Instructions for Tying the Brion Toss Button Knot & High Strength Soft Shackle

[s/v Jedi]

Originally Posted by Seaworthy Lass

These YouTubes are always useful to watch.

In the first video the load test on the grey shackle is particularly interesting. It broke at the taper.
The conclusion was to taper better .

Each leg should only be experiencing a quarter of the load. A leg should never break at the taper, even if no taper at all was made.
So why has this occurred?

This is my theory:
After commenting at the beginning of construction that the eye “looks about right” (whatever that means), there was no care taken that after tying the stopper and tensioning it that it was actually large enough to hold 4 lots of line (the very minimum required).

The presenters almost constantly call the eye a noose (although “eyelet” was used a few times at the beginning), giving the impression that it needed to grip. The only remarks I heard regarding the required size were that you don’t want to make it too big.

So what happens when you form a noose that is not large enough to contain the legs, rather than an eye? One leg is then loose and the load will be taken up entirely by the other leg. This is easy to demonstrate. As the closed shackle is a loop, if there is no other weaker point in the system the leg will break roughly when the applied load is close to twice the breaking load of the line.

Where is it then most likely to break? At the weakest point, which in this case is the taper.

This is precisely what occurred (unless the line coincidentally happened to be defective just in this region).
The grey line was 5mm. The breaking strength of this about 5500 lbf. The leg snapped at the taper at 10,900 lbf.

So rather than needing to taper better, as the presenters of this video concluded, I think care needs to be taken regarding eye size for these high strength soft shackles.

Any comments from anyone about this? Any flaws in my logic? It is a little discussed (and little considered) topic.

SWL

I think you’re right. The problem is that when you say anything about these guys other than adoring them, you will get members attacking you, mailing these guys about it etc. while they simply do make mistakes.

I also don’t like that overhand knot method one bit; I tried it once many years ago when the first video about it appeared but this was before the Brian Toss knot came.

[Seaworthy Lass]

Originally Posted by s/v Jedi

I think you’re right. The problem is that when you say anything about these guys other than adoring them, you will get members attacking you, mailing these guys about it etc. while they simply do make mistakes.

Hi Jedi

This is an area that I find extremely hard to navigate. Critiquing is viewed as criticising and I am stepping on eggshells every time I make a comment. How are we to improve though if no one is permitted to disagree with the experts?

Eye size for soft shackles has been largely disregarded or specified incorrectly, even by those most highly regarded in their field. There may be some flaw in my logic when looking at construction methods, but it would be good to have a discussion about this.

Allen Edwards (who has had a huge amount of experience in making, using and designing soft shackles and other items, and whose L-36 website has masses full of useful information) instructs that diamond knot soft shackles (that have eyes that hold two lots of line) should be made with an eye size capable of holding one line.

Load tests of his soft shackles demonstrate the strength of these is not much more than line strength (see his website for details), despite Evans Starzinger’s tests using the same diamond knot giving an average of 170% line strength.

If the eye of Allen’s shackles is not large enough to hold the two legs, load is taken up by only one leg (including at the base of the diamond knot where these soft shackles typically break when pushed to their limit). Is this contributing to the poor load test results he is consistently reporting? (The risk of poor load distribution in the buried central section of some of the shackles may be another factor resulting in only one leg being loaded).

Even Brion Toss, whose expertise in all things rigging related was phenomenal, instructed that for soft shackles made using his button stopper, “form an eye that fits loosely around two diameters of the rope”, despite 4 lots of rope needing to pass through it when it closes (see page 388 of his last edition of “The Complete Rigger’s Apprentice”).

Evans Starzinger I think agrees that the eye of soft shackles should be large enough to hold the legs passing through it, but I have not seen this discussed in any of his invaluable pdfs.

Check out the eyes in Kohlhoff style shackles for sale in chandleries. Most that I have seen seem smaller than (or barely) one line diameter in size when open. None that I have seen would hold two when open, despite two legs passing through them when closed. They are understandably only rated to line strength.

In addition, the eye is commonly referred to as a noose (following common terminology used by some experts, I was also embarrassingly guilty of this until a few years ago), perpetuating that notion that the eye needs to grip the legs.

