Abstract: The propulsion system for vessels comprises at least one suction sail (3), comprising the suction sail (3) a suction system (10) and a driving unit (8) for driving the rotation of said at least one suction sail (3), in which at least one suction sail (3) also comprises a plurality of sensors (12, 13, 14, 15) connected to a control unit (9), whose control unit determines the operation of the suction system (10) and the transmission unit (8). It permits to provide a propulsion system for vessels that permits to optimize their performance using suction sails.

Abstract: The invention relates to a sail having a variable profile. The sail can vary between a folded non-operative position and an unfolded operative position, wherein they determine the profile of the sail (2) and therefore the aerodynamic surface for contacting with the wind, characterised in that the sail comprises at least one sail element (24) which is inflatable and stiffenable, and which can be actuated by inflation (30) and stiffening means (29), between a folded position corresponding to said folded non-operative position and said unfolded operative position, in which the sail (2) is inflated. The profile of the sail is divided into sections (21, 22) on both sides of a shaft (20), and comprises a support structure (23) on which said inflatable sail elements (24) are disposed, said inflatable sail elements being formed by inflatable pockets (24) which can be actuated by said inflation (30) and stiffening means (29).