Issues with synthetic rigging?
 

Can any of you guys with years of experience using synthetic rigging, fill me in on the following?

The comparison that I would like to see between Dux and 316 SS wire, is @ 18 or 20 years old. Of the countless thousands of boats in our area, (Eastern NC), there has only been one dismasting in the last 5 years to my knowledge, and it was a new racing boat under extreem conditions. If one removes from the conversation the < 5% who are cruising all over the world, or live full time in the tropics... The other 95% around here spend winters in the Bahamas, are daysailors & local cruisers, or make a couple of one or two year Caribbean cruises... still spending the majority of their years in our moderate lattitudes, and brackish water. Of this 95% of cruisers, almost all go over 18 or 20 years before changing out their rigging, some even go to 30 years, (admittedly at their own risk)! Has your accelerated UV testing made a compairison to wire at this 18 + year life span, under the above circumstances?

Another point I am curious about... I have switched to some DUX synthetic rigging 6 months back, they are for my running backstays, and DUX seems like a perfect application here. I normally leave them "made up" and fairly snug, to use as a handhold when boarding the boat. When using the staysail, I will put 4 more turns on the "quick adjust" handle turnbuckles, but so far, haven't given them the acid test.
I go to the boat daily, and have noticed that @ 75 degrees F, the runners are quite snug, but @ 40 degrees F, perhaps that same morning, they hang completely limp. Since solid materials expand when heated, and contract when cooled, it can't be that the DUX has gotten longer on a cool morning. I assume that the metal mast has contracted at a rate vastly higher than the DUX, creating loose runners in the morning. Presumably with wooden or composite spars this is less of a problem,. My wire rigging has never done this "changing tune with temperature", and I imagine that it's because the wire expands and contracts at a rate somewhat similar to the metal mast.

With aluminum mast that are long & skinny, (like mine), and dependant on consistant shroud tension to keep the mast in column, wouldn't this become a problem if I tune the rig in the summer, then go sailing on a cool fall day? Has anyone else noticed this characteristic? I have done a LOT of reading on synthetics, and have yet to see this subject brought up...

Best regards, Mark

Hi Mark,

I´m only at about 18 months with my Vectran rigging, but I too have observed the tune to vary with temperature, as have other sailors I´ve spoken to with aluminum sticks/Dux rigging. Less of a concern with my gaff-headed rig, since all my shrouds are less tight than a bermudian´s, but I´d also really like to know. Perhaps Mr Franta of Colligo will chip in soon.

Poly aramids (Kevlar, Vectran) have a negative coefficient of thermal expansion. I wonder if this applies to the Dynex type materials? If so then the rigging would actually be getting longer in the cold as the mast gets shorter.

Mark,
I too live in Eastern NC and we do get wild temperature swings in a single day. Your question about how temperature affects the dux is interesting and I would sure like to hear more about it from the professionals. I have zero experience with dux but have been reading a lot about it and am very much considering rerigging my 36' cutter with it. I have heard from a sailor that rerigged his 35' yawl with dux about 18 months ago. He had a lot of good things to say about the dux but he also mentioned the same thing about temperature changes affecting the dux tension. He said it was annoying. Overall, I think he is very pleased with it.

Hi Mark, please see the FAQ's on our site about Colligo Dux Rigging.
We now have enough data to say 5-8 years for a replacement interval of Dynex Dux in the Tropics. This data is still coming in and we are watching it closely. As an engineer and a sailor, I can tell you that I wouldn't feel comfortable going offshore with a stainless rig on a saltwater boat over 10 years old unless, possibly, I knew it was washed with freshwater almost daily. Maybe with stayloks that were completely inspected, certainly not swage fittings. To my knowledge, most of the wire rope manufacturers recommend 8-10 years as a replacement interval for stainless wire. I am sure Brion has a valuable opinion here.

On the tuning, 2 things.

