now we have a soft shackle with a spare long tail that we could do something useful with!

I guess you could do this at the end of a halyard, but it would be mildly annoying to build the button knot with such a long tail (the rest of the halyard), and if the shackle eventually failed for some reason, reconstructing it would shorten the halyard by several feet.

One interesting use would be to thread 72 diameters or more of the tail over another line. This would give us a soft shackle that could be slid to any position on the line, but would stay put as soon as a load is placed on it (something like a whoopie sling)!


This type of construction would yield a strength of somewhere short of 100% (of single line strength), but might be useful for something like a backstay pigtail.

I am not following what you have here. It looks like you have one line coming down into a diamond knot but somehow it becomes two strands. I have done a lot with soft halyards but, as I said, not sure what you have here.

This is what I am using now for my halyard. http://L-36.com/HybridHalyard.php

[Essington]

Originally Posted by allene

I am not following what you have here. It looks like you have one line coming down into a diamond knot but somehow it becomes two strands. I have done a lot with soft halyards but, as I said, not sure what you have here.

Actually it is Brion's button knot rather than a diamond knot. When the knot is completed, you have 4 parts exiting the bottom of the knot. 2 legs make the shackle, and 2 legs are "tails". Normally the tails would be buried into the legs that make the shackle, but in this case I left one tail quite long, and buried the other tail into the longer one. That leaves a shackle at the end of a very long tail.

As I said earlier, this construction is probably not ideal for halyards, but might be useful in other applications.

Originally Posted by allene

This is what I am using now for my halyard. http://L-36.com/HybridHalyard.php

Your Hybrid Halyard is what I use for my halyards ... it really is a better solution for halyards. No taper to jam in sheaves, and the shackle at the end can be replaced if needed.

[allene]

^^ I recognized the button knot and misspoke when I said diamond knot. Sorry about that. I guess what you have is a second line inside the cover that comes down into the button knot. It just looked like you had one line coming into the button and one out but there should be four.

Thanks for the kind comment about my halyard shackle.

[Anton B]

I did some destructive testing with my idea of the adjustable diamond knot attachment. Basically what I came up with is that the multiple diamond knots are stronger than the line with spliced loops at the end that I pulled on it with.

I did a very simple eye on both ends, one of them whipped so as to make it an adjustable eye to put over the diamond knot, and a non-secured eye on the other end which I either put over a bolt in my steel table, or luggage tagged to an endless loop that I then attached to the table in some way or another, for adjustability. None of the splices slipped.

I then put the adjustable loop over the outermost of 5 diamond knots at the end of a loop, then luggage tagged the multiple diamond knot loop to a shackle and pulled it with a come-along with a deer scale on it so as to be able to observe the tension at which it broke.

I used 1.75mm dyneema of some sort I had lying around; it is probably be Samson Lash-it, which has a stated breaking strength of 400Lbs.

In 8 tests, in only the first one did a diamond knot fail. It slipped at 350Lbs and failed at 375. It was the first 5 diamond knots I had ever tied in my life. I imagine that the legs were of uneven lengths, as I had trouble making the knots come together evenly.

In all of the other tests, I was not able to break any of the diamond knots on the second set of 5 diamond knots I had ever tied in my life. I am sure were better, more consistent, and tighter than the first 5.

The line mostly broke at the end of the taper in the splice a about 300-400Lbs, even though I tried to make nice long tapers, and I broke one eye at the end where it was hooked onto the diamond knot.

All in all, I am pretty sure that the multiple diamond knots in a row are all at least more than 100% of the strength of the line with loops, which was what I was hoping to prove.

I am assuming that the results would have been the same with the larger line I plan to use, but may do a test later to make sure.

Here is a link to some of pictures of my test rig, and the carnage

https://www.flickr.com/photos/959099...7651093139326/.