Soft shackles

Tranona said:
Dyneema has been used successfully both for shrouds and for tensioning shrouds because of its properties (strength, minimal stretch, abrasion and UV resistance) for many years.
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If we are ( at the insistence of seajet) going to go off thread, I do not think I would use dynema for tensioning shrouds. I can see the use for the main tie but the terminals are a different matter.
I assume you would be doing the rigging screw function using the dynema as you would old fashioned lashings. I cannot see one getting enough tension. My cap SS shrouds for instance are set at 25%. I am not sure I could get that with dynema lashings .

Out of pure interest - how does one achieve the end terminal with dynema? It must pose a problem whereas SS wire can easily be finished off with bronze rigging screws. Where there are junctions at crosstrees that could pose a friction issue. How is that solved?
Do we know?
 
dom said:
OK Snooks to be fair to you this was a really good piece of science journalism: ask some pertinent questions, perform a series of unbiased tests and then deliver a good write-up/vid on how to make something both useful and great value.

It is also a welcome step away from some of YM's tired old staples in favour of modern technology, new ideas, and how everyone can benefit from the many advances that have emanated from the racetrack and its suppliers.

Well done, a cracking piece of work and keep it up :encouragement:
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+1. Unlike many others on here actually buy the magazine and read the articles. Great stuff
 
bbg said:
I suspect that most of the Open 60s that do the Vendee Globe later this year will use Antal rings as their genoa turning blocks.
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On that subject...In a moment of madness when looking for a snatch block I splurged on an antal hook:
http://www.antal.it/eng/HK16_en
Not cheap but I seem to be finding all kinds of uses for it and am tweaking stuff I hadn't previously tweaked. As well as a barber hauler it's found use routing either the outhaul or a cunningham to my mast winch. I think it's rather easier to find somewhere to attach it than it would with a regular snatch block.
 
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Terminals are just eye splices with hard eyes, or in a temporary fix an eye splice cow hitched around a low friction ring then spliced. Most PBO or UHMPE systems use discontinuous rigging. In Open 60s they often have deck spreaders with terminals. On one of Mike Golding's Ecovers the shrouds were the correct length with a splice on each end and no lashings. Tension was achived by connecting it all up with the mast down, and easing the mast the leverage of the mast gave the rig tension.
 
dancrane said:
I like it...but what stops the knotted tail coming out again, just as easily, as the cringle flaps?

My genoa sheets (one long line) were tied by an infernally tight and rope-hungry knot, when I bought the boat. I never undid it (three years) until I laundered the line last autumn...
I like Vics's endless loop and 'pin', I use a bowline tied in the centre of a double length sheet, works for me and never fouls on the babystay or shrouds when tacking. You must slip in about 3 short lengths of 3 strand rope in the bights so you can easily undo the bowline in the winter

...so now I'm hoping to find the least bulky way to attach it to the cringle. There's every opportunity for a bulky knot to jam somewhere...is a soft shackle the answer?
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JumbleDuck said:
As a matter of interest, do you have dyneema or stainless steel shrouds on your new boat?
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Stainless - because that. is what is appropriate for the type of boat. Don't think any cruising boats use dyneema for shrouds. Rod rigging is the next step up.

I was not advocating the use of dyneema for shrouds on cruising boats, just questioning why seajet firstly considered chafe a problem and second suggesting that he might read up on dyneema's properties so that he would understand why it is used in certain applications.

You will find it used for shrouds in light high performance boats because of its strength and lack of stretch, and more commonly as an alternative to bottle screws for tensioning conventional shrouds. Have a look at Swallow Boats for example, and no doubt many more similar applications. Nothing new about using rope for staying masts, both on dinghies and gaff rigged boats for example in conjunction with wire.
 
Daydream believer said:
If we are ( at the insistence of seajet) going to go off thread, I do not think I would use dynema for tensioning shrouds. I can see the use for the main tie but the terminals are a different matter.
I assume you would be doing the rigging screw function using the dynema as you would old fashioned lashings. I cannot see one getting enough tension. My cap SS shrouds for instance are set at 25%. I am not sure I could get that with dynema lashings .

Out of pure interest - how does one achieve the end terminal with dynema? It must pose a problem whereas SS wire can easily be finished off with bronze rigging screws. Where there are junctions at crosstrees that could pose a friction issue. How is that solved?
Do we know?
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Don't think there are any advantages over bottle screws in cruising boats with wire rigging. however rope lashings are commonly used in light performance boats and dyneema is perfect for that job. stronger, lighter, low stretch, uV resistant etc.
 
We're in danger of straying off subject however whilst being an entusiastic advocate of dyneema I still recognize with my riggers hat on that there are issues in certain applications.

The main one is creep which in the early days means repeated tensioning.
Creep does settle and will hold tension but after three or four seasons increases again.
There are variants that suffer less creep but they tend to have a lower swl so the dia increases to compensate.
In a racing boat it isn't an issue as you'd probably swap out the rigging every couple of seasons.

I'm not keen on the lashing process as it's not easy to adjust.
That said I've seen but not tried some terminations that allow you to use bottlescrews.

I also have concerns about wear at spreader ends on dyneema, especially on masthead rigs.

So currently my inclination is to use ss for caps and inters.
Forestay I'd probably opt for SS as well depending on furler type as some are harder on the wire than others.

On a frac rig or swept aft spreader rigs then the backstay, lowers and babystay could all be dyneema.
On a masthead then the lowers, babystay and possibly backstay if you adjust when you go sailing.
Also dyneema would be good for diamond stays if you could protect the rope chafing on the diamond spreaders.
 
JumbleDuck said:
What disadvantages do you see to Dyneema shrouds?
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Really don't know enough about it. As I said my "contribution" was mainly in response to the ridiculous posturing from somebody who clearly knows even less than me about the material!

