Abstract: A sail assembly of variable profile, reversible and collapsible, comprising a mast on which are mounted ribs set apart one from the other, each one being constituted of two flexible laths joined together by hinge members, the ribs being covered with a supple material, such as for example sail cloth. Each rib includes a slide piece on which are pivotally mounted the two flexible laths and on which a mast is slidably mounted, the mast being fast in rotation with the slide and being adapted to be driven in rotation, the slide piece being provided at the back with a first cam which is fast with a shaft driven in rotation and comprising two arms connected together by transmission members pivotally mounted on the rear portion of the flexible laths. The invention finds an application in the production of sail assemblies of variable profile.