The luff of the kite in that picture is far too loose. It needs to be at ~least~ where you grab the luff with a fist and turn 90 degrees. That luff looks like you could do that with about a fore-arm length of luff.
Thanks for the great info guys, sorry if my questions seem dumb, I'm trying to get a feel for this setting. When I set the boat up on the beach I grab the spin and fairly firmly twist it 180 degrees which is about 8 inches of slack, when you guys are testing how tight the luff is are you pulling the spin as hard as you can and just managing the 90 degrees. I've got to drill some extra holes in my 1 month old mast so would like to avoid too many practice holes.
regards Jeff