Hi Mike,

if the windward telltale is flying, the wind enters the jib very smooth and produces a lot of lift and lift-induced drag. Letting the windwrad one stall a bit means a bit more drag due to stalling, but less lift and less lift-induced drag. At the end the ratio between lift and drag (from stalling and induced) is better that way. And the ratio of lift to drag is the key figure for making good vmg upwind.
Before letting the windward telltale rise, you should apply the ussual means for making the sail flat.

to Gilo,

Upwind I play the sheet and the tiller, but the tiller not much. I use the sheet to control the heeling angle and the tiller to profit from the gust in pointing higher to the mean wind direction. I try not to force the boat in a direction, just let it go and give gentle corrections. I think that is the way you described your sailing style as well, and I think it is the right way to do it.
Guess the F18 is simply the faster boat (longer, larger, high mast, daggerboard?), you sailed yours better, but size matters... Just my 2 cent.

btw I really like to discuss sail trim in this forum, better than any book.

Cheers,

Klaus