If I had dollar for everytime this happened I would probably be a rich man. Most riggers know alot about how to rig a boat but not much about material science, since it is not their area of expertise. A big part of my job has been to educate the riggers on the materail properties of Dynex Dux or Dyneema, in general.
Dynex Dux is Ultra High Molecular Weight Polyethylene, which does, as most materials do (even steel), creep. If you understand this property it is easy to design around. See the creep charts on our website at Dynex Dux | Colligo Synthetic Systems | Colligo Marine. as you will see from the charts it is very easy to size this line so as you don't have any creep issues. We generally size the line for 0.1 inches of creep per year, 1 inch in 10 years. For creep we use the pretension that the standing rigging is set to as the dynamic loads are not there for long enough time to induce creep.
For sailboat applications, Dux really has 2 limiting factors, creep and stretch. This is how we successfully size it for standing rigging. If sized this way, it is genarally 2-5 itmes stronger than the steel you replace and only slightly larger iin diameter than the steel wire was, but 1/4 to 1/5 the wieght of the steel. See the stretch information on the same page on our site.
In general, use 5 mm dux to replace 3/16 inch (4.8mm) wire, 7 mm dux for 1/4 (6.4mm) wire, etc.
We have successfully rigged several boats with short travel turnbuckles that wouldn't work if there were creep problems, although most people choose to use lashings for their simplicity.
Dynex Dux is a great product for standing rigging. Its greatest benefit is its low cost and it's do it yourself capabilities.
John Franta, Colligo Marine
My apologies if I'm repeating another thread but I haven't been able to find one. I need to replace all the standing rigging and running on my Folkboat. I've been researching using Dynex Dux rather than wire and it looks the business to me. Lighter, stronger, neater, you can do most of it yourself, no more stainless steel shroud fittings to corrode and fail, and no more brass hanks to take skin off the knuckles. It looked like a no brainer to me. The only negative I could think of would be re-sale value. If I were to sell the yacht, perhaps buyers might shy away from such exotic rigging until it became more fashionable.
Anyway, I chat today with two of the larger and well respected riggers in my home port and both advised against it strongly.
The first guy advised against it because of chafe and UV degradation. I didn't argue with him because he is the rigger and I'm just the googler (my Doctor hates me). But the literature I've read is contrary to this. From what I've read, UV protection is 5 years, but its only 5 years simply because this stuff hasn't been about for any longer than 5 years, so its possible UV protection is a lot longer than 5 years. I'm not sure about the chaffe issue but they use this stuff on fishing trawlers.
The second rigger advised against it because of creep. He said you just have to keep tightening your shrouds all the time. I asked him if it doesn't stabalize after a period and he said no, the creep just keeps happening and doesn't stop. This surprised me.
Í'm wondering if the concerns of the two riggers are simply because they are not "early adopters" (to use marketing parlance) or if their concerns are legitimate? I'd be interested in feedback from folk regarding the amount of creep they've experienced after installing Dynex Dux standing rigging.