a three dimensional sail of one piece construction is made on a rotating roll having a deformable outer surface . the roll is divided into a large number of segments , extending across the width of the roll , with the convex profile of each segment being adjustable . a sail is made on the roll on a continuous basis by applying a first layer of film , deforming the film on the roll , applying adhesive and reinforcing the yarns , and applying a second layer of film to form a 3 - d laminate .