Heat Set Dyneema

[Breaking Waves]

Originally Posted by Dave_S

If you fully cover the synthetic like in the pictures above, how do you check it ?

pretty much the same way as usual - you can visually inspect for chafe/wear, there is absolutely minimal uv if the jacket is intact.

These are typically run at low %'s of their breaking strength so you would need an unusual loading to experience an 'overload but short of breaking' (that window is pretty small for dyneema). That sort of episode also usually leaves some sort of visual clue - lumps or stretched jacket.

Tension-tension fatigue means there will at some point be a replacement livecycle, but it is reasonably long and probably uv will visually eat the jacket before you get to it (unless it is running over a low D/d bend, which these should not be).

[Benz]

Originally Posted by seandepagnier

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.

If you're already at 2x the BL of the original spec wire with 7mm rope, why search further? Multihulls have a wider staying angle, and thus need less initial tension. I would replace 1/4" wire with 7mm any day. Creep only happens when the line is loaded a certain percentage of it's BL, and it happens with agonizing slowness. If you splice it so your turnbuckles are pretty far out initially, it'll take a while before you're tuned it enough times to bottom out. If you're using lashings, then just give yourself an extra-long lashing and never think about it again.
The most important thing is to pre-tension the stay after splicing it, to take the constructional stretch out of the splice. You can so this with a come-along and two trees. Set up a cascade so your come-along pull is doubled, crank it a s tight as you can, and give it a crank every hour or so till there's no more coming out of it.

[seandepagnier]

Yes on my last boat I had 7mm dux but that boat had significantly lower loads (in theory)

The strength is not an issue, but other properties like how much it springs potentially could matter... so that is why I am asking to make sure I am not missing something critical. I would feel slightly more confident with 8mm, but I can't find it for a reasonable price, so the alternative is to coat and/or cover 7mm.

Anyway, the splices did cause the stays to get about 4 inches longer. I think you can do this just by sailing the boat hard against the wind... that s what I did anyway (beating up the sea of cortez) but I guess it is nice to try to do it beforehand.

I did bottom out a turnbuckle.. I ended put putting some off cuts inside one of the stay to make it shorter again in a tapered way..

I will use lashings this time to avoid turnbuckles, I think more reliable and less weight too.

[Benz]

Originally Posted by seandepagnier

Yes on my last boat I had 7mm dux but that boat had significantly lower loads (in theory)

The strength is not an issue, but other properties like how much it springs potentially could matter... so that is why I am asking to make sure I am not missing something critical. I would feel slightly more confident with 8mm, but I can't find it for a reasonable price, so the alternative is to coat and/or cover 7mm.

Anyway, the splices did cause the stays to get about 4 inches longer. I think you can do this just by sailing the boat hard against the wind... that s what I did anyway (beating up the sea of cortez) but I guess it is nice to try to do it beforehand.

I did bottom out a turnbuckle.. I ended put putting some off cuts inside one of the stay to make it shorter again in a tapered way..

I will use lashings this time to avoid turnbuckles, I think more reliable and less weight too.

You need not worry about spring--that is not an issue with heat-set. With lashings, just make them 18" or so long, and you'll have a lifetime of creep to take up.
You can get really scientific by splicing a sample, measuring how much it reduced the length (the deduction, we call it), then pulling it hard with a come-along and measuring how much it grows. Then you can figure out a raw length to cut: BP to BP + 1/2 eyesize plus bury, factor in deduction and splice elongation, splice your ends, and then pull it, and it should give consistent results. I've made several sets of four 180' pieces like this, all of which had to be within 1/2". It works if you're careful in all your steps.

[rgleason]

Interesting discussion. Sean How long do you expect these to last? What are you going to use for uv coating? What is the best lashing technique? How long do you think it would last without uv coating.

[s/v Jedi]

Yes, I also love to see how this works out, don’t forget pictures!

Also, how is pre-tension done with lashings? I normally measure stretch using a tape measure over a 2 meter section to adjust our capshrouds to tension to 20% of breaking strength.

[Benz]

Originally Posted by s/v Jedi

Yes, I also love to see how this works out, don’t forget pictures!

Also, how is pre-tension done with lashings? I normally measure stretch using a tape measure over a 2 meter section to adjust our capshrouds to tension to 20% of breaking strength.

The lashing (or lanyard, really) is the tensioning mechanism--you can lead the fall of the lanyard to a winch or handy-billy and apply all the force you need. This is where deadeyes that separate the legs of the lanyards (like Colligo's) really shine--they keep the legs from interfering with each other.
Once tension is achieved (you can put a Loos gauge on Dyneema, if you calibrate it first in a test bench, which we've done once or twice), you seize the legs of the lanyard tightly together with a Spanish windlass so they don't slip back while you bring the fall back over and hitch it around the lanyard legs.

[40 South]

Originally Posted by seandepagnier

......
Anyway, the splices did cause the stays to get about 4 inches longer. I think you can do this just by sailing the boat hard against the wind... that s what I did anyway (beating up the sea of cortez) but I guess it is nice to try to do it beforehand.

I did bottom out a turnbuckle.. I ended put putting some off cuts inside one of the stay to make it shorter again in a tapered way..

Maybe I'm reading this incorrectly....but how did the splices make your stays 4'' longer? Splices usually shorten the stay.

Did you splice them too long?

When I did mine, I got them to within 5-10mm of the required length and they haven't appreciably changed in the 5 years they have been fitted. The turnbuckles still have plenty left.

[s/v Jedi]

Originally Posted by Benz

The lashing (or lanyard, really) is the tensioning mechanism--you can lead the fall of the lanyard to a winch or handy-billy and apply all the force you need. This is where deadeyes that separate the legs of the lanyards (like Colligo's) really shine--they keep the legs from interfering with each other.
Once tension is achieved (you can put a Loos gauge on Dyneema, if you calibrate it first in a test bench, which we've done once or twice), you seize the legs of the lanyard tightly together with a Spanish windlass so they don't slip back while you bring the fall back over and hitch it around the lanyard legs.

