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Old 12-06-2016, 02:23   #16
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Re: My First Soft Shackle

Further thoughts on retaining the low friction rings:

The brummel is inherently unsuitable for this. Because the eye has to be made with the ring out, and there is no way to get it tight enough.

I think a "noose", like on the shackles, locked with some stitching, ought to be fine. It should work better because you can tighten up the noose as you like, then stitch it.

I am aware that I don't want it too tight in order not to load up the stitching too much, but it needs to be tight enough so that the eye is smaller than the lip of the low friction ring, so that this one stays in.

I would think that a simple seizing would also work fine, so it could be that I'm overcomplicating this.
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Old 12-06-2016, 02:29   #17
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Re: My First Soft Shackle

By the way -- on tools --

I did my first round of splicing last year using a ball point pen and tape. It worked ok.

This year I splashed out on a D-Splicer fid and, even more important, their special Dyneema scissors.

Although a ball point pen works ok (and is still an essential tool), the D-Splicer fid is really nice and convenient. The end of the rope clamps into the end of the fid and Bob's your uncle.

The scissors cut through Dyneema like butter, and allow very neat cuts.

Highly recommended, although they are both costly. I rationalized the purchase by telling myself that the set cost less than one decent block, and I'm never going to buy another block.
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Old 12-06-2016, 02:32   #18
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Re: My First Soft Shackle

Quote:
Originally Posted by Dockhead View Post
Now to the strops with low friction rings --

Any advice on this (or from you SWL? BTW, are you using these wonderful devices?).

The racing boat I was on used pair of the rings joined by doubled spliced loops, with velcro to hold it together. Very neat and very simple. I don't use pairs of them because you can easily have two different lines running through the same eye of sufficient diameter. I guess they're doing that to eliminate chances of chafe?

So how should I make my next generation? My last one I made with a brummel eye in both ends, then put both eyes around the low friction ring. I then seized the two legs together to hold the ring in the eyes (which can never be made tight enough). I made a mistake with the last one by just threading one leg through the padeye, so that there is only a single strand of Dyneema going through the padeye bail, which now looks to me less strong than just looping it through and cow hitching, which would give more material to bear on the padeye bail. Thoughts?

Now I think to skip the brummel eyes altogether and just do spliced loops. I could make a "noose" in them (like the shackle "noose") to catch the rings, or I could just seize the legs together or lock stitch them together. Thoughts? I am thinking that the brummel eyes are unnecessary and might even reduce strength of the strop -- retaining the low friction rings does not require any strength at all.
Hi Dockhead
I have just bought some low frictions rings and more Dyneema back from Australia and I have been having a play.

Estarzinger, I would love some feedback please.

This was my first attempt. The easiest way I can see of securing the ring is just to bury one bit of the line to go halfway around the ring in a loop. It seems to easy and holds so snuggly, that I am wondering why this is not used extensively. Is there something wrong with doing this?

Secondly, I created the loop using a Grog sling, but tapered the ends. Grog recommend 30 x line diameter for bury. I know it doubling up the line will change the forces, but my gut feeling is that more is needed. Would you suggest burying closer to the standard 72 x line diameter that is used for a standard eye splice?

Also, I tapered the ends. Grog did not suggest this. Would you taper?

This is how it looks with a 30 x line diameter bury:




And this is a close up of how the ring is secured:

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Old 12-06-2016, 03:18   #19
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Re: My First Soft Shackle

There was a recent article in the UK magazine Yachting Monthly, and a forum thread here.

For tightening you leave long tails on the stopper, and pull those.
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Old 12-06-2016, 03:33   #20
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Re: My First Soft Shackle

Quote:
Originally Posted by Seaworthy Lass View Post
Hi Dockhead
I have just bought some low frictions rings and more Dyneema back from Australia and I have been having a play.

Estarzinger, I would love some feedback please.

This was my first attempt. The easiest way I can see of securing the ring is just to bury one bit of the line to go halfway around the ring in a loop. It seems to easy and holds so snuggly, that I am wondering why this is not used extensively. Is there something wrong with doing this?

Secondly, I created the loop using a Grog sling, but tapered the ends. Grog recommend 30 x line diameter for bury. I know it doubling up the line will change the forces, but my gut feeling is that more is needed. Would you suggest burying closer to the standard 72 x line diameter that is used for a standard eye splice?

Also, I tapered the ends. Grog did not suggest this. Would you taper?

This is how it looks with a 30 x line diameter bury:




And this is a close up of how the ring is secured:

That's lovely, but doesn't the 30x bury compromise strength? For my application, strength isomorphism important than retaining the ring.

