Abstract: The system includes at least two units each contained in a watertight housing to be installed on starboard and on port side, each containing inside a blade or a fin having a moving device that retracts or projects the fin outboard when necessary for steering or stabilizing. In both cases the blades or the fins are maintained normally inside their housing to reduce sailing resistance and are extended right or left only when activated for steering or for stabilizing. The motion device essentially consists of a plate joined to the blade or fin tilting on a shaft pivoting inside the housing but holding out at least one end passing through a hub provided with a seal providing water tightness and supporting actuators, and capable of supporting remote monitoring systems that record the exact position of the blade constantly and automatic controls of course or an automatic stabilization system.

Abstract: Steering and/or stabilising device for motorised watercraft, with at least two operating units comprising each a retractable fin (4), characterised in that the retractable fins of each operating unit are contained in tubular watertight casings (5) open on the bottom or on the underwater area of the hull sides and located completely or for their prevailing portion inside the hull, one on the starboard side and the other on the port side, each fin (4) being guided axially in the associated tubular casing (5) and being movable by an actuator (10) outwards and inwards in the casing (5), so that it can be retracted in the casing (5) or projected out of the hull for a variable extent in the water.

Abstract: Steering and/or stabilising device for motorised watercraft, with at least two operating units comprising each a retractable fin (4), characterised in that the retractable fins of each operating unit are contained in tubular watertight casings (5) open on the bottom or on the underwater area of the hull sides and located completely or for their prevailing portion inside the hull, one on the starboard side and the other on the port side, each fin (4) being guided axially in the associated tubular casing (5) and being movable by an actuator (10) outwards and inwards in the casing (5), so that it can be retracted in the casing (5) or projected out of the hull for a variable extent in the water