That’s great info. I think a Loos gauge only goes up to 7mm? How do you calibrate it to Dyneema? My guess is that one needs to attach a length of Dyneema to a length of 1x19 wire, tension the combi to a reading with the gauge on the wire, then put the gauge on the Dyneema part and mark the gauge reading there?

[Benz]

Originally Posted by s/v Jedi

That’s great info. I think a Loos gauge only goes up to 7mm? How do you calibrate it to Dyneema? My guess is that one needs to attach a length of Dyneema to a length of 1x19 wire, tension the combi to a reading with the gauge on the wire, then put the gauge on the Dyneema part and mark the gauge reading there?

It requires a test bench with a load sensor. You load the stay to whatever you want with the bench, then put the Loos on it and mark the scale. Some guys made themselves a spreadsheet of sorts to indicate that when the Loos marked X, it was really Y.
I myself don't tension rigging with a gauge--I do it by wing and eyeball, so I can't really say how good this method was, nor if it's worth the trouble unless you're trying to tune a fleet of one-designs, like these guys were.

[seandepagnier]

Originally Posted by s/v Jedi

Yes, I also love to see how this works out, don’t forget pictures!

Also, how is pre-tension done with lashings? I normally measure stretch using a tape measure over a 2 meter section to adjust our capshrouds to tension to 20% of breaking strength.

I don't know yet but I thought I could just attach a halyard and get it fairly tight, then tighten the lee side under sail. The forestays could be easy to tension if the backstay is loose, then the backstay may have to get winched.

Originally Posted by 40 South

Maybe I'm reading this incorrectly....but how did the splices make your stays 4'' longer? Splices usually shorten the stay.

Did you splice them too long?

A few of them yes. This is because the slice setting it grew quite a bit.

When I did mine, I got them to within 5-10mm of the required length and they haven't appreciably changed in the 5 years they have been fitted. The turnbuckles still have plenty left.

Mine didn't change either until I was beating in 30 knots against a short swell and going submarine every 3rd swell. After that they didn't change much for 8 more years.

Originally Posted by Benz

The lashing (or lanyard, really) is the tensioning mechanism--you can lead the fall of the lanyard to a winch or handy-billy and apply all the force you need. This is where deadeyes that separate the legs of the lanyards (like Colligo's) really shine--they keep the legs from interfering with each other.
Once tension is achieved (you can put a Loos gauge on Dyneema, if you calibrate it first in a test bench, which we've done once or twice), you seize the legs of the lanyard tightly together with a Spanish windlass so they don't slip back while you bring the fall back over and hitch it around the lanyard legs.

Yes, but colligo's fittings are very expensive. I am looking to use a size larger thimble, but I realize this won't give me a 5:1 radius on the lashings. It is my understanding that a 1:1 radius gives 50% of the strength, so with 6 lashings of regular ( not heat set) dyneema 1/4" this will be enough? I think it will have slightly better than 1:1 bend radius as well.

Originally Posted by rgleason

Interesting discussion. Sean How long do you expect these to last? What are you going to use for uv coating? What is the best lashing technique? How long do you think it would last without uv coating.

I expect to last 10 years without the coating. With the coating it should last 40-50 years?

[s/v Jedi]

Originally Posted by seandepagnier

I don't know yet but I thought I could just attach a halyard and get it fairly tight, then tighten the lee side under sail. The forestays could be easy to tension if the backstay is loose, then the backstay may have to get winched.


A few of them yes. This is because the slice setting it grew quite a bit.

Mine didn't change either until I was beating in 30 knots against a short swell and going submarine every 3rd swell. After that they didn't change much for 8 more years.



Yes, but colligo's fittings are very expensive. I am looking to use a size larger thimble, but I realize this won't give me a 5:1 radius on the lashings. It is my understanding that a 1:1 radius gives 50% of the strength, so with 6 lashings of regular ( not heat set) dyneema 1/4" this will be enough? I think it will have slightly better than 1:1 bend radius as well.



I expect to last 10 years without the coating. With the coating it should last 40-50 years?

There’s special rooe for lashings now: https://www.marlowropes.com/product/lashline

[seacap]

Originally Posted by seandepagnier

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?

Heat set does eliminate needed compensation for constructional stretch. So if you don’t get HS it means you have to re tune your rig a couple of 3 times more before the constructional stretched is worked out of the Dyneema. Otherwise the 78 has the best creep characteristics, but is not used in HS rope, usually 75 is used.

Don’t worry about an extra 1mm for windage. The 9mm will have greater strength left at 10 years compared to what is needed. Your weight savings aloft will more than compensate for the minute amount of additional windage for the 9mm.

And if you really want to extend the UV life of the Dyneema, use black.

After 10 years of use here in the deep tropics I felt the need to replace because of UV damage. I had a sample piece tested and it broke about at the equivalent wire size.

So I am replacing with non HS Amsteel Blue (SK75). I’m using black 9.5mm (3/8) on a 28’ 17000lb blue water cruiser. I am buying from go2marine.com for 1.97/ft.

Yes I have to fiddle with it a bit more and I have more windage. But since I’m a cruiser I’m not worried about the loss of .1 kts of speed.

[smacksman]

I've used galvanised wire standing rigging for years. It certainly lasts longer than the 10 years insurance companies insist on as a life span.

[seacap]

Originally Posted by smacksman

I've used galvanised wire standing rigging for years. It certainly lasts longer than the 10 years insurance companies insist on as a life span.

The ten years is for stainless steel. Galvanized will last much longer. Good decision.