So how Strong are Soft Shackles?

[estarzinger]

I have just tested two at 194% and 195% of the line strength. I worked particularly carefully at getting every thing the same/right length and milking everything tight. The practical maximum for these (without taking multiple passes before closing the diamond/noose) has to be somewhere around 200% (400% cut in half by the diamond knot). It does seem possible to get very close to that just by being careful.

By the way, I also tested whether the diamond knot position in relation to the pin makes any difference. There was a theory that the diamond should be in the middle of a span rather than against a pin. But it does not seem to make any difference.

[Stumble]

As an aside, is there some way we can contribute to this? Making and breaking stuff is fun, but I know it gets expensive.

[estarzinger]

Hey stumble, have you ever spliced NER WR2? If so what did you do? It's really stiff stuff. It looks to me like the only real option is to strip back the cover and do a core only splice.

[Weyalan]

Evans,
If you are a patient man (and I assume, based on what I have read here, that you are), you might want to make a few shackles and leave them out in the sun for 3, 6 and 12 months and, possibly 2, 3, 4 and 5 years. Maybe have another set that you do the same, but also repeatedly submerge in salt water for some proportion of that time.

I'm only partly kidding, too. At the risk of stating the obvious and teaching grandpa to suck eggs...Rope, like anything, ages... UV, temperature (high and low), exposure to aggressive environment all impact on mechanical properties. We have a Houndsfield Testing rig here. Many years ago I did a bunch of testing, and analysing of the data on a whole bunch of "exotic" sail cloth materials that had been "aged" in various ways and for various lengths of time. It was amazing how much the strength of the cloths were compromised by age and environment. The paper I wrote was, from memory, delivered by Bob Fraser (Fraser Sails)... not sure I merited a mention, heh.

[Stumble]

Originally Posted by estarzinger

Hey stumble, have you ever spliced NER WR2? If so what did you do? It's really stiff stuff. It looks to me like the only real option is to strip back the cover and do a core only splice.

I haven't played with the WR2, and frankly I don't see the point. You loose a lot of strength to get the cover, and I think either adding a cover, using a bigger line in the first place, or adding the dyneema cover is a better plan than this stuff.

That being said as I understand it the recommend a brummel on the core, and whipping the cover back in place. Which to me again misses the point of having a covered line, since you can't cover all of it with this method. I think using endura and a core-to-core splice would be a better idea, even if it is a bit weaker for the same size, but then it comes in more than two sizes.

[estarzinger]

Originally Posted by Weyalan

Evans,
At the risk of stating the obvious and teaching grandpa to suck eggs...Rope, like anything, ages... UV, temperature (high and low), exposure to aggressive environment all impact on mechanical properties. . . . . . It was amazing how much the strength of the cloths were compromised by age and environment.

I actually have some pretty good data on UV aging of Dyneema single braid line, and it is major . . . let's just round it and say 30% strength loss in 24 months.

Originally Posted by Stumble

I haven't played with the WR2, and frankly I don't see the point. You loose a lot of strength to get the cover, and I think either adding a cover, using a bigger line in the first place, or adding the dyneema cover is a better plan than this stuff.

That being said as I understand it the recommend a brummel on the core, and whipping the cover back in place. Which to me again misses the point of having a covered line, since you can't cover all of it with this method. I think using endura and a core-to-core splice would be a better idea, even if it is a bit weaker for the same size, but then it comes in more than two sizes.

Ok, thanks.

I agree about the WR2. But I was interested in testing it, to prove or disprove my opinion.

Frankly I think they should pull the 3mm size off the market, as "Not fit for purpose", because it does not meet the ISAF minimum core size requirement for any size vessel.

[mikereed100]

Originally Posted by estarzinger

I actually have some pretty good data on UV aging of Dyneema single braid line, and it is major . . . let's just round it and say 30% strength loss in 24 months.

Have you had a chance to test UV degradation in different diameter Dyneema?
I would suspect that UV penetration of single braid is limited as the outer fibers would absorb most of the radiation, forming a protective barrier for the inner fibers. As line diameter increases, the ratio of damaged to undamaged fibers would be expected to decrease, as would the percentage of strength lost. On the other hand, I may be wrong about the outer fibers forming a UV barrier, in which case degradation could be expected to be roughly the same for all diameters.

[estarzinger]

Originally Posted by mikereed100

Have you had a chance to test UV degradation in different diameter Dyneema?
I would suspect that UV penetration of single braid is limited as the outer fibers would absorb most of the radiation, forming a protective barrier for the inner fibers. As line diameter increases, the ratio of damaged to undamaged fibers would be expected to decrease, as would the percentage of strength lost. On the other hand, I may be wrong about the outer fibers forming a UV barrier, in which case degradation could be expected to be roughly the same for all diameters.

I have not done such testing myself, but the rope companies have, and they tell me that generally the way single braid is constructed that most all the fibers come to the surface and get UV damaged, no matter what the size it. They tell me the damage curve may be very slightly different but that there is still/always significant UV damage to strength no matter the size.

Single braid, almost by definition, does not have a 'core' of fibers shielded from uv by a cover, as double braid lines have. But our own thinwater did a test (described in the load testing thread) which suggested that even with a double braid line, the Dacron cover lets thru a lot of UV to still damage the core.

[Stumble]

Originally Posted by estarzinger

Ok, thanks.

I agree about the WR2. But I was interested in testing it, to prove or disprove my opinion.

Frankly I think they should pull the 3mm size off the market, as "Not fit for purpose", because it does not meet the ISAF minimum core size requirement for any size vessel.

I really think this stuff is a solution looking for a problem. But I certainly agree with you about the 3mm. Frankly I am of the opinion that anything sold for boats should meet the ORC rules period. If for nothing else but liability protection.

I have a long history of screaming at riggers about being willing to install coated wire lifelines. Not only are they dangerous, but the potential legal liability for a professional being willing to install them is huge. I have flat out told my clients that if they get used over them they will almost certainly loose.