The invention relates to a sail propulsion element comprising a mast (3), an
inflatable sail (1) consisting essentially of two adjacent surfaces (5) which are substantially sealed and connected to each other around their periphery, thereby forming between them at least one
closed cavity, said sail comprising an upper part (6), a lower part (7), a
leading edge (8) and a
trailing edge (9), the sail comprising different curves forming bulges over the entire length, at least one air duct arranged between the inside and the outside of the cavity of the sail, at least one means for injecting air into said cavity, the sail, once inflated, having a profile which remains permanently symmetrical, regardless of the movement of said propulsion element, the direction or intensity of the wind, a headpiece (10) arranged on the upper part (6) of the sail,and a sail receptacle (11) arranged between the
leading edge (8) and the
trailing edge (9) on the lower part of the sail. The element according to the invention is characterized in that it comprises a guide line (12) arranged in the
closed cavity of said sail, for the hoisting and lowering maneuvers of the sail, said guide line extending from the
leading edge (8) to the
trailing edge (9) of said sail, passing through the headboard (10) and the sail receptacle (11). Figure for the abstract: figure 2,