1. The coeficient of thermal expansion (COTE) of dyneema is less than that of aluminum, so you get a difference in expansion rates in the temperature ranges you see on a boat. If you do some calcs on an aluminum mast you would probably be surprised on how much growth you can expect. The COTE of Steel is also different than aluminum but not as much and is usually masked by the higher amount of pretension with turnbuckles.

If you use turnbuckles with some amount of pretension you will usually not see the loosening of the shrouds, if you use lashings than you will probably notice it as the amount of pretension will probably not be enough to cover the thermal expansion of the mast. Some of our customers have noticed this and after tensioning in colder weather they have enough pretension to not see the issue again. If you have a rig that requires more pretension (or better control of tension) we recommend using turnbuckles for pre-tensioning.

We also now have Loos gauge calibrations for several sizes of Dux to help with setting the tension.

You will have a little more maintenance with Colligo Dux, especially with lashing tensioners, but you should expect this as you need to inspect for chafe more (than steel) also. All synthetics, PBO, Carbon, Dyneema, Aramids, etc put more responsiblity in the hands of the sailor as there are alot of unknowns as none of them have been used as long as Steel.

You will not find a synthetic rig that will give you the same amount of confidence as steel for probably about another 100 years or so.

John Franta, Colligo Marine

Return
 

Hello all,
We are in the process of returning to a world where sailors are a living part of their rigs, responsible for design and fabrication, as well as maintenance and use. Part of that process requires familiarizing ourselves with the assorted materials, and the interactions thereof. The expansion issue being discussed here is a piece of that.
As John notes, the pretension required for a (proper) tune with wire masks differences in expansion rates for aluminum and steel. But if you put a tension gauge on the wire on a cold day, and then a warm one, I think you'll be surprised at the difference. In the Northwest, we can use this to our advantage, as the colder days usually have higher windspeeds.
With Spectra, very little pretension is normally needed, so there's less "travel" needed for the rigging to go slack. This might mean more frequent or seasonal adjustment, and it might mean finding an average pretension -- under the "creep" level -- to tune to.
As for longevity, it looks like uncovered Spectra will last at least as long, safely, as stainless in the same climate. Covered Spectra, which costs about 40% more and is more difficult to splice, might still end up being long-term cheaper, as it will basically be immortal. That's why I'm recommending it to cruisers who expect to be in the Tropics for any length of time. Might make a difference in resale value, too. And even with the extra cover weight, it's still lighter than wire.
Fair leads,
Brion Toss

Dux Pre tension
 

Hi Brian,
Your explanation about my Dux runners "seeming" to have a larger temperature induced expansion differential than the wire ones did, being partly because, unlike the rest of the rig, I had them snug, but with no pre tension, makes good sense.

The thing is... when my runners were wire, I had the exact same practice of having them rigged up "just" snug as a hand hold, and putting 4 or 5 turns on them for the rare occasions that I needed my staysail. (I have folding handle, "quick adjust" turnbuckles on the runners).

When I had the previous wire runners, and there was a difference between morning temps, to 35 degrees hotter that afternoon, the difference in wire tension was small enough that I couldn't tell without using a tension gauge. I never noticed it at all in fact. With the Dux, starting with the exact same tune, they hang completely loose in the morning, with some slack as well, and that afternoon, if it is 35 degrees hotter, they would be REALLY tight! (So much so, that to oppose my staysail stay, I might only put one more turn on them! The difference between the two materials behavior, at least in my admittedly limited observation, is pronounced!

It is of no consequence in my application, with such easily adjusted turnbuckles, and I think my runners is an ideal application for these lighter synthetics, but for the rest of the rig, I thought that this observation would be useful for others in deciding where they apply and where they don't... (like a short fat extrusion with all shrouds at similar pre load, VS a long skinny one with really tight uppers and fairly slack lowers. Just something to consider...

Mark

If the mast were composite............would there be any issues along these lines???

So let's look at some actual data for coefficients of linear expansion:

Aluminum 6061: 24E-6 per deg C
Stainless steel 316: 16E-6 per deg C
Dyneema: -12E-6 per deg C

I'm not sure how accurately the value I found for Dyneema applies to Dynex Dux, but I'll assume it does.