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Old 12-06-2016, 04:19   #21
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Re: My First Soft Shackle

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Originally Posted by Dockhead View Post
That's lovely, but doesn't the 30x bury compromise strength? For my application, strength isomorphism important than retaining the ring.
Do you mean you would like more bury? Making it only 30 x line diameter did bother me.
It would be easy to make it any amount though, you just end up with a longer loop. 30 x gives a very short loop once the cow hitch is tied, which is not ncessarily needed.

I will make the next one longer, but will wait on some feedback from Estarzinger first.

The system of retaining the ring seems extremely secure and dead easy to do. Why isn't this the standard way of retaining the ring?

SWL
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Old 12-06-2016, 07:11   #22
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Re: My First Soft Shackle

Quote:
Originally Posted by Seaworthy Lass View Post
Do you mean you would like more bury? Making it only 30 x line diameter did bother me.
It would be easy to make it any amount though, you just end up with a longer loop. 30 x gives a very short loop once the cow hitch is tied, which is not ncessarily needed.

I will make the next one longer, but will wait on some feedback from Estarzinger first.

The system of retaining the ring seems extremely secure and dead easy to do. Why isn't this the standard way of retaining the ring?

SWL
I still don't completely understand how you did it - maybe a sketch?

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Old 12-06-2016, 07:41   #23
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Re: My First Soft Shackle

Couple of thoughts on the low friction rings . . .

Most commercial versions of this use a simple spliced loop tight to the ring. In theory and extreme testing (to breaking strength) this is not ideal because the 'throat angle' of the spliced loop is too high (near 1:1), which weakens it (by about 20%). But in actual practice these things are usually way "strong enough", and if the 20% loss does matter you just use a size bigger dyneema.

But if you want to use 'best practice' there are two three solutions. One is what SL is showing. It requires just a little care to be done correctly or it can be even weaker than the above high throat angle solution. This is a bit hard to explain in words, but the 'incorrect' failure mode is if the bury points for the loop around the ring are placed too far apart, too far around the ring, so the exiting line pulls out against the looped line and stresses 1/2 the fibers. The exit points need to be both on the 'top half' of the ring so the exit line pulls against the ring. That is not hard to accomplish. I will note that I did not test this solution extensively and I don't know if there is any weakness due to the line 'crushing itself' around the loop - I don't think so but can't say with certainty.

The second solution is to splice a longish loop around the ring, long enough to have a throat angle at least 2:1, preferable 3:1. and then just add some sewing, perhaps with some dyneema fishing line (but it really does not matter because it is not loaded), across the throat, under the ring, to capture it. There is no major way to mess this up, but the small trick is to load the ring loop and then sew it loaded so that the stitching is in the right place with the right tension. This seems more common than SL's method. It is perhaps just a bit less elegant but also just a bit less 'skilled'.

The third solution also addresses SL's question about the grog loop. The grog loop is a bit like the the tight loop around the ring - not theoretically right but practically usually ok. The brummel in the grog loop just adds a bit of friction but is mechanically 'backwards' and does not function as a true lock, and it twists the fibers which weakens them a bit. I tested with grog and we agreed that the 30 bury was the absolute minimum - longer is better - the heavy lift industry would say that 42 is really the absolute minimum to handle shock type loads. You only use the grog loop if your application requires you to keep the buries to the absolute minimum length. If you can use longer buries, the standard end to end splice with long tapered buries is the correct solution. And one solution that 'solves' both problems (capturing the ring, and making loop) is to make a loop that is long enough for full buries, and long enough to put twice around the ring (not buried just looped around twice), one of those loops is tightened up on the ring to capture it and is then just sew tacked (just a couple stitches each side) to the other portion (eg to the legs that leave the ring) to hold it tight. I guess I think this may be the 'best' solution. But, as I said above, did not do a ton of testing on it.

I can take photos if any of this is unclear.
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Old 12-06-2016, 07:52   #24
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Re: My First Soft Shackle

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I still don't completely understand how you did it - maybe a sketch?

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Creating a circle by burying part of the dyneema and then tightening it around the low friction ring means there is no need for a throat. I don't like the idea of the force acting to pull this apart.

A Grog sling seemed the easiest way to then form a loop.

This is what I did:

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Old 12-06-2016, 08:12   #25
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Re: My First Soft Shackle

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Originally Posted by estarzinger View Post
Couple of thoughts on the low friction rings . . .

Most commercial versions of this use a simple spliced loop tight to the ring. In theory and extreme testing (to breaking strength) this is not ideal because the 'throat angle' of the spliced loop is too high (near 1:1), which weakens it (by about 20%). But in actual practice these things are usually way "strong enough", and if the 20% loss does matter you just use a size bigger dyneema.

