Rigging question.

[Allan]

I have a sloop rigged Westerley 33 with, what I consider to be standard rigging. Forestey, babystay, cap strouds, lower strouds and adjustable backstay. We were sailing today, I tightened the backstay a little and found the lower stay on the leeward side was loose on both tacks. I was sailing hard on the wind (~15-18knots). I have never noticed this before. Would increasing the backstay tension do this?
Allan
PS. I am thinking of buying a gauge to check the tensions, does anyone know what size wire I have on my boat?

 

[William_H]

I don't find it so surprising that the lower leeward stay was loose on both tacks.
The backstay pulls on the forestay which stretches a little so that the top of the mast moves backwards. Hopefully the baby inner forestay will pull the middle of the mast forward to induce some bend but at the same time you have tightened the forestay to reduce forestay sag. (you want the sag out to minimise camber in the jib)
The lower stays are usually led to chain plates aft of abeam the mast (to provide triangular location of the middle of the mast in fore and aft direction.)
However with the mast head moving aft both inner side stays will go slack (the stiffnes sof the mast itself will not allow it to bend much) however the windward inner side stay will remain tight because the cap shroud has stretched a little with wind pressure. Your leeward cap shroud was probably fairly loose also.

I might be wrong but I think that cable tension gauges are a waste of time.
Static tension on the rigging is nothing compared to the loads when sailing.
So it is not the actual tension but the ratio of tension or lengths of stays that locate and shape the mast when under load.
So under load and boat heel the cap stay and intermediate should together hold the mast straight when viewed from the front or back and the backstay tension along with intermediate forestay tension should produce a slight bend middle forward. However when static or in light winds with less backstay tension the mast should be straight.
Actual total static tension should be just enough to keep everything tight and tidy with mast not moving when the boat sways with waves.

My argument is that no matter how tight you set up the rigging when static you will always get lee stays loose to a degree. So you can not minimise fatigue of the wire as you can with bolts and similar fittings under load. There is just too much other flexible structure ie the hull to permit real tensioning of the stays. In fact I think too much tension on the stays can distort the hull in some cases permanently. Any way that is my theory disagreed with by many. good lcuk olewill

 

[wotayottie]

the kemp advice booklet now available from the selden website is as good a way as any of answering these questions. click on the union flag in

http://www.seldenmast.com/frameset.cfm?id=6740&randnum=689050109

 

[Twister_Ken]

Whether to do anything about it depends mainly on the degree of slackosity. Going to windward the lee shrouds are almost redundant. However when you tack they become vital. The question, therefore, regardless of leeward slackness, is whether windward tightness is sufficient? The way to assess this is to go to the mast when sailing hard upwind, put your eyes somewhere close to the gooseneck, and look up the mast track (do this on both tacks). This should describe a smooth curve, bending aft and very slightly to leeward. Any irregularities in that curve mean that one element or another of the standing rigging need adjustment. At this point, it helps to have a book or rigging crib sheet to let you know what adjustments will have what effect - often it is not straightforward! Until you've done that I wouldn't worry about slack leeward lowers, unless they are flapping in the breeze.

 

[Salty John]

A tension gauge is a reliable way of checking your rig tension. I believe the W33 is 6mm wire but you would need to check. The Loos type B gauge or the Loos PT2M covers 5mm, 6mm and 7mm. (For high tensions on 7mm wire you need the PT3M, which does 7mm, 8mm, 9mm and 10mm).
You can use the hoisted tape method of setting up your rigging or for a quick and easy check on rig tension you can use a tension gauge. Racers use them to get the most out of their boats, the big sail suppliers provide tuning guides which refer to tension gauge settings. But cruising sailors also benefit from correct rig tension.
Loose rigging imposes shock loads when you tack; overtight rigging can, in extreme cases, over stress a fibreglass hull so it makes sense to have it right.
Be aware that I have a commercial interest as we stock Loos tension gauges.
I've carried a gauge on my cruising boats since 1985 and wouldn't be without one but many use the hoisted tape method or just make an eductated guess on the basis of 'feel'.

 

[Refueler]

Loose or slack ? Loose implies it was waggling about with excessive slack.

Cruise boats usually will have some slack in leeward stays based on windward stays giving a little with the wind / sail pressure on them ... but it should not be too slack or the mast when tacking / gybing will move and stress stays / fittings when it takes up on other tack. Overtightening can lead to compression of coachroof on deckstepped mast or strain of keel former on keelstepped. A balance is to be sought of sufficient tension to look after mast, but not so much as it strains boat.

 

[Bilgediver]

Any way that is my theory disagreed with by many. good lcuk olewill

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Totally agree with you for the majority of cases... My deckhouse would have distrorted or been severely damaged years ago if following some of the advise given on tensioning.