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Integrated Soft Shackles

Message from Johan Domeij:

I'm an expedition sailor from Sweden, with a love of ropework. A while ago I found a cool way to integrate a soft shackle into the end of a line, on the youtube channel "@PremiumRopes". A few days later, by the grace of the algorithm gods, I found another, different way to accomplish the same thing, on the channel "@TheRigLoftMatthewOtto4775". And I'm intensely curious to see how they compare! If either proves strong, it seems like an excellent way to terminate a halyard for example.

Both methods use a short piece of extra line which is spliced (for type 1) or knotted (for type 2) into the longer line to make the shackle. They look similar but are however spliced completely differently, although it might be hard to see: On the viewing example, I made the shorter piece from a different color to highlight this, but for the samples I wanted everything to be from the same spool to eliminate variables.

Type 1 will only load one strand of the knot, and that strand is the part that splices into the rope. Type 2 will load both strands of the knot, but instead, all the load comes on a brummel splice.


* All samples are identical on both ends.

* Above the special brummels etc. that make up the soft shackles, all samples have exactly the same splice: a locking brummel, a 50x diameter bury, plus a 15x diameter taper. There is about 25 cm of unspliced rope before the taper of the other splice starts. There is no locking-stitch or -whipping, which I would strongly recommend for real world use, but which might affect consistency in testing.

* The button knots are tied as hard as I can with fids and pliers, but not set beyond that. The ends of the knots are buried ~5x diameters, and cut diagonally.

* The rope used is "4mm D-pro" from Liros, which is a heat treated and impregnated SK78 Dyneema, in a 12 braid. All from the same spool. It has a listed breaking strength of 1300 daN (dekaNewtons, which means 13 kiloNewtons or 1326 kilograms-force or 2923 pounds-force). Line from this spool seems to measure more like 3.5mm to me.

* Both original videos use a traditional diamond knot for the soft shackle, but I have opted for a button knot instead. Ryan has thoroughly convinced me that they are both stronger and (importantly for testing as well as safety) more repeatable.

* For anyone attempting type 1, be extra careful to tighten the knot really hard before use. For anyone attempting type 2, consider making an extra brummel lock below where the button knot sits. I have not done this for the samples, but have instead been very careful to keep things consistent and comparable.

* The more basic way to achieve the same thing as these integrated soft shackles, would be to splice a normal eye, and then use a normal soft shackle in the eye, perhaps tied or seized in place with some other string. This is very functional, though less elegant. I thought of including samples for this as well, but we already know that both spliced eyes and soft shackles are stronger than the rope, so it wouldn't be very interesting to test. If anyone wants to discuss these splices, ropework in general, or expedition sailing, you can reach me at I also run a small-time rope workshop from time to time, when I'm on land.

Type 1

Type 1

From YouTube channel "@PremiumRopes": "8.3 Splice a soft shackle on a rope" or, alternate video of the same splice from the same channel: "Splice an integrated soft shackle on a rope". Note that they use a double-braided rope in these videos. The outer braid is a sheath of polyester which makes the Dyneema core easier to tie knots in and use in friction devices, but adds nothing to the strength of the rope.

Type 2

Type 2

From YouTube channel "@TheRigLoftMatthewOtto4775": "Making my version of a integrated soft shackles" A simplified version of this can also be made by tying the button knot directly at the ends of the splice where the eye normally goes, and then close it by pushing the knot through the extra-brummeled-eye that is used for the separate line in this method. This is simpler, but the downside is that you have to thread the head of the knot through whatever you are attaching to which is less convenient.

Our Results

MBS is 13kN - we got slightly higher in 1 but the rest were lower. Dyneema breaks all over the place, even pulling it apples to apples.

Freedom Units

Units everyone else uses

They broke in the brummeled sections

What's Next

See what different qualities do!


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