But if you want to use 'best practice' there are two three solutions. One is what SL is showing. It requires just a little care to be done correctly or it can be even weaker than the above high throat angle solution. This is a bit hard to explain in words, but the 'incorrect' failure mode is if the bury points for the loop around the ring are placed too far apart, too far around the ring, so the exiting line pulls out against the looped line and stresses 1/2 the fibers. The exit points need to be both on the 'top half' of the ring so the exit line pulls against the ring. That is not hard to accomplish. I will note that I did not test this solution extensively and I don't know if there is any weakness due to the line 'crushing itself' around the loop - I don't think so but can't say with certainty.

The second solution is to splice a longish loop around the ring, long enough to have a throat angle at least 2:1, preferable 3:1. and then just add some sewing, perhaps with some dyneema fishing line (but it really does not matter because it is not loaded), across the throat, under the ring, to capture it. There is no major way to mess this up, but the small trick is to load the ring loop and then sew it loaded so that the stitching is in the right place with the right tension. This seems more common than SL's method. It is perhaps just a bit less elegant but also just a bit less 'skilled'.

The third solution also addresses SL's question about the grog loop. The grog loop is a bit like the the tight loop around the ring - not theoretically right but practically usually ok. The brummel in the grog loop just adds a bit of friction but is mechanically 'backwards' and does not function as a true lock, and it twists the fibers which weakens them a bit. I tested with grog and we agreed that the 30 bury was the absolute minimum - longer is better - the heavy lift industry would say that 42 is really the absolute minimum to handle shock type loads. You only use the grog loop if your application requires you to keep the buries to the absolute minimum length. If you can use longer buries, the standard end to end splice with long tapered buries is the correct solution. And one solution that 'solves' both problems (capturing the ring, and making loop) is to make a loop that is long enough for full buries, and long enough to put twice around the ring (not buried just looped around twice), one of those loops is tightened up on the ring to capture it and is then just sew tacked (just a couple stitches each side) to the other portion (eg to the legs that leave the ring) to hold it tight. I guess I think this may be the 'best' solution. But, as I said above, did not do a ton of testing on it.

I can take photos if any of this is unclear.
Thanks. That is all extremely helpful. I was "winging it" with this first attempt . I agree about the length of the bury around the top the low friction ring. If is is made any longer than half the circumference it pulls in a nasty manner on the lower half of the loop.

To avoid much crushing, perhaps make the bury as as close as possible to a semicircle, but just shy rather than just over to avoid the above? Given how dyneema seems to perform when kinked a sharp 180° around objects with a narrow diameter (the fibres must crush appallingly in the bend) I would guess crushing the line a bit by not making the semicircle quite complete would not weaken the arrangement greatly.

Its does produce a very neat result .

SWL
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Old 12-06-2016, 09:14   #26
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Re: My First Soft Shackle

Check out the July 2016 edition of Yachting Monthly for a detailed article on tying different dyneema loops and a review of those commercially available (in the UK). Good information from a reliable source
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Old 12-06-2016, 09:23   #27
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Re: My First Soft Shackle

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Check out the July 2016 edition of Yachting Monthly for a detailed article on tying different dyneema loops and a review of those commercially available (in the UK). Good information from a reliable source

Thanks, I will see if I can get hold of a copy.
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Old 12-06-2016, 09:28   #28
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Re: My First Soft Shackle

Estarzinger, have you tried incoporating a low friction ring into a soft shackle, or simply winding the soft shackle around the ring and securing it as you described as the third alternative in your post above?

It would sometimes be very handy to be able to move the ring around without unthreading the line going through it.

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Old 12-06-2016, 09:47   #29
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Re: My First Soft Shackle

Following on the soft shackle idea, a simple wind works very well. If a very short arrangement is needed, this seems a unique way of achieving it.

If a longer loop is needed, then it could be bound at 2:1 to stop the ring falling out.

Here I have just grabbed one of the early BB soft shackles I made and wound it once around the ring:




View of how the ring is gripped:

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Old 12-06-2016, 10:09   #30
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Re: My First Soft Shackle

Using the same old BB shackle, a cross over could also secure the ring.

2:1 for the throat does seem to enable the ring to pop out though. In practice does this simply not occur?



Edited to add: a cross over almost fixes the problem of strain on the throat. I will have a bit of a play tonight and see what I can make that does not put any unwanted stresses on the shackle.
A High Strength Shackle (no central bury) may work very well crossed over in this application.

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