Rigging Tension and tuning

AndyAndKatie

AndyAndKatie

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Me - Greenhithe, Kent. Boat - Gillingham, Kent
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Hiya guys. Can anyone give me any helpful hints and tips about tensioning my rigging??

I was out last weekend and saw that my Shrouds on either side are flapping around on the unstayed, downwind side...
Ive tried to look for any info on the web and found some good advice but would like to know what problems I am likely to come up against, if any...
This was a good site Kemp Sails but its always ghood to talk to people that might have done it and know what its like in the real world..

I've never done it before and I'll be basically loosening everything and starting from scratch.

Good Idea???, or 'Dont Bother..'

Thanx
 
The biggest danger here is that you take out the slack and tighten the lee stays ... and in so doing end up with over-tensioned stays.
It is not uncommon to see a slight lessening of tension on lee stays ... but flapping around as you say would indicate they are slack ...

Make sure you only take up enough to stop "flapping around" ... a slight movement is ok. Also when boat ihas no sails up and is not sailing, quiet - take main halyard and check side to side that mast is vertical .........

Basically stays are not guitar strings and should not play as such !! But a healthy "twong" when flicked is ok. A "twang" is too tight ! /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/cool.gif
 
As a rough guide if sailed to windward in say a force 3 the leeward rigging (of a mast head rig) should just start to go slack when the boat heels to about 15 - 20° If the shrouds are still tight at more than 20° then they are probably too tight.

Typically the rigging should be tightened to 15% of the breaking strain of the wire This may be determined by measuring the extent to which a 2 metre length is stretched. Irrespective of the wire diameter an elongation of 1mm in 2metres represents approx 5% of the breaking strain so 3mm in 2metres is equivalent to 15%. (the wire should not be tensioned above 25% of the breaking strain. (Note you only do this on one side you do not repeat the process on the other.)

There is a "Hints and Advice Manual" on the Selden masts website Seldenmast.com which gives details of this method.

Fractional rigs are a different kettle of fish but are also covered by the above manual.

I hope that helps, it a bit more scientific than "twongs" and "twangs". I assume you will find similar advice on other mast makers websites
 
[ QUOTE ]
"Hints and Advice Manual" on the Selden masts website

[/ QUOTE ] Pages 28 and 29 from here
I could not download it earlier but it seems to have appeared all by itself now /forums/images/graemlins/confused.gif

It's a big pdf and it looks as though its been jazzed up since i last looked at it
 
"I hope that helps, it a bit more scientific than "twongs" and "twangs". ... "

The human ear is remarkably accurate in sound ... witness guitar / piano tuning ... yes there are gauges and electronic gizmos ... but the ear has them beat more often than not.

I said twong ... twang ... as that is best word I can find to describe the sound and the difference !! The ear is good at getting all stays to sound same ... well mine are at least !! OK - I learnt what my boat was suited to in terms of tension by sailing it ... checking the Bog door could open / close etc. (if too tight mast compresses coach-roof enough to stop door opening as it passes under the mast backing plate). Learnt the sound of the stays when flicked by hand .. a definite TWONG sound !!

When sailing hard and heeled about 20 deg. my lee shrouds slack a slight bit .. enough to see .. but not so much that mast can move significantly when tacking etc.
 
[ QUOTE ]
"twongs" and "twangs

[/ QUOTE ] Won't the note depend on the thickness of the wire and its length as well as the tension.

You had better indicate on here the exact notes for various wires and their lengths.

eksstaves.gif


It won't help me though I couldn't tell a middle C from a flat chest. 3mm on the other hand is something I can measure.
I've seen people playing the spoons, a saw, wine glasses, bottles even, but Nigel on his yacht's rigging ??? I cant wait. Bring back "Opportunity knocks"

Twing, Twang and Twong and their musical junk /forums/images/graemlins/laugh.gif
 
/forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/smirk.gif

Seriously as I said - I tuned mine and then learnt the sounds so that later I could re-rig without resorting to gauges etc.

Guy who looked after my race boat - he was same !! And we did very well with her !!

/forums/images/graemlins/cool.gif
 
Sorry to diss all you twingers and twangers, but the role of rig tuning is to set the mast up, not to achieve a certain tension in a certain stay. Forget about tension in individual stays, and make sure the mast is shaped how you want it (which should also be pretty close to how the designer wanted it, and how the sailmaker cut the sails). Accept that you are very unlikely (unless you're a power lifting gorilla on steroids using a crowbar) to overtighten rigging. Just use the rigging to get the mast in the middle of the boat, and shaped properly.
 
yep thats some thing I agree with
not that I'd know but if the mast isnt being bent out of shape why over tension things afterall you will only cause stress !

cheers
Mick
 
Agree ... except - no-one is talking individual stays / shrouds ... I was talking overall. I like to hear similar sound from my stays indicating that all is evened up ....

I use halyard to check mast is not one way or other ... I use forestay bottle screw mark to have mast at fwd / aft rake ... and once set-up - first sail out ... check set of sails and any creases / shape that is not in keeping with sail ...

