I always start a new design on the board with an HB filled .5mm mechanical pencil, got started in this yacht designing just before CAD went mainstream. I like ACAD for drawings and quick 3/D persectives to place under vellum as a guide when sketching. Acad is a great perspective generating tool with adjustable focal lengths.
Have used Solidworks but its constrained when you want to do flowing surfaces. Rhino is my drug of choice and now to cinch it they go and offer a yacht specific package:
http://www.rhinomarine3d.com/
Solid modeling is best if you do basic shapes like an engine room and equipment. Exterior styling is best if sculpted by hand and scanned in, if not, Rhino can be tortured (and torturing) to make its production possible.