Thank you people for your advice I’m going with 10mm, the next issue to sort is, all halyards go back to centre cockpit, there is a winch mounted on the gas bottle locker, to the rear of cockpit, I can’t see that working as the locker is built of 3/4 “ plywood, adequate for a gas locker but not sturdy enough for much else, I shall see, also I can’t see how the halyards from the foresail will get back, without a row of “washing lines “ across the foredeck. No doubt things will become clearer when I start to rig,
thanks again for all the advice
Hazel