Synthetic Rope Standing Rigging

[Ron Bowman]

Thought I'd start a separate thread about this even though it's really a follow up on my questions about how to rig a two spreader mast.

I'm going to replace my upper shrouds and am considering going with some kind of rope rigging. Maybe dyneema or some other fiber. When I originally built my boat, I was interested in rigging with fiber but decided that it was not quite ready for prime time. It seemed like steel wires were bullet proof, easier to rig and easier to replicate settings. But I think in the not too distant future, synthetic rigging is likely to replace steel wires as the rigging material of choice. And replacing my upper shrouds might be well suited for synthetic rigging now.

I know Kevin looked carefully at this at one time as has Chad. So the questions are: What's the current thinking about the relative advantages of steel wires vs synthetic and what options should I consider in fittings and how best to rig synthetic shrouds. A related question is what size and type of rope is the best choice for replacing stainless i550 wires generally and, specifically, my upper shrouds which won't be loaded very much except when flying a kite from the masthead. Are the lashing plates sold by Precourt and Colligo the best options for adjustment. Why not just use a turnbuckle?

Ron Bowman
Lunatic Fringe #108

[Chad]

With Precourt being out of business, the only viable remaing method of attaching soft stays to a mast seems to be with one of two t-ball connections, either the ones with a welded loop (Navtec T-Ball Bail Terminals) for luggage tagging the stay, or the Colligo method that adds a gucci fitting into the mix. At the bottom, the ability to use turnbuckles is going to depend on line choice and your ability to accurately splice the lengths while anticipating the initial stretch as the new splices and the line itself settle in ("construction stretch"). The Colligo lashing method can accommodate more length adjustment, as can a simple purchase. The Swift Solo guy has a nifty set up that uses micro triple fiddles to get 9:1 purchase, with a snazzy cleat arrangement too.

So, first the construction stretch needs to taken out before the line goes on the boat- after splicing, load the line to something like 50 percent of BL and let it sit for a few minutes. Once it's on the boat, to effectively eliminate post construction stretch, the load on spectra should be kept under 10-20 percent of break strength. The much used "creep" (long term non-elastic elongation) word simply won't be a factor for a boat stored with the mast down, nor a line left permanently loaded less than 10 percent of BL.

Some 3mm dyneema specs and sources- the screen names are from SA:
(edited to update the links)

Alpha Ropes D-Core 78 XTM
3mm, break strength 4075#, Weight (?), Price US$0.90/foot
(through "pickles" in AUS)

Plasma by Puget Sound Ropes/Cortland:
3mm, break strength 2800#, Weight 0.54#/100', Price US$0.50/foot
http://www.psrope.com/images/products/Plasma112006.pdf
(through "sloansailing" in Anacortes, WA)

New England SK90
3mm, break strength 3400#, Weight (?), Price US$0.99/foot
(through "Super Delegate" in Newport, RI)

Marlow D12 Max 78
3mm, break strength 3325#, Weight 0.45#/100', Price US$2.67/foot (through APS, special order)
http://www.marlowropes.com/index.php?op ... &Itemid=89

Maffioli DSK 78 Ultra
3mm, break strength 1984#, Weight 0.33#/100', Price US$(?- no US source)
3.5mm, break strength 3085#, Weight 0.49#/100', Price US$(?- no US source)
http://www.gottifredimaffioli.com/en/

Maffioli DSK 75 Ultra
3mm, break strength 1984#, Weight 0.33#/100', Price US$0.59
(through http://www.mauriprosailing.com/category ... Ultra.html
-or- http://hallinc469.corecommerce.com/Cord ... tra-c5209/)

Hampidjan Dynex Dux
5mm, break strength 10472#, Weight 1.26#/100', Price US$1.76 (Colligo)
(Interpolated for comparison, no 3mm available) 3mm: break strength 3770#, Weight 0.45#/100', Price (n/a)

[Chad]

The above post was significantly edited to add lots of links that didn't come through on the first try, so "bump", in case it looks the same to those that may have already looked.

[Kevin]

I'd like to 2nd Chad's words on loads. You want to stay below 10% of breaking strength. If you do that, the "creep" over time will not happen. If you unload the rigging or drop the rig when not sailing a i550 should never have an issue with this.

I met the guy from Colligo and worked with him to figure out the small 1/4" terminator. I even have drawings with my chain plate spacing with his terminators.

The navtec t-ball bails are on the newer side. They will create a tight bend in the line so you have to be sure the line will not fail when it makes the tight radius. The dux stuff in particular doesn't like that tight of a bend. I think basic dyneema is ok with that kind of a bend. For real security, I'd use a lashing (with lash-it) to connect a eyespliced line to the bail. And colligo has a t-ball fitting for lashing as well, but I think it's overkill sized wise for the i550. Not sure how you connect to his t-ball fittings because they look like they want a terminator which would put your lashing at the top instead of the bottom.