Sure, the strength of even poorly made soft shackles in use often greatly exceeds the load they are subjected to (partly due to larger diameter of rope selected for improved handling), and errors in construction are less important, but shouldn’t we at least be aware of the characteristics that give soft shackles optimal strength?

SWL

[s/v Jedi]

Originally Posted by Seaworthy Lass

Hi Jedi

This is an area that I find extremely hard to navigate. Critiquing is viewed as criticising and I am stepping on eggshells every time I make a comment. How are we to improve though if no one is permitted to disagree with the experts?

Eye size for soft shackles has been largely disregarded or specified incorrectly, even by those most highly regarded in their field. There may be some flaw in my logic when looking at construction methods, but it would be good to have a discussion about this.

Allen Edwards (who has had a huge amount of experience in making, using and designing soft shackles and other items, and whose L-36 website has masses full of useful information) instructs that diamond knot soft shackles (that have eyes that hold two lots of line) should be made with an eye size capable of holding one line.

Load tests of his soft shackles demonstrate the strength of these is not much more than line strength (see his website for details), despite Evans Starzinger’s tests using the same diamond knot giving an average of 170% line strength.

If the eye of Allen’s shackles is not large enough to hold the two legs, load is taken up by only one leg (including at the base of the diamond knot where these soft shackles typically break when pushed to their limit). Is this contributing to the poor load test results he is consistently reporting? (The risk of poor load distribution in the buried central section of some of the shackles may be another factor resulting in only one leg being loaded).

Even Brion Toss, whose expertise in all things rigging related was phenomenal, instructed that for soft shackles made using his button stopper, “form an eye that fits loosely around two diameters of the rope”, despite 4 lots of rope needing to pass through it when it closes (see page 388 of his last edition of “The Complete Rigger’s Apprentice”).

Evans Starzinger I think agrees that the eye of soft shackles should be large enough to hold the legs passing through it, but I have not seen this discussed in any of his invaluable pdfs.

Check out the eyes in Kohlhoff style shackles for sale in chandleries. Most that I have seen seem smaller than (or barely) one line diameter in size when open. None that I have seen would hold two when open, despite two legs passing through them when closed. They are understandably only rated to line strength.

In addition, the eye is commonly referred to as a noose (following common terminology used by some experts, I was also embarrassingly guilty of this until a few years ago), perpetuating that notion that the eye needs to grip the legs.

Sure, the strength of even poorly made soft shackles in use often greatly exceeds the load they are subjected to (partly due to larger diameter of rope selected for improved handling), and errors in construction are less important, but shouldn’t we at least be aware of the characteristics that give soft shackles optimal strength?

SWL

You are right to challenge that from anyone. Because if one is an expert then being challenged on such things is of great value and expected. Especially when done so thoughtful as you do compared to my blunt approach

Did you compare outside radius of 4 parts of line vs 2 parts that contain the other 2 parts spliced as a core? I think this is different.

The trend to use small eyes or even call them a noose comes from a fear of the shackle opening itself when flogging on the clew of a sail or something similar. I have sailed with a soft shackle from 3-strand for years and it had a fixed eye that the stopper knot fit through. It attached the sheets to the clew of the jib and it never came off even though we had lots of flogging as it was a hank-on sail.

So I think it is unwarranted and I make the loop larger than the shackle body, just a little smaller than the stopper knot. I don’t think I want to jinx it by making a shackle with a loop that closed still allows the knot to go through but I really believe it would not open.

Edit: which chapter/part of Brion Toss’s book? I have it on kindle but oage numbers are meaningless

[Seaworthy Lass]

Originally Posted by s/v Jedi

You are right to challenge that from anyone. Because if one is an expert then being challenged on such things is of great value and expected. Especially when done so thoughtful as you do compared to my blunt approach

Did you compare outside radius of 4 parts of line vs 2 parts that contain the other 2 parts spliced as a core? I think this is different.

It is complicated. This is my rough thought process on this:
UHMWPE compresses very easily so 4 seperate legs clenched together will have roughly the same total cross sectional area as the sum of the 4 individual legs.
BUT, the outer portion of 2 legs expands (and possibly thins) to contain the buried portion and so it will decrease the total cross sectional area a small amount I think. All 4 legs will also elongate and thin under load having the same effect.
The eye will also enlarge a bit as it thins under load, increasing its size, so all this will contribute to a better relationship between size of the eye and the 4 legs.
Regardless, the eye needs to be large enough to hold whatever contains it under load when closed, not smaller.

