System for towing equipment at sea, preferably in relation to seismic surveys, comprising a main vessel (7) adapted to tow equipment (8) in a given direction of movement, at least one deflector (1) on each side of the main vessel (7) adapted to, during towing, pulling at least a part of the towed equipment (8) transversally in relation to the direction movement. The system comprises at least one support vessel (9) for supplying an additional towing force in the moving direction of the vessel and/or providing the active deflector(s) with power and possibly controlling signals to through a cable (6).