Rigging tension

[Dek]

I have galvanised standing rigging on my wooden boat (+ wooden mast)
It seems that no matter how the shrouds are tensioned there are always expert volunteers who will say "too tight mate" or "too slack mate". In their own way I am sure that each are right. I am looking for a rule of thumb that might attract the comment - "seems about right mate". Any suggestions?

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[bruce]

for SS it appears to be between 15 and 25 % of working load of stay

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[jeanne]

I have galvanised rigging, too, but I thought I was the only one!
The rule I have always used is this: when sailing to windward in a decent breeze, the leeward rigging should be 'tight to the eye, but slack to the hand'
That is it should not visibly sag, but should feel slack.
You can't adjust it safely while sailing , though.

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[William_H]

Hello Dek I think that Jeanne's comment is pretty right although you should not worry about slack rigging on the lee ward side. Much depends on the flexibility of the hull and mast. I say just tight enough to keep the rigging tidy on the leeward side and of course the mast straight or required curve for multiple levels of stays. I am horrified at the concept of tensioning rigging to a percentage of the wire breaking strain. There is more than the wire in the circuit. ie hull stiffness and mast stiffness etc.
If the breaking strain of the wire were our only concern then to minimise fatigue you would set it up for 15% of breaking strain as you do a cylinder head bolt (stretch the bolt to reduce susceptibility to fatigue) but I think you could permanently strain the hull etc with large amounts of wire tension and fatigue failure is not likely to be a problem compared with corrosion etc.. You set up the rig standing tension of course to control what happens to the rig under pressure of sail so it is more important to look at the mast behaviour under pressure.This is in my uninformed opinion of course regards will.

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[bruce]

by measuring tension, you will have same forces exerted on mast on both sides, 'tidy rigging' sounds more 'horrifing' than a balanced rig. over here it is done by the numbers rather than the eye, perhaps galv rigging makes a difference, didn't intend to offend...

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[Norrsken]

Agree that the mast should stand straight when under pressure and hard on the wind. I was taught to lie on the deck and look up the mast to make sure this was so. If you over tension there is a problem of strain on the boat. The usual area of a proble is winding too much backstay tension on. Selden suggest that you wind put a metre rule on the backstay with the top end firm and the bottom free to move, and you then tension the rig. they have a table which shows how much tension this gives and I guess it could be used for shrouds as well. If you want to know what the figures are I think it is 2.8 mm for 20% of the breaking strain of the wire which is the maximum for the wire. They go on to add that you should take the tension off when the boat is not being used. Incidentally they say a 20$ static load can lead up to 40% in working conditions.

If you want to know the stretch factors I will look them up for you when I next go to my boat.

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