The Offshore Voyaging Reference Site

Dynice Dux, Part 1: Practical Low-Stretch Rope Rigging For Offshore Sailboats

Since writing about the three refits I’ve done for offshore voyaging, the most comments I’ve received are from people interested in the synthetic Colligo Dux rigging we fitted on Arcturus. That rigging project was the funnest part of the entire refit and, six years later, Arcturus is still sailing strong with her synthetic shrouds and lifelines.

But Dux is not for everyone, nor is it suitable for every use. So here’s a look at what it is, where it’s great, where it’s not so good, and why it can be considered to have already passed John’s 20-year field test.

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Richard Dykiel

Looking forward to your part #2. Meanwhile a couple questions regarding the lifeline application. I just redid my life lines with standard dyneema. The only splice I know to do in that application is brummel lock splice:

– Do you have an example about splicing dyneema around a thimble? Could not fund an easy one to follow on the net.

– Are you sure about using dyneema for the lashing? Isn’t it too slippery for this application? I used a small diameter spectra line (I was even ready to use tarred seine 🙂


John Harries

Hi Richard,

Just to clarify, I’m pretty sure that Dynema and Spectra are the same materials, just different brand names. They both have the problem of slipping though knots. That said I have used Spectra lashings for years without issues. The secret is a lot of half hitches (at least 20) around the lashing and then, if your as anal retentive as I am, sew the end down.

Richard Dykiel

OK the multiple names are confusing. But the spectra line felt definitely less slippery than the 1/4″ Amsteel I used for the life lines. I agree on the half hitches frenzy.


Some of the different companies dye the line different colors, and this can add a sort of ‘stickiness’ to it. In some cases this is good, in others it’s bad – for example, the slipperiness of the line actually allows for easier tensioning when you’re doing a lashing. Tie it off right and it won’t slip at all, and this becomes an advantage. The stickier, dyed lines are harder to tension properly.

John Harries

Hi Andy,

I never thought of that, but I can confirm it’s true. Just bought some blue Spectra and it is indeed harder to get a lashing tight with it, as against the natural colour stuff. Great tip.


I installed dyneema lifelines on my previous boat. For the lashings I used double braid with a dyneema core and polyester cover. No trouble with slipping or making half-hitches.

Marc Dacey

Andy, how is Dux different from PBO, which was being touted as the way forward in “soft” standing rigging about a decade ago? I find some of these trade names/generic names somewhat confusing, particularly in the Spectra/Dyneema/Amsteel realms. I certainly agree they are great products when used selectively: I went to four Dyneema-core, Dacron covered halyards last season (6mm core, 1/2″ cover) and am very pleased with the results. (By the way, this stuff is far cheaper by the 500 foot reel and you’ll use what you have left over). I haven’t, however, felt the need to change my mainsheet tackle, staysail halyards or sheets, where lack of creep is less critical and is sometimes desirable.

John Harries

Hi Marc,

PBO is a completely different material than Spectra/Dynema/Ansteel, which are all the same thing. The really scary thing about PBO is, as I understand it from a professional rigger, it loses a lot of it’s strength when wet! That’s why PBO shrouds are always covered in a plastic shell. Also, PBO can’t be spliced, it is wound to length.

Marc Dacey

Ugh! No interest, then, as it sounds very limiting and, frankly, unsuitable. Thanks for the warning.


Interesting article, thanks. Like the backstay idea.
Another use for dyneema never mentioned is for temporary repairs – if you mix dyneema fibres in with some epoxy it can make a really strong joint. My Aries windvane connecting rod is probably stronger than new 🙂


Hi, that idea of synthetic backstay antenna is neat.

Just that it might require a bit of further attention to work on all condtions.
There’s two possible issues:
– How performance is affected when the stay is wet, and there’s no additional insulation bits between deck and lower end or mast top.
– How to make sure that insulation is sufficient to avoid it to arc to crew members from backstay.

With 150W HF set, probable highest voltages on feedpoint end might be something like 1000V. That’s too much for regular 600V wire insulation, so arcing might happen along wet backstay – or to head of the helmsman, if almost touching the stay.
And, yes, 150W of RF doesn’t kill, it’s more of a nuisance, so this thing is not a life-or-death issue. (Except, perhaps, antenna performance on emergency, usually during a storm.)
Also, the whole wire from antenna tuner below to mast top is part of a radiating antenna. So, wire exiting from deck should have extra insulation.

