Rig Tension

[trapezeartist]

If a boat has not had the rig tension touched since it was set up six years ago, what (if anything) is likely to have changed? I believe it was all done properly back then.

 

[alahol2]

Rigging wire can certainly stretch, especially in the first year or so of its life.

 

[Simondjuk]

If everything was new then, lots. If everything was old and pre-stretched then, not quite such a lot.

 

[merlin3688]

When checking rigs over we find most do not have enough tension, slack rigging is not good as movement can happen between the terminal and the mast. You can buy all sorts of rig tensions which cost a lot however it can easily be done yourself, check out mast companies websites, they all give instruction on setting up rigs.
If your rigging was new and never touched then certanly the wires will need tightening. Also its best to give it a quick once over to check all is ok. Check around each swage for rust stains which would indicate you may have a damaged or broken wire inside the swage. Most local riggers will offer a free rig check as if any problems found will probably get the job.
Hope this helps.

 

[KellysEye]

It's very easy to do. Undo the nuts each end of the bottlescrew, turn the bottescrew until the wire won't bend when you push it and ensure the mast is upright forward/aft and side to side. That's what we do.

 

[VicS]

If a boat has not had the rig tension touched since it was set up six years ago, what (if anything) is likely to have changed? I believe it was all done properly back then.

You will find a useful guide to adjusting rigging, including a method of setting the tension without a tension gauge, on the Selden masts website.

http://www.seldenmast.com/_download.cfm?id=6740&download=2956550&filename=595-540-E.pdf

It's a fairly large pdf so well worth saving for future reference.

Only comment to make is that if your rigging has been upgraded to heavier wire than the original tension it only to the tension you would have set for the original wire size. Don't upgrade the tension!

 

[Bosun Higgs]

If a boat has not had the rig tension touched since it was set up six years ago, what (if anything) is likely to have changed? I believe it was all done properly back then.

You're very trusting! Whilst new rigging might bed in a little and require re-adjustment, it doesnt move after that at the temperature and stress you might put it under. The same cannot be said of your boat hull so your rig might well benefit from some tuning.

Its easy enough and fun to do yourself. Try the Selden / Kemp guide

 

[CAPTAIN FANTASTIC]

It's very easy to do. Undo the nuts each end of the bottlescrew, turn the bottescrew until the wire won't bend when you push it and ensure the mast is upright forward/aft and side to side. That's what we do.

Agree, that is what I used to do.

However, I now have a rigging gauge tensioner to adjust my rigging, every season; costs ~£60 and I was amazed with the difference it makes when the rigging is properly adjusted.

 

[pvb]

I had my rigging replaced a couple of years ago, and the riggers who set it up for me said that very few owners dare to tighten the rigging as much as it should be tightened! When they'd finished, it was a lot tighter than the old rigging had ever been. Probably well worth getting a local rigger to check every few years.

 

[Poignard]

Agree, that is what I used to do.

However, I now have a rigging gauge tensioner to adjust my rigging, every season; costs ~£60 and I was amazed with the difference it makes when the rigging is properly adjusted.

When I bought my boat 15 years ago I got a friend with a similar boat, who raced it successfully, to check and set up my rigging. Then I bought a used Loos tension gauge and made a note of the tensions my friend had set. When I re-step the mast each spring I just apply the same tensions.

 

[Simondjuk]

I had my rigging replaced a couple of years ago, and the riggers who set it up for me said that very few owners dare to tighten the rigging as much as it should be tightened! When they'd finished, it was a lot tighter than the old rigging had ever been. Probably well worth getting a local rigger to check every few years.

Very true. On modern, and in particular fractional rigs, if you're not starting to worry that something is about to break, you probably need to go a lot tighter.

 

[trapezeartist]

Interesting responses. I was surprised to find that the tension was very close to the recommended figures, even after all this time.

I slackened everything off first, which meant taking 13 turns off each cap shroud. I then tensioned it according to the Selden book and that involved putting 14 turns on the caps. ( I also had to make a very slight side-to-side adjustment on the lowers to take out a slight transverse bend.) The result is 20% breaking load in the caps with the backstay hard on and 23% with the backstay off.

I was not entirely surprised to find that there is virtually no pre-bend in the mast and the backstay has minimal effect too. It's a very chunky mast and there's not much purchase on the backstay.

I was more surprised to find that there is a LOT of rake on the mast. Approx 380mm in 11.5m. If my estimate is right, that works out at over 3 degrees.

I found the two-metre-rule method reasonably easy to use, although it's a bit time-consuming. Care needs to be taken as you are measuring fairly small dimensional changes. However the biggest disadvantage with the method is the need to start from slack: it would be so much easier to use a Loos gauge where you can measure your starting tension.

