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Dyneema shrouds?


DrWatson

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Use the new C20 or SK99, supposedly creep free. Coincidentally I'm making some test strops using C20 this morning. The plan is to load and hold and see what happens. It'll be interesting.

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All good. Tightened the Dyneema shrouds four times over about four months and they seem to stretch no further haven't had to adjust now for several months. No risk of corrosion or fatigue and should be obvious visually if they wear out. Touch wood. :thumbup:

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We have dyneema shrouds - both cap and inners which for a 46 ' cat take massive loads - no issues so far ( hope isn't a bad omen!) but think the key is to get good quality per stretched and take up the initial give when they will stretch a little... After that uv protection and anti chafe are key factors in them keeping their integrity ...

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Dynex or similar side rigging is fine on a multihull, but I wouldn't go near them on a mono, especially one with spreaders and without a mast base jacking system.

 

Sorry to be negative, but if it was the magic solution, everyone would be doing it. But they aren't because it isn't.

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The play with the C20 (which will probably be called DM20 in the market) has been very interesting. It is a lot different then the usual SK's.

 

Had a strop on the test bed and found it has bugger all initial stretch, a lot less than the SK's, and the creep is all but gone. I like it so far and are picking this to kill off Vectran, or a good amount of it. Had a strop loaded to 1000kg and it moved a couple of mm. Then loaded it to 2000kg and it moved a huge 3mm more. held the 2000kg load and it moved 2mm. That 2mm could easily have just been play in the rams so we are going to hang a static 2000kg under a strop for the weekend. At 6%% BL, if their creep we will see something come Monday.

 

What's even better is they sent some to a large well known brand name in NZ to play with as well. Our splicing got 17% higher break loads than theirs .... I love it when that happens.

 

So the initial play has DM20 as good shite. More news as it comes to hand.

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Well that all seems to make sense.

 

"We're nearly there but not quite for us Monogamists", seems to be the take home. Back to the cold hard steel.

 

Sorry to be negative, but if it was the magic solution, everyone would be doing it. But they aren't because it isn't.

 

Yup, that's pretty much it (not taken as negative).

 

By the way, what did you use on Wild Thing?

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For me, the best way to compare a rigging product is a comparison with diameter and tested load being the constants. Stretch could be measured in mm per M at that given load. That way it’s very easy to compare a new development against the current products. To make a stretchy fibre perform better, you need to increase diameter, which in turn increases the weight and windage. Un covered fibre rigging also gets heavy when wet. So the gains start to diminish.

 

More stretch equals a greater loss in headstay tension (more luff sag) which means the boat can’t point as high up wind. For a multi this is not such a problem, but in a mono it’s a big consideration as upwind performance is a much more heavily weighted point of sail.

 

KM, would be really interesting to see the fibre numbers from your testing added to the table below.

 

Carbon is really the benchmark on all levels at the moment. Only downfall is cost. But its lifespan is exceptional.

 

I used Dyform on Wild Thing because I was on a budget. But I spend 50% more to have high modulus carbon in the mast tube. That gave me a greater $/kg weight saving than going for composite rigging.

Rigging comp..JPG

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Don't forget peeling a bit of 'Dynex' of a roll in Burnsco and turning it into a shroud is 100% No8 bodgy fibre rigging. The Pros used very different stuff altogether. With WT's mob it's carbon a lot of it and I must say done in a very damn clever way.

 

And as a FYI, we just spliced some 'Dynex' brand dyneema and it's changed from what it was, changed a lot. Why we don't know. Interestingly they are now following what most of the others do in the way of treatments and construction. No idea if that has anything to do with it though.

 

I'll suss for you WT. I do think this DM20 is far better for shrouds than the SK60's and 75's being used, have been but is it up good enough to use on our monos yet? I'm replacing my old rod rigging with new rod rigging if that give you any idea of my thinking on it.

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Dynex isn't a fibre, it's only a brand name.

 

Stop calling Dyneema fibre Dynex. Some of the worlds engineers can't handle thinking for themselves so write Dynex and when you go to change it to what the actual rope is they want it creates all sorts of unnecessary drama. That very thing just happened with our Navy. As someone wrote 'dynex' not dyneema in the Specifications for the new land frigate and dynex didn't make what they needed it created a massive amount of paperwork, a 2 week delay while engineer's re did everything and probably added 0.5 of a degree to the Earth temperature. None of that needed to happen.

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UHMWPE fibre then if you want to fight about it ;-)
Yo have a deal :lol:

 

I'd just got another bit of paper from the large US military supply company, due to using the wrong name, about an hour before your post so I was in a grumpy at more paperwork just due to one name used wrong, at a time when I'm drowning in paper and slack arsed boaties.

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I've had Dynex Dux as my sidestays and lower stays for four years now. Yes they did stretch a little for the first few months, but then so does wire. Other than that I've been very pleased with them.

The real cruising advantage on a multihull is the slack lee shroud isn't beating the snot out of the back of the mainsail. Wire does this, and wears through the batten pockets very quickly...

I had Vectran lowers before that, and was happy with them too.

I cycled out all of the original standing rigging after 9 years. It seems cheap insurance on not having a failure.

I would consider a composite forestay next time (current one is wire). I run (Wichard) hanks up my vectran inner forestay and haven't had a chaff issue.

When it comes to change again I'm sure there will be another solution...

20141206_172426-1.jpg

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