Which soft shackles are in vogue?

Mozzy Sails

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I tend to use the diamond knot with two separate legs (not buried) as it's simple, quick and can be made quite short for fixings that need to be close. If I'm using them somewhere I'm worried about them flogging open I tend to use the buried option (but I find them a bit more fiddly to open and I'm not sure they spread the load quite so well).

I don't use the button knot because I find it them harder to tie, and the shackle needs to be longer to allow for the buried tails. Plus, the knot isn't as big relative to the neck which increases the chance of it flogging open when not under load. The diamond knot method far exceeds my needs and I could always up line diameter before going for a button knot, although I suppose I would use the button knot if for some reason I couldn't increase line diameter and it was in an application which is consistently loaded.

However, I've recently seen this method, basically two eye splices, tied in and overhand knot, then the tails run though the eye splice. How does this compare to the button knot? 




 

Mozzy Sails

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If I make them bespoke then I can get them to specific lengths. With the diamond knot it's a 5 minute job. Compared to other rigging jobs I'd say it's one of the easiest savings over buying made / getting a rigger. 

Obviously if you're earning $120/hr then it's still not going to be worth your time.. but who knows, you might just enjoy it?
 




 

estarzinger

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I've recently seen this method, basically two eye splices, tied in and overhand knot, then the tails run though the eye splice. How does this compare to the button knot?
That was the original of the 'stronger' (buried tail) designs.  It is easy to tie, and tests very slightly stronger than the button. Many people don't find it as attractive as the more symmetrical diamond and button. And you need to make sure the eye splices are small enough - fi so then it is great but if they are too large the stopper can invert/capsize. 

If I'm using them somewhere I'm worried about them flogging open  . . . . increases the chance of it flogging open when not under load.
Honestly, I would really not worry too much about any of these (properly made) flogging open. They are very resistant to that.  The more common real-world failure mode is the diamond knot having the tails cut too short and not being pre-tightened enough, and then when it is highly loaded it sucks the tail ends in and comes untied.

The diamond knot method far exceeds my needs and I could always up line diameter before going for a button knot, although I suppose I would use the button knot if for some reason I couldn't increase line diameter and it was in an application which is consistently loaded.

Yea, the basic soft shackle strength is quite good, and as you say you can usually just size up the line if you have any concern.  There are a few applications where you can't size up - thru chain link/chain snubber attachment is probably the most common one - where the 'stronger' designs are merited from an engineering perspective. But the button and other stronger designs are really not that hard to tie if you practice on a few and then 'why not make them stronger'.

Personally, I think rubber-coated aluminum toggles are the way to make the best 'soft' shackle.  You can make the toggle for very small money from parts available at any DIY/hardware store, and it is the most reliable/predictable/strongest for material design available.  But I understand some people like the textile purity of the stopper knot designs.

 

duncan (the other one)

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15 hours ago, Mozzy Sails said:

I tend to use the diamond knot with two separate legs (not buried) as it's simple, quick and can be made quite short for fixings that need to be close. If I'm using them somewhere I'm worried about them flogging open I tend to use the buried option (but I find them a bit more fiddly to open and I'm not sure they spread the load quite so well).

I don't use the button knot because I find it them harder to tie, and the shackle needs to be longer to allow for the buried tails. Plus, the knot isn't as big relative to the neck which increases the chance of it flogging open when not under load. The diamond knot method far exceeds my needs and I could always up line diameter before going for a button knot, although I suppose I would use the button knot if for some reason I couldn't increase line diameter and it was in an application which is consistently loaded.

However, I've recently seen this method, basically two eye splices, tied in and overhand knot, then the tails run though the eye splice. How does this compare to the button knot? 


one thing I like, depending on application, is having longer tails out the knot - which allows you to sort-of pre-feed the stopper through the constrictor.

Definitely handy when I rig my dinghy with a long softy around the boom to hold down the clew, and the other softy on the vang/boom connection.

Can't do that with the above design.

 
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Mozzy Sails

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Thanks for replies. 

Yes, having the tails stand proud is definitely useful sometimes. I've also used a diamond knot, but loaded in reverse on my downhaul. The downhaul needs to be pre-tentioned when you attach it to the gooseneck to allow for maximum range on the RS 800. So, the final line in the cascade, which is dead ended via a splice  to the goseneck passes through the main tack has the end looped over, a diamond knot tied, then one tail burred in to the other. This stopper then feeds through an opening eyesplice which comes from the first block i the Cunningham cascade. The small loop below the diamond knot, which would normally have the noose of soft shackle in it, can then be used to pull down and load the downhaul as you slip the eyesplice over it.

It's hard to explain, but works well... I do wonder if it's okay to load the diamond knot in reverse like this, however. 

 

NORBowGirl

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However, I've recently seen this method, basically two eye splices, tied in and overhand knot, then the tails run though the eye splice. How does this compare to the button knot? 
I only make this version, because it's easier to remember. I don't make them often enough to remember how to tie the diamond knot. Maybe just a handful of times every summer. 

And as long as the eyes are small enough and the bury is longer than the knot, it's supposed to be a lot stronger than the diamond knot shackle. The thing to remember is that the more you fuck around and the more loops and shit you make, the weaker it gets. Dyneema likes long buries and simple solutions. At least that's what a proper sailmaker told me :)

 

estarzinger

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4 hours ago, NORBowGirl said:




I only make this version, because it's easier to remember. 

