Sail Cloth: What Weight?

I have just received the following note:

I will be having a new mainsail made at Jeckells. Please would you advise me which one I should  to have, 5 or 6 ounce cloth, as you now I do go out in heavy weather some times.

The writer probably remembers me taking this picture of him in October 2008:


I've just checked my invoice from Jeckells from when I replaced my sails in 2005 and it states that 6.2oz cloth was used. I certainly didn't specify that weight. I simply asked for a standard set of sails for the boat. If I was asked at all about weight, which I don't recall happening, I would have left it to them.

As with anything SeaHawk there are no class rules, so I believe it is down to the owner to specify. What would others specify for a sailor expecting to tackle winds up to force 7 or so on inland waters?

My new mainsail from Jeckylls is in 6oz cloth - probably original spec as they have been making them since the 60s!
Brian