So, if for the sake of simplicity, we assume a shroud of equal length to an aluminum mast (as would be a good approximation for a deck-stepped, masthead rig), we have the following differential coefficients of linear expansion between mast and (cap) shrouds:

SS 316 rigging: 8E-6 per deg C
Dyneema rigging: 36E-6 per deg C

So the effect of differential expansion is 4.5 times greater for Dyneema in this case.

To get an idea of what this means with Dyneema/Aluminum, consider a variation in temperature from 0 to 30 deg C. This gives a relative length change of 30*36E-6 or 0.0011. Assuming all the elasticity is in the Dyneema (i.e., neglecting elasticity of the hull and mast), this corresponds to a change in load in the shroud of order 6% of breaking strength, based on the Colligo data. This value is probably greater than the pre-tension acceptable in terms of creep.

For comparison, with a SS 316 shroud, the change in load would be of order 2.5% of breaking strength, which should be compared with a typical pretension of say 15% of breaking strength for SS.

I worked these numbers quickly, so I’m open to correction on the math, but assuming it’s correct, the difference between Dyneema and SS is quite significant in this regard. Obviously I’ve made a number of simplifications in my model, but I think the general results will be reasonably valid.

Maybe
 

Hi,
And thanks for the numbers. I can see that this might be an issue, but would like to throw in some qualifiers. First, the range, in rational measure, is from freezing to 86 degrees. Not likely to happen in a day, or in a given season. Next, the 15% tension you give for stainless is typical for long wires, like uppers and jibstays. Next, it seems to all depend on what kind of pretension the Dux would be set at. If these numbers are accurate, one could have shrouds at about 6% when slackest, and 12% when tightest, which would keep it under the worst creep levels. In my climate, this varying tension works out for stainless, as the winds tend to be highest when temperatures drop, so this could actually be a feature.
Anyway, looking forward to further documentation and analysis. And to the adaptations we come up with in response.
Fair leads,
Brion Toss

Hi Brion,

Well, I would say that my 0-30 Centigrade temperature range is quite reasonable, even conservative, for a boat left in the water year round (or hauled for winter rig-in) in New Jersey (where I used to sail), having on the one hand wilted in summer heat in the high 90's (Fahrenheit), and used my former boat as an ice breaker in the destination harbor (and near frozen to death) on a December trip to Mamaroneck, NY.

Regarding loads and creep, I just went to the Colligo site to refresh my memory on their creep data, and could not find the relevant information. It seems to have been removed - Google cache still has it though.

Assuming the old data was correct, a load 12% of breaking strength would cause creep of over 3" per year in 50ft at 22 deg C. I'm not sure that is acceptable.

The question now is, was that old Colligo data valid, and what happened to it? Insofar as creep is probably the dominant consideration in sizing Dyneema for stays, it's important to have good information on it.

I'd also like to raise another point related to temperature effects, and that is the temperature dependence of creep. Creep is typically strongly dependent on temperature, and the equation on the old Colligo graph would imply that the creep rate for a given load in Dyneema doubles with every 4 deg C temperature increase. So in discussing creep, it is surely essential to indicate the expected ambient temperature. Temperatures in the tropics could easily be 5-10 deg C higher than the 22 deg C reference point used in the old Colligo data. Probably a topic for another thread, really.

Creep
 

Hi again,
No, no, the range is quite reasonable, just not so likely to happen in one day, for most of us. In the boats I've seen and rigged, day-to-day temperature changes don't seem all that significant. As for the creep data, John Franta from Colligo will be checking in here shortly.
Fair leads,
Brion Toss

Due to many issues with understanding the creep data (or misunderstanding it), we are keeping it interrnal now. We can assist with sizing Colligo Dux Rigging with anyone who asks. For the time this is how we size the line in order of priority:

1. Stretch
2. Creep
3. Breaking strength.

We almost always have the line at much less than 10% of strength effiiciency, mostly based on stretch. Creep is figured at pretension and 0.1" per year is a maximum target. (@22C). This seems to be a good conservative number as we have many boats now rigged with normal travel turnbuckles that have not gotten into creep issues. One 65' monohull in the Carribean. For offshore boats we factor in long term dynamic loads as well. Keep in mind that creep happens over time, so average temperatures are what you need to look at, or time at temp if you have access to that kind of data.

