slack rigging

Jmc1764 said:
How much lee side slack in the wire rigging would you expect when heeled at around 20 degrees ?
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None.

I would wind on half a turn at a time until it no longer appeared.

What was explained to me, and made sense, is: if the rig is able to go slack then it will experience shock loads. If instead it's permanently tight then the peak load will be the same but the troughs will be higher. It's not the static load that fatigues the rig, it's the working from load on/off.
 
I disagree. Slack lee shrouds is normal inevitable. Certainly not desirable and Op should tighten up to some degree. However the total load path of rigging athwart ships is from the top of the shroud down the mast to the keel then around the hull to the chain plate and so the shroud itself. The problem is that boats do not have the rigidity of hull and possibly cabin top to match the longitudinal strength of the shroud. So while you can tension up the shroud to a percentage of max strain that doesn not take in to account the hull distortion in the load path. So I say live with some slackness of lee shrouds but don't expect shroud wire to last for ever. ol'will (I will get my coat)
 
Jmc1764 said:
How much lee side slack in the wire rigging would you expect when heeled at around 20 degrees ?
Click to expand...
What wind speed are you sailing in ? Up to around F5 there shouldn't be any slack. Over F5 a bit of slack will appear but not really noticeable until you hold the stay. In an idea world there shouldn't be any slack but boats flex, etc.
 
+1 for the above comments on no slack.

What is your boat? I know some 40+yr designs which will always have slack due to hull flexing. Our old Centaur used to lift the deck moulding off the interior cabinetry by a full 1/2 inch in heavy weather. Never any problem with rigging, mast or structure - it's just how it was.

A modern design should tolerate being set up taut enough.
 
I've set my late '90s fractional rig up exactly following the manufactures manual and using a wire tension gauge.

Windward and leward upper and lower stays are all in tension in normal conditions but in strong gusts or if the boat is overcanvassed the lowers on the leeward side show a little slack and that means its time to dump the main , or luff or put a reef in.
 
Jmc1764 said:
How much lee side slack in the wire rigging would you expect when heeled at around 20 degrees ?
Click to expand...
If it's a mast head rig the lee shrouds should just start to go slack at 20° of heel

Go to the Selden "Hints and advice" pdf to see this advice and details of adjusting the tension without a tension gauge using the "folding rule" method. Also advice on adjusting other types of rig.

https://support.seldenmast.com/files/595-540-E.pdf

.
 
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VicS said:
If it's a mast head rig the lee shrouds should just start to go slack at 20° of heel

Go to the Selden "Hints and advice" pdf to see this advice and details of adjusting the tension without a tension gauge using the "folding rule" method. Also advice on adjusting other types of rig.

https://support.seldenmast.com/files/595-540-E.pdf

.
Click to expand...
That's my experience too. My Sadler 34 shrouds had exactly correct tension measured by Loos gauge. Upwind in about force 4 the leeward shrouds go slack but without clearance at the chain plates.
 
The boat is an Albin Singoalla, shes 51 years old. The stays are all tight as far as I can see and under good tension although not checked on a gauge. Under most conditions there is no noticeable slackness, but under strong winds and when heeling a lot there is a noticeable slackness in the stays. Its an old boat and does have some flex and a few creaks when the wind blows hard but she rides the waves really well and your never in fear.
 
The Selden rigging guide linked above says the #1 cause of rig failure is rigging that is too loose. Having just suffered a serious fatigue failure in both sides lower shroud tangs, I 100% support the statement that there should be *no* slack in the leeward shrouds. Any slack there induces shock loads when rolling, tacking and gybing.
 
Jmc1764 said:
So, If the wire tension is correct and there is still slack when heeling should the tensions be increased beyond the recommended tension?
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I don't believe so - others have referred to this in #7, #8, #9. When under high load it is possible that flex and distortion in the hull and deck structure will create slack even with the rigging at the correct static tension. If you overtighten you risk distorting the structure.

