Does my soft shackles looks right?

[fxykty]

Originally Posted by Sailing Ohm

The diamond knot looks wrong to me at first glance. Maybe a little loose looking?
And as others have said the eye is way to big.

If you’re referring to freeriver’s soft shackle (or mine), that’s a Button knot (the legs come out the bottom, rather than out the top).

That said, freeriver’s knot looks a bit loose. It should feel very hard and solid before setting with winches. It takes a lot of working.

Noose can be pretty big before it come off over the knot, so it’s likely not too big. We use our soft shackle to attach our bridles to our chain.



Here’s a Diamond knot arranged with a Bullseye weave to create a captured soft shackle. This was developed by seaworthylass and posted on CF a while ago. We use this for our third reef line at the clew of our main.

[Sailing Ohm]

I prefer to make mine like this and bury one of lines through the other. ...not sure why I guess I like the look more.
I also keep the eye pretty small to ensure there is no chance of popping out especially when there isn’t a load.


Just read about button vs diamond knots and I guess I’ll need to learn to tie the button variety for that extra strength.
I’m not sure it matters much with 3/8 dyneema but why (pause for effect) knot...

[Dockhead]

Originally Posted by thinwater

The flip side of this argument is...

• During strength testing, the shackles break in the knot, not at the noose, so the effect of a narrow throat angle is theoretical, not practical.
• They normally fail somewhere else due to chafe.
• Most soft shackles are way over strength, because the minimum size is too hard to work with the fingers, particularly when cold and wet. Go oversized.
• A loose noose increases the risk of the soft shackle coming off at low load, when a sail is flogging. This is the greater risk in many or most applications.

So I differ. A tight noose is better, primarily for the last reason.

Remember also that the noose can not tighten past a critical angle (about 90 degrees included angle) due to the rules of physics and friction. Just can't. Try it.

I think this is all exactly correct. And the main point is that it is so easy (even inevitable) for the shackle to be way overstrength, that you just don't care about minor variations of throat angle. You DO care about security under low load, however, so don't oversize the loop.


I've been using these for many years, and have never had one break, chafe through, be significantly damaged by chafe, or shake loose. They are fantastic. I make mine using Evans Starzinger's knotless version, because I am too klutzy to make the button knots. The knotless ones are much faster to make as well.

[Seaworthy Lass]

Originally Posted by thinwater

The flip side of this argument is...

• During strength testing, the shackles break in the knot, not at the noose, so the effect of a narrow throat angle is theoretical, not practical.
• They normally fail somewhere else due to chafe.
• Most soft shackles are way over strength, because the minimum size is too hard to work with the fingers, particularly when cold and wet. Go oversized.
• A loose noose increases the risk of the soft shackle coming off at low load, when a sail is flogging. This is the greater risk in many or most applications.

So I differ. A tight noose is better, primarily for the last reason.

Hi Thinwater,
These soft shackles are little marvels, aren’t they .

I agree with much of what you have said, but I disagree with you entirely regarding eye size.

For these “high strength” soft shackles (ie all the designs where the ends finally come back down into the legs giving potential strength of around 240% of line strength) the eye is actually the weak point, not the knot, so the effect of a small eye is entirely practical, not theoretical. The vast majority of images I have seen after load testing anything other than soft shackles made with diamond knots show the line snapping at or close to the eye.

In addition, if the eye is sized to barely fit the line passing through, if you have misjudged the eye size even slightly and it ends up being even a whisker smaller than the line passing through (creating a noose rather than an eye), the strength will be reduced dramatically.

In well over a decade of use worldwide in a huge variety of applications including underwater, I have never, not one single time, heard of a soft shackle coming off when under low load, so I doubt this is much of an issue.

I am very much in favour of oversizing these soft shackles (except for large diameter line that is expensive and at some point makes the shackle harder, not easier to handle), but even if you do so, unless you make the eye larger than the knot (it would have to be huge for this to be the case), I see no good reason to deliberately reduce the strength by creating a very small eye, or worse still a noose.

Originally Posted by thinwater

Remember also that the noose can not tighten past a critical angle (about 90 degrees included angle) due to the rules of physics and friction. Just can't. Try it.

I don’t understand what you mean by this. Could you please elaborate?

SWL

[thinwater]

Yes, marvels that look like they could have been invented 200 years ago... but the materials didn't exist. Except they are that old. I'll come back to this.

Originally Posted by Seaworthy Lass

...In well over a decade of use worldwide in a huge variety of applications including underwater, I have never, not one single time, heard of a soft shackle coming off when under low load, so I doubt this is much of an issue....


SWL

I have experienced soft shackles coming loose, and so have others. It's rare and associated with applications that flog. Perhaps they were not closed perfectly, but they were always soft shackles where the noose was a little large. In fact, I could argue that the noosing soft shackle design is completely unnecessary if a large noose is acceptable. In fact, strops of this latter type have been in use for 200 years and are quite secure, but have been replaced by noosing soft shackles because they were not always secure enough.


