“Twisted” & “Reinforced Super Strength” Soft Shackles

[Breaking Waves]

Originally Posted by Seaworthy Lass

I think my ideal size would be bigger than your ideal.

yes, seems like it, and idk if there is a 'right' answer. I tested almost every aspect of the shackles except the eye size. There is definitely too small (when it chokes the legs) and too large (when it could come over the stopper) but IDK if there is an optimal in between there or if it does not matter. Interesting question.

Originally Posted by Brocky II

their stopper is a complicated overhand and bury.

yea, actually most likely my design, the first stable 'stronger' (stronger than the diamond) soft shackle. I personally don't really rate the design very high anymore and prefer the button, but I know some people still like it.

[Seaworthy Lass]

Originally Posted by Breaking Waves

yes, seems like it, and idk if there is a 'right' answer. I tested almost every aspect of the shackles except the eye size. There is definitely too small (when it chokes the legs) and too large (when it could come over the stopper) but IDK if there is an optimal in between there or if it does not matter. Interesting question.

Online instructions are extremely vague about eye size, but where specified I have come across sizes that would just accomodate one leg not two when made with a Diamond stopper. All the ones I have come across in chandleries have also been the same. Some are positively minuscule. I make tut tutting noises under my breath when I see this .

Also, if just enough room is allowed to fit the legs in exactly, there is a tearing force at the base of the eye plus there is absolutely no room for error if the legs alter in length slightly during the formation of the stopper and pretensioning resulting in an eye that is too small to contain the legs.

I think constant references to the eye as a noose (there is nothing noose-like about it) and the concept that the eye must be super snug for soft shackles to work are largely to blame for these errors.

PS I have also seen photos of soft shackles that break along a leg during load testing rather than the expected spot, and I am guessing that eye size being made too small is the reason for this.

[Seaworthy Lass]

Here are the promised photos of potentially an “extra high strength” soft shackle made using the twisted design with a Brion Toss Button stopper and the eye reinforced with a 150 mm tapered segment inserted at the eye before the twists were formed (Dyneema size 3 mm). The legs were buried conventionally at the end.

Rather than twisting the line as I described above, I plaited it carefully to ensure there were no actual twists as it curved around. I made an error though in that with the buried portions the line then thickened and the optimal number of twists were less than I had made and following the bury of the legs I ended up with the legs having an actual twist in the middle thin portion. I forgot that ideal number of twists per length depends on diameter.

The eye looks too large in the side view, but the third photo from underneath shows it to be a neat size.

I am not advocating this design. Apart from it being untested, more care needs to be taken with construction and I still prefer a conventional eye, but it is intriguing what can be done.

It at least looks cool .

[Seaworthy Lass]

All this lead me to thinking about strengthening the eye in a normal high strength soft shackle. This is the usual failure point in this design.

Burying a portion of line in the eye is an obvious solution and has been vaguely discussed in the past. I have seen no photos or description of what was done and no load testing data. I had not attempted this thinking it was not successful for some reason. Breaking Waves, what actually happened when this was tried and why was it abandoned?

The success with strengthening the eye in the twisted version lead me to try this in a conventional high strength soft shackle this morning using 5 mm UHMWPE (Stealth Super 12).

I inserted a 200 mm tapered portion of the 5 mm centred at the apex of my cut portion (1.6 m). I wriggled a Marlin spike to create the hole to enable the eye to be formed. I had expected this to be difficult, but surprisingly it was not. I then just made up the soft shackle as I usually do (unless I want a shackle with a small diameter I always either make a crossing or bury a small section of one leg in the other as this improves handling and stops the legs from flopping disconcertingly when not under load).

I am smitten .

It takes a little longer to open and close the eye, as there is added friction where one thickened leg passes through the thickened portion of the other, but it results in a beautifully secure eye. The whole shackle just has a lovely feel to it.

Photos will follow. The shackle is just being pretensioned outside using a winch.

[Seaworthy Lass]

Unveiling the “Reinforced Super Strength” soft shackle:

The name is a little premature, as I have no idea how much stronger it is than the usual design . Anyone with load testing gear that can check this out?

If it is significantly stronger than the usual “High strength” version, the appeal over making a soft shackle from thicker material is purely cost. Bumping up diameter from, for example, 6 mm to 8 mm line (the next available size) adds significantly to the price. This method just requires a small extra portion of line.

Here are a few views of this little beauty:

[Brocky II]

Originally Posted by Breaking Waves

yea, actually most likely my design, the first stable 'stronger' (stronger than the diamond) soft shackle. I personally don't really rate the design very high anymore and prefer the button, but I know some people still like it.

This is another concept than the big and little overhand soft shackles, the girth hitch replaces the noose. Sorry can’t provide picture or link, could someone do me a solid and search Gin Soft Shackle and post results?

