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Simi 60 · 24-02-2020, 19:38

Following on from this post....

8mm spectra goes BANG. Sun degradation?
https://www.cruisersforum.com/forums...on-230528.html

And comment being made that tight radius is bad with dyneema/spectra, how does soft shackle for anchoring work????????

Most of you would use 8, 10 and 13mm chain so that's a pretty bloody tight radius.
I'm sure 1 read somewhere that 5x is the minimum.

thinwater · 24-02-2020, 19:44

Quote:

Originally Posted by Simi 60

Following on from this post....

8mm spectra goes BANG. Sun degradation?
https://www.cruisersforum.com/forums...on-230528.html

And comment being made that tight radius is bad with dyneema/spectra, how does soft shackle for anchoring work????????

Most of you would use 8, 10 and 13mm chain so that's a pretty bloody tight radius.
I'm sure 1 read somewhere that 5x is the minimum.

Around a pulley and around an eye are different.

The manufacture says 1:1 for and eye. For a soft shackle, you will lose ~ 50% vs. a larger radius... but the strength of soft shackles is usually rated on 1:1 pins, so no correction is needed.

Tillsbury · 24-02-2020, 19:55

Don't forget that a soft shackle is using at least two lines, and if you're doing that in 8mm Dyneema you can afford an awful lot of reduction in strength with a 1:1 radius eye or bit of chain.

Simi 60 · 24-02-2020, 20:16

Quote:

Originally Posted by Tillsbury

Don't forget that a soft shackle is using at least two lines, and if you're doing that in 8mm Dyneema you can afford an awful lot of reduction in strength with a 1:1 radius eye or bit of chain.

Its only a single line where it goes around the stopper knot which is also a tight radius.

Tillsbury · 24-02-2020, 22:52

Quote:

Originally Posted by Simi 60

Its only a single line where it goes around the stopper knot which is also a tight radius.

The radius there is more than 1:1 as there are four lines coming out of the button. But you can double the breaking strength for two lines -- the line runs around the button in a loop so carries the load across both lines.

Paul L · 25-02-2020, 03:18

I've used a soft shackle to connect my snubber. I replace them every few years, as they are easy to make. In one case I had a fairly young 5/8in brait snubber snap. The soft shackle looked fine.

kas_1611 · 25-02-2020, 09:43

And stainless steel doesn't go BANG! ???

At least when a soft shackles goes it doesn't fire shrapnel everywhere like the steel one on my outhaul did when it went.

nortonscove · 25-02-2020, 09:59

Tried a couple soft shackles as extra tie up lines for a couple storms last fall. One was 1/4" and the other 3/8". They were rigged to take the majority of the loads from the regular lines just as an experiment and to ease my mind when used in the future. Two storms of more than 130 kilometre winds and they were in exceptional shape with no noticeable degradation of the shackle. Most impressive given they were onto my aluminum toerail.

EmeraldCoastSailor · 25-02-2020, 10:03

Quote:

Originally Posted by Paul L

I've used a soft shackle to connect my snubber. I replace them every few years, as they are easy to make. In one case I had a fairly young 5/8in brait snubber snap. The soft shackle looked fine.

Did the soft shackle chafe the braid?

thinwater · 25-02-2020, 10:03

An engineer's answer to this is "test one." Which they have done on 1:1 pins. So long as it is as strong as the snubber, the wear and fatigue life will be longer than the snubber.

I think that is all you really need to know. Experience backs it up (I've never heard of one failing in this application). Engineers like experience-based standards; they include all the factors you would otherwise argue over. They work.

Simi 60 · 25-02-2020, 10:57

Quote:

Originally Posted by Tillsbury

The radius there is more than 1:1 as there are four lines coming out of the button. But you can double the breaking strength for two lines -- the line runs around the button in a loop so carries the load across both lines.

Quote:

Originally Posted by thinwater

An engineer's answer to this is "test one." Which they have done on 1:1 pins. So long as it is as strong as the snubber, the wear and fatigue life will be longer than the snubber.

I think that is all you really need to know. Experience backs it up (I've never heard of one failing in this application). Engineers like experience-based standards; they include all the factors you would otherwise argue over. They work.

Thanks.
I guess I am a bit put off after having that spectra dinghy lift rope break without really knowing why.

And I only very recently starting using a soft shackle on my storm snubber to chain connection so am understandably, in my eyes, now a bit uneasy about it.

alansmith · 25-02-2020, 12:01

Simi, but didn’t you say that line was older than dirt?

Tillsbury · 25-02-2020, 12:10

Quote:

Originally Posted by Simi 60

Thanks.
I guess I am a bit put off after having that spectra dinghy lift rope break without really knowing why.

And I only very recently starting using a soft shackle on my storm snubber to chain connection so am understandably, in my eyes, now a bit uneasy about it.

The clue is in the original post:

"8mm spectra was the inner core from a 10mm halyard off of a previous vessel we had. It was probably 15 years old but was in good condition when replaced after a couple of years and had only had the outer case removed and put into service as a winch rope 3 years ago."

I wouldn't use the inner core from any rope for more than a year -- it's just not capable of putting up with UV, it's not designed to. The stuff you make soft shackles with is UV treated. It's also usually not 15 years old when you start using it. Was it really 8mm? The inside of a 10mm halyard isn't usually 8mm it's more like 5-6mm.

New 8mm single-braid Dyneema is unbelievably strong, way over what's required for an anchor snubber. It's not far from being able to hang your boat up with a good soft shackle made from it (note: not a recommended strategy). When it starts looking pale and frothy at the edges it it time to replace it.