I also found it impossible to use the rule on the backstay as I couldn't get high enough to tape it on. Not a problem in this case as I can't get much tension on the backstay anyway.

 

[Simondjuk]

Just one extra turn in six years is very little. Was the rigging new back then? I had to take about four extra turns after two days firm sailing when we last re-rigged, but then the chainplates, knees, mast step and just about everything else had been disturbed so perhaps it was due to all those things taking position.

Out of interest, what size wire are we talking and did you have a slight feeling of lack of mechanical sympathy when winding it back up to 20%?

 

[wklein]

How does this work? Do selden give you the tension figures for your individual boat or just a recommendation for a wire size? There is a huge difference in how you set up boats based on a number of factors. You can't just say 7mm wire needs X. That way madness lies. Get it done properly, we only change 25 quid for a rig tune and most riggers would do similar. There is no substitute for experience.

 

[trapezeartist]

Simondjuk, the boat was new 6 years ago. The original owners only did 60 miles (+320 delivery miles) in their four seasons of ownership. When I bought the boat she was green all over the deck and the fouling on the bottom was incredible, so I assume they didn't touch the rig either. I then have to confess that I hadn't touched the rig either in two years of ownership, up until last weekend.

I too thought that it was an impressively small loss of tension in that time. I wouldn't expect the wire to stretch but it certainly goes to show that some AWBs at least are extremely robust (though it's generally only the MAB owners who think they aren't ).

I didn't feel I was being unkind to the boat in winding the tension up tight, as the boat exhibited no signs of stress at all. When I sailed a wooden Fireball we used to pull on the tension until the centreboard stuck tight, then ease it off a bit. That was unsympathetic!

Wklein, there is no set tension force. Selden recommend 20% of breaking stress on the cap shrouds with the backstay hard on and no more than 25% with the backstay off. This is independent of wire gauge. Youngs Modulus of 1x19 stainless wire is such that 1mm extension over 2m length is equivalent to 5% of breaking stress. Therefore you just tape on a 2m length of wood and accurately measure the gap between the end and the ferrule on the shroud. Not as easy as a Loos gauge, but quite do-able with care.

 

[wklein]

Wklein, there is no set tension force. Selden recommend 20% of breaking stress on the cap shrouds with the backstay hard on and no more than 25% with the backstay off. This is independent of wire gauge. Youngs Modulus of 1x19 stainless wire is such that 1mm extension over 2m length is equivalent to 5% of breaking stress. Therefore you just tape on a 2m length of wood and accurately measure the gap between the end and the ferrule on the shroud. Not as easy as a Loos gauge, but quite do-able with care.

What i was saying was that the rig tune is influenced by:
Spreader length (huge factor)
Continuous / Discontinuous Rig,
In mast / Slab
In lines / swept spreaders
Weight of spar
Hull construction
Raced or cruised
Drift on lowers
Stiffness of spar
Angle of forestay intersection

I think selden were giving a maximum strain for maximum wire lifespan not giving a universal tension for a given wire diameter.

 

[VicS]

What i was saying was that the rig tune is influenced by:
Spreader length (huge factor)
Continuous / Discontinuous Rig,
In mast / Slab
In lines / swept spreaders
Weight of spar
Hull construction
Raced or cruised
Drift on lowers
Stiffness of spar
Angle of forestay intersection

I think selden were giving a maximum strain for maximum wire lifespan not giving a universal tension for a given wire diameter.

have you actually read the Selden document referred to .

It may not be the ultimate treatise on rig tuning but its gives far more information and guidance than simply giving a maximum strain for maximum wire lifespan or a universal tension for a given wire diameter.

 

[Lakesailor]

Of course if your boat has a coachroof stepped mast and is not in the first flush of youth you may find that tightening the rigging is merely driving the mast foot through the coach roof or distorting the frame that is supposed to support it.

Been there.....

 

[wklein]

have you actually read the Selden document referred to .

It may not be the ultimate treatise on rig tuning but its gives far more information and guidance than simply giving a maximum strain for maximum wire lifespan or a universal tension for a given wire diameter.

I had not actually read it and it is in fact a very good guide and a good thing for a conscientious sailor to know, however an experienced rigger will do a better job for very little of your hard earned taking into account the things i listed above, it takes a long time to get a good feel for rig tuning.

 

[Simondjuk]

Of course if your boat has a coachroof stepped mast and is not in the first flush of youth you may find that tightening the rigging is merely driving the mast foot through the coach roof or distorting the frame that is supposed to support it.

Been there.....

It has and it's not, but on an Evolution 25 it's not a concern. The mast is stepped onto an aluminium arch spanning the bulkheads and further supported by the housing for the hydraulic keel ram that Brunel would have been proud of. It's a nice thing, very substantial but very light.