A couple of comments on pretension: Since steel has such a low creep rate, sailors for years have been over tensioning with no short term consequences. This makes it easy to over tension at the dock and cover for any load conditions you may encounter. Some long term issues may result, stainless stress crack corrosion, Creep in the fiberglass at the chainplates, etc., but who cares about the long term stuff we are Americans!

If you oversize slightly you will be really surprised how little tension you need with Colligo Dux Rigging. I just installed/tensioned the diamonds on a F27 yesterday. We used 9 mm dux to replace the 1/4 inch wire, oversized for creep. The 1x19 1/4" wire was previously tensioned at around 2,000 lbs to get the required mast bend. With the 9 mm Colligo Dux we tensioned to around 400 lbs to get the same amount of mast bend! Yes, we have loos gauge calibrations for it now. For a 50 foot length of 9 mm UHMWPE line at 1200 lbs pretension you will get about 0.1 inches of creep per year. So this is 400 lbs and only about 20 feet long, so creep will be much less @ 22 degrees C and can tolerate much more temperature before you get into creep issues.

I don't have the time now to go thru the thermal expansion math again but suffice it to say that pretension seems to take care of it. You should expect to adjust some over long periods of environmental cycles. Fall to winter, etc will need some adjustment if pretension is critical. I can tell you I met a customer at the Oakland show this month that has a Catalina 36 (with turnbuckles) and Colligo Dux standing rigging in the Bay area, (pretty big daily temp cycles) and he was literally jumping up and down with joy about the performance of his boat. The pretension seemes to mask the linear expansion/contraction of his rigging and it still stays in the performance window for stretch.

We did have a boat (50 foot ketch) that sailed from Argentina to Greenland that used lashings initially but after getting into the cold north needed to change to turnbuckles. Lashings are somewhat limited in their ability to create pre-tension.

So bottom line as I always say, this is a new material, it is not steel and should not be sized like steel. Stretch and creep are its limiting parameters. Do not, and I repeat do not size it for breaking strength. We also like to think of it more as plastic than rope as rope carries with it certain paradigms that do not apply here either. Did I say do not size it for breaking strength???

Hope this helps. Would like to say more but no time. Please stay tuned to our website for Newsletters and our Facebook page for more and more examples of this rigging. The proof is in the pudding.

John Franta, Colligo Marine

A return to thermal expansion considerations with Dynex Dux standing rigging
 

Hi John,

Thanks for your response. I would like to return to discussion of thermal expansion issues, which was one of the original topics of this thread. I will start a new thread to address the creep question.

As a starting point, there is the question of the coefficient of thermal expansion for Dynex Dux.

Do you believe the value I quoted above of -12E-6 per deg C (n.b., that's a negative value), which I found quoted in various places for Dyneema fiber, to be correct for Dynex Dux line? If not, what is the appropriate value?

Testing
 

Lets see, I spent about 45 minutes yesterday composing a posting with links for this discussion, only to loose the whole thing when I selected 'preview'. So before I go thru that again, I want to run a test.

Hi All,

Oh, good. This old chestnut.....again.

What all you data seekers need to realise is that Dyneema braid should be thought of as a structure, not a material and that all the data about UHMPE should be tempered with an understanding of how it behaves when braided/twisted/knotted.

The foremost authority on fibre and it's use in tension structures - Marlow... refuses to make any hard and fast claims about creep/stretch/thermal elasticity, solely because no one knows yet.

Use the fibre, embrace it's virtues and stop getting bogged down in minutae.

