Improved soft shackle

E

estarzinger

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www.bethandevans.com
The conventional soft shackles all break at the diamond knot. So the question to explore was: is there an easy to tie replacement for the diamond that is stronger? The answer turns out to be yes. There is an alternative that makes the soft shackle 230% of line strength, which is about a 50% increase over the conventional diamond soft shackles, and which moves the weak point to the bend radius at the noose. There is a full write up here (http://www.bethandevans.com/pdf/improvedsoftshackle.pdf), with some summary pics below:

View attachment 40813

View attachment 40814
 
A vast improvement over the old knot and much simpler to tie.
Fantastic find.
It's going to put a lot of chandlers out of business!!!
 
estarzinger said:
The conventional soft shackles all break at the diamond knot. So the question to explore was: is there an easy to tie replacement for the diamond that is stronger? The answer turns out to be yes. There is an alternative that makes the soft shackle 230% of line strength, which is about a 50% increase over the conventional diamond soft shackles, and which moves the weak point to the bend radius at the noose. There is a full write up here (http://www.bethandevans.com/pdf/improvedsoftshackle.pdf), with some summary pics below:
Click to expand...

Genius, Evans. Brilliant. How many hours have you been tying knots in your head to come up with that :cool:

Have you named it?

Starstopper? , "a diamond knot is good for soft shackles, but a Starstopper is the way to go" :)
 
GHA said:
Genius, Evans. Brilliant. How many hours have you been tying knots in your head to come up with that :cool:

Have you named it?

Starstopper? , "a diamond knot is good for soft shackles, but a Starstopper is the way to go" :)
Click to expand...

Congrats starstopper, didn't realise it was your knot.
 
I think migelmercier has my same doubts:
A) How do You get the "central" loop? My guess is that You make what I usually refer to as an "aussie splice", inserting the slicing fiddle through the centre of the middle point of the length of rope and passing one end of the rope through it until You end up with the "eye".

B) how do You make the eye splices at the 2 ends of the rope? I guess again that You insert the splicing fiddle INSIDE the centre of the rope (and not "through it", as in A) and use it to insert the final part of each end inside itself. My question is: for how much? 10 cm? 8 times the rope diameter?

Am I correct? Or, for B), it should be "as long as it reaches the centre eye"?
 
sorry, I was assuming basic dyneema single braid splicing knowledge.

For (a) - yes, exactly - make a hole sidwways, thru the middle of the line, being careful it is in the middle with the same number of strands on each side (6) and then pass one end thru the hole. That forms the center 'noose'.

For (b) there are two techniques and tools. For 6mm and bigger dyneema you can do it the way you suggest - push a fid down, length-ways, the center hollow of the braid. Or an alternate way is to use a piece of wire bent in half, push it in the other way thru the hollow center, snag the tail you want to pull in the bend, and pull it back thru the hollow center.

For length of bury . . . .62 diameters is the most you need to do. But half that will work in this application. In this application you want a minimum of an inch of bury sticking out from the knot. It is the bury that provides the extra strength.

There are a bunch of sources on the net for dyneema splicing info . . . http://l-36.com/soft_shackles.php?menu=4 is particularly good related to soft shackles. Allen and I have been working together on this, and this design builds on his prior work.
 
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I'd be interested in finding out the breaking strength of ordinary dyneema soft shackles. If, say, 6 mm dyneema has a breaking strength of around 3,500 kgs, at what pressure does the shackle break? Anybody know?
 
Yes I have to say that I don't understand it either and I generally splice all the dyneema lines on my dinghy, for which I have used the Marlow or Rooster videos to explain. With diagrams I think it is always harder, unless you literally show every step.
 
srah1953 said:
I'd be interested in finding out the breaking strength of ordinary dyneema soft shackles. If, say, 6 mm dyneema has a breaking strength of around 3,500 kgs, at what pressure does the shackle break? Anybody know?
Click to expand...

