@qwerty2008:
Nice work Lextin!
That looks like a lot of time in stitching, you will be sick of it by the time you have finished.
I don't know the exact process you are using, but if it is any help, there is some thin 6mm wide double sided tape available that is used for model sailmaking that could perhaps be used to advantage with these sails. I imagine there would be a supplier somewhere near you in California, I only know of Australian suppliers. For each side of the sail, you could turn over the flap and tape it to the sail and it would then be firmly held in place while you do the stitching and you would not be reliant in the stitching alone for the strength of the sail. With the few square sails that I made, I found it really difficult to get the stitching to sit right and to look anything like it was supposed to... But when it comes to sewing I am hopeless anyway!