I THINK, the best starting point is going to be to hoist the main and get the mast curve to fit the luff of the main through a combination of diamond wire tension and spreader rake.
I have always wondered about this when people are talking about doing that. Wouldn't you want the curve of the luff to match the curve of the mast only when max downhaul is on? Theoretically, the sail matching the curve of the mast would make the sail as flat as possible, right?