Talk to a RIGGER that is not out to make a quick buck from do it yourself rigging, and make your own mind up.

There are many many boats and rigs out there in Dyneema.

It is a legitimate material. It is tough. You wont break it. Your boat will benefit.

John Franta is to be trusted.

Regards,

Joe Henderson.

Well said, Joe.

cause of spectra backstay failure?
 

Hi,
I am a relative newcomer to this group; the answer to my question should be out there somewhere, but I haven't been able to find it. I have had some brief discussion with Brion Toss, but I still don't have a very convincing answer. The problem: why did my 2 year old spectra backstay break when I was still dockside? Some background...
My unsheathed Dyneema 6mm backstay (I believe it is SK75) from a reputable supplier broke after less than 2 years of light use. The failure occurred at the start of the upper eye splice when I applied the backstay purchase by hand when tied up in the pen. So far I have identified the following possible causes of failure, none of which seem entirely convincing to me.
1. Overloaded
The stay was definitely not overloaded – probably less than 30% of breaking load at the time (see end-notes 2 and 3 for details).
2. Chafe
There is nothing near the backstay up at the top splice so chafe is almost impossible to occur. A rigger specialising in synthetic rigging said it might be the cockatoos (parrots) pecking it. This happens to the dinghies in the dinghy park but I have never seen the cockatoos on the jetties here and there was no evidence of beak damage on the broken stay.
3. Badly made splice
The splice was longer than standard recommendation, though the amount of taper was not very much from what I can tell (Brion notes this is an important issue). It was made by a rigger who does a lot of plastic rigging work on both racing and cruising yachts, and has a good reputation.
4. U-V degradation
This is my main concern. There is a lot of variation in the data about how Dyneema etc. degrades with U-V exposure. Some reliable sources suggest a gradual decrease in strength by 20- 30% over 2 years, then stable thereafter (Brion mentioned similar figures). The stabilisation is probably due to the oxidised material forming a protective barrier over time, a bit like the oxide on aluminium alloy. I guess the actual figures depend on the amount and type of U-V stabiliser added to the rope. The u-v out here in Western Australia is truly fierce (the annual average noon u-v index is 8, and over the summer it averages 12 with many days over 13. I understand this is worse than Miami and much worse than the Med).
5. Fatigue
I have not investigated this possibility, but I noticed that one of the disadvantages of switching from a stainless wire to a braided rope backstay is the humming noise off the backstay in the wind. Given that the tension and the windspeed are the same for both materials, the two differences are the diameter and the surface roughness of the rope/wire. This may affect the Karman vortex street generated, which is a main cause of vibration, which in turn is a source of fatigue cycling. Fatigue properties of Dyneema?.....

My solution has been to revert to a stainless steel backstay seeing as I never has a strength issue with it. That is a pity given all the claimed advantages of dyneema, so I’d like to get to the bottom of this puzzle. The most likely reason I can come up with so far is a combination of a less than ideal splice, severe u-v degradation and possibly a helping hand from fatigue cycling. If that’s the case, we have a time bomb of rigging failures for uncovered spectra ticking quietly away here in sunny Western Australia.

Note 1: Materials selection criteria
An adjustable backstay is a different application from other standing rigging because stretch and creep are largely irrelevant, it is just a weight v windage trade-off (plus longevity and price).
Note 2 – Load calculation:
I applied the 24:1 backstay purchase by hand on my Van de Stadt 34 (when tied up in the pen). I estimate the load at failure (50kg*24=1200kg, less block friction) was at most 40%, of breaking load more likely 25% (see note 3 below).
Note 3- breaking load:
It is difficult to determine the true breaking load of the rope used - the supplier quoted 2,900 kg; Amsteel-blue shows 3,500kg; Melbourne Rope and Splicing Dutch SK75 says 4,200kg. I suspect the huge range may in part be due to some of the figures being safe working load whilst others are breaking load, or one of the many variants in between. Suppliers can sometimes be ambiguous in their definitions, and retailers are much worse. The bottom line is that the 7/32'' 1x19 316 stainless backstay at 2,450kg " breaking load" has worked fine for 30 years of use on this boat (rigging replaced every 8-10 years), so I should be able to account for safety factors etc. by sizing the plastic rope using the stainless as my benchmark