It is interesting reading these sorts of comments . . . . the various 'experts' panned this design, but they all tie diamonds and buttons frequently enough that they can in their sleep and thus 'easy to tie' is not a factor for them. 

Just for transparency - this is/was originally 'my' design (originally developed here in a thread with Allen and brion), but I personally have switched to rubber-coated aluminum toggles if I want max reliability/strength, or if it has to be all textile then "Brion's" design (button with buried tails) simply because the buried tail button has no 'sloppy construction' failure mode (which both the diamond and overhand do). 

 a lot stronger than the diamond knot shackle.

Yup, the various buried tail designs are roughly 40% stronger (for the same amount of Dyneema) than the diamond unburied designs.  Tested very very carefully, this eye splice/overhand knot buried tail design tends to be some few percent stronger than the button buried tail designs, but that is within the noise level of most people's construction and testing repeatability.

The thing to remember is that the more you fuck around and the more loops and shit you make, the weaker it gets. Dyneema likes long buries and simple solutions. 

This is a super super relevant and accurate comment. I was reminded of it while I was recently testing various ways to capture a low friction ring in a strop. I started off with a number of 'interesting' designs which all tested lower than I had expected, so I did a second set adding some more 'sophisticated' design features (like overlapped buried tails)  which should theoretically have increased strength but in the actual tests they did not because the dyneema was more disturbed and it was harder to get exact same lengths in different legs.  I then switched to a set of absolutely dead simple (the simplest ways I could image) designs and they tested way higher than the complex/sophisticated ones. Even adding lock stitching on the bury noticeably reduced test strength (but only a few percents and is still viewed as a useful trade-off to absolutely forbid low load slipping).

 
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is there anything showing how you are making these?
Do a search for dogbone soft shackle or toggle, you are essentially eliminating the knot keeper  portion in favor of a alloy, aluminum or titanium round stock piece.  This is actually super similar to a traditional toggle with bone or otherwise.  I'm sure Evan has some info or testing lurking around, but he may have moved on to other things.  These are as easy to make as all line soft shackles but you add a bit of metal in the mix.

 

us7070

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you are essentially eliminating the knot keeper  portion in favor of a alloy, aluminum or titanium round stock piece
sure - i've seen them...

where i see them is on halyards and sheets, where all that's needed is a splice.

the other way i've seen them used is with dynema loops - for which, if i understand correctly, there are strength concerns - especially for the DIY loops unless they are really long

what i read above seems to indicate that you can basically make a shackle, with the knot replaced by a dogbone - sounds great, but how are you attaching the dogbone?

 

estarzinger

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 sounds great, but how are you attaching the dogbone?
hey 7070, hope your sailing season was great.

I'm 'unfortunately' not 'documenting' my rope work much, that just ended up created more headache than it was worth.

But I have done an absolute ton of work and testing on soft shackles, trying to come to the best solution for applications (like commercial lifting) where you need high reliability and consistency.

With toggle shackles there are two basic designs, and two basic 'tricks' to getting max strength.

The two 'tricks' are the toggle diameter needs to be 'sufficient', which means around (or better than) 1.2 x rope diameter - that is easy, just pick right size rod, and then the 'neck' (where the loop will close the toggle) also needs to be sufficient diameter, which usually means it needs to be bulked up either with cover or core.  If you do those two things, plus of course careful rope work on the splices (and bury tapers) then you should end up with no points weaker than the basic line itself and it should break at a taper end right at max strength of line.

There are two basic designs, which one you pick depends a little on the application (and how long of a shackle you need) and a bit of preference.  

There is a 'double loop' design, (exactly as a 'normal' all textile shackle is a double loop). 

Attachment-1.png

With this, the easiest construction is simply two eye splices tight around the toggle.  There are other options but that is most direct.

And there is a single loop design.

IMG_1325.JPG

Here you essentially have a spliced eye on each end, one around the toggle, and one for the 'noose'.

Both these use bury splices.  These can be shorter than the 60x, probably down to like 42x (if they are then carefully set and lock-stitched). But if you need a really short shackle there are some simple solutions (like just use a longer one but loop it twice or more) and some 'clever' solutions (like overlapped tails) which can create weaknesses unless your skills are good.

Hope that helps.

 

us7070

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Thanks Evans.., I will give them a try.

what are you using to make the toggles - a bench grinder or something like that?

 

estarzinger

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I have mostly been using 7075 rod from McMasterCarr - basically just because I can - bog-standard 6061 rod from ace hardware will be perfectly fine.

I just cut to length and round off the ends (yea with a grinder). I have not seen any need to groove the middle, because my rubber dipping pretty much locks the strop in place from slipping.

I would think a small lathe would the tool if you wanted to do any fancier shaping.

 
I spent a bit of time trying to find a off the shelf pin that would work.  A vise 1/2" drill motor and grinder will make alot in a hurry like Evan said. If you put a bolt in the vise in the drill motor handle with a ziptie on the trigger you can make a mini lathe easy to shape aluminum with a flap wheel in a grinder.

 
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