Thanks Guys, those are a couple of lovely boats.
I hadn't considered displacement, my boat is pretty lightly built , probably not much more than 150 kilos/340lbs including crew so I guess there's not as much need for a heavy mast, actually, there's no need for 100sq ft/10sq m of sail either I suppose, it's more like 75 sq ft plus a 25 sq ft ghoster that'll be reefed at force 2 or sooner.
I'll take it out with my dinghy rig in the next day or two and see how it goes with 70 sq ft on a 2"/50mm with 17.5% walls 12'/3.7m hollow mast, if that doesn't break I'll have an idea of how heavy to make the new mast :)
Do you have any info you'd be willing to share on your sail build David? I'm planning on a rectangular aero junk myself and have no idea what size the battens should be.
Bill F