(I use non-noosing stropes for many things, and it is VERY rare for them to come off either. About the same as a soft shackle with an oversized noose.)







Originally Posted by thinwater
"Remember also that the noose can not tighten past a critical angle (about 90 degrees included angle) due to the rules of physics and friction. Just can't. Try it."


First, I typed the wrong angle. 120 degrees.



A noose cannot passively choke up past a certain angle. You cannot create a circle with a line coming out of it. The throat angle will not noose up to less than 120 degrees, because the tension on the legs will not let it draw up. You can set it tighter than that, but within a few shaking cycles, it will loosen to 120 degrees. This equalizes the forces. Thus, a small noose does not approach infinite force. This weakening is well known in the rigging industry and is right in lifting tables.



At this angle there is some weakening. The force on the legs is perhaps 50% greater than it would be at a more shallow (but still secure) angle, but for most applications, the secureity is more important than the theoretical strength gain.



This is a compromise, that is all. The best answer depends on the use. Some are stronger, some are more secure, some are more chafe resistant, some are less prone to clogging with dirt, some are easier to tie. It depends.

[Seaworthy Lass]

Originally Posted by thinwater

.... In fact, I could argue that the noosing soft shackle design is completely unnecessary if a large noose is acceptable. In fact, strops of this latter type have been in use for 200 years and are quite secure, but have been replaced by noosing soft shackles because they were not always secure enough.
(I use non-noosing stropes for many things, and it is VERY rare for them to come off either. About the same as a soft shackle with an oversized noose.)

I agree that an eye that is way too large (large enough to fit the head through) is unacceptable under low load. Our opinions just differ regarding what is acceptably small .

Originally Posted by thinwater

First, I typed the wrong angle. 120 degrees.

A noose cannot passively choke up past a certain angle. You cannot create a circle with a line coming out of it. The throat angle will not noose up to less than 120 degrees, because the tension on the legs will not let it draw up. You can set it tighter than that, but within a few shaking cycles, it will loosen to 120 degrees. This equalizes the forces. Thus, a small noose does not approach infinite force. This weakening is well known in the rigging industry and is right in lifting tables.

At this angle there is some weakening. The force on the legs is perhaps 50% greater than it would be at a more shallow (but still secure) angle, but for most applications, the secureity is more important than the theoretical strength gain.

An eye that is too small is not acting as a conventional noose. Surely we need to consider what occurs when the diameter of the “noose” is smaller than its contents and it cannot adjust to fit because the load is distributed evenly on both sides of it?

Something has to give. As far as I can see, if the contents cannot be compressed then the “noose” must stretch to accomodate the contents and if it can no longer do so it will snap.

If this is not the case, what am I missing?

SWL

[DefinitelyMe]

Originally Posted by Seaworthy Lass

In well over a decade of use worldwide in a huge variety of applications including underwater, I have never, not one single time, heard of a soft shackle coming off when under low load, so I doubt this is much of an issue.
SWL

Following this thread with interest and have already learned a number of things from your vastly superiour knowledge of this subject. However I can attest that I have experienced this twice - in both cases where soft shackles were used to secure sheets on a racing boat. They were of the type that is under-sized (to save weight on the clew) and with plastic baubles instead of diamond or button knots. The smooth plastic makes it much easier to un-do in a hurry during sail changes, but doubtless also contributed to those two failures.

[thinwater]

Originally Posted by Seaworthy Lass

...An eye that is too small is not acting as a conventional noose. Surely we need to consider what occurs when the diameter of the “noose” is smaller than its contents and it cannot adjust to fit because the load is distributed evenly on both sides of it?

Something has to give. As far as I can see, if the contents cannot be compressed then the “noose” must stretch to accomodate the contents and if it can no longer do so it will snap.

If this is not the case, what am I missing?

SWL

Not missing anything there. If the noose is too small you are loading one leg. That is simply a construction error. Any shackle where the load is more on one side that the other is faulty.

[Seaworthy Lass]

Originally Posted by thinwater

Not missing anything there. If the noose is too small you are loading one leg. That is simply a construction error. Any shackle where the load is more on one side that the other is faulty.

The danger of calling the eye a “noose” and advising it should be tight is that precisely this will occur.

The easy conclusion I draw from this is that it is critical that the eye is not too small. Extreme care needs to be taken to ensure this.

To try and get the size of the eye exactly the same as the contents is difficult to do, as the legs will often shift slightly unevenly once the soft shackle has been pretensioned before use. Particularly if any portion of a leg is buried in the other, I have found it near impossible to judge an eye size perfectly beforehand. So in my view it is vastly safer making the eye a bit bigger rather than risk it being even slightly too small.

Originally Posted by thinwater

So I differ. A tight noose is better, primarily for the last reason.

Remember also that the noose can not tighten past a critical angle (about 90 degrees included angle) due to the rules of physics and friction. Just can't. Try it.

