Rigging tension problem

[AndrewB]

I have a problem tensioning the rigging after my mast was put back on my elderly Moody 376..

The yard rigger wanted a fortune to re-rig, so I decided to do it myself, takng the PBO expert advice at: How to set up your rig: tension your shrouds on masthead or fractional - Practical Boat Owner. Not having a tension gauge, I followed the idea of tensioning until the rigging stretched by 3mm over a 2m range. At the end it felt really, really tight, certainly compared with similar cruising boats nearby.

Then I went out for a couple of hours fun in a fresh F4-5. On returning, blow me if the rigging wasn't as slack as Granny's suspenders. Tighten it all up again, repeat a couple of hours thrash, and the rigging is once again just as slack.

So now what? If I tighten it again, am I just bending the boat? Or if I leave it like it is, do I risk the dire warning in the PBO article that "Rigging that’s under-tensioned puts infinitely more load on the wire, bottlescrews, terminals and hull structure".

 

[vyv_cox]

I agree with the warning but cannot offer much help. Something must be wrong and I doubt if it is the boat bending. Are the swaged ends made properly or could the wire be pulling through one? Thread stripped in a bottle screw? Mast post collapsing? Chain plate(s) broken? Could a bottle screw be unwinding?

 

[Neeves]

I think you ca simply check the various nightmares that Vyv lists by have fixed marks (felt pen) on each component, taking a phone photo of each mark, before and after.

Jonathan.

 

[Martin_J]

And we assume you held the swage at the lower end of each stay fixed whilst rotating the bottle screws to tighten (to ensure the stay doesn't wind itself up)... Apologies if that is too basic a question.

And it'll only take one bad swage or bottlescrew to slip or even a single elongating hole in the mast to cause slackness all over.

I hope you find the issue easily.

How often do swaged get badly made...? There must be hundreds of thousands of them around and it can't be a common issue.

Did the forestay get replaced and wss whatever fitting used fully tightened within the lower end of the furling drum.

 

[Refueler]

"held the swage at the lower end of each stay fixed whilst rotating the bottle screws to tighten (to ensure the stay doesn't wind itself up)... "

A very important point that many miss .... if the stay turns while adjusting - it does not always untwist when you stop adjusting ... it may wait till load comes on ...

Its very important to have stay in its 'natural' fall and to only turn the bottle screw ........

The other matter of course is whether the masthead toggles are correctly seated - but OP mentions it slacked twice ... so I would suspect it lies at bottom end of stay ......

 

[AndrewB]

Thanks guys for these suggestions. (Yes, I did hold the stays while turning up the bottle-screws!) The rigging is brand new, Jimmy Green, which is the reason for lowering the mast. But I'll check if by any chance it is pulling out of a swage, or that the mast itself is being compressed.

If not, perhaps the very newness means it is stretching a little in use. Or maybe as Martin_J & Refueler suggest, the seating wasn't quite right. I am encouraged by Vyv's remark that the boat is unlikely to be distorting, so if I see no other problems I will try tightening once more.

 

[LittleSister]

. . . or that the mast itself is being compressed.

I think that Vyv was suggesting that the post (or pad or beam) that supports the mast (rather than the mast itself) may be being compressed,

 

[Stemar]

I always knew when the rig on Jissel was tight enough because the head door bolt wouldn't close...

 

[AndrewB]

I always knew when the rig on Jissel was tight enough because the head door bolt wouldn't close...

Heads door sticking... That happens if my boat is stored ashore for a while, though it sorts itself on refloating. So I now ask the yard to put an extra chock right aft when it is stored ashore. This stops the problem.

P.S. I guess that door would serve as a check that tensioning the rig is not bending the boat!

 

[Daydream believer]

You could be pulling a chain plate out of the deck. Check around the bow fitting. The mast support should also be checked. If all Ok then the rigging itself needs examination
I would look at the forestay first. If the shrouds are slackening an equal amount & the mast still sits centrally, then that is could be where the problem lies. If the adjustment is inside the furler (as it is on my profurl) it could be that the locking nuts have not been fitted to the bottlescrew. The action of furling "might" undo the bottlescrew. But knowing how hard they are to tension, I doubt they would go slack that quickly.

I would suggest wrapping electrical tape around every thread when adjusting rigging. This gives a visual aid to how much thread has been tightened/eased. Lines with markers tend to wipe off, if the threads have been properly greased prior to adjustment.

The fitting at the mast may be the issue. If this is failing, that could be the problem. But it would have to be signifficant to need 2 sets of tensioning. It is worth a trip up the mast to have a look before making any more adjustment. Are you masthead or 11/12 rig? if 11/12 then the forestay box in the mast may be the problem.

I also think that the investment in a loos gauge is well worth it, if one is going to do one's own rig adjustment.

 

[Refueler]

I always knew when the rig on Jissel was tight enough because the head door bolt wouldn't close...

My heads door scrapes the underdeck mast backing pad !

 

[doug748]

Thanks guys for these suggestions. (Yes, I did hold the stays while turning up the bottle-screws!) The rigging is brand new, Jimmy Green, which is the reason for lowering the mast. But I'll check if by any chance it is pulling out of a swage, or that the mast itself is being compressed.

If not, perhaps the very newness means it is stretching a little in use. Or maybe as Martin_J & Refueler suggest, the seating wasn't quite right. I am encouraged by Vyv's remark that the boat is unlikely to be distorting, so if I see no other problems I will try tightening once more.

New rigging wire does stretch but it should only be a turn or so of the rigging screw, and it will should stop after a couple of sails. I use less tension than sometimes recommended and it's ok, the lee rigging tension comes off in about 15kts of breeze.

 

[Refueler]

You could be pulling a chain plate out of the deck. Check around the bow fitting. The mast support should also be checked. If all Ok then the rigging itself needs examination
I would look at the forestay first. If the shrouds are slackening an equal amount & the mast still sits centrally, then that is could be where the problem lies. If the adjustment is inside the furler (as it is on my profurl) it could be that the locking nuts have not been fitted to the bottlescrew. The action of furling "might" undo the bottlescrew. But knowing how hard they are to tension, I doubt they would go slack that quickly.

I would suggest wrapping electrical tape around every thread when adjusting rigging. This gives a visual aid to how much thread has been tightened/eased. Lines with markers tend to wipe off, if the threads have been properly greased prior to adjustment.

The fitting at the mast may be the issue. If this is failing, that could be the problem. But it would have to be signifficant to need 2 sets of tensioning. It is worth a trip up the mast to have a look before making any more adjustment. Are you masthead or 11/12 rig? if 11/12 then the forestay box in the mast may be the problem.

I also think that the investment in a loos gauge is well worth it, if one is going to do one's own rig adjustment.

Rigger pal of mine used his spike tool ... one that he used to tighten bottle screws ... he would 'play' the stays and listen to the sound when tapped with the tool. Seemed to work for him over many many years till he went for pension.