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Old 06-10-2021, 00:05   #1
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Heat Set Dyneema

I am not so much concerned with creep as strength. From the specs listed, the heat set rope has the same strength per cost nearly, but a smaller diameter.

The smaller diameter is desirable for rigging for reduced windage. Am I missing something obvious? Forgetting stretch, isn't this enough reason to use heat set dyneema for rigging?

In any case, another issue is size. There is only 7mm and 9mm available and I prefer 8mm (strength of 7/16" amsteel) but cannot find it anywhere. The 7mm is stronger than ever and is probably fine at least if new. The 9mm could maybe work but cost 70% more (almost double) with only 25% stronger. Any advice on sources of heat set dyneema for price comparison for size?

My understanding is that over time the outer 1mm loses strength, so after few years a 7mm is as strong as 5mm and maintains this strength for many more years. So it would still be stronger than new stainless wire rope for much longer.

In any case, has anyone success with shrink wrap? This would add a very small thickness, but maybe improve windage over 12 braid (smoother??) no idea about it, but the overall thickness increase not much. This would give some protection from chafe and UV. Any suggestions for a specific shrink wrap? I imagine black shrink wrap blocks UV however, the "critical temperature" of dyneema is between 55C and 80C. Assuming it is only 55C, then black shrink wrap could in "theory" achieve this in hot sunny conditions?? Could there be two layers of shrink wrap, one for UV, another white one to stay cooler?? Or can a white shrink wrap actually block UV? Or could a UV paint be used first, then white shrink wrap?
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Old 06-10-2021, 00:22   #2
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Re: Heat Set Dyneema

The key factor for dimensioning dyneema rigging is not the breaking strength but the elasticity.
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Old 06-10-2021, 00:52   #3
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Re: Heat Set Dyneema

Quote:
Originally Posted by noreen View Post
The key factor for dimensioning dyneema rigging is not the breaking strength but the elasticity.
This is more to do with regular dyneema not heat set and more of a consideration if you use turnbuckles.

After 10 years of UV, the recommended sizes are only marginally (20% or so) stronger than recommended steel cable.
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Old 06-10-2021, 03:34   #4
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Re: Heat Set Dyneema

There are lots of sources of heat-set dyneema, and lots of grades of it as well.
Marlow has a complete selection of heat set (MAX, they call it), in SK78, SK99, and DM20. They also have it in every mm size, and even some half sizes.
Maffioli makes it as well; Hampidjan (distributed in the US by Colligo Marine); New England Ropes--it's everywhere.
As for sun, the best thing to do is slide a dyneema cover over it, then paint that with Armourcoat or Maxijacket. It adds cost and thickness, but less thickness than heat-shrink tubing.
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Old 06-10-2021, 04:13   #5
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Re: Heat Set Dyneema

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Originally Posted by seandepagnier View Post
This is more to do with regular dyneema not heat set and more of a consideration if you use turnbuckles.

After 10 years of UV, the recommended sizes are only marginally (20% or so) stronger than recommended steel cable.
I have the opinion that it has to do with how much the mast will bend onder load how much the jib will sag. The elastic elongation of SK78 HS is almost three times that of steanless steel 316 1x19
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Old 06-10-2021, 15:55   #6
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Re: Heat Set Dyneema

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Originally Posted by Benz View Post
There are lots of sources of heat-set dyneema, and lots of grades of it as well.
Marlow has a complete selection of heat set (MAX, they call it), in SK78, SK99, and DM20. They also have it in every mm size, and even some half sizes.
Maffioli makes it as well; Hampidjan (distributed in the US by Colligo Marine); New England Ropes--it's everywhere.
Thanks but I cannot actually find many good sources.

The marlow I find only very high price.

I cannot find maffioli

This leaves only hampidjan (colligo) and new england ropes which both only offer 7mm and 9mm, but no 8mm. Do you have any good sources for 8mm that is cheap.

Quote:
As for sun, the best thing to do is slide a dyneema cover over it, then paint that with Armourcoat or Maxijacket. It adds cost and thickness, but less thickness than heat-shrink tubing.
Are you sure? Heat shrink is a lot thinner. The one I have here is about 0.1mm, so would add only .2mm to the diameter.
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Old 07-10-2021, 03:22   #7
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Re: Heat Set Dyneema

Quote:
Originally Posted by seandepagnier View Post
Thanks but I cannot actually find many good sources.

The marlow I find only very high price.

I cannot find maffioli

This leaves only hampidjan (colligo) and new england ropes which both only offer 7mm and 9mm, but no 8mm. Do you have any good sources for 8mm that is cheap.


Are you sure? Heat shrink is a lot thinner. The one I have here is about 0.1mm, so would add only .2mm to the diameter.
While Dyneema cover does have variety of thickness across brands (Maffioli being thinnest and Cousin the thickest I regularly use), it would not add much more than 1mm to the diameter, and certainly be a lot more durable than .1mm shrinkwrap.

As far as cheap, I'm afraid not. Marlow and Maffioli are both higher-end products, and their price reflects that.
Kaya Ropes has a warehouse in Boca Raton, and they carry Dyneema in 8mm, both in SK78 and SK99. It'd be worth a call to see if they have heat-set. I'll bet they're cheaper than Marlow, though I don't know the quality of their ropes (they're sending me some samples to see how they splice and wear, but I haven't received them yet.)
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Old 07-10-2021, 03:58   #8
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Re: Heat Set Dyneema

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Originally Posted by seandepagnier View Post
isn't this enough reason to use heat set dyneema for rigging?

sure, for rigging, heat set (or one of the new variants like dm20) is technically preferred. . . except for cost.

