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I have been playing with soft shackle design and have come up with a new concept. Currently the strength of well made soft shackles is limited from around 170-230% of line strength, depending on design. Either the base of the stopper or the noose is the weak spot. This new design tries to minimise this. The Crown Jewels Soft Shackle is not a replacement for conventional designs, but may be an excellent addition to the arsenal . I hope the fresh concept helps the quest for improving soft shackles: Advantages of the design: - The stopper is one most people making soft shackles are familiar with. There are no new skills to learn. - Although this new design utilises the Diamond stopper, the load at base of the stopper is distributed quite differently. I think there is a high possibility that strength may be increased substantially as a result. Twin stoppers mean the usual loop that makes up the noose is eliminated entirely. There is no noose with a loop at the apex. Drawbacks: - The connection point needs to be large enough for a stopper to pass through. - It uses slightly more rope than a conventional shackle using a Diamond knot, but on the other hand it is less than the length needed for current "High Strength" (230% of line strength) versions. - The design is as yet untested. The instructions are simple: - Cut two lengths of dyneema the inner length of soft shackle when open + 2 x 45 x line diameter for the stoppers. The length needed for the stopper depends on your skill making these. You can get away with 35 x line diameter if you are at ease with making these stoppers. I made the above 200mm long one (100mm when closed) using 1.1 metres of 5mm dyneema. - Tape the two pieces firmly together so that 40x line diameter is left free to make one of the stoppers. - Tie a Diamond stopper. - Tighten the weave securely using a Marlingspike. Twist the tails around some pliers and pull to tighten these. - Carefully mark the chosen length on both legs (for good load distribution these need to be identical) and 4 x line diameter short of there cleanly create a hole leaving 6 strands on each side of the hole and feed the other leg through. - Tape the two legs securely at the marks you just made. - Tie another Diamond stopper and tighten up as for the first. - Pull on one leg below the stopper to open the gap and push the other stopper through. - Pretension the shackle closed between two winches and leave sitting for 20-30 minutes (as you should with all soft shackles) -Cut off the tails about a line diameter from the stoppers. I prefer not to make these too short and nor do I melt them. Keeping the same principle two stoppers, lots of variations in design are possible: - If one stopper is made a toggle (tails are spliced over it) it could be pushed through a small aperture. Strength is likely to be higher than the current designs made with a toggle, as the base of the Diamond acts as the apex of the noose. - The central portion could be buried and a "Better" opening created. I would do this without locking either side of the bury though and milk the cover of the bury vigorously before immediately securing it so it doesn't spring back. Getting the load distribution good is difficult though with a long central bury, so strength is likely to suffer. - A tiny amount of central bury could be made for better handling, as I do for the BB soft shackle. -Depending on where the weak point is with this design, it may help to make one stopper a Button stopper. The opening still needs to be below a Diamond stopper. I can't wait to test the design. It looks very promising . SWL
I have just bought a decent supply of dyneema and I am making up another batch of soft shackles. As usual I have been playing further with design. Irrestistable :). I have a few thoughts about how to maximise the strength when making soft shackles. There is HUGE variation in strength reported for any one type of soft shackle. For ones made using the diamond knot, I have seen values for breaking from around 100-195% of line strength, with approximately 170% averaged when "well made". The reasons have been proposed for this are poor load distribution between the two legs, and in addition for high strength ones the stopper not being pre-tentioned well before load is applied. I think the size of the noose at the end also adds dramatically to the variability found, although I have not seen this discussed. Most online instructions are even super casual about noose size and just vaguely state "form a noose/eye". The only ones specifying size say to make the noose one line diameter in size, even though two legs will be passing through it. I initially started making the noose for my high strength soft shackles (using Brion Toss's brilliant button stopper) four rope diameters in size, but found it looked unhappy under load and I increased this to six line diameters. In this latest batch I am increasing size to about eight rope diameters (noose length 12 x line diameter), which in addition gives a throat angle of just over 2:1 for the noose when the shackle is closed. For the first time it looks "happy". It is still capturing the stopper well and closing quickly without fiddling. I won't have the opportunity to test this out for a few months, but I am so confident this will be good that I plan to use it immediately as our snubber to chain connection. I will report back later. Any comments from anyone regarding this? Allen, your website is the current gold standard for making soft shackles, and noose size specified is only one rope diameter for ones using the diamond stopper. I know that these will typically break at the stopper end, but this is not always the case. The second reason I think the variability in strength may be occurring is due to poor load distribution in the buried section of the body. When I first started making soft shackles it did my head in trying to work out the correct relationship between the outer and buried portions. If I am making one with any bury, I now milk it as hard as possible and quickly grab the end and tape this very securely before the outer portion springs back. This needs care, which may not always be taken by everyone, therefore I think reducing reliability substantially. The locks at the ends of the buried portions also bother me. They don't allow for free load distribution. Without these the shackle can redistribute comfortably with simply an alteration in noose size (if the insertion for the bury is made in a "locking relationship" relative to the noose, the noose will tend to lengthen in size under load and vice versa). I have been leaving locks off for well over a year now. Allen or Brion, do you (or does anyone else) currently have any access to load testing equipment? I think it would be worthwhile testing some Kohlhoff style soft shackles (to completely eliminate the issue of poor load distribution in a central buried section) with nooses that are about 12 times line diameter in length, both for the basic versions using diamond stoppers and the high strength ones using button stoppers. If the stoppers are pre-tentioned well (and for high strength ones the tails buried as close as possible to the stopper after pretentioning), and a larger noose used and there is no central bury, my theory is that breaking loads will be consistently high (maybe close to 200% for soft shackles using the diamond stopper and 250-260% for those using the button stopper). These would also be simple to make, reducing the risk of weaker shackles when less "care" is taken. SWL PS I am making my latest soft shackles Kohlhoff style with button stoppers and a small buried portion (approximately 10 x line diameter from the noose with no locks on either end, which improves handling quite a bit, but minimises the chance of poor load distribution) and buried tail lengths of 30 x line diameter. They look good, handle well and I think strength will also be high. I will take some photos when making the next one.