Dyneema rope suitability

[Topcat47]

The failure of the dyneema winch rope is NOT a safety issue. There was so little energy stored in the rope at the point of failure that it did not "whip".

I once acquired a 60m length of "spent" 12 mm climbing line and for use on my boat. It was NOT a success as replacement sheets so was related to mooring lines, where it served me well for many years ( no need for snubbers). The problem was it's "stretchiness". I've had a glance (no more) at Marlow Ropes website and it's clear that modern dyneema ropes are quite different to the stuff I played around with in the '70s so I'll bow out of this right now. I'd certainly put the problem to Marlow these days and see what they had to say about it's use in this way.

 

[penberth3]

The failure of the dyneema winch rope is NOT a safety issue. There was so little energy stored in the rope at the point of failure that it did not "whip".......

What about the falling load - isn't that a safety issue?

 

[coveman]

We don't have a bow roller, we have a chute that is angled to let the chain slide in. Lifting the sinker with the riser 12mm or 16mm chain doesn't present a problem It flows in smoothly and there is no snatch. The extra strain on both rope and wire occurs when the ground chain is hauled into the chute. Ground chain can be up to 40mm the huge links make it very jerky.

I would still think a bow roller for the chain would be beneficial - pulling the chain 90 degrees or so without a roller must exert a lot more force than if one was present. An anchor wouldn't be pulled up in that way except perhaps a very light weight one! Pulling the ground chain aboard ( even a few links ) must snatch a lot and be more liable to snagging (causing extra snatch loading) than if hauled over a roller.
Yes, the wire has obviously worked well in the past in that you have not had any accidents yet, but times change, together with H&S legislation, and it would appear Dyneema would be much safer to operators, but professional advice needs to be obtained on the size of rope and winch that you require.
Wire can also have the habit of not winding evenly on a winch and being crushed by over riding loops if care is not taken to keep a steady tension on the wire when being retrieved into the winch. Once crushed the strength of the wire is reduced or individual wires can be broken leading to possible failure in the future. I would imagine this is much less of a problem with Dyneema.

 

[KREW2]

We had a roller in the past, but found the roll in smoother with the chute, maybe we needed a bigger roller.
To sum up; we all want the dyneema to work. To me one of the test team talks sense. He has been in contact with Marlow and is trying to locate the failed ropes so they can be sent to them for analysis to see why they failed.
I will post the results later on here for those who may be interested. Until then I think we can put this to bed