[jtsailjt]

Very clever innovations SL, thanks for sharing!
Lots of discussion about strength here but in most uses of these soft shackles made of Dyneema, even a single strand is stronger than what it’s attached to. I guess it’s sort of fun to figure out which version of soft shackle is strongest but it’s difficult to think of a use where the soft shackle would be the weak link since the material it’s made of is so much stronger than traditional double braid of a sheet or the nylon used in a snubber. The same seems true of your twisted, utilitarian version since it’s only intended to hang things that weigh a small percentage of the lines breaking strength. But I wish I still had access to the testing equipment we used when I was an engineering student taking Strengths of Materials class because Dyneema is SO much stronger than anything we had access to back then. Maybe a CF member has a son or daughter currently enrolled in a mechanical or civil engineering program who could test some of these soft shackles so we could quantify how their strength compares to the materials they are commonly attached to?

I use Dyneema soft shackles to attach my jib and staysail sheets to the clews and small ones to secure the turning blocks for my furling lines and a larger one to secure my snubber to anchor chain. But now I’m going to make up a bunch of these twisted ones to neaten up lots of hanging things both on my boat and at home. Thanks again for providing this very useful resource!

[thinwater]

Originally Posted by Seaworthy Lass

...I am not advocating this design. Apart from it being untested, more care needs to be taken with construction and I still prefer a conventional eye, but it is intriguing what can be done.

It at least looks cool .

Very nice!


Not all soft shackles need to be super strong. I use my polyester short-cut versions (I have several) for securing tarps (no knots to jam and nothing to scratch gelcoat), as sail ties (can't freeze), hanging coils of rope, and as a quick means of securing cargo. In most cases, the minimum cord size is set by handling requirements,, not strength.



I wouldn't think of these for halyards, but I would consider them anywhere a bit of knotted cord is used. I hate jammed knots.

[Seaworthy Lass]

Originally Posted by Brocky II

This is another concept than the big and little overhand soft shackles, the girth hitch replaces the noose. Sorry can’t provide picture or link, could someone do me a solid and search Gin Soft Shackle and post results?

Here you go:

https://www.ukairsports.com/product/gin-soft-shackle/

I have attached an image from their website.

It is always interesting to see variations, but I can’t say I am impressed by the design. The stopper chosen does not have a wide base, making the girth hitch more likely to slip off in my opinion. If the O-ring fails the girth hitch is very likely to just loosen and slip off when not under load. A lot hinges on the O-ring not failing.

Can anyone see any benefits compared to a doubled over conventional soft shackle (made with either a Diamond stopper or a Brion Toss Button)?

[Seaworthy Lass]

Originally Posted by jtsailjt

Very clever innovations SL, thanks for sharing!
Lots of discussion about strength here but in most uses of these soft shackles made of Dyneema, even a single strand is stronger than what it’s attached to. I guess it’s sort of fun to figure out which version of soft shackle is strongest but it’s difficult to think of a use where the soft shackle would be the weak link since the material it’s made of is so much stronger than traditional double braid of a sheet or the nylon used in a snubber....

Yes, that is very true. I would guess most soft shackles used are way stronger than necessary, with the line diameter oversized for better handling. When dozens of these soft shackles are in use, the cost of the line does become an issue though and if a slightly smaller diameter can be used and still provide the same strength there is a tangible benefit to having a stronger design.

Occasionally the diameter of the line is limited by the opening the soft shackle is passing through (eg through a chain link when attaching a snubber) so a higher strength design becomes particularly valuable then. It is nice to have a bit of strength in reserve if chafe occurs during storm conditions.

For some uses ease of handling is a consideration. I find the button stopper is so much nicer to use with its smooth top that this has become my stopper of choice even if strength is not needed.

And I agree there is also just the pleasure of playing with design and pushing boundaries and seeing what is possible .

[Breaking Waves]

Originally Posted by Seaworthy Lass

Burying a portion of line in the eye is an obvious solution and has been vaguely discussed in the past. I have seen no photos or description of what was done and no load testing data. I had not attempted this thinking it was not successful for some reason. Breaking Waves, what actually happened when this was tried and why was it abandoned?

Yes, this was exactly the area Brion explored (and I tested) way back when.

the best versions are again meaningful stronger than the stronger button design (the button with buried legs). Off the top of my head I can quite remember how much stronger, nor where the failure mode now shifts to - I could go dredge up all that info. . . but it IS stronger (make sure you taper the ends of the insert - I remember that was important).

In use it seemed meaningfully clumsier to operate which Brion did not like, And Allen (of L36) was never really a fan of the stronger designs and thought it was not needed. They were the main opinion leaders at the time, so it sort of died off as an idea at that point.

I have always liked the stronger button because you are using the tails rather than cutting them off and throwing them away (as you do in a diamond) - seems elegant. But I agreed this approach was clumsier to work and seemed like it would be the 'best' solution in relatively few situations (only those where you needed even more strength but could not accommodate larger body diameter). I did not see any applications on my boat where I would prefer this to the burried button.

