How tight should standing rigging be?

[vyv_cox]

I don't think the air temperature is what counts. Try grabbing a piece of stainless when it has been sun irradiated for a while!

I am in the Cyclades where the ambient temperature is about 30 C. There has been bright sunshine all day and there is currently no, or very little wind. I just went on deck (very hot outside) and felt the temperature of the mast and four shrouds. None of them feels any different from the surroundings, in fact the mast actually felt cool. I agree that horizontal pieces of steel can absorb a lot of heat, in fact I wrote about it only yesterday in relation to stress corrosion cracking, but it doesn't seem to apply to mast and rigging.

 

[Graham_Wright]

I am in the Cyclades where the ambient temperature is about 30 C. There has been bright sunshine all day and there is currently no, or very little wind. I just went on deck (very hot outside) and felt the temperature of the mast and four shrouds. None of them feels any different from the surroundings, in fact the mast actually felt cool. I agree that horizontal pieces of steel can absorb a lot of heat, in fact I wrote about it only yesterday in relation to stress corrosion cracking, but it doesn't seem to apply to mast and rigging.

Well then, the next thing to do is to see if your rigging tension alters between the depth of the night and the heat of the day.

 

[Joker]

Rigging will tighten as the temperature increases

Hang on. If it expands as the temperatures rises, then the rig will become slacker.

 

[pvb]

Hang on. If it expands as the temperatures rises, then the rig will become slacker.

Do try to keep up. The gist of the argument is that the mast (aluminium) expands a weeny bit more than the rigging (stainless steel), therefore if the temperature rises a lot, the mast will grow a bit more than the rigging, hence the tension will increase.

 

[30boat]

What happened to the original point here?How to set the rigging on a multihull?

 

[pvb]

What happened to the original point here?How to set the rigging on a multihull?

That was ages ago, this is thread drift.

 

[30boat]

That was ages ago, this is thread drift.

At its worst!

 

[zimp58]

Good article on rig tension gauges on http://www.yachtsandyachting.com/

http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=3937&PID=144562&title=lap-counters-for-single-handersttp://

Zimp58

 

[Lakesailor]

Again let me warn against over-tightening. I have had two small yachts with coachroof stepped masts which have suffered coachroof sag through over-tensioning rigging.
Ask yourself, what purpose does the rigging serve? Isn't it to keep the mast up and resist the bending effect of the balance of power between the wind in the sails and the righting effect of the hull, ballast and foil dynamics.

 

[pvb]

Again let me warn against over-tightening. I have had two small yachts with coachroof stepped masts which have suffered coachroof sag through over-tensioning rigging.
Ask yourself, what purpose does the rigging serve? Isn't it to keep the mast up and resist the bending effect of the balance of power between the wind in the sails and the righting effect of the hull, ballast and foil dynamics.

It takes a certain amount of experience to know how much tension to apply to any particular boat, which is why I suggested getting a rigger to do the job. It's certainly the case that boatowners generally won't tension the rigging sufficiently. And it's also the case that under-tensioned rigging is a prime cause of rig failure, resulting from work-hardening caused by vibration.

 

[Lakesailor]

Must be me then. I hate vibration ( and fluttering). But winding on more and more tension is madness.

 

[PuffTheMagicDragon]

And it's also the case that under-tensioned rigging is a prime cause of rig failure, resulting from work-hardening caused by vibration.

And also the repeated shock-loads when the going is bumpy.

 

[William_H]

Must be me then. I hate vibration ( and fluttering). But winding on more and more tension is madness.

+1 The link to Loos guage repeatedly says refer to boat manufacturer rig manufacturer etc but then goes on to give the 15% of ultimate capability of the wire.
When talking about metals and fatigue it is clear that to stretch the metal in tension gives it more ability to resist fatigue failure. hence we tension cylinder head bolts to stretch the bolts and resist fatigue from the repeated tensioning of cylinder firing. So it follows that if we want to extend the fatigue life of SS wire then we must stretch it. That is fine from the riggers point of view.
However from the boat owners point of view he has a hull as a part of the load circuit. The hull and especially mast support system are much more flexible than the wire. So as said if we crank up shroud and forestay/backstay tension we are stressing the hull. Now hull materials I believe are susceptible to creep and bend when subjected to continuous load. So over a period of time you can get a bend in the hull. I think it far easier to replace wire than try to return any distortion in the hull to original. Further the failure of wire in rigging may not be simple fatigue anyway but a corrosion type given that it so often fails at the entry to bottom swages. And anyway insurance companies tend to insist on wire replacement on a calender basis 10 or 15 years. All of the above leading me to think that you are foolish to tension wire to try to minimise fatigue failure.

Now coming to a catamaran. Here is a generally structurally lighter shape with much greater beam. The mast support structure is on a wider base so even more susceptible to bend. So even more so I would not put a lot of permanent tension on rigging. Sure the stress is applied when sailing and this can be huge but at least it is not applied 24/7 for years on end. So tension should be set up so that mast is stable. and especially of the right shape ie relative tensions are correct. The rig should remain vertical when hard pressed when sailing. But note the lee shrouds will always go slack and that can not be stopped. Minimised a little perhaps but it is a result of hull flex.
So yes a little static tension but nothing like the nubers that many experts promote. Thats my opinion olewill

 

[KellysEye]

Don't take any notice of all the sites giving rigging tension they are for GRP monohulls not wooden cats, I suspect the tension on the rig of a wooden cat would be less, also, as said, the angles are more than a monohull. Find a rigger who has experience of wooden cats and ask.

 

[Rum_Pirate]

Don't take any notice of all the sites giving rigging tension they are for GRP monohulls not wooden cats, I suspect the tension on the rig of a wooden cat would be less, also, as said, the angles are more than a monohull. Find a rigger who has experience of wooden cats and ask.

:encouragement:

 

[lydiamight]

Had a friend who was the owner of a OOD34 and a keen racer. His technique was to tighten everything up until you couldn't close the door to the heads!