Originally Posted by s/v Jedi

Edit: which chapter/part of Brion Toss’s book? I have it on kindle but oage numbers are meaningless

It is the last appendix of his last edition. Just before the glossary.

SWL

[s/v Jedi]

Originally Posted by Seaworthy Lass

It is complicated. This is my rough thought process on this:
UHMWPE compresses very easily so 4 seperate legs clenched together will have roughly the same total cross sectional area as the sum of the 4 individual legs.
BUT, the outer portion of 2 legs expands (and possibly thins) to contain the buried portion and so it will decrease the total cross sectional area a small amount I think. All 4 legs will also elongate and thin under load having the same effect.
The eye will also enlarge a bit as it thins under load, increasing its size, so all this will contribute to a better relationship between size of the eye and the 4 legs.
Regardless, the eye needs to be large enough to hold whatever contains it under load when closed, not smaller.

It is the last appendix of his last edition. Just before the glossary.

SWL

Hmmm is that the yellow cover? I have the blue cover old edition even though I didn’t buy it that long ago….

For the size of the loop: yes, under pressure from the loop, the fibers will all compress to a single uniform part. But how does that interact with load on the shackle itself… I could see less tension on the inner part than on the outer part, so the outer part is also squeezing and it all gets impossible to guess what happens but I think it’s clear that you have a point unless someone comes up with something that caused a “duh” moment or physical tests showing otherwise… for now those tests support your idea.

Has anyone tested a soft loop instead of a soft shackle, with either an O-ring or velcro holding the loop closed? So without the sliding “noose”…

[Seaworthy Lass]

Originally Posted by s/v Jedi

Hmmm is that the yellow cover? I have the blue cover old edition even though I didn’t buy it that long ago….

It is the 2016 edition. The front cover is mainly yellow with a rim of blue.

Originally Posted by s/v Jedi

For the size of the loop: yes, under pressure from the loop, the fibers will all compress to a single uniform part. But how does that interact with load on the shackle itself… I could see less tension on the inner part than on the outer part, so the outer part is also squeezing and it all gets impossible to guess what happens but I think it’s clear that you have a point unless someone comes up with something that caused a “duh” moment or physical tests showing otherwise… for now those tests support your idea.

To complicate the issue, if Brion Toss’s button knot is used, although ideally the buried portion should start as close as possible to the base of the soft shackle, often there is a gap (particularly if the tails have been buried before pretensioning, so the stopper has slid even further from the insert of the bury). In this case the eye ends up containing 4 seperate lots of line, not any buried portion, or possibly only a partially buried portion.

My head hurts thinking about it .

Originally Posted by s/v Jedi

Has anyone tested a soft loop instead of a soft shackle, with either an O-ring or velcro holding the loop closed? So without the sliding “noose”…

Do you mean a loop with a large overhand or a button stopper knot? Not that I am aware of, but I very much doubt the line would EVER break where the buried tails taper. Unless the line was defective, it would break in the vicinity of the apex of the loop where the bend radius results in this being the weakest point in the system.

SWL

[Iron E]

Originally Posted by Seaworthy Lass

Hi Jedi

This is an area that I find extremely hard to navigate. Critiquing is viewed as criticising and I am stepping on eggshells every time I make a comment. How are we to improve though if no one is permitted to disagree with the experts?

I haven't commented on their videos, but I have questioned Ryan directly using his contact information and found him extremely receptive to questions and comments. He addressed every single question I had and even added a few questions he was curious about regarding sailing and uses.

if you haven't tried doing that, I would recommend it. I felt that he wanted to know every angle and have complete information.

[Seaworthy Lass]

Originally Posted by Iron E

I haven't commented on their videos, but I have questioned Ryan directly using his contact information and found him extremely receptive to questions and comments. He addressed every single question I had and even added a few questions he was curious about regarding sailing and uses.

if you haven't tried doing that, I would recommend it. I felt that he wanted to know every angle and have complete information.

Thanks for the information.
I will try that.

