Correct wire size for forestay?

[Kelpie]

Hi
I am looking to re-rig my 33ft S&S designed keel/centreboard yacht. She is currently rigged with 6mm all round, including the forestay. There is a profurl roller jib on the forestay and I am wondering if 6mm is not a bit light? I have been informed previously that a extra weight of a furling system requires a heavier forestay.
The boat has a design displacement of about 12,000lbs.
The jib is a bit smaller than she was designed for, as the boat has been converted to carry a self tacking blade rather than the original overlapping genoa.

Would there be any disadvantage to increasing the size of the forestay (other than cost).

Thanks

[Brion Toss]

Hi,
First, the weight of the furler is of no significance, unless perhaps it is made out of very thick lead. There is also no reliable correlation between displacement and rig loads. The jibstay -- and all the rest of the rig -- is loaded most when you are going to weather in a breeze, with or without a furler. So the question, as always, is: what is the load? I recommend you consult the righting moment chart in the (New!) Rigger's Apprentice, and/or do an incline test for your boat. It is possible that at least some of the wires on your boat are appropriately-sized.
Fair leads,
Brion Toss

[Kelpie]

Thanks for that. Perhaps I am worrying over nothing then.