SS vs Synthetic rigging

Discussion in 'Multihulls' started by fhrussell, Apr 3, 2016.

  1. fhrussell
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    fhrussell Boatbuilder

    Searching the forums for any experience on the cost of SS vs Synthetic rigging, but not finding much info.

    I have been interested in converting my standing rigging from stainless steel to Dynex Dux; given the claims of lightness, strength, ease on the sails, etc... Also, the claims that synthetic is similar in price has me very interested, yet I'm not finding that to be so true. I've priced out the Dux vs steel, turnbuckles vs dead-eyes and lashing and find the synthetic route to be considerably more expensive. Is this the experience of others who have looked in to this conversion?

    Thank you.
     
  2. Stumble
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    Stumble Senior Member

    I have two boats with synthetic rigging, in each case it cost less than replacing the wire would have been.

    First what line are you using, Dynex is a brand name of Heat Set Dyneema, there are others that are less expensive. Look around for other HSR Dyneema

    Second is what fittings are you using? I love Colligio's but they are expensive, swapping to simpler options where possible may be in order. I for instance am using sailmakers thimbles and turnbuckles for the Trimaran, which is far cheaper than a set of deadeyes.

    Third, there is a cost to switch in the first place. A lot of the HSR cost is in setting up the boat correctly the first time. This isn't something that has to be done every time you change the rope. Like reworking the spreader ends, or installing new mast fittings.


    My catamaran was about 90% the cost of wire, the trimaran was about 75% the cost of wire. The weight savings on either was substantial.
     
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  3. catsketcher
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    catsketcher Senior Member

    Like Stumble I avoided the use of the expensive terminators. I used sailmakers thimbles too. Works fine on my 7 metre trailer sailer cat. As for price - I can't remember now but I wouldn't have done it if it was expensive. I did it all myself and it was quite easy and satisfying to do the brummel splices. With the cost of labour to get the wire swaged the Dux probably came out cheaper.
     
  4. Tom.151
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    Tom.151 Senior Member

    Hello Frank,
    I've found prices for 1/4" Amsteel (9200# rated) to range from 40-ish to 60 cents per foot - depending on whether you buy from Defender or the internet. I have plenty (500 feet) of the 1/4" Amsteel Blue for you at my cost if you find that size will do the job.

    I followed Samson's (the manufacturer) directions to the letter - no fancy splicing (Brummel) needed. Just a few solid thimbles at the hounds for piece of mind ;)
    Is your rig a rotating mast? My experience with converting the Gougeon wing mast on my Twiggy to synthetic was that, because the rotating rig doesn't require high static tension loads, the "expensive" deadeyes etc are not needed hence the cost was substantially less.

    Cheers,
    Tom
    Salem, MA
     
  5. Stumble
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    Stumble Senior Member

    Amsteal is not sutable for standing rigging. It has far to much stretch and creep.

    You have to step up to one of the heat set versions.
     
  6. fhrussell
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    fhrussell Boatbuilder

    Good morning and thank you for the replies.

    Stumble, is that to say regular Dyneema is also not suitable? Amsteal is Dyneema, correct?

    The mast I'm converting is an oval, non-rotating, and was a 9 point rig (which was overkill for inshore sailing). I'm going to either go spreader-less or install diamond stays. Not sure just yet.

    Good to hear from you Tom, and thank you for the offer. I may take you up on the 1/4" if it is what I can use.
     
  7. fhrussell
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    fhrussell Boatbuilder

    Catsketcher, what size and brand did you use?
     
  8. waynemarlow
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    waynemarlow Senior Member

    Somewhere there is a very long thread on using synthetic rigging, can anyone pointus back to it as I to are about to rig a boat.
     
  9. BobBill
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    BobBill Senior Member

    I too would like to read more information. I lost the link in computer change. I am conflicted between synthetics and metal rigging etc.

    For what it is worth, I had a problem with tag ends and solved, I think, using electrical heat-shrink tube and a tip of left over epoxy, if I remembered to use it.

