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Old 25-07-2015, 17:10   #91
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Re: DIY Standing Rigging

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Originally Posted by Dave852 View Post
It's sized for creep first always as this dictates the size as the previous poster and I have previously stated.


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Old 25-07-2015, 17:37   #92
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Re: DIY Standing Rigging

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Originally Posted by poiu View Post
I promise you they didn't with my boat. I got out the old email to check first.

Ok I believe you, but it's well documented that creep is the criteria to design around. It's great stuff and I am sure you will be fine.


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Old 30-07-2015, 08:13   #93
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Re: DIY Standing Rigging

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Originally Posted by mikereed100 View Post
This image, shamelessly lifted form Evans Starzinger's article on load testing ( Load testing) shows that 10 years on dyneema single braid will have lost between 40 and 60% of it's tensile strength. When used in rigging, dyneema is sized for creep, not for strength, with the result that it will have a far higher tensile strength than SS rigging in the same application, which will allow for some loss of strength due to UV damage. For example, my cap shrouds are 14mm 1x19 stainless with a breaking strength of roughly 33,000 lbs. My dyneema deadeyes have a breaking strength of 80,000 lbs. After 10 years in the sun, I expect the deadeyes will have a breaking strength of between 32,000 and 56,0000 lbs, still higher than that of the wire, although I will replace them long before that.



Otherwise, if there is chafe or a strand is broken, it will be obvious, whereas with wire one could easily have a microscopic crack in a swage, or broken wires inside the outer layer and not know it. I believe that is what BPW means by "more noticeable failure modes".





(

Thanks, you saved me a bunch of typing.

It's also worth noting that the wire manufacturers only recommend using wire for 8-10 years. I know many people go far longer, but in a boat seeing heavy use like ours we would be replacing wire about as often as the Dux and it would cost more each time.



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Old 30-07-2015, 08:34   #94
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Re: DIY Standing Rigging

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Originally Posted by poiu View Post
Colligo size for stretch to match the stainless it is replacing, not creep. It still results in oversized rigging though from a load perspective. I expect creep will be a factor in limiting life with the current Dux product, especially if the rig is pre-tensioned a fair bit. If the new Dyneema Max were used where creep is hugely less then there is little reason why Dyneema should not last even longer than 10 years.
I'm afraid you are right. From the Colligo website concerning replacing wire with Dux:

Dux is "Sized for equivalent stretch so you will get the same performance. With our sizing methods, you will get virtually no creep."
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Old 30-07-2015, 09:45   #95
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DIY Standing Rigging

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Originally Posted by mikereed100 View Post
I'm afraid you are right. From the Colligo website concerning replacing wire with Dux:



Dux is "Sized for equivalent stretch so you will get the same performance. With our sizing methods, you will get virtually no creep."

From the Colligo website:
I have used Dux on my boat and have seen considerable creep which seemed to settle down after some sailing time. Doesnít Dynex Dux creep too much for use on a boat?
Invariably, what we have seen here is that people will splice the line and then put it directly into use. As the line is loaded the upset braid in the splice will continue to stretch out and reset. This results in elongation of the line which can be mislabeled as Creep or even stretch. Once the line has been stretched to its peak load, the elongation will stop. This is why we pre-stretch all of our standing rigging systems, to reset the braid after splicing.
Dynex Dux will creep but the loads need to be substantial and constant. "We size the line for creep" based on the experimentally determined creep tables that we have and the constant loads the line will see, not the dynamic loads. Some of this data can be seen on our website. It is very easy to size the line such that you will see a minimum of creep. 9 mm dux with a constant load of 1200 lbs on it (substantially higher than the pretension on most sailboats) will creep about 0.1 inches (2.5 mm) per year.

And from the Colligo website:
Why do I need to use 7 mm Dynex Dux that breaks at over 15,000 lbs-f to replace 1⁄4 inch wire that breaks at 8,000 lbs? Isnít that overly strong?
Dynex Dux UHMWPE line is a different material than steel and needs to be treated as such. It needs to be sized for stretch and creep. If this is done correctly it will perform the same or better than steel systems with much less weight. In addition, the extra breaking strength offers a better factor of safety. In most cases the line can chafe 1⁄2 way thru and still be stronger than the steel it replaces.



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Old 30-07-2015, 10:16   #96
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Re: DIY Standing Rigging

As a real world data point,

It took a few months to get all the construction and splice stretch out of our rig, but after that it has not been touched in the last year and almost 7000 miles at sea.

Strangely, it does seem a bit temperature sensitive. The rig would soften up a bit in cold weather when we where in chile. Not enough to matter but noticeable. I looked into the expansion rates of both the aluminum mast and the Dux and neither moves much with temp so I never did figure out exactly what was going on.



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Old 30-07-2015, 12:02   #97
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Re: DIY Standing Rigging

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Originally Posted by Bpw View Post
As a real world data point,

It took a few months to get all the construction and splice stretch out of our rig, but after that it has not been touched in the last year and almost 7000 miles at sea.

Strangely, it does seem a bit temperature sensitive. The rig would soften up a bit in cold weather when we where in chile. Not enough to matter but noticeable. I looked into the expansion rates of both the aluminum mast and the Dux and neither moves much with temp so I never did figure out exactly what was going on.



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The issue here is that all materials elongate due to temperature differences. Stainless and aluminum get just a tiny bit longer when the get warm, so a traditional rig will tend to breath just a touch. the difference is subtle but noticeable.

Dyneema (specifically Dux) actually shrinks when it gets warm and expands when it gets cold. So the mast and the rigging act in opposition to each other. So the difference is compounded instead of negated. As a practical issue it isn't much since over the size of a rig it amount to a few mm for a 40C change. But winter/summer changes may be noticeable.
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Old 30-07-2015, 12:26   #98
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Re: DIY Standing Rigging

Interesting, that makes more sense. We where dealing with big temp changes, warm summer weather to freezing down south and then back to the tropics.

Was never an issue, but noticeable. Last time we tightened the rig was in the beagle channel, it's nice and snug sitting in buzzards bay today!


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