My understanding is that over time the outer 1mm loses strength, so after few years a 7mm is as strong as 5mm and maintains this strength for many more years.

This depends ALOT on the specific line - what sort of coatings it has and its braiding, and also on the usage (what sort of UV intensity it is in and how much rubbing/chafe there is). The testing results range suggests that the UV might penetrate 1mm (a dsm test on smallish lines) or 4mm (a samson test on bigger lines), and you might have 50% reduction in 2 years or in 8 years - all depending on line and usage factors). Something to realize with 12 strand single braid is that all the fibers come to the surface and get cooked somewhere along the length of the line.

In any case, has anyone success with shrink wrap? I imagine black shrink wrap blocks UV however, the "critical temperature" of dyneema is between 55C and 80C. Assuming it is only 55C, then black shrink wrap could in "theory" achieve this in hot sunny conditions?? Could there be two layers of shrink wrap, one for UV, another white one to stay cooler?? Or can a white shrink wrap actually block UV? Or could a UV paint be used first, then white shrink wrap?

The current 'best' UV protection approach is to dip/coat the line with (black) plastic - see like this from southern spars:

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Hall Spars did used to use black shrink film as a cover - it was a relatively narrow tape wound up the line (while the line was stretched out) and then 'shrunk'. They did in some cases put on two wraps. It was quite thin and light but not very resistant to chafe.

Benz's solution (Dyneema cover plus coating) has the advantage of providing chafe protection in addition to UV - but is a bit thicker and more expensive.

Both the southern spars and the harken approaches were used in the tropics with 'black' covers and in practice, there was no heat-related strength loss noted.

Unfortunately, I can't help you with 'cheap' sourcing of heat-set product - it is an innately expensive product and if you find 'cheap' I would be a bit suspect about quality (and would want to see some independent testing results).





.............
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Old 08-10-2021, 21:40   #9
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Re: Heat Set Dyneema

Thanks for all the interesting feedback. I think the coatings designed for this rope are something I want to try.

I am back to choosing either 7mm or 9mm because the new england ropes hsr options are these. the 8mm options cost much more and the specs are not really better.

I feel like 7mm is strong enough being more than 2x the strength of the cable it is replacing (1/4"). I have read that generally on multihulls the "stretch" (not creep) is not very important, and it was mentioned here that the rope is sized for this. Is it to mimimize shock loading? I still don't really think it is very important anyway. Especially without diamond stays (I have no spreaders even)

Am I missing anything obvious? The 7mm is much cheaper, and if I protect it with some kind of coating or perhaps a spectra sheath, it should do well? Or is there a compelling reason why 9mm would do better? I am concerned by the added windage at that point decreasing performance.
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Old 09-10-2021, 00:29   #10
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Re: Heat Set Dyneema

Someone from Colligo once explained me that for standing rigging, you size the Dynex Dux for creep, not for strength.

What has changed?
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Old 09-10-2021, 07:09   #11
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Re: Heat Set Dyneema

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Originally Posted by s/v Jedi View Post
size the Dynex Dux for creep, not for strength.
J,

There are 'dyneema' fibers today with (essentially) zero creep - much lower than dux. But that is not what the op is talking about.

I don't know much about multi-hull rigging, but I could imagine the design parameters are different than a mono - wider shroud base, probably more movement in the staying base, rotating masts stepped on ball sockets - I could imagine they are less sensitive to shroud creep. But idk.
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Old 09-10-2021, 08:21   #12
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Re: Heat Set Dyneema

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Originally Posted by s/v Jedi View Post
Someone from Colligo once explained me that for standing rigging, you size the Dynex Dux for creep, not for strength.

What has changed?
That Colligo sizes not for creep but for elastic stretch. Creep is something that takes years. Not very interesting for standing rigging. The life expectancy of dyneema standing rigging is not that long that creep will be the keyfactor. That's the reason Colligo uses SK75.
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Old 09-10-2021, 13:25   #13
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Re: Heat Set Dyneema

Quote:
Originally Posted by noreen View Post
That Colligo sizes not for creep but for elastic stretch. Creep is something that takes years. Not very interesting for standing rigging. The life expectancy of dyneema standing rigging is not that long that creep will be the keyfactor. That's the reason Colligo uses SK75.
Really? I went back to their website and found that you’re wrong because they still state the same as they told me years ago, see attached image…
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Old 09-10-2021, 13:54   #14
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Re: Heat Set Dyneema

If you fully cover the synthetic like in the pictures above, how do you check it ?
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Old 09-10-2021, 16:51   #15
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Re: Heat Set Dyneema

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Originally Posted by s/v Jedi View Post
because they still state the same as they told me years ago
guys - you are both (sort of) right - they in fact have dual specs for sizing:

(a) similar stretch to the wire it replaces ("Dux is sized according to how much it stretches...We always size our rigging to have the same or less stretch then the steel (rod or wire) that it replaces.")

(b) "Our creep target is 0.1” of creep pre year or less."






https://www.colligomarine.com/askcol...ning-a-dux-rig
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