If you pre-stretch your lines after splicing there is no reason you can't use a turn buckle. You just have to get the length correct. That's a tall order for the diy type. I know colligo will make up lines for you and then tension them. He has that down to a science and has the equipment accurately load up the lines.

I personally like the idea of synthetic rigging. It's just building up my personal rig tuning knowledge to the point that I can effectively use the stuff. I lacked the confidence in myself and the materials involved when it came time to rig my boat. The lines keep getting better so this will only become more viable over time. At this point, I'm glad I have the wire even though it's kind of a pain to rig and un-rig. The thought of just having coiled line that I could pull out and use is a nice one. My future setup would probably be... navtec t-ball bail at the top, lashing to shroud line, shroud line, terminator to turnbuckle. The trick will be finding a fitting or toggle to go from the turnbuckle to the terminator. If the shroud line puts the turn buckle beyond it's range, then you adjust the lashing at the top and worse case, shorten the shroud by re-doing the eye-splice. That's a diy solution we should be able to put to use.

Cheers, Kevin.

[Chad]

For standing rigging, the line will always be sized for stretch instead of strength- but we have to deduce stretch from the published strength numbers since that is all that's generally available. For a bend radius that is about the same as the line radius, the Colligo guy says you should expect a strength reduction of about 50%. SInce line strength will almost always be 5-10x the load, I don't see a problem with using the t-ball bails and taking 50% reduction in strength at that point. And if you luggage tag to the bails instead of simply splicing a loop through, then the load is shared by the two legs and you're right back to 100% or close enough. Colligo's t-ball solutions are not the spiffiest, in my opinion. I much preferred Precourt's Olivier Links, but those are no more.

Interesting idea of Kevin's to use a lashing at the top as the length tuning element- I think I'd want to use a stout sailmaker's eye or one of those snazzy aluminum thimbles so the lashing has a more durable surface to bear upon.

A big part of my decision to use synthetic rigging is that I could then also more easily make it adjustable, so no turnbuckles for me if possible. I find things that are a hassle to adjust don't get adjusted nearly as often as they should...

[Merit 25]

So, first the construction stretch needs to taken out before the line goes on the boat- after splicing, load the line to something like 50 percent of BL and let it sit for a few minutes. Once it's on the boat, to effectively eliminate post construction stretch, the load on spectra should be kept under 10-20 percent of break strength. The much used "creep" (long term non-elastic elongation) word simply won't be a factor for a boat stored with the mast down, nor a line left permanently loaded less than 10 percent of BL.

Alpha Ropes D-Core 78 XTM
3mm, break strength 4075#, Weight (?), Price US$0.90/foot
(through "pickles" in AUS)

New England SK90
3mm, break strength 3400#, Weight (?), Price US$0.99/foot
(through "Super Delegate" in Newport, RI)

Hello, I'm Tim's rigger friend and will be doing the work setting up the wand. I had a couple questions about synthetic rigging.
I’ve been having a hard time getting hard numbers on creep and going by what you state above, creep really isn’t an issue (if left tensioned with less than 10% breaking load).
• So does that mean that the i550’s are typically using less than 300 lbs of tension at the dock on their shrouds? Assuming the shrouds have a tensile strength of roughly 3,000 lbs?
• Are there any pictures of the spreader ends that have been modified to deal with chafe?
• Most importantly, would SK78 be acceptable to use for all shrouds and forestay?
Reason I’m asking is b/c I’m a New England ropes dealer and can get a good price on SK75-78-90, but currently, NER doesn’t carry its own brand of Dux…….(yet). Cost savings between 78 and Dux is approaching 50%. It looks like we can save a good deal of money by going with SK78 3mm (1/8” – breaking load 9,700 lbs, that seems high, but I can double check when I get home). Assuming my numbers are right, that’s 970 lbs for 10% load. The i550 shouldn’t even see ½ that at rest.

So what do you think? SK-78 all around?

[Chad]

I'm at around 300# for my caps (to the hounds), but I'm a little soft on the forestay- just getting 200 or so and a little more deflection than I want. So far I've gone without D1's (mast maker advised he thought it would be fine just with a gnav D0.5), but adding the D1's is in my near future and I expect both the caps and forestay to bump up a little, shooting for around 400# caps and 300#+ on the forestay. I think everybody else is running wire and a more conventional geometry, so their numbers will be better for you I suspect.