Glad to see that Javelin has answered the question. Seems to make sense to me.
 
Javelin said:
We're in danger of straying off subject however whilst being an entusiastic advocate of dyneema I still recognize with my riggers hat on that there are issues in certain applications.

The main one is creep which in the early days means repeated tensioning.
Creep does settle and will hold tension but after three or four seasons increases again.
There are variants that suffer less creep but they tend to have a lower swl so the dia increases to compensate.
In a racing boat it isn't an issue as you'd probably swap out the rigging every couple of seasons.

I'm not keen on the lashing process as it's not easy to adjust.
That said I've seen but not tried some terminations that allow you to use bottlescrews.

I also have concerns about wear at spreader ends on dyneema, especially on masthead rigs.

So currently my inclination is to use ss for caps and inters.
Forestay I'd probably opt for SS as well depending on furler type as some are harder on the wire than others.

On a frac rig or swept aft spreader rigs then the backstay, lowers and babystay could all be dyneema.
On a masthead then the lowers, babystay and possibly backstay if you adjust when you go sailing.
Also dyneema would be good for diamond stays if you could protect the rope chafing on the diamond spreaders.
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Creep seems to be well known about these days, without the need for retensioning..
http://www.colligomarine.com/fundamentals/

Case study..

http://www.sailmagazine.com/diy/dynex-dux-fiber-rigging-after-6000-sea-miles/
 
JumbleDuck said:
What disadvantages do you see to Dyneema shrouds?
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There are now quite a few people using Dyneema for shrouds, but I'd say the technology still has to mature a little longer before it is viable for everyone.

I was going to make a Dyneema backstay (mast head rig so under plenty of constant tension and actually required to hold up the mast), so did a fair bit of research.

The main points, 3 types of stretch:
- Normal stretch under load, that will return when tension eased off.
- Creep, were the rope stretches permanently over time.
- Constructional stretch, as you tension the line for the first time, all the fibres contract closer together, your splice stretches etc. This can be considerable.

The first 2 points can be addressed by using some of the latest fibres that exhibit much lower creep and stretch than previous ones. Although I can't remember their names off the top of my head, its easy to research.
And also by over specifying the diameter, which will also give peace of mind as the rigging will be far stronger than the original.

The 3rd point can be partially addressed by using a heat set version of whatever fibre you go for, however you will still get 'some' stretch and also your splices will stretch out as well. I could never get my splicing technique close enough to be able to accurately judge how much the line would stretch.

If you can solve those 3, you're most the way there.
Some protection where the shrouds go through the spreaders is required, though there are (expensive) fittings you can buy from Colligo marine to make this easier.
Splicing eyes, if you're worried about chafe than use them, but its been pretty conclusively proven that as long as you go around a clevis pin of at least 1x the diameter of the dyneema than you will retain almost (I think it was around 95%) the full strength of the line.

That's all I can remember off the top of my head, but there was a good discussion here:

http://forums.sailinganarchy.com/index.php?showtopic=170606&hl=+dyneema++rigging
http://forums.sailinganarchy.com/index.php?showtopic=171827&hl=+dyneema++rigging#entry5225651

Sorry for going off topic.
I also enjoyed the vid!
 
I would have though dynema would be an excellent substitute for a removable inner shroud for a storm jib. Whereas a SS wire could get kinked in storage a dynema shroud could store easily, be light & stowable. Easy to set up. If it had to be permanently fitted to the mast it could be released from the deck & the excess rolled at the bottom & bagged or fastened easier than a wire.
The issue of term creep would not apply as it would not be in use for extended periods like other standing rigging.
I believe dynema has been carried for emergency uses as spare shrouds
 
Ceirwan said:
There are now quite a few people using Dyneema for shrouds, but I'd say the technology still has to mature a little longer before it is viable for everyone.
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Thanks for the detailed reply. Sounds as if it might be worth looking at for my Hunter 490 - the loads aren't terribly high, half the shrouds are tensioned wit lanyards already and Dyneema stays would be much easier to store over winter.
 
Snooks, thanks for this.

Can I ask roughly what the cost of the Dyneema was? Suppliers online are quoting over £3/m for 5mm line. If you got a good deal, can you let me know where? Thanks.
 
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KAL said:
Snooks, thanks for this.

Can I ask roughly what the cost of the Dyneema was? Suppliers online are quoting over £3/m for 5mm line. If you got a good deal, can you let me know where? Thanks.
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The strongest stuff we found is by Marlow and English Braids at £3-4 / m (1.9 tonne)

The cheapest I've found was at YouBoat Gosport, Robline Ocean 3000 at £0.95/m (1.83 tonnes)
 
Daydream believer said:
If we are ( at the insistence of seajet) going to go off thread, I do not think I would use dynema for tensioning shrouds. I can see the use for the main tie but the terminals are a different matter.
I assume you would be doing the rigging screw function using the dynema as you would old fashioned lashings. I cannot see one getting enough tension. My cap SS shrouds for instance are set at 25%. I am not sure I could get that with dynema lashings .

Out of pure interest - how does one achieve the end terminal with dynema? It must pose a problem whereas SS wire can easily be finished off with bronze rigging screws. Where there are junctions at crosstrees that could pose a friction issue. How is that solved?
Do we know?
Click to expand...

KAL said:
Snooks, thanks for this.

Can I ask roughly what the cost of the Dyneema was? Suppliers online are quoting over £3/m for 5mm line. If you got a good deal, can you let me know where? Thanks.
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Wherever you go, you'd better be quick. When I went into Force 4 yesterday to get some they laughed - apparently Dyneema and soft shackles have been walking off the shelves since the article came out.
 
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