In any case, no-one at the time was very interested in pursuing/popularizing this approach. As you know, even the stronger button never developed much of a 'mass' following (which I have never understood because it is clearly better).

I explored it with like 5 rounds of different designs and tests but we did not fine-tune this 'insert' approach - mostly testing where and how the insert should be placed and what thickness (we wanted it to be as thin as possible while still strong enough to move the failure point). There is probably quite a bit of opportunity to optimize it.

[StuM]

Originally Posted by Brocky II

This is another concept than the big and little overhand soft shackles, the girth hitch replaces the noose. Sorry can’t provide picture or link, could someone do me a solid and search Gin Soft Shackle and post results?

https://www.gingliders.com/en/gear/c.../soft-shackle/
The only "Gin Soft Shackle" I can find is nothing like a girth hitched loop.



FWIW, I thought I had seen one in ABOK, but it's not there (and I haven't found an image of one anywhere, so I spent about 10 seconds knocking one up from a bit of small stuff I had lying around. Guess we should call it a "girth hitch soft shackle"

[StuM]

Originally Posted by Seaworthy Lass

Here you go:

https://www.ukairsports.com/product/gin-soft-shackle/

I have attached an image from their website.

It is always interesting to see variations, but I can’t say I am impressed by the design. The stopper chosen does not have a wide base, making the girth hitch more likely to slip off in my opinion.

There is no girth hitch involved in that soft shackle. It's a stopper at one one end and a running eye (ABOK #1699) at the other end of a single line.

[Breaking Waves]

Lass,

It's too bad you did not get to know and work with Brion. You and he would have gotten along famously. He was interested in design ideas - less personally interested in the quantitative/testing side of things. But he did appreciate when we worked together how a testing/breaking feedback loop allowed him to make more targeted design improvements faster.

[Seaworthy Lass]

Originally Posted by Breaking Waves

Yes, this was exactly the area Brion explored (and I tested) way back when.

the best versions are again meaningful stronger than the stronger button design (the button with buried legs). Off the top of my head I can quite remember how much stronger, nor where the failure mode now shifts to - I could go dredge up all that info. . . but it IS stronger (make sure you taper the ends of the insert - I remember that was important).

In use it seemed meaningfully clumsier to operate which Brion did not like, And Allen (of L36) was never really a fan of the stronger designs and thought it was not needed. They were the main opinion leaders at the time, so it sort of died off as an idea at that point.

I have always liked the stronger button because you are using the tails rather than cutting them off and throwing them away (as you do in a diamond) - seems elegant. But I agreed this approach was clumsier to work and seemed like it would be the 'best' solution in relatively few situations (only those where you needed even more strength but could not accommodate larger body diameter). I did not see any applications on my boat where I would prefer this to the burried button.

In any case, no-one at the time was very interested in pursuing/popularizing this approach. As you know, even the stronger button never developed much of a 'mass' following (which I have never understood because it is clearly better).

I explored it with like 5 rounds of different designs and tests but we did not fine-tune this 'insert' approach - mostly testing where and how the insert should be placed and what thickness (we wanted it to be as thin as possible while still strong enough to move the failure point). There is probably quite a bit of opportunity to optimize it.

Initially Brion seemed to be the only enthusiastic one for the design with the button stopper. Allen actually used some very choice words on SA when describing the ease of tying this knot . I was enamoured as soon as I made my first one, although I initially struggled terribly with tying the knot, just as Allen did. At the time online instructions were hard to follow.

I think I never pursued the option of adding reinforcing to the eye as nothing had seem to come of it by the time I started thinking about options for strengthening the apex. Adding reinforcing also seemed clunky and inelegant and I had no real need for a stronger design with a thicker eye so I had little enthusiasm pursuing this.

It was the ease of inserting the reinforcing section in the twisted version that made me want to have a go doing this with a conventional “high strength” design.

I was very surprised not just how easy to was to make, but how much nicer the extra stiffness of the eye felt. It needed a little force to open it, but this could be done by pushing the eye larger rather than pulling it. It also needed a tug to close it, but it just felt beautifully secure when shut.

I guessed that a minimum of 30x bury would be needed, usually a third of which would be tapered, so for my 5 mm line this would be 150 mm with 50 mm of taper at one end. I just added another 50 mm of taper for the other end and so that is why I chose 200 mm for the insert.

I tapered the reinforcing before bury (I always do this) and I made the insert and exit point a generous distance equidistant from the apex, fed it through and smoothed the taper, then held the mid point and buried the tails. It was fairly easy to then judge the centre and proceed as normal with the rest of the construction.

I went straight to a 5 mm diameter insert, as otherwise I had no idea what the length should be. I presume that it would need to be longer the thinner you go.

Even if the strength is not needed I very much like the handling of this super strength version. If it is not too much trouble could you please dig up the data for breaking loads and failure point and what diameter and length of reinforcing was chosen? I have never seen anything discussed.