Personally, I would use high-voltage tested wire as antenna wire, e.g Huber+Suhner Radox 125, that is tested with 3500 volts on delivery and is tinned. Though it has an insulation that resembles more of a bicycle brake bit than PVC, so it might be a real nuisance to get into the rope. Perhaps better to attach it externally. Shouldn’t be much of additional windage.
That way, wire insulation takes care of RF insulation.
If HV tested wire is not readily available, adding heat shrink to whole wire might improve insulation sufficiently.
Sorry for a long-ish post…


Now, it migt be a bit heavy-handed to dismiss 600V cable as unsuitable, since it seems that the test voltage for a cable that has 600V continuous rating is about twice of that. Exact data is on UL and IEC test standards, that are not readily available. Thus, e.g. regular Ancor 14AWG marine cable or similar, or EN H07 2,5mm2 that is rated to 750V continuous, could have sufficient insulation.

So – If cable has extra shielding (heat shrink) below head height and cable rating is at least 600V, it seems that it would work okay.


Thanks for the comments gang, sorry for my absence. Just dropped anchor in Portsmouth, VA after a gorgeous overnight sail down the Bay – the last time Isbjorn will sail the Chesapeake for at least 3 years! I’m back ashore now and look forward to commenting on this and the next in the series about Dux!

Hans J.

It’s probably a stupid question, but hey, it’s better to be stupid for a second than for the rest of your life. How are the Dux/Dyneema ropes holding up against wear and tear for standing rigging purposes, compared to wire rigging? Will the UV kill the Dyneema rigging faster than corrosion kills steel wire or does Dyneema offer benefits there too?


UV is indeed the culprit. Stay tuned for part 2 where I address this in detail and answer your questions!


So other than avoiding meat-hooks on lifelines or a lightweight warp spool, what is the motivation for using these materials over standard rigging? Always thought this was for racers shaving every last ounce.


1. More righting moment = less heel, more power upwind.
2. Easiest DIY rigging solution going. Easier to stow (no rust), easier to splice & make jury-rigs.
3. Potentially longer-lasting, but the jury is still out.
4. Easier on hands, sails & any other soft materials.

That said, limited in standing rigging applications to those who have a curiosity to it and are hands on. There’s an education gap with the folks who don’t do their own maintenance and not enough riggers fully understand it as full-blown standing rigging. Dux is not dyneema, even though they start as the same thing. That causes confusion.

Marc Dacey

I wonder about the use of Dux in snubbers or bridles (wrapped around those rubber shock absorbers?) It strikes me that certain sizes of Dux might be stronger than chain or shackle.

Or, perhaps in mainsheets? Do you see other uses around the boat?

Ronnie Ricca, JR

Glad to see you put the post up on here! We recently just finished rigging our Kaufman 47, a 30klb high aspect cutter sailboat. We have still have to take her out sailing and tune the rig, but other than that it’s complete. Couldn’t be happier with it and the team at Colligo. John and Joe are absolutely great to work with and they are very knowledgeable about their products. As soon as we get the rig tuned and have a few sails on it we are going to write up a nice piece on it. We definitely shaved a good 150+ pounds off our rig aloft which I think will be a great improvement in pointing upwind.


Eivind Haugan

As ‘pensioned’ offshore racer, I like to keep my cruising boat (a Danish X-Yachts, X-50, so I guess a lot of you wouldn’t see it as real deep water cruiser) with the tools to keep it going fast and have well trimmed sails.
My boat like the two previous yachts it have been equipped with Dyneema halyards and sheets of DSK 75 quality. Last year however I replaced an 7 season old roller furling halyard with DSK 90 from Gottifredi Maffioli, which is also a heath treated Dyneema rope. The step-up in quality was without doubt noticeable, as there was no longer a need to tighten it regularly due to creep. So there is definitely a way to increased performance by heath treatment of Dyneema, I believe that you could have added the trade-off between price for high-quality and size. In my case I could have opted for an even higher quality line, DSK 99 in 10 mm, instead of 12 mm DSK 90. But as a thinner line will have less resistance to UV, more prone to chafe as a result of it being less material and finally the 10 mm line would less safe in the selftailer on the winch and the halyard clutch. The was maybe a bit to technical and boat specific, but the point that I feel you could have made is that for a lot of uses, the possible trade-offs between price and quality can be used to keep costs down or increase safety margins.

For me with an discontinuous three spreader rig a change to Dyneema based rigging is not an easy change to do. But I fully agree that for jury rigging high quality/low stretch rope is the way to go, and as such an important recommendation for all long distance cruisers.

