On the "How Realistic Can One Make Sails" thread, I posted one option to add fullness to sails, using a drawn fabric technique.
Here's another technique for adding fullness to a (three sided) main sail. This simple technique can be used on fabric, paper and silkspan.
All sail patters (I've seen) show a 90* right angle at the tack of the sail. If you increase this angle, by one or two degrees, the length of the leech will increase by ~1/8". That doesn't sound like a lot, however, when the sail is attached to the boom and mast, the leech will be too long.
In the second photo, the foot and luff of this paper sail were taped to the cutting board at a 90* angle. The additional length in the leech 'billows' and gives a natural looking shape to the sail.
The increased angle will vary, pending the angle of the boom.
Very nice sails Druxey. FWIW, my modeling interest are working boats and classic wood boats, not warships.