Hm
 

Hello,
Thanks for all the details. For the information of most of the people reading this, what follows is a follow-up to an earlier contact by email, and a delightful Q and A, via Skype, with the Freemantle Sailing Club.
So, to take things in order, "probably less than 30% is distinctly overloaded; 20% is a good design load for most rope (or wire rope), and 10% is good to shoot for with Spectra, in order to minimize creep.More on this later.
Glad to hear that the cockatoos hadn't been attacking your rope. We don't get a lot of that here in Port Townsend, either, though we do have problem with bird poop in blackberry season.
The splice does not appear to have been tapered at all (I have a picture under separate cover). According to Starzinger's tests, this could weaken the rope by at least 15%.Note also that, as creep progresses, the rope is somewhat weakened (https://www.dsm.com/content/dam/dsm/...plications.pdf). So now we have a stress riser, plus the effects of creep.
Next, a biggie for Spectra: UV. I agree that this is a time bomb in your part of the world; after two years with no treatment, uncovered Spectra could easily lose 25% of more of rope strength.
Finally, note that it is not you who applies load to that backstay, it is the wind. I recommend having someone monitor a tuning gauge next time you are under way, so see what the loads get to.
In sum, we have a not-great splice, plus undersized rope, plus time in the sun, plus uncertainty on loading. It does not seem surprising that the rope failed.
Try this with your wire backstay: use cable clamps instead of swages for your terminations. Use an undersized thimble, for a too-tight radius. Apply some tape along the standing part, to trap water and salt inside. In other words, do the things that are known to weaken wire rope. Of course that is a bad idea, but that kind of describes what happened to your Spectra backstay. I recommend HSR or similar, not Amsteel blue, for standing rigging, and I recommend sizing it appropriately. For your part of the world, a covered version seems important; you'll still save considerable weight.
Fair leads,
Brion Toss

hmmmm...
 

Great forum! Thanks indeed for your further thoughts Brion, and for putting the issue in perspective for the general reader. I still think there is something unexplained going on, and would appreciate further ideas from yourself and others.
So as I understand it for the general reader we have to note that:
1.
Whilst variations in splicing technique will lead to fluctuations in breaking load, so do fluctuations in wire swage tolerances. And its probably a lot easier to tell if a splice has been done badly than it is to tell if a swage has been done badly. Advantage plastic rigging.
2.
Both plastic rigging and stainless wire degrade in the environment - plastic due to u-v and wire due to salt etc. (however, the degradation rate in wire increases as it gets older whereas the degradation rate in plastic is greatest in the first few years then levels off). U-V degradation of Dyneema implies a covering is advisable in extreme sunlight. No advantage to either plastic or steel, just different.

Then to the specific case of the broken spectra backstay:
The load in this case was not applied by the wind, it was applied by me pulling the backstay tackle on in the pen before we even put the sails up. This is just a standard cruiser-racer with a standard block and tackle. I have sailed on lots of boats that apply a very much higher pre-tension in their (wire) backstay. Without revisiting the sums, the bottom line is that the spectra broke when the backstay tackle was applied whereas the wire never broke under very much higher loads exerted by the exact same backstay tackle plus the much bigger loads of wind and waves. This despite the plastic rope having a higher quoted breaking load than the wire. Even when you consider all the factors (u-v –salt corrosion, splice quality, swage quality, creep-induced weakness etc.) it just doesn’t add up that a stronger plastic rope breaks at a hugely lower load than a weaker stainless wire.

