Dyneema standing rigging on a cat

[madprops]

I have to change my standing rigging over the next 2 years. I want to replace my side stays, split back stay and running back stays with dyneema. The one problem I'm having is trying to figure out sizing, right now I have 1/2" SS wire rigging and the boat is a prout quasar 50 catamaran.

So if I was sizing for creep would I be using 16mm 17mm or 18mm dyneema? I have emailed and called Colligo as I have read good things, but they have yet to return my emails or calls. So I was wondering if anyone new a good dyneema supplier that would also have the knowledge I need for sizing on my prout quasar 50 catamaran. I know that I need pre stretched heat-treated dyneema but I would like to talk to someone with knowledge before I order anything. Thanks for any help.

[smj]

Google Kraken Structures

[Cattle Dog Oz]

not recommending anything ....or anyone .... but it seems the type is at least as important as the size...but you may have already known that
on https://www.marlowropes.com/dyneema-...al-information

DM20 has slightly lower tenacity than SK78, but has one major advantage in that it exhibits virtually zero creep. Used mainly for static load applications such as standing rigging.

[madprops]

I have heard of both of those companies, and I did know the type of dyneema is important, but from what I understand the main thing is to keep the dyneema line under 10% of its breaking strength (as long as it's heat stretched) . But I'm not sure how over spec my standing rigging is. On Tula's endless summer they had 8 mm ss wire on their cat, I think it was 44 footer. They ended up using 9 mm dyneema. So I would think 16mm dyneema would be good for my standing rigging but again I would like to know more before I jump in. Right now I have 1/2 inch ss standing rigging.

Does anyone know the amount of tension I should be cranking up my standing rigging to?

And yes I know I need to talk to a professional. I am trying to. But it also will help if anyone can teach me a bit more about standing rigging, especially if you know anything specific about a prout quasar 50.

[jt11791]

I put dyneema standing rigging on a mono I used to own. I went with Dux line and Colligo fittings. I don't know why Colligo has been hard to communicate with, keep trying, they were very helpful for me with sizing and other concerns.


As for amount of rig tension, the unhelpful truth is "as much as it needs." I'm not even aware of a gauge that will work with synthetic rigging, so it's all done by practiced eye. Set up your mast at the dock to be straight in column with a degree of rake that gives you the performance you want. Then go sailing and tighten the leeward shrouds to remove excessive slack while counting the turnbuckle turns so you can adjust the other side on the opposite tack.

[mikereed100]

Heres a link to Dux sizing for stretch from Colligo Marine. Looks like you would be using 15-16mm Dux to replace 1/2" 1x19 wire. Keep trying to contact Colligo. Sometimes they are very busy, but John is very knowledgeable and can set you up right.

https://static1.squarespace.com/stat...quavalents.pdf

[smj]

Call Luke at Kraken, he is also very knowledgeable and will take the time to talk to you. We used him for our Dyneema shrouds and he was close to half the price of Colligo.

[out42]

I installed dyneema standing rigging on my 42' Outremer and did 5 seasons with it in the Med. Provided you are prepared to retention it perhaps twice per season, you will get on fine. This presupposes that you have a long enough bottlescrew to allow you to get the thing set up and then take up the initial stretch and then the inevitable creep.
I used Colligo terminals at either end with regular bottlescrews pinned through the terminal.
I repositioned the eye annually so that there was enough slack in the system. That takes about 30 mins per side so isn't too bad, especially in the sun by a Greek Island. After repositioning, go sailing and tension the lee side then tack and do the other as someone says already here.
The weight saving is massive. It is also much nicer on the hands when going forward or climbing aboard and weirdly, it's grippier when wet. You will know it is coming to the end of its life when you have to retension it every couple of months. This occurs quite abruptly and is a good safety feature.
I used 13mm Max SK99 D12 fibre. Breaking strain (not very relevant really) was 24500 kgs. To make slightly less work for yourself and on a 50, I would go to 15mm or 16mm. Mine was a 65 square metre main and a 65 square metre gennaker if that helps.
Good luck and don't be afraid of doing it - it's much nicer than steel.

[jdaltonpe]

I changed out wire for Dyneema Dux on a 50' trimaran a few years back and rather enjoyed the process of figuring it all out, splicing and rigging it. I found that sailing with the new Dyneema required a steady monitoring of the stretch for the first year or so with occasional adjustments to keep things snug. Not at all difficult and keeping an eye on standing rigging is something you want to do anyway. As far as creep goes it was no problem to deal with - just make sure you leave enough room for the adjustments between your rigging blocks. You will know when the creep is settled out but that is no reason to stop monitoring. I have not seen it but I understand that if the creep shows up again all of a sudden it is time to change out the rigging right away. Better to change it out before it gets to that point but that is a definite warning sign. Don't forget to thread your rigging blocks so that the multipart tensioning line exits the last block in the upward direction so you can use a halyard to help tension with. Good luck and have fun.