SWL

[s/v Jedi]

Originally Posted by Seaworthy Lass

It is the 2016 edition. The front cover is mainly yellow with a rim of blue.
[…]
Do you mean a loop with a large overhand or a button stopper knot? Not that I am aware of, but I very much doubt the line would EVER break where the buried tails taper. Unless the line was defective, it would break in the vicinity of the apex of the loop where the bend radius results in this being the weakest point in the system.

SWL

Just the loop with button knot like sold by chandleries. By not forming a sliding loop from threading one part of the Dyneema through the other, you take the size of the loop out of the equation.

I also think they would all break at the loop and never at the taper. So that automatically means that a different pattern of breaking with a sliding loop must be caused by that sliding loop or the way it is sized and/or constructed.

Originally Posted by Iron E

I haven't commented on their videos, but I have questioned Ryan directly using his contact information and found him extremely receptive to questions and comments. He addressed every single question I had and even added a few questions he was curious about regarding sailing and uses.

if you haven't tried doing that, I would recommend it. I felt that he wanted to know every angle and have complete information.

I never had any trouble with Ryan and he actually invites criticism. The problem I had was here in the forum when some of the fans he has here were offended when I pointed out a mistake he made.
Part of the problem is then that people expect me to go and fix the world on that subject, while I’m just a guy on a forum who incidentally happens to know something that others had wrong but who has no desire to take more effort than a post on the forum to reveal that

[Seaworthy Lass]

Originally Posted by s/v Jedi

Just the loop with button knot like sold by chandleries. By not forming a sliding loop from threading one part of the Dyneema through the other, you take the size of the loop out of the equation.

I also think they would all break at the loop and never at the taper. So that automatically means that a different pattern of breaking with a sliding loop must be caused by that sliding loop or the way it is sized and/or constructed.

I haven’t seen tests on any of the high strength stopper knots, but Allen Edwards did some initial tests on the diamond knot in a similar the manner to the one you describe (he tested the shackle open):
https://l-36.com/ss_test.php
He concluded the strength of the diamond knot was somewhere between 1 and 2 times line strength.

It is a great pity he did not pit the diamond knot against other strengths of test line (and not use a cow hitch), as I think he would have found similar results to Evans’ ie that the strength of the diamond was on average 170% of the line strength used in its construction. Evans found up to 195% in his samples.

It would have made Allen focus on what he was doing wrong with the rest of his construction that was resulting in his diamond soft shackle strengths consistently being closer to merely 100%. I think the fact that his shackles still broke at the diamond made him erroneously think his knot was the limitation.

Looking at his construction more closely, I think for his Colligomarine style soft shackle (with the legs completely buried) the eye size selected needs to be large enough not just to hold two lots of the rope used, but also it needs to allow for equalisation of the load in the buried portion (the outer part is bound to elongate more than the inner, as it is impossible to get right just milking it by hand).
Unless this is done, the load is bound to fall on one leg, regardless of whether or not the eye size looks correct to start with.

For Allen’s Better soft shackle where the bury starts a distance away from the eye, I think the strength of his soft shackles would jump roughly 50% if he did three things:
1. Make the eye large enough to hold 2 lots not 1 lot of line to start with.
2. Not lock the buried portion at the eye end (this would enable the legs to freely equalise in the buried portion).
3. Construct the central bury so that the eye enlarged when the buried portion equalised, not became smaller, resulting in a noose.

A 50% increase in strength in his standard soft shackles would be a significant improvement (he does not apparently use the high strength version, as he prefers to just bump up line size to increase strength).

SWL

[Seaworthy Lass]

I was reading a thread on SA that Brion Toss had posted in several years ago.
I had forgotten about his comments there. He said that he had done some testing on eye size and that “tight eyes” reduce break strength.
Anyone know where these results were posted or published?

He also stated that he subsequently sized his eyes as a “comfortable fit for the rope diameters”. This was in 2017, after the latest addition of his book “The Complete Rigger's Apprentice” had been published. I am sure that he would have revised recommended eye size in future additions.

[s/v Jedi]

Okay, I have some development on this front. Always being on the lookout for products, I came upon these improved soft shackles made out of Amsteel Blue in 7/64” or 2.5mm made and sold by Treavor Bates of Hanging High Hammocks.

