Is there a good reason for not using Dyneema for shrouds on a gaff cutter?

[Andrew Craig-Bennett]

People like me



are hidebound by tradition and cost and have galvanised wire that lasts for ever (those lower shrouds, parcelled and served full length, date from 1977; the rest dates from 1985) but the racing smack owners are unconstrained by cost and tend to feel that getting ahead in a race is worth more than tradition.

I suspect the answer may be either UV degradation, chafe or "creep" - I understand the first two but not the last - someone here is bound to know!

[Brion Toss]

Hello,
I am in the delightful position of having been prophesizing for years that HM standing rigging was on the way, and that much or most of my reluctance to recommend it for almost anybody stemmed from a desire to let someone else play around with it, and work the bugs out. For many boats, yours included, I believe the way is now fairly clear. Yes, you have to worry about (i.e. prevent) chafe. Yes, UV will be something of an issue, but reports from the field are that it happens slower than we used to think, and that the rate of decay slows as the surface yarns' decay acts to shield the yarns below.
Creep is also largely addressed, at least with materials like Vectran, which has essentially no creep, and some forms of pre-stretched Spectra. With deadeyes you will in any event have lots of room for take-up for this.
So I think that your racing compatriots are indeed commendably conservative and cheap, and that is likely why they aren't switching.
A galvanized rig, fully-served, will last longer, given some maintenance, but how much longer is difficult to say.
Finally, think of this question in a historical context. About 150 years ago, people with some of those same boats were debating whether or not to switch to this newfangled, low-stretch, high-strength stuff called wire rope. It had obvious merit, but you know it was going to have problems with rusting, that a sharp turn would weaken it radically, that it was hard to work with, etc. Any material we use for rigging will have limitations, though; we just need to work out whether or not its advantages are compelling enough to outweigh those limitations.
Fair leads,
Brion Toss

[Andrew Craig-Bennett]

Thanks, Brion.

I think I'll take this further. I'm about to lengthen the mast by six feet, in order to do away with the very annoying topsail yard, and that will mean new cap shrouds, so they will be some form of magic stuff, which will save the weight of the extra length of mast, at least.

I do wonder if, with the much lower loading on shrouds set up with deadeyes, creep would be such a problem - only one way to find out...

Will report back next year!

[Joe Henderson]

Dear Brion and Andrew,

I am so glad that this question has risen it's head again.

We have just finished replacing all the standing rigging on 'LANDFALL' Mike Strong's 1930's S&S designed 40 footer built in Tasmania out of native timbers. She was the first S&S design built outside the States we believe and is still going strong.

We used his special Strong Ropes blend of Dynex Dux with overbraid with Gibb turnbuckles and our served thimbled eye. We pre-stretched in the loft to ensure reliable finished lengths.

We have shipped several similar sets of standing rigging to multihull users and they seem
to have no trouble with it.

As I am a "British Standard Cautious Rigger" who, like you Brion, was also waiting for someone else to have the failures I was paranoid about stretch and creep so when making the shrouds and backstay I set the turnbuckles at just below safe bury.

Much to my surprise and delight I found that after the initial settling had taken place it became taut and responded to tensioning in a fairly linear manner.

I was expecting to struggle to get them connected and then wind the turnbuckles down into the deck while the material stretched like licorice!

But to set up it felt just like the last 7/7 rig I did. In fact the caps were if anything a little short and we had a hell of a job to get them on in the first place and their turnbuckles have rather too much travel left on them for my liking.

This was fine for me who had all the gear at hand to connect shrouds that were just 10 mm too short to start the threads, but for an owner at the other end of a mail order system we have developed turnbuckles with 50% extra thread length. This avoids the 5 PM phone call telling us that we don't know how to measure rigging!

Mike sailed the boat from Sydney back to his mooring in Port Hacking 35 miles through a lumpy sea and a 25 knot headwind and reports that there seems to have been no creep as yet. His garboards are still weeping but that is another story.

I have no hesitation in recommending this material for any rig with decent shroud angles. I do not think that it would suit very low shroud angles or an extreme tall skinny rig. But then again I was sceptical about using it on LANDFALL and it has worked like a charm on her.

My mate Simon Flitcroft in Brisbane is going to put our stuff on his swept spreader sports boat in place of Nitronic rod. I will report back.

Andrew, take the leap of faith and get your stuff replaced. with the increased mast height you will want to chase every kilogram out of your rig.

From your photo it looks like you are in the West Country. There are several good riggers around the area or, if you like, although it is against the spirit of Spartalk, I can put you in touch with a good man for the job.

Best regards,
Joe Henderson.

[Andrew Craig-Bennett]

Thanks, Joe.

That really is most encouraging.

I should have written "lower static, or initial, tension, in shrouds set up on deadeyes with lanyards" - the dynamic loadings won't be so different by the time the boat is on her ear in a short cross sea - and I do enjoy sailing her on her ear, being of the very firm opinion that any old boat that cannot be sailed that way needs a rebuild. Our local waters can be relied on to produce the short cross sea!

Actually, that photo was taken in Suffolk, in the East of England - it's an anchorage in the river Deben, though it does indeed look as if it ought to be Devon.

We have a very good firm, skilled in deadeyes as well as Dyneema, in Maldon (no names, this is Spartalk!) and I'll be going to them.

I know I need to save weight - the weight of the dressed mast on the yard crane is 400 lbs!

[Joe Henderson]

Dear Andrew,

The East Coast was my next guess. I should have known really, looking at the colour of the water. I was standing on the banks of your river only last April drinking a pint with my mate. He has a rigging loft on the Deben and is the chap I was going to recommend but thought it may have been a bit far for him to travel all the way to the wilds of Devon,

If the firm you mention in Maldon starts with a capital 'TS' then you will be well served by them. (no pun intended)

We have been using CNC machined alloy deadeyes from two makers in the States and cast 316 heart shaped thinbles from, probably, China, but they all look very clumsy for the job and are like something that you would obtain from a commercial fishing shop and not at all yachty.

I don't know if you can still get Tuphnol in sheet, bar and tube form, but I reckon that if you had conventional deadeyes machined from decent sized round bar they would be perfect with minimal maintenance, and look right as well. I suggest round bar because the last time I looked the fabric was wound round like a roll of wallpaper to form the bar and so will stand the type of diametric forces better than a deadeye cut from sheet. I know that sheaves are made from sheet but those that are required to withstand high loads have to be riveted axially to keep the layers of linen together. I have seen several split.

But then again, the wrapping and containing effect of the lanyards may support the laminations in sheet components. maybe talk to the makers about the properties you need.

Do let us know how it all goes, your boat looks like an ideal candidate for - as some would have it - this type of retrograde step in the history of tension members !

Regards,
Joe Henderson.

[Bob Pingel]

Joe-

I am interested in the deadeyes you have been using. I am familiar with the ones from Precourt in Canada, and some recently developed ones from Colligo Marine. Are there others?

I agree that these don't have a salty appearance to them, but they are nicely finished in a high-tech sorta way...

Thanks,

Bob Pingel