hey rustle
there was an article once in the UK's boards mag on how to re-rig your sail with a broken mast, it might be on their web page. If they have still got the article up .....well worth a read, loads of useful tips to save your bacon and your gear.
whenever i've snapped a mast out at sea i've somehow managed to derig, save everything and paddle back in. It's a huge ballache though and noy very good to lie on a rolled sail while you paddle.

if you snap a mast or a uj... get a fellow windsurfer to slip the broken rig over his, help them waterstat then either paddle back in or get a tow off them.... i think it's quite east to do... but i have seen it done!!!!!!