On Amazon, I only paid $10 for two of these with a 3” closed length.

So when I received them, I stretch them out to make the legs even and I see a really small loop… a noose And sure enough, when I close the shackle, the loop is too small for the two legs, resulting in one leg being longer than the other. Exactly the problem we discussed.

So normally one gives up and goes on with other stuff, but I had this feeling this was a small business that is really trying to get good products out, so I sent an email, explaining the issue, linking to this thread and suggesting improvements as well as maybe larger diameter Dyneema for more applications for boats.

This started some conversation and a couple days later I receive two new and improved shackles and they are done right. With that I mean they are flawless. The button knot perfectly tensioned, tapered, equal length buries etc. The variation between the two shackles now is the difference in loop size around the two legs, one showing a little more clearance than the other, instead of legs being shorter than the other.

I told Treavor that this could become good business for him but how many shackles can one tie before going nuts? I mean, I’m looking to buy standard size shackles because I feel too busy to tie more to replace steel shackles aboard. He can of course tie them much quicker because it’s probably a daily task for him, while I always get the button knot wrong the first time.

One thing he tried is send some shackles out for independent testing and now that his shackles look perfect, I’m thinking maybe one of our members is willing to test some? These should be around 1,500kg breaking strength. I’m not sure if Evans still has access to the test bench he used?

We also discussed different diameter Dyneema. What would be the most usable for the average cruiser? 5mm? I’m using 6mm most of the time but that’s just because I buy that by the spool but 8 tons breaking strength is a bit high for most applications?

I think it would be great if we could just make a list of shackles, loops etc. we need and have someone like Treavor make them at the realistic price level he is at, being outside the traditional marine market.

Here’s the product I ordered: https://www.amazon.com/gp/product/B099BZ7SSY

[Seaworthy Lass]

Originally Posted by s/v Jedi

Okay, I have some development on this front. Always being on the lookout for products, I came upon these improved soft shackles made out of Amsteel Blue in 7/64” or 2.5mm made and sold by Treavor Bates of Hanging High Hammocks.

On Amazon, I only paid $10 for two of these with a 3” closed length.

So when I received them, I stretch them out to make the legs even and I see a really small loop… a noose And sure enough, when I close the shackle, the loop is too small for the two legs, resulting in one leg being longer than the other. Exactly the problem we discussed.

So normally one gives up and goes on with other stuff, but I had this feeling this was a small business that is really trying to get good products out, so I sent an email, explaining the issue, linking to this thread and suggesting improvements as well as maybe larger diameter Dyneema for more applications for boats.

This started some conversation and a couple days later I receive two new and improved shackles and they are done right. With that I mean they are flawless. The button knot perfectly tensioned, tapered, equal length buries etc. The variation between the two shackles now is the difference in loop size around the two legs, one showing a little more clearance than the other, instead of legs being shorter than the other.

I told Treavor that this could become good business for him but how many shackles can one tie before going nuts? I mean, I’m looking to buy standard size shackles because I feel too busy to tie more to replace steel shackles aboard. He can of course tie them much quicker because it’s probably a daily task for him, while I always get the button knot wrong the first time.

One thing he tried is send some shackles out for independent testing and now that his shackles look perfect, I’m thinking maybe one of our members is willing to test some? These should be around 1,500kg breaking strength. I’m not sure if Evans still has access to the test bench he used?

We also discussed different diameter Dyneema. What would be the most usable for the average cruiser? 5mm? I’m using 6mm most of the time but that’s just because I buy that by the spool but 8 tons breaking strength is a bit high for most applications?

I think it would be great if we could just make a list of shackles, loops etc. we need and have someone like Treavor make them at the realistic price level he is at, being outside the traditional marine market.

Here’s the product I ordered: https://www.amazon.com/gp/product/B099BZ7SSY

Hi Jedi
What a good thing to do! I imagine it was very appreciated.

Any improvement in these, whether commercially made or for personal use is beneficial.

I think either 5 or 6 mm would be the most useful size for cruising boats (racing would depend entirely on size of boat). On our 49’ boat 6 mm is needed the most, 5 mm reasonably often and 8 mm rarely.

