rigging options

[catalac08]

hi
my 8 m catalac has standing rigging about 9 years old and although in an ideal world I would replace the lot, because it has twin backstays and twin forestays (cutter rig) plus a baby stay I feel the fore and aft support is prety belt and braces so I am inclined to just replace the cap shrouds and lowers on the basis of cost avoidance now. (My recent insurance survey noted the age of the rigging but made no recommendation to replace any at this stage and my insurance renewal did not demand this either-perhaps they will want this all replaced next year anyway) Is there any sense or merit in having a bigger size cap shroud wire when I do replace them as this is the one which looks the most vulnerable to failure as not twinned up ie replace 6mm 1x19 stainless with with 7mm? The rigging screws are 10 mm and look to be plenty big enough for this size of boat, albeit a catamaran.

 

[Boathook]

As far as I am aware the 6mm wire is more than adequate on both the 8m and 9m Catalac. Persoanally I would replace the whole lot in one go in a few years unless you think the rig has been abused which is unlikely !!

 

[wotayottie]

I'm not sure you would achieve anything much by going up a size - my guess is that rigging rarely fails by stretching to the yield point. Its more likely to fail by bending so I'd spend the extra money on ensuring all rigging is well articulated at mast and on deck.

no one can advise you on when to replace except perhaps the insurance company. even then it will be more of a case of what you have to do to maintain insurance of the rig rather than telling you when its going to fail.

worth taking the mast down and examining the rigging with a magnifying glass to see if there are any cracks / strand failures at the swages at either end

 

[Talbot]

When I re-rigged my Catalac 9m the first time, I noted that the baby stay and lower shrouds were a smaller diameter than the main shrouds and backstay, and the forestay was another size up.

I kept the forestay at the larger size, but changed the lowers and babystay to the same size as backstay and main shrouds.

A catamaran has much higher loads on the standing rigging than a monohull, especially in gusts. As the monohull will lean over to absorb some of the additional pressure, on a cat this is all taken by the rigging until the extra pressure translates to acceleration.

 

[vyv_cox]

I have read that increasing the wire diameter can have a negative impact on overall security. In order to achieve the same tension in the larger wire you will need to tighten them to a higher force. This will impose higher forces on the hull with, in the case of a catamaran, considerable bending forces around the base of the mast.

I doubt that there is much benefit in trying to out-think the builders, who presumably knew more about their design than any of us do.

 

[William_H]

vyv's comment shows up the falacy of tensioning wire on the basis of size alone. he is right you could damage the boat by trying to get so much tension.
I agree with Talbot that loads on a cat are huge and it doesn't have that heeling ability to dissipate the rig loads.
However I tend to agree with catalac's theory that it is the shrouds that matter most. The forestay is also supported by the luff tension of the jib and the backstay is supplemented by the mainsheet tension but the shrouds just have to do the job. While the cap shroud looks more vulnerable it is IMHO just as critical and takes just as much load.

9Years old might be a bit on the young side but if it helps you sail more relaxed it is worth the comparatively small cost to replace the rigging wire. Likewise if it makes you happy go to the larger size.

Don't let anyone fool you into a false sense of security by inspecting the wire. It will let go without warning or sign most likely inside the bottom swages. But hopefully not for a few years yet. Good luck olewill