    Seems synthetics would make replacing some rigging easier...
     
  10. Stumble
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    Stumble Senior Member

    Amsteel is just a brand name of normal dyneema. I like it a lot, but it won't work for standing rigging.

    What you need is some flavor of Heat Set Rope (HSR), which is basic dyneema that has then done thru a heat annealing process. This process dramatically reduces stretch and creep of the line, while reducing the line size, but retaining the same strength. So for the same size, the HSR is stronger.

    Dynex Duc was the first of the HSR's to market, and is still sold under the Colligio Dux label. It is still one of the better ones, but it is also the most expensive. Take a look at Alpha Ropes, NER, and Samson, among others, now all make a HSR sutable for standing rigging.
     
  11. BobBill
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    BobBill Senior Member

    Greg, I have entertained the notion of using a stiff line called Technora for jib/fore-stay on my smallish rig (18 footer) but have read some negatives about it...no rush, the metal will last awhile.
     
  12. Stumble
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    Stumble Senior Member

    Technora is highly subject to UV damage. It will work, but I wouldn't. Not unless you are planning to replace it regularly.

    On my A-Class Cat I am using 2.5mm Marlow D12MAX SK78 shrouds. The line itself for all four shrouds cost $95 for 94' of it. The splicing is very easy to do yourself, though this time I had it professionally done since I was running out of time before a regatta.
     
  13. Tom.151
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    Tom.151 Senior Member

    Frank,

    True, Amsteel does has a significant "mechanical set" when freshly manufactured -- the strands are not aligned and compressed together. People who have used Amsteel and discovered this have reported it as creep.

    Creep is a continuous lengthening that is caused by permanent deformation due to the line being loaded at too high a proportion of it's strength. So you MUST size the line for the load.

    To overcome the one-time stretch due to aligning the strands, you can buy the HSR version as Stumble so correctly described, or you simply put the line under steady load until it stops stretching - the fibers are then "permanently" aligned and there's no further mechanical alignment stretch.

    I used a large 5000# come-along in line with a length of 1/4" Amsteel Blue Plus (9200# rated) long enough to produce both shrouds with spliced eyes included. This was set up between two telephone poles. I ratcheted up to a guestimated 2000# and let it rest a while. The line gradually becomes slack, so you crank up the tension again, and repeat. The first time you get a lot of elongation, but as that is accomplished the line gives less and less until the stretch is finally gone. Took me 8 maybe 10 cycles before the line got obviously bar taut.
    I had the shrouds on the boat for 24 months, never needed any tightening.

    I'll happily give you a hand doing the stretch-out if I get paid off with a sail -- you know I love the Choy boats.

    Cheers,
    Tom
     
  14. Stumble
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    Stumble Senior Member

    Tom,

    You are right that people often mistake constructional stretch with creep, since CS has to be pulled out by either heavily loading the lone (about 1/2 MBL) initially, or will slowely work itself out over time. But normal amsteel also suffers from creep.

    How quickly will creep occur? Well it depends on how heavily loaded the lines are relative to their rated strength. But generally sk-75 (standard) will creep about four times as much under the same load percentage as sk-78 (HeatSet) will.

    I am working from memory, so may be wrong, but I think standard sk-75 creeps at a rate of .1% at 20% MBL per month, where sk-78 (heat set) creeps at a rate of .03% per month. But creep rate is a function of MBL and so since HSR is substantially stronger than the same size sk-75 it is even more favored.

    As an example a piece of 1/4" amsteel has a MBL of 8,600lbs, where NER's HSR at 15/64 has a MBL of 12,385lbs.

    To get to the same creep numbers the amsteel has to be roughly twice as strong as the HSR it replaces, so you would need to go all the way up to 7/16" to match the performance of the HSR. Possible, but expensive and rediculiously large.
     

  15. BobBill
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    BobBill Senior Member

    2.5mm Marlow D12MAX SK78 is "better" Dyneema. Works on your A, will do job. Thanks for that. Will also use to replace some Technora I added for outhaul and a traveler bridle...very kewl...
     
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