3 mm is sufficient for lots of small tasks on board, but without reinforcing the eye, even with my thin fingers I find it too thin to handle easily (the eye needs to be picked open with fingernails and in time it becomes fluffy as the strands start to break). After reinforcing the eye of 3 mm it has solved this problem and a couple of dozen are now in use here. They are incredibly handy and cheap as chips to make, but the $ earned per hour of labour compared to thicker soft shackles makes them a less viable commercial venture I think. No matter how quick you get, they are still labour intensive to make.

Evans may be still load testing. He dismantled his equipment, but then did some work on strops a few years back. Apart from rope manufacturers (who usually sell soft shackles themselves) I am not aware of anyone else.

It is a market that is hard to break into. Perhaps he could contact some sailing clubs, particularly those with racing interests? Chandleries would be another venue, but he would make more selling directly to customers.

SWL
PS By the way, I sent Ryan from How Not 2 Highline an email over a month ago now regarding the eye size issue I raised earlier and have heard absolutely nothing back. Not even “thanks, we are looking into it”. Clearly not interested in the suggestion their technique could be improved.

[AKA-None]

Originally Posted by s/v Jedi

Okay, I have some development on this front. Always being on the lookout for products, I came upon these improved soft shackles made out of Amsteel Blue in 7/64” or 2.5mm made and sold by Treavor Bates of Hanging High Hammocks.



On Amazon, I only paid $10 for two of these with a 3” closed length.



So when I received them, I stretch them out to make the legs even and I see a really small loop… a noose And sure enough, when I close the shackle, the loop is too small for the two legs, resulting in one leg being longer than the other. Exactly the problem we discussed.



So normally one gives up and goes on with other stuff, but I had this feeling this was a small business that is really trying to get good products out, so I sent an email, explaining the issue, linking to this thread and suggesting improvements as well as maybe larger diameter Dyneema for more applications for boats.



This started some conversation and a couple days later I receive two new and improved shackles and they are done right. With that I mean they are flawless. The button knot perfectly tensioned, tapered, equal length buries etc. The variation between the two shackles now is the difference in loop size around the two legs, one showing a little more clearance than the other, instead of legs being shorter than the other.



I told Treavor that this could become good business for him but how many shackles can one tie before going nuts? I mean, I’m looking to buy standard size shackles because I feel too busy to tie more to replace steel shackles aboard. He can of course tie them much quicker because it’s probably a daily task for him, while I always get the button knot wrong the first time.



One thing he tried is send some shackles out for independent testing and now that his shackles look perfect, I’m thinking maybe one of our members is willing to test some? These should be around 1,500kg breaking strength. I’m not sure if Evans still has access to the test bench he used?



We also discussed different diameter Dyneema. What would be the most usable for the average cruiser? 5mm? I’m using 6mm most of the time but that’s just because I buy that by the spool but 8 tons breaking strength is a bit high for most applications?



I think it would be great if we could just make a list of shackles, loops etc. we need and have someone like Treavor make them at the realistic price level he is at, being outside the traditional marine market.



Here’s the product I ordered: https://www.amazon.com/gp/product/B099BZ7SSY

So you are saying what you get from that link is now tweaked from your feedback and now they might be suitable for our boats?

[s/v Jedi]

Originally Posted by AKA-None

So you are saying what you get from that link is now tweaked from your feedback and now they might be suitable for our boats?

Yes, it is. Two soft shackles at 1,500kg breaking strength for 10 bucks. That’s different from Harken, isn’t it?

I’ve been looking at strength of Wichard shackles and this 7/64” soft shackle has 50% more breaking strength than a 5/32”, 4 mm Wichard shackle.

When you go up to 1/8” Amsteel Blue, you match a Wichard 6mm shackle, which is 2,200kg breaking strength with the soft shackle at 2,300kg.

A Wichard 8mm shackle is 3,600kg breaking strength, which equals an Amsteel Blue 5/32” 4mm shackle at 3,680kg.

A 10mm Wichard is at 5,200kg breaking strength, which a 5mm, 3/16” softshackle just doesn’t match at 5,060kg.

Then a 10mm Wichard, which I’m notsure I have on a 64’ boat, is 5,200kg while a 6mm, 1/4” Amsteel soft shackle is 8,050kg.

This stuff is still, after all these years, mind blowing.