I would also like to add that the article would be of better use for your global audience if it was less product specific, as Dynice Dux is not available everywhere. And I also feel you underestimate the knowledge of a lot of riggers, as I’m quite confident that it would be easier for me to find that skill than a local reseller of Dux.

John Harries

Hi Elvind,

I too am a pensioned racer, so I totally get you desire to keep your boat performing well.

In your comment: “the article would be of better use for your global audience if it was less product specific”. I can certainly see that in a perfect world Andy would have covered all of the high modulus rope rigging options available, world wide. However, that would not be in keeping with our editorial focus. Here at AAC we mainly write about products we have real first, or at least reliable, second hand experience with and I think that’s a lot of what makes our content as valued as it is.

When you see an article in a yachting magazine that covers an entire genre of products it is almost always sourced from a bunch of manufacture press releases and web sites warmed over and reworded by a journalist who may not even have used any of the products. Worse still, it will be carefully worded to include every manufacturer and not to upset any of them so the magazine’s people use said piece as an advertising sales lead in.

To me, real experience is a lot more useful than that, and can often be extrapolated by the reader to apply to other products of the same type.

Eivind Haugany

I get your point about only recommending only products that you have used yourself, but then it gets a little bit limited in its use. So additional comments and specifics about the technical/physical abilities of the product would have been appreciated and extend the usefulness of the article.
An additional comment would be that the use of rope as lifelines is a bit contrary to your otherwise belt and braces attitude to risk, and there are a lot of wet racing crew members that can testify that these are more prone to chafe than wire. And as it is pointed out some race organizers don’t allow them, RORC in England amongst others.
Thanks again for an informative website and your quick replies.

John Harries

Hi Eivind,

Good points. One more editorial issue. Please understand that just because Andy recommends Dux for lifelines does not mean that I do, see our editorial policy here:

Chuck B

Hi Andy, great info thank you! I have no experience with Dyneema (yet) but I love the idea of easier to manage spares, lighter weight, and easier to cut away in an emergency.

What are your thoughts on using it for steering cables?


John Harries

Hi Chuck,

I’m not sure what Andy’s thoughts would be, but I would definitely not use Dux for steering cables. Any creep at all, even just that from the splices setting, could cause the cable to jump a sheave. And then, being a soft material I can see the Dux getting jammed between the sheave and the shell to make things way worse. In my experience, good quality wire lasts at least 20,000 miles as a steering cable, and is easy to check (just run a paper towel along it to check for broken strands)—classic example of it’s not broken (wire) so don’t fix it (with Dux).


Good information, thank you. We carry 2 emergency Colligo stays onboard our Moody 40 that store easily in a small compartment. They replaced the huge hoop of stainless rigging wire that we originally had to store lashed to the rail. They come pre-made with instructions and a wooden fid to make the necessary splices. Great product.



Can I clarify your usage of the term “Dux.” To me it is a proprietary heat-treated form of Dyneema (SK75/78) but at times I get the sense that you are using it as generic for UHMWPE.

If you are using it in its specific meaning, then I’d argue that it is not the most appropriate material for lifelines. Heat treating UHMWPE reduces creep and improves strength, but is more costly, degrades abrasion resistance (or merely maintains it – depending on source – but does not improve as suggested in the article), and demands a larger bending radius to avoid failure.

As lifelines are lighlty pretensioned, creep is not a factor as it is in standing rigging. Ultimate strength of UHMWPE (which is what matters for lifelines) is already better than that of the steel + plastic coating of the same diameter. Increasing the strength and decreasing the stretch further by going to Dux will also put greater peak loads on your stanchions and their bases which judging by most boats I’ve seen are already the weakest link in the system.

Altogether, in my opinion, for cost, performance, and availability, the average sailor would be better served using the Spectra or Amsteel found at every local chandlery.

John Harries

Hi Philip,

It’s unlikely that Andy will answer. See comment guide line #3

That said, I edited the piece and I’m sure that every time Andy used the term Dux, it was the proprietary product from Colligo Marine he was referring to:

As to using any of these high tech rope products for lifelines, and having read quite a bit on the subject, I’m still in two minds about it, and therefore we have stuck with uncoated 1×19 wire on our boat.

John Harries

Hi Philip,

The Colligo requirement to change lashings every two years and the lines themselves every five adds to my general feeling that 1 x 19 wire is still a good solution.