There’s something missing in the analysis which needs a bit more investigating. Suggestions, anyone?
Kim

Loads
 

Hi again,
According to one insurance company's claims for dismastings, most occur in low windspeeds. This has to do with characteristics of metal, especially work-hardening, plus wave action, plus most boats are in relatively low winds most of the time. It is not because low windspeeds inherently make things break.
Likewise it is safe to assume that your backstay didn't break because you pulled on the tackle under way. It is far more likely that it had been approaching breaking for quite some time, and when you put the load on it (an unknown load, I will add), your effort exceeded the rope's capacity to stay together.
And I disagree; I think that it does "add up" that a series of factors resulted in an ostensibly stronger rope breaking, when wire in similar circumstances didn't. It was rope not optimal for standing rigging, it had an at best utilitarian splice; it was sized far too small for the load, it had been living, unprotected, in very harsh sunlight, and, perhaps most importantly, we don't even know what the rope was, so we can't make any judgement relative to its original quality. Too many variables.
For one chart on the expected behavior of Spectra in UV, see file:///C:/Users/Brion/Documents/Rigging%20Information/Rope/US%20Sailing%20Spectra%20UV%20chart.htm. You can find the original document, which is about lifelines, here: http://www.ussailing.org/wp-content/...n%2020 14.pdf.
Fair leads,
Brion Toss

cause of spectra backstay failure?
 

Hi,
Fascinating article by Evans on Spectra lifelines, thanks.
I think we are more or less agreed on the need to protect spectra from sunlight in extreme climates, and that quality control of splices requires comparable standards, and has similar implications, to the required QC on wire swages.
We shall just have to agree to disagree for now, about whether the load I applied to the backstay was excessive. Seeing as nobody else has posted on this thread recently I'll close. If I get the opportunity to take some load measurements I may revisit the discussion.
In the meantime thanks for a very enlightening and thought-provoking thread. As with most research, questions lead to more questions!
Kim

I am interested in rerigging my sailboat and trying to decide what material to use. When I read all the comments about synthetics 25% strength loss due to UV, failure due to incorrect splices, increased cost, why use it? Standing rigging is pretty important. Why spend so much more for a rig that deteriorates so much so quickly?

To start with synthetics typically start out around double the strength of steel wire in order to control creep. So you loose 25% of the strength and still have rigging that is 175% stronger than the wire it replaced.

Stumble, true enough. But, for some it's not that simple. I have dyneema life lines--and I like them. I incorporates a dux forestay for my stays'l so I could gain some personal experience with dux. So far, it has held up well in the tropics for the past three months. I've had it on the boat for 9 months. All that time with bronze hanks for the stays'l. No complaints. I briefly considered going with dux for all my standing rigging while building the new mast for my 8 ton bermuda rigged cutter. I liked the whole idea, especially the ease of splicing and the lighter weight. But, as I recall I had to go with 5/8" turnbuckles as I needed 9mm dux when sized for creep. Have you priced them lately? Yow! The rig is too big for dead eyes. When I priced it all out the whole dux setup was nearly three times the cost of 7x7 316 SS that I spliced myself and that did not include the price of the bigger turnbuckles delux required. I expect to see very little work hardening in the standing rigging with Liverpool splices around bronze thimbles. I think I should be able to get 10 good years out of the 7x7. I can see any sign of fatigue in my rigging pretty easily. That is not to say that it's perfect. I do like dux and it may well be the way of the future. It was just more than I could afford at the time and way more than what I ultimately went with. In time, I think dux will get less expensive. I also was not completely confident in how it would hold up over time and my ability to recognize when it needed to be replaced. How does one really know? I would never rule dux out though. I particularly like the new EHLF dux furling system Colligo is selling. Very cool. I'd love to have a test rig of dux on my boat that I could swap out with my current standing rigging setup and compare the performance and ease of tuning. That would be very interesting.

I would also say I have had nothing but great experience with John Franta and Colligo.

It used to be that Dux was the only game in town, but these days there are real competitors out there. It may be too late now, but I would suggest taking a look at some of the other heat set dyneema ropes out there, some, particularly the Alpha Ropes, are substantially less expensive.

For a side by side comparison see.

http://www.chicagoyachtrigging.com/stretch-test/