Rig Tension

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jaminb

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I had the standing rigging replaced on my Jeanneau 37 at the beginning of this season. The rigger said the rig would need tensioning after a while of sailing. As we moved home port I got a different rigger to tension for me and now the forecabin door is binding slightly (but I have a lovely curve in the mast ). Should I back off a fraction of backstay tension and see if this improves the binding or should all the stays be eased equally ?

Also the boat is due to be lifted tomorrow - should i ease the rig tension prior to this?

Many Thanks
 
I always knew when Jerry the Rigger had done my boat - the head door wouldn't latch! One day, I found a Loos gauge for not a lot and did my own tension, taking it to 15%. The door would still latch - just, and the mast didn't fall down. My new boat's rigging is too big for the gauge, so I'm on the lookout for the right sized gauge for 6mm wire.

My club requires the mast to be removed for lifting, so I can't answer your last question, apart from to say that you don't want the rig loose ashore. Why not ask the people who are doing the lift?
 
jaminb, I would suggest you invest in a Loos rigging guage. They seem expensive, but I have bought 2 sizes as I found the smaller one would handle 6mm wire, but not at 20% for my ¾ rigged mast. Both were bought secondhand on eBay. Just set up a search on eBay and when any are listed you will be notified.

As you stated your forecabin door is binding shows your hull is not rigid and does flex. Once your boat is liffted and has no support from the water it will take a slightly different shape. Then once sitting on the keel and chocked, it will be a slightly different shape. Keeping the rig tensioned in not very wise as it could overload it. On my 32ft Fulmar I always slacken off before lifting every stay by 3 turns, but for your 37ft I would suggest 4 turns. That makes it easy to retension to exactly the same tension.

How to use Tension Gauges - Loos & Company, Inc. - Cableware Division
 
Maybe an expert will be along but in the meantime:

I would not touch anything except the backstay until you have your own gauge and/or more experience with the rig. You can't hurt anything by doing this with discretion. If sounds like the rigger has set the boat up well for going upwind in a blow - flattened mainsail and foresail luff as tight as it gets.

Take some photos of the rig as it is, esp up the mast showing the bend.
Begin to loosen the backstay but note the number of turns so you can return it if necessary.
Observe if the mast becomes straight or straighter.

If the mast straightens right out, a spirit level (this only works if you keep the same boat trim when checking) may help to judge if there is any rake - lean backwards or forwards. This is useful for future reference
It's most common for the mast to be raked a little aft.

With luck you may find the mast becomes straight your doors open properly and there may still be a little tension in your backstay. Put more into the backstay till you have some bend but the doors still open. Leave it at that.

You have established a workable range of mast trim for a cruising boat using backstay tension. If you could modify your backstay for adjustment by the helm, it would be possible to trim the rig for up, down and heavy winds; though many cruising sailors probably settle for a happy medium.

Putting the boat ashore like this should be fine but, personally, I would not do it with the rig fired up to the max.

.
 
If yours is a Sun Odyssey 37 I have a near-identical boat.

When the standing rigging on my Jeanneau SO35 was replaced about 3 years ago the riggers said to call them back after a few months sailing to tension it up. This seems to be a standard thing to say, and on many boats it is almost certainly correct.

However on mine no doors started to bind. After a few months I decided it did not need tensioning: the hull was rigid enough not to flex much. The same riggers replaced the genoa furler and forestay two years later, and before they started the job said the rig tensions still looked fine. It was set up with the amount of mast curve as specified by Jeanneau. This is a non-tweakable 15/16ths rig, no user adjusters or backstay tensioners.
 
Another vote for buying a Loos gauge. I had the bigger one on my boat, and after getting all the tensions right and the boat sailing well I wrote down the tensions for every stay. It was then easy to check and correct at the beginning of each season and periodically thereafter. I always took a small amount of tension off for winter layup, but you have to be careful doing that to leave enough. I had a masthead rig with mostly 10mm wire, and it was pretty bulletproof.
 
Thanks everyone looks like I need a loos gauge long term but will take a number of turns off the backstay tomorrow if the lift guys agree.
 
I am not convinced re the concept of wire tensioned to 15% of max rating. Yes I understand the oncept of tensioning any metal liable to fatigue from cyclic loads. Like cylinder head bolts. However our wire rigging while it would benefit by being pretensioned is part of a long load circuit. That is mast wires then hull so the hull must take the load of the pretensioning. Hulls generally are not stiff enough. As shown by typically toilet door won't close. It does not mean the hull is weak just not so stiff.
I go with relatively slack rigging though relative tension is critical to get correct mast shape and support especially under load. I then go with replacement of rigging at 15 years though I am yet to be convinced that rigging wire failure is just fatigue. Perhaps more a function of corrosion and fatigue. (especially at swage entry) ol'will
 
I helped my pal tension his rigging on his elderly Macwester ketch using a borrowed Loos gauge. We were slightly concerned that the deck fittings might not be up to the recommended tension so downrated it slightly (although I'm aware that more boats fail through under tension than over). Very simple and quick with the Loos.
One puzzle was what tension on the stay connecting the tops of the two masts (triatic?) so I just tensioned it so that it wasn't floppy.
 
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