G'day Bill,
If sailors REALLY want to know the hows and whys of the performances of hulls through the water and of the sails through the air together with their interaction at the boundary layer of the two, they should get a copy of one (or more) C.A.Marghaj's "sailing theory and practice", There is not a great deal more (unless they want to get really high tech') that a designer of performance boats really needs to successfully design by.
Darryl J Barrett.