The Colligo marine website has breaking strains in pounds. In their video they show how to make a soft shackle using 5mm dyneema. The shackle is then a 9mm size. This makes a shackle with a breaking strain of 10,000lbs (22000kg) and a SWL of 4000lbs (8,800Kgs). Of course if you use the Dyneema max it will be even stronger!

TudorSailor
 
I proposed the use of the shake hands knot for soft shackles, but nobody was interested or seemed to see the relevance.
http://www.youtube.com/watch?v=_yckxG32Zcw
obviously your new knot is much superior, but I can vouch for the safety of the above knot, and how easy it is to untie.
It could come in useful if you don't have a vid handy to make a splice in a rope.
 
srah1953 said:
I'd be interested in finding out the breaking strength of ordinary dyneema soft shackles. If, say, 6 mm dyneema has a breaking strength of around 3,500 kgs, at what pressure does the shackle break? Anybody know?
Click to expand...

I have recently done extensive testing. The weak point in classic soft shackles is always the stopper knot (usually a diamond), and the shackle will break at the stopper at about 160% of the dyneema cord tensile strength (I have seen some break at 100% and others up to 180%).

The 'engineering' of this is: a loop will have twice the tensile of the line used (because there are two pieces holding the load in a loop), and a soft shackle is a doubled loop (there are two strands around a soft shackle). So in theory, a 'perfect' soft shackle will be 400% of line tensile. However, knots in dyneema cut the strength. The diamond knot is about 45% of line strength. That gets you to 180% (400% x .45). There are then typically small imperfections in the shackle construction (typically the two strands are not exactly the same length so one takes more load than the other). And that imperfection gets you down another 20%, on average down to 160% (although if you are very very careful you can/I have made one with near 180%). My 'improved design' replaces the diamond with a stronger stopper, which moves the weak point to the small bend radius at the noose. This is about a 2:1 bend radius, which 'should be' 65% strength, so in theory 400% x .65 = 260% strength, but again there are imperfections in the construction and my samples have tested at 230-240%.

Regarding basic dyneema splicing . . . you can find a ton of videos on youtube. Just google "soft shackle instruction video" (like https://www.youtube.com/watch?v=sP74FE4p8to and https://www.youtube.com/watch?v=jH66tGsWv_Y) . But here are two written instructions from rope mfg's: Bury splice (http://www.bethandevans.com/pdf/amsteel12Strand_C2_Eye Splice_JUL2012_WEB.pdf), brummel splice (http://www.bethandevans.com/pdf/endrua12_splice.pdf). I would just add that these are by far the easiest splices to make, compared to all other rope splices. There is nothing complex at all, no weaving or braiding, just sliding one part into the other part - it is all about the Chinese finger trick.
 
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tudorsailor said:
The Colligo marine http://www.colligomarine.com/docs/catalogs/catalog%202012-13.pdf has breaking strains in pounds. In their video they show how to make a soft shackle using 5mm dyneema. The shackle is then a 9mm size. This makes a shackle with a breaking strain of 10,000lbs (22000kg) and a SWL of 4000lbs (8,800Kgs). Of course if you use the Dyneema max it will be even stronger!

TudorSailor
Click to expand...

Is your conversion from lb to kg correct????

I make 10,000 lb (US) to be 4,536kg and 8,000 lb (US) to be 3,628kg

As a quick conversion 1kg is approximately equal to 2.2lb

It looks like you've "gone the wrong way" kg should always smaller than the equivalent lb
 
Just as a note . . .the Colligo shackle design is a couple generations old and pretty much obsolete. It is harder to work than more recent designs - particularly in milking the noose closed.

Soft shackles are dead easy to make, in about 10 minutes with a couple eruos of rope. You just need to follow the instructions, which are not at all difficult. The 'splicing' is easier than any other sort of line splicing - much much much easier than the double braid dacron splice, even easier than the traditional 3 strand tuck splice. You really don't need to buy them. And if you make them yourself you can make the exact length you want.

The are inexpensive, light, and as strong as steel.
 
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