Isola 21' is a sailing cabin cruiser with a movable leeway with 4/5 rigged mast and outboard or inboard engine; Inner structures and furnishings knit you to the hull by means of stratification: - 3 main bulkheads and 4 dividing ones in marine ply-wood; - The longitudinal reinforcements are in unidiretional fiberglass GRP. Deck constructed with isophtalic resin strengthened with glass fibers with sandwich of expanded PVC and sea ply-wood for equipement assembly.3 locker galleys. Appendixes:rudder with a lead and VTR movable leeway; Mast and Boom constructed with anodized aluminum with inox steel spiral shrouds and halyards.