A simpler soft shackle knot

[Renoirpierre]

I should start by saying thanks to the greater community here for all the education you have all shared with me.

One of the topics that has interested me greatly is the use of modern materials to create soft shackles. I have recently purchased some dyneema and I am playing around with them.

Professionally, my work has led me to be a student of Human Performance (sometimes called Human Factors), in short it's the study how people interact with their systems or environments with a focus on how to reduce error rates around critical steps and improve the resilience of systems by working to reduce the consequence of failure when (not if) it will occur.

As I have been making soft shackles, particularly tying the button or diamond knot I'm looking at the spaghetti in my hand thinking that I'm in a situation where error is likely and the consequences of my error may by difficult to mitigate. I recognize that with practice the knots will become easier, however I'm not convinced that the likelihood of error will reduce by an order of magnitude or more.

I recently watched a video of shackles made using a much simpler overhand knot where the tails are buried and the shackle is fed through the loops created by the bury to tie the knot together. During the testing it appeared that the knot was not the failure point.

The referenced video can be found here

https://www.youtube.com/watch?v=jU_mmdbQeCQ

I would appreciate the collective thoughts about the pros and cons of taking this approach to create a (perhaps less error prone) shackle.

I'd like to be clear that I'm not in any way denigrating the current shackle designs, I'm just wondering if there is an alternative that may maintain the benefits of the current shackles that would be simpler to tie for newer or less dexterous folks.

[StuM]

Probably strong enough, but they sure are fugly!

[Seaworthy Lass]

Originally Posted by Renoirpierre

I should start by saying thanks to the greater community here for all the education you have all shared with me.

One of the topics that has interested me greatly is the use of modern materials to create soft shackles. I have recently purchased some dyneema and I am playing around with them.

Professionally, my work has led me to be a student of Human Performance (sometimes called Human Factors), in short it's the study how people interact with their systems or environments with a focus on how to reduce error rates around critical steps and improve the resilience of systems by working to reduce the consequence of failure when (not if) it will occur.

As I have been making soft shackles, particularly tying the button or diamond knot I'm looking at the spaghetti in my hand thinking that I'm in a situation where error is likely and the consequences of my error may by difficult to mitigate. I recognize that with practice the knots will become easier, however I'm not convinced that the likelihood of error will reduce by an order of magnitude or more.

I recently watched a video of shackles made using a much simpler overhand knot where the tails are buried and the shackle is fed through the loops created by the bury to tie the knot together. During the testing it appeared that the knot was not the failure point.

The referenced video can be found here

……..

I would appreciate the collective thoughts about the pros and cons of taking this approach to create a (perhaps less error prone) shackle.

I'd like to be clear that I'm not in any way denigrating the current shackle designs, I'm just wondering if there is an alternative that may maintain the benefits of the current shackles that would be simpler to tie for newer or less dexterous folks.

Hi RenoirPierre
Welcome to CF.

Using an overhand knot as shown in the video was first described by Evans Starzinger at least 6-7 years ago. He called it an “improved” soft shackle. Several members here are successfully making their soft shackles using this technique.

Evans reported that, if well made, the strength of these is similar to other “high strength” designs where the tails are buried in the legs: ie approx 230-240% of line strength. He cautioned only to make the eyes that were used to form the knot as small as possible otherwise there was a risk of the knot capsizing under load. Videos I have seen explaining this technique don’t seem to mention this.

SWL

[Renoirpierre]

Thanks for the replies SWL and StuM.

Other than watching the eye sizes, are there any downsides to the "improved" design over the better, BB, or strong?

Thanks

RP

[Seaworthy Lass]

Originally Posted by Renoirpierre

Thanks for the replies SWL and StuM.

Other than watching the eye sizes, are there any downsides to the "improved" design over the better, BB, or strong?

Thanks

RP

Not that I am aware of. The stopper does look a bit clunky, but beauty is in the eye of the beholder . The larger than usual stopper knot may actually be advantageous at times.

Care must be taken with the construction of all soft shackles to gain maximum strength. I think the above design contains, if anything, fewer opportunities to make errors. It is relatively easy to make if rope work skills are not high.

When making these here are a few tips from me to help maximise potential strength:
- Make sure the main eye at the end (that secures the shackle closed) is not a noose. Personally, I would make this large enough to hold 6-8 x the dimeter of the line (4 lots of line will actually be passing through it, as the tails are buried in that segment).
- Secure the eye size with tape while working so that it does not shift inadvertently.
- Ensure the two legs are absolutely an identical length when the bury is completed before the knot is tied. If they are not, when the knot is tensioned the size of the main eye could alter.
- Don’t twist the line during construction.
- Use the usual techniques to tension the finished shackle carefully by hand, then pretension under load (eg using a winch) and leave to sit for 20-30 minutes with the load applied. Strength can diminish significantly if shock loads are applied before this is done.

Edited to add: After the main eye is formed and secured with tape, trim the ends so that the length of the two legs is identical. Although any excess will be buried, the difference in bury length will alter the final length of the leg as the outer portion bunches up when filled. By far the easiest way to avoid this is to initially trim.

Have fun making these.

SWL

[Jim Cate]

Use the usual techniques to tension the finished shackle carefully by hand, then pretension under load (eg using a winch) and leave to sit for 20-30 minutes with the load applied. Strength can diminish significantly if shock loads are applied before this is done.

Ange,do you know why this is? Seems kinda odd...

Jim

[Seaworthy Lass]

Originally Posted by Jim Cate

Ange,do you know why this is? Seems kinda odd...

Jim

I think that it occurs (at least partly) because sudden loads will cause the line in the knot to move very rapidly when it tightens up, heating it. The melting point of UHMWPE is relatively low: roughly 140-150°C so damage to the line can occur with this rapid movement, weakening it.

Someone else may chime in with more inform regarding this.

[Renoirpierre]

I appreciate the warm welcome and the informative response. I'll go make a couple and come back if I have any questions.

RP

[Breaking Waves]

Originally Posted by Renoirpierre

I appreciate the warm welcome and the informative response. I'll go make a couple and come back if I have any questions.

RP

The buried tail button design is (imho) the best of the 'stronger' designs. It has essentially no failure mode; while the overhand does have the 'collapse mode' if loops not sized correctly; and the diamond has 'pull apart' if allowed to suck in its tails.

In theory, the button and overhand are the same strength. In actual testing the overhand may be very tiny bit stronger - but practically speaking they are the same strength.

The button is relatively easy to make once you have made one, and SLW here has written quite good instructions for it. The overhand is easier to learn the first one, but after you have made a few they are about the same difficulty.

And the button is better looking.

If I were you, I would learn to make buried buttons.

[SeanPatrick]

I've used a lanyard knot (a.k.a. diamond knot) in combination with a butterfly loop to make expedient soft shackles. Both knots are relatively easy to tie IMO. I leave the working ends, which I have kept to a minimum while working the lanyard knot tight, sticking out of the "top" of the knot. They don't seem to get in the way too much. I make the butterfly loop just big enough to be able to get around the lanyard knot with a little coaxing.

NB: I have never used this particular arrangement for high loads, so I'm not sure of its suitability for such a purpose.