Just going back to this point (regardless of whether it is 90° or 120°). If the eye size is such that it is cinched tightly to fit the legs without leaving room for the 120°, what happens then?

I know I may be completely missing some basic vital thing, but I am grappling to understand how this can possibly not compromise the strength of the eye.

Thanks for your patience .

SWL

[thinwater]

Originally Posted by Seaworthy Lass

... I know I may be completely missing some basic vital thing, but I am grappling to understand how this can possibly not compromise the strength of the eye.

Thanks for your patience .

SWL

I never implied that these things do not weaken the eye a bit. What I said was...

• Most often that is not where they break. It is normally due to chafe (which can be anywhere).
• Security is important. The closed dimension of the eye must be significantly smaller than the knot. You agree. How much smaller is something that many sources disagree on.
• Peak strength is really not that important to most people (not all people--applications vary). Most soft shackles are significantly oversize and are replaced due to wear.

[Seaworthy Lass]

Originally Posted by thinwater

I never implied that these things do not weaken the eye a bit. What I said was...

• Most often that is not where they break. It is normally due to chafe (which can be anywhere).
• Security is important. The closed dimension of the eye must be significantly smaller than the knot. You agree. How much smaller is something that many sources disagree on.
• Peak strength is really not that important to most people (not all people--applications vary). Most soft shackles are significantly oversize and are replaced due to wear.

At least we agree the eye should be smaller than the knot, but larger than the contents. That is a healthy starting point in this discussion .

I tend to err on what I consider is the conservative side, particularly for applications where strength is critical and it is not possible to merely upsize line diameter to compensate (eg the soft shackle connecting our snubber to chain is limited in size as it needs to fit through a chain link).

Wind strength peaked at 81 knots at anchor this weekend (70+ knots for extended periods) and I am glad my soft shackle construction did not add to the stress .

SWL

[fxykty]

Originally Posted by Seaworthy Lass

... the soft shackle connecting our snubber to chain is limited in size as it needs to fit through a chain link) ...

We found a comfortably strong soft shackle doesn’t fit through our chain links easily (1/2” 12/13mm G40) and the galvanising wears on the soft shackle fibres. So we thread a 10mm Dyneema climbing sling through the chain and capture the basket loops (and bridle eyes) with the soft shackle. The Dyneema webbing is more chafe resistant and much cheaper. We use a lot of these webbing loops on our boat.

For strength, the basket configuration doubles the rated 22kN strength so is sufficient for our purposes.

[Seaworthy Lass]

Originally Posted by fxykty

We found a comfortably strong soft shackle doesn’t fit through our chain links easily (1/2” 12/13mm G40) and the galvanising wears on the soft shackle fibres. So we thread a 10mm Dyneema climbing sling through the chain and capture the basket loops (and bridle eyes) with the soft shackle. The Dyneema webbing is more chafe resistant and much cheaper. We use a lot of these webbing loops on our boat.

For strength, the basket configuration doubles the rated 22kN strength so is sufficient for our purposes.

Sounds like a good solution .

Our chain is 12mm G40 as well. An 8mm soft shackle just fits through. It fluffs slightly with prolonged use, so I replace it routinely about once a year.

By the way, the Bullseye soft shackles used with LF rings that are used to divert the snubber along the deck also chafe slightly. I added dyneema sleeves to these (just loosely slid on) and the latest Bullseyes are looking pristine after more than a year.

SWL

[Seaworthy Lass]

I have just modified the pdf I created a while back with instructions on how to make a “high strength” soft shackle using the Brion Toss Button Knot. This is a work in progress that has spanned many years of both making and using these extensively (as an amateur for personal use, cruising full time).

I had previously noted there was a risk of soft shackles opening, but I had never heard of this occurring, so this has now been altered. It still seems to be a very rare occurance.

I have also altered the word “noose” to “eye”, as I found I was guilty of using this term interchangeably in the document . I think the term “noose” is extremely misleading as the eye is not designed to clench the base of the knot.
As Thinwater has pointed out, if the eye is not large enough to accommodate the contents then only one leg is loaded and the soft shackle is faulty.

Optimal eye size is somewhere between larger than the legs at the base of the knot where it will sit, but smaller than the knot itself. My eyes are on the generous size so as not to create a tight throat angle that is detrimental to the strength of the weakest point in this design of soft shackle, other opinions and priorities will clearly differ .

Basically, make these to best suit your needs.

The pdf unavoidably needs to be divided into two parts as the file size was too large:

[Free Rider]

Well, I certainly did not think my question would stir a debate!

I found that my first shackle was too large at the eye because the legs did not stay as they were first set when I was tying the button knot. I managed to work one of them back into the button, giving back the intended size to the eye. I was more cautious for the next shackle.

Thank you again for your help. Here is my first 4 shackles (The one in the upper left corner has no lock). I still have to tighten them with a winch :