As to needing to be a gorilla to overtighten ... I have to disagree ... a) I have seen consequences of overtightening of a bottle screw on a cabin top ... where the top compressed and crazed ... it was necessary to fit a compression pillar as well as repair the area.
I have a situation on my boat that I can easily - even though cabin top is subdstantial moulding - compress top enough to jam my heads door.

A bottle screw can exert a vast amount of pressure / force on the fittings ... if not then bending fractional rig etc. would be difficult. I've seen and even intervened when seeing mast bent sideways by over-enthusiastic tightening of cap shroud one side against babys other side ...

My replies are about overall - well that's the intention ...

So how many actually have rigging gauges ? Bet majority do not and rely on "feel" + eyeball to set up their rigging ... as I do ...
 
[ QUOTE ]
Sorry to diss all you twingers and twangers, but the role of rig tuning is to set the mast up, not to achieve a certain tension in a certain stay. Forget about tension in individual stays, and make sure the mast is shaped how you want it (which should also be pretty close to how the designer wanted it, and how the sailmaker cut the sails). Accept that you are very unlikely (unless you're a power lifting gorilla on steroids using a crowbar) to overtighten rigging. Just use the rigging to get the mast in the middle of the boat, and shaped properly.

[/ QUOTE ]

Agree 100%. Remember, the only reason you have a mast is to support and shape the sails.
 
Actually, an under tensioned rig is more likely to fail because of fatigue through movement and by shockloads on the rig when you tack and the slack leeward shrouds snap tight. The load applied by the windward shrouds to the chainplates is the same on a loose rig as on a properly tensioned rig because the weight of the rig plus the wind force always exceeds the preloading of the shrouds, unless hugely overtensioned.
The leeward shrouds should lose tension but not go slack or you are subjecting your rig to shock load and metal fatigue.
 
[ QUOTE ]
and make sure the mast is shaped how you want it

[/ QUOTE ] The Selden Masts Hints and Advice Manual explains all that. The method of setting the tension I referred to is just a couple of pages of an 80 page document.

If Truant_now has as good an ear for musical pitch as sbc I am sure that having set his rigging up correctly once he be keen adopt the twing twang twong method. (If he is much of a Physicist then he able to calculate the correct musical notes in the first place!)

Someone along the way might have suggested a rigging tension gauge. Some yacht clubs have them available for members to use.
 
It is not quite that simple Ken.

You are quite right that getting the mast shape right is very important, but there are an infinite set of shroud tensions that achieve that and the issue is working out what is correct.

The methods I know all start with getting the basic shape of the mast correct with as little tension in the rig as possible and then progressively tensioning the shrouds while maintaining that shape. An under-tensioned rig is much more prone to failure than an over-tensioned one (and let's face it, the chance of someone accidentally overtensioning a rig is minimal)
 
Bedders,

Yes and no.

Sitting on the mooring you can set up the mast 'correctly' using minimum tensions. That's only stage one, though, what you do immediately after you've wiped the yard staff's greasy footprints off the coachroof, after the mast has been stepped.

Stage two is to get out there and see what happens to the mast when pressure comes on the sails. That requires some real tension to be put in the rigging, to do things like stop the top of the mast falling away above the hounds, and keeping the column true from deck to truck.

I learnt about this from a guy who wrote a book about it and we'd often spend the first weekend of the season sailing up and down, tweaking this bottle screw or that, timing runs with different amounts of rake, calibrating the back stay tension against winds strengths, etc. until he was totally satisfied. Consequently it's a bit of a religion for me, even just pottering about as I do now.

As to SBC's comments about rigging distorting the boat, there are plenty of apocryphal stories of this (including bendy Benny 40.7s), but that usually comes down to dodgy boatbuilding or engineering, rather than brute force in rigging adjustment.
 
A bottle screw / rigging screw can and will exert tremendous force if overtightened ..... it is one of the reasons I try to stop people when helping me to rig a mast from using too long a spike / tool to tension the item. Short lever so that it's harder to turn as you get to tension I want ... in fact often I just advise them to attach ... take up enough turns to just start to tension - then leave it for me to go round the stays ... in a criss-cross pattern ... doing opposites to balance up etc.

Deck stepped masts are worst for distortion usually of GRP / mouldings ... but a keel stepped mast can also have serious consequences if over stressed on rigging.

I agree with the slack rigging can lead to failure - cause the shock loads on the mast as loads come on can be catastrophic. But overstressed rigging can be near breaking as well ... when real weather hits an over-canvassed rig.

There is a balance ....

As to rigging gauges ... some clubs might have them - but I've been member of 4 clubs and none had a gauge to lend out. In fact I don't know anyone with a gauge ... except for one guy who had one of the small jobs as freebie on front of a mag years ago ... it's useless as well !!
 
The point of the tension method is that it enables a good set up (adequate for cruising) quickly and simply.

What you describe, while undoubtedly superior, requires more time and experience, and a weekend with a nice F4 for the testing!
 
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