Thanks Graeme,
Just as a side note its a mast top hawk not a yey level one - the genoa will not work with an eye level one...
OK so yes I have tell tales on the genny, and follow the principles in the heron info sheet (they should fly parallel on either side of sail).
So when I'm stationary the flag / hawk points in the direction of the wind. When I'm moving it points in the direction of 'apparent wind' - what I don't actually know is what that has to do with anything! There's going to be something absolutely basic that I'm missing here.... The one website I found that talked about apparent wind and what it meant for sailing must have been talking transatlantic because it needed computer software to do calculations... wasn't planning on taking the computer out with me!
Like the cassette tape idea! I used chandler sold tapes before but they get shredded to pieces when the wind kicks up in the dinghy park.