Synthetic Standing Rigging: The Modern and Traditional

12 Oct

In my last rigging post I gave a quick rundown on how we stepped my mast, and some of the hardware specific to the synthetic standing rigging I am using. My rig is lines of Dynex Dux spliced and fitted with deadeyes and lanyards by Colligo Marine. In this post I want to look at the specifics of this rig, especially the unusual tensioning system Colligo has re-introduced in place of the ubiquitous turnbuckle. Colligo’s deadeye and lanyard setup is made possible by the use of high-strength synthetic lines but is actually a throwback to the rigging used for centuries before the introduction of wire rope. 

Colligo Dynex Dux rig on a Westsail 32 (Photo Credit: Colligo Marine)

A deadeye (which gets its spectacularly heavy-metal name because the most common configuration of three holes in a triangular pattern looked similar to the empty sockets of a skull) is simply a block, traditionally of lignum vitae or another hardwood, which has holes bored into it and through which runs a lanyard. This accompanying lanyard is a length of line, traditionally a natural fiber rope, which runs through a pair of deadeyes to form a very simple static tackle. This can then be attached to a shroud or stay (or in other applications) and used to produce a good deal of tension. For many centuries before the introduction of wire rope this was the system used on sailboats for standing rigging. 
A shroud on the tall ship Excelsior tensioned with a deadeye and lanyard (Photo credit: Wikipedia)
 On my boat lignum vitae has been superceded by 6061-T6 aluminum and the fiber rope by Dynex Dux synthetic rope but the centuries-old principle is unchanged.
Two of my shrouds
To understand what this ‘new’ system really brings to the table we need to look at what sailors have been using to rig their vessels for the past century- wire rope. Whether stainless steel or the now nearly-obsolete galvanized variety wire rope is a far superior material for most standing rigging than the natural fibers which preceeded it because of greatly increased strength and virtually non-existent stretch.
Typical rigging installation on a small sailboat. The shrouds terminate in turnbuckles. One is covered with PVC a move that is intended to minimize chafe but may increase the potential for corrosion.
 However, with these advantages come a new set of problems stemming from two properties of stainless (and other) steel – that it tends to corrode when not exposed to air and that it fatigues under flexing of any kind. When rigging a sailboat with stainless steel we force the material to take on the properties of rope by twisting strands together in a process which creates a variegation of corrosion-susceptible crevices and then we terminate it in ways that often wick in water and create further opportunities for corrosion. Lastly we install it on a boat as part of a system- the rigging- which is prone to a great deal of flexing. 
Failed wire rigging (Photo credit: dmccarthy, SY Lady Shamrock)
Simply put, it takes a lot of cajoling to make rigid steel perform a task meant to be filled by rope and while it can be done it is nonetheless a complicated and imperfect system. Not surprisingly, the failure of stainless steel wire rope and its attendant fittings is one of the more common serious dangers that sailors face. Nevertheless we put up with this because there just isn’t much else in the way of options. 

Dynex Dux – An alternative to wire rope?
 What interests me about new synthetic lines is that for the first time since the widespread adoption of wire rope rigging they offer an effective, rugged, and affordable alternative to this material. Now obviously I’m not talking about Spectra or PBO or Kevlar or any of the myriad of high-tech options used by racers. While they have their merits to some none of these meet the criteria of rugged and affordable which I am looking for in a rig. I’m talking about the newest iterations of synthetic rigging which use high-strength Dyneema-based line (Currently the forerunner is Dynex Dux, made by Hampidjan. It is essentially braided Dyneema which has been annealed by stretching it at high-temperatures). While high-tech these new lines are actually cheaper, by the foot, than stainless steel wire rope. They also represent a potential game changer in the rigging industry because they allow the return from faux-rope steel wire to genuine rope. Much of the noise generated about this stuff focuses on the reduction of weight aloft but to me this is just icing on the cake.  I think the real potential for the budget-minded, weekend, cruising, or whatever sailor is that these synthetics, being lines in the most literal sense, do not share the fickle nature of steel wire. Synthetic rope has potential to eliminate many of the modes of failure which plague sailboat rigging because it bypasses much of the complexity that is required to make steel act like rope. 

