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Dyneema for guy ropes

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Though not in the sailing community, I am interested in your experience with Dyneema rope:  I am considering this material for use as guy ropes for military antenna masts.  Particularly long term reliability, and UV resistance ( for rope without a protective polyester cover ) in adverse environmental conditions.  Your comments and experience most welcome.

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Long ago & far away at a rigging shop we tried to quote synthetic for radio towers in Hawaii. What stopped us was the requirement for a constant, set tension. Synthetic at that time could not satisfy the requirements.

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Are those masts permanent or temporary?  Dyneema guy ropes would need regular replacement if permanent.  If in a tropical environment with significant UV exposure, they may need frequent replacement.   It would depend somewhat on the design loadings. 

In addition, dyneema guy ropes would require re-tensioning several times after installation due to stretch.  

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Very light and soft on the hands when not tensioned. Allegedly good UV and abrasion resistance and it floats.

It will creep a lot and as Dash34  says, will need retensioning a number of times if a permanent installation. I am about to retention my standing rigging for the third time.....

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Fuck off and show us some  tits 

 

This is first time I have done this feels strange but WTF 

 

Tits please

 

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4 hours ago, longy said:

Long ago & far away at a rigging shop we tried to quote synthetic for radio towers in Hawaii. What stopped us was the requirement for a constant, set tension. Synthetic at that time could not satisfy the requirements.

I have heard people asking rigging shops about precise splices for towers in the military before. In fact a very large order large order. However, it wasn't the rope that was the issue as heat set dyneema is designed for very low stretch applications, it was the fact that no matter how much you try, the splice itself will set.   Then asking a rigger doing manual work to nail precise measurements for 100 splices will never be perfect.  In fact, the rigging shop didn't even want to do it as they would get blamed when things were off by millimeters. 

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The line has to be tensioned after the splices are done and some shops even heat temper them as they do the aftersplice tensioning.

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You can avoid the creep issues of Dyneema if you oversize the line. It should never see the loads required for it to creep. The UV issue is more important. You really need a cover/jacket.

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13 minutes ago, CaptainAhab said:

You can avoid the creep issues of Dyneema if you oversize the line. It should never see the loads required for it to creep. The UV issue is more important. You really need a cover/jacket.

Totally agree with oversizing and covers for the line if windage isn’t important.

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I'm not sure why you would consider anything other than good steel wire, properly terminated of course, for this application.  It's all so well established and documented.  And reliable over long periods if properly prepared on day one.

What is the weight advantage to go with anything else?

Mystified. 

Unless you're looking for temporary masts, up and down, in which case sure, exotics will work well, since you have the onsite maintenance crew to adjust tensions.

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Unless it's metallic, the Sun will win.   So go PBO!

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On 4/27/2018 at 12:43 PM, savoir said:

There are industrial ropes which might suit your needs and don't creep.  Take a look at Samson Tech 12 made from Technora and Validator 12 made from Vectran.

http://samsonrope.com/Pages/ProductList.aspx?CategoryType=2&Category=Stage, Event, and Special Effects Rigging

You are mistaken.  All lines creep.  Some heat-stretch Dyneema (like DynIce Dux (the old Dynex Dux)) and Vectran creep less.  The rate of creep is highly dependent on the tension/breaking strength rratio.  

 

That being said - Properly dimensioned, Dyneema will last a long time - especially with proper coating and a cover.  The minimal creep can be managed.

The Validator (Vectran) is a poor choice for that application.  While it has low (but not 0) creep it does really not like long term UV so will break down far faster than Dyneema

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On 4/27/2018 at 10:23 PM, IMR said:

Pbo 

Probably the absolute worst choice as both UV and Humidity break down PBO and the failures are sudden

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Contact John Franta from Colligo Marine. He will give you honest answers and can help for sure.

 

Thor

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