I used 5mm Dux for my caps and forestay, mostly because I was pretty uncertain at the time of the other strings out there, and I felt like I owed the Colligo guy a purchase after bending his ear several times. So I now have a very "safe" starter rig, and I can get more adventurous from here.

Two things at work, the formulation and whether it's heat set, both effecting the creep curve and the allowable percent of BS you can use for constant tension. For formulation, sk78 is better than sk75 and 90. Heat-set is better than plain- my understanding from the folks I've chatted with is that the heat-set stuff can take a constant load closer to 20% of BS while keeping an acceptably flat creep curve, rather than the more typical 10% limit for non-heat-set.

Back when I was putting together that line list, Marlow's D12 Max78 seemed the best choice, but I couldn't find a source to buy from at the time. Now Vela stocks it at $1.12/ft, and I've bought some from him for my D1's.

Of New England's offerings, yeah I think their sk78 is the best available. Their site links to the sk75 data sheet from the sk78 page (whoops)- I suspect it's 5-10% below the sk90, so maybe around 3000-3200# BS? If Tim drysails the boat and takes the rig down or eases the tension a bit between use, then I think the 3mm would be fine for everything, but just barely. If the stick stays up and the stays are kept tight all season, then maybe it's worth going to the 4mm for the caps at least. With either scenario, I would imagine it would be necessary to shorten the lashing before each new season, by mebbe 1/2" to keep the turnbuckles in the same adjustment range.

My spreader ends are here:
viewtopic.php?f=3&t=141#p1727
...and a few pics of some others a little further up the page, but for wire. My grooves are gently radiused, and I use the inner hole to just lash the stays into the groove.

[Merit 25]

Chad, thanks for the thoughtfull reply. I have no problem going with 4mm to build in a bit more safety (creep) factor. I'm seeing 3322# BS on other SK78 line for 3mm, so 4mm should be around the magic 4k lbs mark. I believe Tim will leave the rig up for weeks at a time so having something a little larger would be nice. I'm not planning on using lashing at this time. If need be I'll just re-splice the shrouds next season.

[Chad]

Actually, for Tim I think 9/16" Sta-Set would be ideal. And use knots, lots of 'em. And baggy-wrinkle to sort the chafe properly. Oh, and those wooden shroud covers you see in the magazines, he'd like those. A proper little ship is what he really needs!

-big smiley-winkie emoticon here-

[Merit 25]

haha, I'm sure he'd appreciate those additions. I was thinking 1/4" chain would probably have some great stretch and chafe resistance. Might effect the self righting properties though.

Good news, I talked to NER, they said the numbers for SK78 are bogus on the site and my price list. However, 78 is going to phase out 75. They will offer 78 at the same price. Currently 75 and 78 have the same BS numbers, just less creep.

More good news, NER is currently testing their version of Dux (pre-stretched, heat set, 75) and (fingers crossed) it'll be hitting the market in 5,6,7mm sometime in April. 3, 9.5, and 11mm will follow. Probably 4-6 weeks later if nothing needs to change in the design. Now, its' up to Mr. Ford if he wants to wait that long. 3mm Dux would be ideal, but nobody has it. Yet.

[admin]

OK, Chad. I see what you did there.
I was actually thinking of going Floating Polyprope and Campbell Anchor shackles.

[Tim Ford]

Heck yes, can wait until April.
Is NER looking for beta-testers?

[Merit 25]

Not sure, I can certainly look into it, but I think they'll do all the testing they need in house.

[Chad]

Tim, I think I read that as mid-to late May for the 3mm stuff? Don't let him tell you the 3/8" polypro is actually good for RM/self righting because it acts like a mast float....

Merit, a heat set 78 from ner would be awesome, especially if it was widely distributed. I thought the Alpha stuff from "pickles" would be great, but couldn't get it. Same with the Marlow good stuff, just Bainbridge (=pia, and expensive) and now Vela (3mm only). If ner can make their stuff widely available in various sizes, that will make small boat synthetic rigging lots more accessible to us retail shoppers. Which is cool!

[Kevin]

@ Merit,
Curious about what you plan to use for terminations. I'm thinking about my d1's and d0.5's (to my gnav gooseneck). I have t-ball plates mounted and was going to shorten my wire d1's for the d0.5's. But now I may leave them as is and add something for the lowers to the gnav gooseneck.

@ Chad,
How big of a toggle did you need to go around the Colligo 3-6mm line terminator? I was under the impression that they were pretty big, but maybe not.

Curious, and spring is coming. Kevin.

[Chad]

From his SA posts, Merit and Tim plan to use sailmaker's thimbles at the bottom. The single-point contact sorta rankles my delicate sensibilities, but with the small loads it'll definitely work. For 3mm line, there's no need for anything gucci-er, nor anything really available.