Which brings us back to deadeyes and lanyards. First, let’s do a little side-by-side comparison
A typical attachment for stainless wire rope shrouds
These are two of my three starboard shrouds
Now tell me, which do you think has more potential points of failure? On a typical wire rope installation each shroud has at least four and often more than six pieces of attachment hardware (ie. a swaged terminal or compression fitting and a combination of forks or toggles at each end, plus a turnbuckle at the base). This hardware, especially turnbuckles, is mechanically quite complex and has many points for crevice corrosion to start. 
An array of fittings used for wire rope rigging (and one or two for rod)
My rig, on the other hand, has three fittings per shroud- two deadeyes at the base and an eye at the mast which attaches to the tang. These fittings are solid pieces with a few holes bored in them – mechanically about as simple as it gets. This simplicity allows them to be made from anodized aluminum which is less prone to corrosion than stainless steel and shows damage or corrosion more readily. Compared to turnbuckles these things are bulletproof – I really can’t imagine a way for them to fail other than through many years of hard use and with plenty of warning signs.
My line terminators attaching the lower shrouds to the mast. There are only two types off fitting in the entire system.
As for the rigging lines, they are spliced directly to these aluminum deadeyes/thimbles – a virtually fail-safe attachment when done correctly which is far more reliable than swages or even mechanical terminations such as Norseman or Sta-Lok. Here, already, we’ve eliminated failure of swaged or compression end fittings, failure of turnbuckles, and failure of wire rope due to stresses at the point of termination – this is something like half of the common causes of rig failure! In a move from wire fittings to deadeyes/thimbles there is also great potential cost savings in having just a handful of very simple fittings rather than an array of meticulously machined parts. These deadeyes/thimbles are also all the same, including those at the top and base of the rig. There is one which functions as a deadeye and thimble for an eye splice and a second as a deadeye without an eyesplice. 
The second type of fitting, a deadeye without thimble
Actually, having two fittings is only for aesthetics- the deadeye/thimble would work equally well everywhere which means that for replacement I would need to carry only one part. At least in theory , in terms of reliability, safety, longevity, and cost my deadeyes and lanyards are a far superior system to the terminals and turnbuckles necessitated by the complexity of wire rope. But theory is one thing, and the real world another. So how do they perform in practice?
My backstay all lashed up
Mechanically these parts a simple, light, and extremely rugged. That’s great, but as they are a means tto an end the real question boils down to one thing- how well do they hold the mast up? Tensioning the rig with  Colligo’s deadeye and lanyard system is simple in theory but rather tricky in practice. It is also, I find, quite fun. The system works like so: the stay or shroud terminates with a splice on the deadeye/thimble (They call them ‘terminators’) which is drilled with four holes. Below it, attached to the chainplate with a standard clevis pin, is a second deadeye. Running between them is a lanyard of Dynex Dux sized significantly smaller than the stay or shroud. This line runs through the eight holes on the end fittings to create a static block and tackle which allows you to tension the rig. 
Using the deadeyes to pull slack out off the rig
With the exception of final tensioning on the shrouds, which I’ll come back to, it is not possible to get a strong enough grip on the small, slick line used as a lanyard to tension by hand. Instead this is done by taking a convenient line and running it to the end of the lanyard. You then tie the two together and use a winch on the temporary line to get sufficient tension. I use a halyard.
A futile exercise- to get enough tension you need a winch!
 This part is simple. What gets a bit tricky is releasing the tension on the bitter end of the lanyard and tying it off without losing tension on the rig. The knot used is an ingeniously simple one- essentially a series of half-hitches that are rolled under and pinched up against themselves in order to create friction.
The deadeyes create enough friction that even with a great deal of tension on the stay you can hold the lanyard off with just two fingers but nonetheless releasing the halyard and holding tension on the lanyard while tying it off is a job for two people which takes a little getting used to. I’ve found it impossible to manage without at least a slight loss in tension so I’ve learned to over-tension a little in order to end up where I want to be.
My father and I tying off the backstay when we stepped the mast
Even doing this I’ve had to re-tension the rig quite a few times. I don’t doubt that the lion’s share of this re-tensioning was due to my own inexperience but my father, who probably knows what he is doing more than I, also found that is Dynex Dux rig needed pinching up after the initial installation.  I suspect that this readjustment is simply inherent in a tensioning system consisting of a static tackle which is tied off with a simple knot- much like installing a brake cable on a bicycle there is bound to be a little slack somewhere in the system which is pulled out during initial use. The question which remains is whether this is merely an issue of re-tensioning a few times during initial use or if this is an issue with the system. In the case of the former, which is what I think is going on, I see this is a non-issue – a system of deadeyes and lanyards, involving a separate line, a static tackle and a knot will of course be a little more labor intensive and complex to adjust than a turnbuckle. Regardless, tying a couple of knots and cranking on a winch a few times is a small price to pay for all the advantages of increased reliability that come with a deadeye and lanyard system. In doing some online research I have found many owners of Dynex Dux rigs (typically from either Colligo Marine or Précour) who have had Dynex Dux rigs for a period of years with no tension issues beyond initially figuring out how to handle the lashings.
            If, on the other hand, I find that the rig continues to require re-tensioning I may consider going back to turnbuckles. Colligo’s Dynex Dux works just fine with turnbuckle tensioning and in fact this is often the only option on large boats (I think the cutoff hovers around 40-45′) on which it is impossible to get sufficient tension with deadeyes and lanyards.
Dynex Dux rigged to turnbuckles on an Open 60
 For now, I quite like fiddling around with my boat and (at least so far) I haven’t found this re-tensioning task at all onerous. Rather it is a fun experiment learning how to use this technology. This is especially true of the shrouds for which the easiest and most fun method of tensioning is to sail close-hauled in a nice stiff breeze and (one at a time!) untie the upwind shrouds, pull out the slack, and re-tie them.
Pinching up the shrouds while underway
 I’ll be sure to keep reporting on the status of the rig and whether I find a way to keep things tight. I suspect much of the problem is that I’m being a bit timid with the winch and need to just crank the whole thing down tighter than I have been.
So that’s my rig, and the tensioning system. While I still don’t entirely have a handle on it, I’m quite enamoured and having a lot of fun learning how to use it. However, even if it works well at first all the potential advantages to this high-tech ‘traditional’ system of rope rigging is very much dependent on how well the line itself holds up. It is also important to consider the possibility of introducing new modes of failure specific to this new technology, foremost among them being UV damage. While wire rope involves pitfalls with its termination system the wire itself is reliable, long-lasting, and will nearly always warn of impending failure by stranding – when you see a single broken strand in a wire rope you know it is time for a replacement. What about Dynex Dux – how long does it last, how does it wear, and how can we know when failure is imminent? These are the questions I’ll look at in my next post.

What is the working life of Dynex Dux?


 See my:
 Index of DIY and How-to Posts

First and second posts on synthetic rigging.

This article was syndicated from Safe At Harbour But Meant For The Sea: DIY Sailing with Paul Calder


  1. Interested

    Thanks for the writeup, was looking for info on tensioning
    and lashing.

    Seems you have a typo: “untie the upwind shrouds”, should
    be the downwind or leeward shroud no – the upwind one
    will be under load.

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