Your description says you only get slack in strong winds, not in normal sailing. I would enjoy your sailing and take the time to check mast and deck fittings for corrosion/stress each season. At 51 years old I think your boat's builders got it about right!
 
I would not think there was much shock loads on rigging tight enough but still slack on lee ward side when pressed. The fact that distortion of the hull etc means you can't get rigging stretch (that might ease fatigue problems) means that as you tack or gybe the hull itself will make a giant spring to cushion shock. In other words as hull stands upright in middle of a tack the rigging will become tensioned to static degree before the hull distorts int he other direction.(slowly) ol'will
 
William_H said:
I would not think there was much shock loads on rigging tight enough but still slack on lee ward side when pressed. The fact that distortion of the hull etc means you can't get rigging stretch (that might ease fatigue problems) means that as you tack or gybe the hull itself will make a giant spring to cushion shock. In other words as hull stands upright in middle of a tack the rigging will become tensioned to static degree before the hull distorts int he other direction.(slowly) ol'will
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If the leeward lowers have slack in them, it doesn't matter so long as the boat never rolls to windward, and so long as you never tack or gybe. The lateral movement at the cross trees broke my jury rig in a big sea before I'd even got the sails out.

If you think about it, for the lowers to slacken, the cross-trees must have moved to leeward a bit, and will move the other way on the other tack - there's the movement that causes fatigue.
 
William_H said:
I disagree. Slack lee shrouds is normal inevitable. Certainly not desirable and Op should tighten up to some degree. However the total load path of rigging athwart ships is from the top of the shroud down the mast to the keel then around the hull to the chain plate and so the shroud itself. The problem is that boats do not have the rigidity of hull and possibly cabin top to match the longitudinal strength of the shroud. So while you can tension up the shroud to a percentage of max strain that doesn not take in to account the hull distortion in the load path. So I say live with some slackness of lee shrouds but don't expect shroud wire to last for ever. ol'will (I will get my coat)
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Not all hulls are the same. A solid laminate hull of 12mm thickness is flexible. A cored hull of two layers of 6mm glass with a 25mm core sandwich will be 37 times stiffer. Same amount of glass. You can't generalise.
Overload the hull and the forces through the rig also increase. It's more complicated than static rig tension. My experience suggests that if the hull is stiff you don't want floppy leeward shrouds. If the hull isn't stiff don't load the rig. You won't achieve a taught rig. You might find the misses stuck in the heads though?
 
While it is desirable for rigging to be tightened to specification, there must be thousands of older craft sailing around with rigging that is no more than hand tight. Most of these boats will be sailing inshore and not subject to great loads and so little harm ensues fortunately. The books used to warn one off from tightening the lee rigging when under way, lest the mast be driven down through the boat when the new load is applied.
 
When I first had my boat ( new in 2003) the lee rig was slack when pressed to windward. It is 11/12 fractional. It was set up by the supplier.
One day in heavy weather, I let the main flog for a couple of minutes to stop the boat & level it up a bit, while we all used the heads. I noticed the mast pumping & inverting badly. That can lead to mast failure & no one has mentioned that possibility yet.
Obviously I tightened the rig soon after.
The boat was very heavy on the helm & not having an adjustable forestay I changed it 4 times before I was happy with the mast rake. I also found that upper rig tension had to be set ( using a tension gauge) at 25% max load. That is about as tight as I can tighten the screws using spanners. The mids & lowers are much less.
The boat actually balances better & is much much faster upwind. It has taken a lot of trial (+ 3 mainsails & 5 jibs) to get the right rig set up.
 
Note that the rig may be undergoing countless stress cycling when it is not being sailed.

A shroud failed in fatigue on my Hobie 16 when it was parked on shore. The mast rotates on this boat and wind was enough to cause it to turn repeatedly.

On my website there is a case history of two failures of a forestay on a boat that was kept on a mooring in a wave affected bay.
 
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