I used jaw-jaw turnbuckles, no extra toggle. Ronstan ones, from APS- heavy clunkers...

[Merit 25]

Merit, a heat set 78 from ner would be awesome, especially if it was widely distributed.

Unfortunately it won't be 78. I'm sorry if I gave that impression. For the April-May-June timeline it will be heat set prestretched 75. Same as Dux. I do believe that eventually dyneema SK90 will be available prestretched and heat set. It's just a matter of manufacturers having the demand and being able to justify the R&D costs. SK60-75-78 were great, but dyneema is still pretty new and keeps getting better.

For these boats I seriously doubt one needs fancy sk90 heat set, blah blah. If the boat/rig is that technical, just pony up and use PBO. No stretch, no creep, at all, ever.

nor anything really available

At this time, but colligo is working on that. Basically it's like their current end fittings but with a stud on it that will screw into a turnbuckle. I believe they're exploring titanium as a material and will offer it in a complete turnbuckle package.

BTW - if anybody needs some NER stuff, just shoot me a note, I can beat almost any price.

[Kevin]

3mm SK-75 should cover the diagonals with no issues so SK-78 is a bonus. I'll probably leave the caps as they are for now in 1/8 wire. I can't justify a big spend on something that actually works now. If I went there I'd probably consider adding some cover at the spreader end. If NER makes pre-stretch and heat set anything smaller than 5mm that would be nice too. Seems like that's a lot to ask though. Maybe they are open to input .

So for the top end of the merit/tim shrouds are you just luggage tagging to a t-ball fitting like the navtek's [url="http://www.apsltd.com/c-926-t-ballfittingsandplatesj-hooks.aspx"]here[/url] at APS?? Seems easy enough if you inspect regularly and don't leave the rig fully tensioned.

Seems like a titanium stud fitting for the top 1/2 of a turnbuckle is pretty high on the gucci scale. But colligo could make a wide and deep toggle to fit their terminators to standard toggle studs. But that's just me, I like simple and cheap. He has t-ball connectors too, but they don't look rope friendly to me either.

The ronstan turnbuckles are just the 1/4" pin version? Not sure toggles differ much between makers but maybe Ronstan's are generous. Maybe I just go the easy route and use lashings at the bottom to distributors.

[Merit 25]

Given that we're sizing these things for creep and not breaking load my original plan was to directly splice the line to the T-ball fitting down to the eye on the turnbuckle. No thimbles at all, cheap, simple and light. There was mention about the tight radius reducing the breaking strength by 50%, even still, that's 2,000 lbs (for 4mm sk78) giving you a pretty good safety margin. Using dux, you have 5k lbs not using thimbles and a huge safety margin. In either case, a rig should be inspected in detail at least once a season. Cable, line, fittings, etc. everything.

So we decided using thimbles would keep the line much closer to its original breaking load, be a lot cheaper and lighter than colligo, and prevent any chafe at the connection points.

[Chad]

The ronstan turnbuckles are just the 1/4" pin version? Not sure toggles differ much between makers but maybe Ronstan's are generous. Maybe I just go the easy route and use lashings at the bottom to distributors.

Yeah, 1/4" pin, pic from other thread (both ends of turnbuckle are the same):


If you are doing your D0.5's in 3mm line, just use a small ss sailmaker's thimble. It'll fit easily, and you won't need to spread the jaw (toggle) like I did.

[Merit 25]

Do you remember how much constructional stretch you had?

[Chad]

I had the Colligo guy do my 5mm Dux, so I couldn't tell ya (see note above about feeling guilty just buying some string from him after bugging him a bunch).

For 3mm stuff I allow (deduct) a half inch per splice for bedding in (after adding 20% of the bury length for the swelling and shortening there), and the actual construction stretch of the line between splices varies significantly with the various lines. Dux claims practically none, and non-prestretched stuff will be something like 2%.

So for 3mm line with an eye splice each end using 9" of bury my sums look like: cut line length = (2 * eye circumference) + (2 * 1/2" brummel allowance) - (2 * 1/2" splice bedding in) + (2 * 9" bury) + (2 * 9" * 20% shortened fattened line over splice) - (Line Length * 2% construction stretch)

and first crossover from each end is then: 9" bury + 1/2" brummel allowance

You'd rework the numbers for 4mm line using 11-12" of bury, and have to do a quick splice and pre stretch test to verify your splice bedding in amount. The 2% is the wild card, and will depend on the effectiveness of the manufacturer's prestretching done on the line you use- near 0% if it's as effective as Dux, and probably right at 2% if it's like Amsteel Blue.