Advice/comment please.
I have an elderly Smokers (3076).  Hog stepped mast with 3mm stainless shrouds running to simple quadrant levers through fairleads in the side deck -  as I understand it, a bog standard arrangement.

Yesterday, when setting up we had a catastrophic failure (technical term, meaning - it broke) of one shroud at the exact point where it entered the metal fitting which links to the quadrant lever.  I am now replacing both. 

However there is no sign of damage on the other one, nor is there any evidence that the metal fitting has been incorrectly crimped and put the shroud under stress.  I should add, that I have no way of knowing how old the shrouds are, but I had checked them during the winter with no loose ends or signs of wear.  The only difference to the norm that I can think of is that we were trying greater rake which would presumably have moved the pressure point on the shroud.

Questions:  Is this in any way related to the change of direction as the shroud passes through the sidedeck?  Alternatively is it linked to the metal fitting coming too close to the point of change of direction?  And what, if anything, can I do to minimise the risk in future?

Look on the bright side - it could have happened on the water and really done some damage.

Exactly the same did happen to us on the water in 1620 a few years ago. Windward shroud broke with zero warning in a really strong breeze and of course we lost the mast. Like 3076 the shroud broke off right where it entered the fitting; no particular stresses or kinks there, and no previous signs of weakness. The other one was in absolutely perfect condition; I was unable to break it even using tools designed to that effect.

It did teach us to have a small budget to change them every now & again.

Bill,

I have used similar sytems and have two bit of advice. 1) use plastic only deck fitting so the wear is on the plastic not the wire, it's cheaper to replace the plastic fitting than the shroud! 2) When you get new shrouds made up get the rigger to leave about 1/4 inch sticking out past the splice, this will reduce the hard point where the wire emerges from the metal splice and should make the shroud last much longer.

BECAUSE I AM NOT FAMILIAR WITH THAT SHROUD ARRANGEMENT AM NOT QUITE SURE FROM YOUR DISCRIPTION EXACTLY WHAT YOU MEAN. HOWEVER, HAVE NOTICED THAT A GOOD NUMBER OF RIGGERS INCORRECTLY TALURIT THIMBLES (HARD EYES) INTO WIRE.

WHAT THEY SHOULD DO, BUT DO NOT ALWAYS, IS TO PUT THE THIMBLE IN LOOSE - NOT SO LOOSE THAT IT FALLS OUT OF COURSE BUT JUST LOOSE ENOUGH TO BE MOVED BY HAND. IF THE THIMBLE IS NOT LOOSE THEN THE WIRE IS PRE-STRESSED & IT IS DIFFICULT TO TELL BY HOW MUCH...

OFTEN THE RIGGERS WILL SAY THIS IS NOT NECESSARY BUT THAT IS SIMPLY BECAUSE IT IS EITHER EASIER TO DO IT THAT WAY &/OR COVERS A MISTAKE. THE MECHANICS INVOLVED WITH A TALURIT MACHINE ARE SUCH THAT SMALL DIAMETER WIRES CAN BE CONSIDERABLY PRE-STRESSED & SOMETIMES EVEN BROKEN IN THIS WAY. MOST FAILURES, OF COURSE, OCCUR SUFFICIENTLY LONG AFTER FOR THEM NOT TO BE THE OBVIOUS CULPRITS!

HOPE THIS HELPS.

Dave, Charlie, thanks, but I suspect the set up is slightly different.  The shroud runs directly into a sleeve the other end of which is flattened as an eye which can be connected to the shroud plate or, in my case quadrant lever.  I don't know how the wire is secured inside the sleeve, although my guess is that it must be crimped in some way despite the absence of any markings on the outside.  However, the wire is not doubled back on itself at all.  It has therefore broken at a point which, for all intents and purposes should be a straight pull and cannot possibly come close to the declared breaking strain on a simple lever with about 3:1.

Rod & Jo, thanks for your comment, relieved to know I'm not the only one.  But why?

Bill - I have a similar type of arrangement on the shrouds of 1728 as you know except that the swaged ends are to a threaded fitting which is held in position with a knurled thumb screw and the tension is adjusted by screwing the nut up and down!!  All very simple but my guess is that your tension will be much higher.  I suppose over the years there is moisture which runs down the shroud into the swage and there is some type of corrosion and it pulls out.  I suppose too that you never know when the other one might give up.

A bit confused. 
Was this a swaged "Brunton" end? That is to say a stainless steel fitting with an eye, thread or fork that was swaged - that is  "rolled" onto the wire, (Such as aircraft control wires are or the best yacht rigging.) after the wire has been inserted in to the terminal, or a standard eye splice made with a talurit or similar crimping device? 
In either case assuming 1X19 stainless steel preformed wire rope, replacement as a matter of course after 5 years would be prudent, 1X19 is not flexible per-se but it will take distortion with a little loss on strength. - Such as through deck bushes -(In Merlin Rocket terms anyway.) What it does not like is constant flexing around a point it's simply not what it is designed to do. For this use preferably 7X19X19 (The last 19 is in the opposite twist to the first!) (such as cranes and lifts use, or if you cannot get that and very few yacht riggers keep it 7X19
One other thing many so called riggers have in the past used alloy ferrules on stainless wire for talurit splices, this is incorrect and a good guide to spilce reliability is: 
a.) Have they used copper ferrules on stainless alloy on galvanised? 
b.) Have they filed off the "flashes" after the compression (Right!)or put it through the machine again (WRONG!!!!) 
Best get your rigging from a pro' or at least check it preferably by watching it being done.
None of the above should be done with fibre (Natural or synthetic.)cored rope though there is not much around these days. Having said that most dinghy rigging when new is very under-stressed. It's when anno-domini hits it gets iffy. But then don't we all. Some people say running rigging wire is best in galvanised as rust showing is a good indication of nearing its lifes end.

'Swaged'  a new and useful word for my vocaulary.  Yes, Rigger, from the way you describe it, it is swaged, and your explanation makes perfect sense.  Next time I will remember the 7x19x19 requirement assuming it comes in 3mm; in the meantime, I will just count the five years.

Many thanks.

Ours was indeed a swaged s/s Brunton end, complete with threaded end & knurled nut; no particular flexture at the point where the wire emerges, and where it failed. OK, it might well have been the original, and so 35 years old!

I have a complete spare rig if your not sorted for the weekend it'll be no trouble to stick it on the boat on sat morning.

can you still get galvanised wire? If so from where?

Try this

Good find Gary, but see caveats about fibre cores this wire rope has a fibre core. So Hand Slicing and Talurit ok; swaging not. There is neat quick hand s[lice whereby you unravel into two equal parts the wire and then remake it the opposite way making an eye, experiement will give you the right size to make an eye to take a thimble, whip the stray ends and use the whipping to tighten the thimble in place too.

the last splice discussed above is called a flemmish eye(at least thats what we call it on the trawlers in scotland!!!) and would do a good job I have used it on wire up to 75mm so would be a breeze on this weight of wire, needs a fair amount of free end, but you end up with a neat finnish. recon about 90% of the strength of the wire( dont know what the equivelant is with swages?)

About the sames, at last a name for the slice I've used in extremis for 45 years or so! Thank you.