Duke: yeah but this time I knew when I was successful...
Thanks to all for the replies especially decrepit, JF I might try the train on the next big wind. Would be so nice to see another windsurfer 'out there' for once, they're like the loch ness monster as far as I'm concerned. Everyone knows about em but no-one's seen em...
That video of gnaraloo wipeout showed some guy waterstarting, I couldn't believe how quickly he managed it, even did it a couple of times until the poor bugger ran out of puff after the fourth monster wave hit him... I've done the same thing in waves about a quarter the size of those ones, and uphauled each time, got smashed until I was in shallow water. ouch

Been practicing in my head as to what went wrong, I reckon with a steadier wind I might have managed it more often but hey at least I know it's vaguely possible...