[Tupaia]

Try Mike Strong of Strongrope https://www.strongrope.com/contact.htm- Australia he will detail how to measure supply with thimbles for existing turnbuckles or for lashing. Shipping is not a problem as as synthetic shroud is less than 1 kg. Fitted minor adjustment first few months nothing since.

[bcboomer]

I've heard good things about this outfit:

https://www.hampidjan.ca/

but I don't have any personal experience with them.

Probably quicker to ship accross Canada than around the world.

[spiv]

Originally Posted by out42

--- I repositioned the eye annually so that there was enough slack in the system---.

Hi mate,
what do you mean, why?
Could you explain in different words please?

[fxykty]

Just to emphasise the point, as there were some mentions of “strength equivalence” earlier, that the only factor for sizing fibre rigging is stretch. It should have the same stretch characteristics as the wire it replaces. That typically generates a fibre shroud that is 3-5 times stronger than the wire it replaces.

On our 55 foot cat with 80sqm mainsail had 14mm 1x19 SS316 cap shrouds and were replaced by 18mm Dyneema Dux. Colligo has a handy chart https://static1.squarespace.com/stat...quavalents.pdf. Selecting a heat set line minimises the fibre stretch and provides higher strength (e.g. SK75 Dux MBL spliced 40.6ton, SK99 MBL spliced 38.5 ton).

Fibre is also subject to creep, which is non-recoverable elongation in response to constant tension. The lower the ratio that the tension is to the breaking strength of the fibre the less the creep. Colligo has a table for that too, https://static1.squarespace.com/stat...eep+Chart.jpeg, but it is also dependent on how big your dynamic loads will be. We upsized our shrouds based on stretch (16mm) to reduce the creep.

Finally there is pre-tensioning, to remove the constructional stretch of all the splices. Effectively, you’ve loosened and opened the fibres where you’ve done the splices, so now the fibres need to be pulled back together. The tension required is about 1/3 the working tension.

Note that a rig’s static tension is usually between 10-15% of breaking strength (wire). This will be somewhere around 2-5% of the dyneema breaking strength. A rule of thumb when sailing is that the leeward side should be just soft when fully powered up (that is, just at the time you should reef) on a close reach or close hauled.

We pre-tensioned at about half of the recommended tension, so had a fair bit of movement over the first day. Our turnbuckles started out with threads 300mm extra long and that was gone after 3 tensionings (600mm stretch in a 17.9m shroud with eye splice top and bottom). Then we cut the excess lengths and shortened another 100mm over the next 3 days. 6 months on we’ve brought in another 6mm, so we’re pretty much there. The other way to do it with existing turnbuckles would be to use lashings between the bottom terminator and the turnbuckle top pin, until you can finally get the pin through the bottom terminator. Smaller boats or rotating masts can use lashings instead of turnbuckles.

Keep trying with Colligo. John Franta is on CF and albeit busy is very helpful. Try calling him.

[out42]

Repositioning was the wrong word. The Turnbuckles have a limited length from full closed to full open. I didn't want lashings between the turnbuckle and the chainplate, so only had that limited length of adjustment to take up the creep/stretch which occurs.
That meant that the bottom splice of the dyneema had to be undone and repositioned so as to shorten the whole span of fibre at the start of the season and maybe once during the season.
Sorry - could have been clearer

[fxykty]

Originally Posted by out42

Repositioning was the wrong word. The Turnbuckles have a limited length from full closed to full open. I didn't want lashings between the turnbuckle and the chainplate, so only had that limited length of adjustment to take up the creep/stretch which occurs.
That meant that the bottom splice of the dyneema had to be undone and repositioned so as to shorten the whole span of fibre at the start of the season and maybe once during the season.
Sorry - could have been clearer

Sorry for confusing you. The lashings I suggested using were only for during the initial tensioning phase, when there are relatively large movements as the splices settle in. Lashings are needed only if you don’t have new turnbuckles with over-long threads that can be cut as the constructional stretch gets taken out.

Properly sized, the amount of creep movement is several turns of the barrel per year (so I’m told by local riggers who have built fibre rigs for well over a decade - we only have 6 months so far on the rig).

Same for stretch; there should be effectively no stretch at the relatively low level of static tension vs breaking strength of the dyneema.

Certainly not so much movement that the bottom splice has to be redone twice a year! How is that possible?