Thanks John,
I had decided to try Dyneema lifelines, but maybe I should take another look at bare SS. I don’t remember an article around here about SS benefits in this application – do you have any recommended readings?
Also, to be clear: my comment was more that if one was going use Dyneema, I don’t think Dux is the right subspecies. I did read the Colligo material – sounds like propaganda to me. Small amounts of stretch are your friend in lifelines the same as in jackline tethers, creep isn’t relevant in this application, and you’d need to prestretch the construction stretch out of Dux lifelines the same as regular Dyneema lines if you make them yourself. Their advertising ignores all of this.

John Harries

Hi Philip,

No, I we don’t have any specific reading on SS lifelines. That said ours are now 12 years old and still looking fine with no indication of problems at the swages. I would guess at a shorter life in the tropics and/or full time use. (We have been laying up most winters and also spent 18 months out of the water when I broke my leg.)

Bottom line, I guess my thinking is that if it (uncoated 1×19 wire) works, don’t fix it. I’m also not sure that there is any real benefit in stretch in the lifelines. That said, creep might be a negative issue. The one thing I’m sure of is that coated wire is a bad idea.

I thought Colligo’s page was actually quite useful. Sure, they are trying to sell something, that’s their business, but they were honest about the replacement cycle.


Thanks John,
I want you to know that I do respect your opinion. I have no intention of being argumentative but I do just want to explain why I said the above and then I promise to leave it at that. But I’m happy to learn if you see somewhere I’ve made an error in rationale please point it out so that I can adjust my thinking/plans.

Stretch: I’m not suggesting that we seek out stretch, only that the striving for the absolute minimum stretch is irrational when it means accepting undesirable features in the fiber or decreased performance of the system. Just like your comments about not using high modulous lines for lazy jacks, we need to look at the system as a whole. We are not looking for bungee cords, but once a line has low enough stretch to keep us safely aboard and to reduce chafe to tolerable levels, more resistance to stretch only transfers higher shock loads to the other parts of the system: i.e. stanchions, their bases, and the deck, hardware, and sealant underneath. This is a case where increasing what we think of as a positive attribute in one part of the system could lead to it’s failure as a whole – like adding ballast without upgrading the rigging to handle the larger righting moment.

Creep: Creep needs 3 things to be a problem. Strain, time, and the inability to take up the slack. Lifelines are just not under that much strain (even proportionally to their smaller diameters) until someone falls against them, and then it is only for a very brief period. So it is much less of a concern than in the standing rigging. In addition to this, even if it did creep some, lifelines are lashed and so there is a lot of capacity to take up the slack. Why I’m disappointed in Colligo is because they know this material intimately and because the ‘allowable creep with lashings to take it up’ model was how they started doing rigging. Iirc it wasn’t until about when they started focusing on compatability with turnbuckles that they needed to increase line sizing specs to target minimal creep. So, I don’t think this was an oversight but rather hiding part of the story to peddle their proprietary line instead of a widely available cheaper one that would satisfy the needs of their customers as well (and I believe better). Like an Danforth “High Strength” salesman who preaches to a voyager planning on going to kelp infested Baffin about the ultimate holding power but doesn’t mention how the shank has been known to bend.

I have been reading Colligo’s information for years (along with users experiences like Paul Calder, the Rigging Dr., and the Zartmans – although I think they used sheathed Vectran). I really do appreciate that they have been a tremendous resource to informed me about this subject. I’m concerned though that there is not a clear delineation between education and advertisment. But I guess I have the same concerns even about sailing magazines these days.
I had planned on going to synthetic rigging and lifelines, but the more I read around here the more I feel like I may just stay with 1×19 for both (bare).

Philip Wilkie

I know this is an old thread, but this interview with a well respected local rigger is pertinent:

I’ve met Peter and several cruisers with Dyneema rigs he’s done for them; and so far all I’ve heard are low key ‘no drama it just works as advertised’ responses from everyone. More than 80 re-rigs with no problems is starting to be a reasonable dataset.

The only problem is that Peter has retired this year.

Eric Meury

hello john and andy Owner of a Garcia Passoa here. The boat is brand new to me and is way past due for a rerig. I’m having the boat redone including the backstay with colligo dux. Everything except the fwd stays as both will be on furlers. I’m wondering if you have any updates thoughts since his post was first put out

John Harries

Hi Eric,

I’m still of the opinion that wire is a better bet for offshore cruising boat standing rigging, with the exception of running back stays, than Dux or other HM ropes. My biggest concern with rope for both standing rigging and life lines is still chafe.

Not sure what Andy’s thoughts are now, but if memory serves I think he is still using wire on his newly refitted boat and the older Swan 48, except for runners and maybe the permanent back stay.