Patent ID: 7672760

Claim:
A searchlight ( 3 ) for use on a moving vessel ( 1 ), in which said searchlight ( 3 ) is arranged for sending a light beam with a beam axis ( 3 a ) which is arranged for illuminating a point or position ( 2 p ) of an object ( 2 ) which is situated on the surface of the sea, in which said searchlight ( 3 ) is arranged in a given elevation (h 1 ) above the sea and is revolvable about a perpendicular axis ( 15 a ) with respect to a base plane ( 16 ) having a reference direction ( 16 r ) and a base plane parallel axis ( 15 b ) parallel to said base plane ( 16 ); in which said searchlight ( 3 ) beam axis ( 3 a ) is arranged for being revolved about said perpendicular axis ( 15 a ) and said base plane parallel axis ( 15 b ) for steering said beam axis ( 3 a ) towards said point ( 2 p ); in which said searchlight ( 3 ) is provided with a first motor ( 5 a ) for movement of said beam axis ( 3 a ) about said perpendicular axis ( 15 a ), and a second motor ( 5 b ) for movement of said beam axis ( 3 a ) about said base plane parallel axis ( 15 b ); characterised by the following features: a control unit ( 8 ) arranged for receiving measurements from the following devices: a first heading sensor ( 4 a ) for measuring an angle (v 1 ) of said beam axis ( 3 a ) projected down onto said base plane ( 16 ) with respect to said reference direction ( 16 r ); a second heading sensor ( 4 b ) for measuring an angle (v 2 ) of said beam axis ( 3 a ) with respect to said perpendicular axis ( 15 a ); vessel movement sensors ( 6 ) for measuring said vessels ( 1 ) rotational angles, in which said vessel movement sensors ( 6 ) comprise one or more of a yaw sensor ( 6 d ), a roll sensor ( 6 b ) and a pitch sensor ( 6 c ); a position sensor, for instance a GPS-receiver ( 7 ) which calculates geographic latitude ( 7 a ) and longitude ( 7 b ) in a coordinate system; a heave sensor ( 6 a ) arranged for calculating said vessels ( 1 ) heave position; in which said control unit ( 8 ) on the basis of the received measurements of said vessels ( 1 ) movements, said vessels ( 1 ) position, and said searchlight ( 3 ) orientation and position on said vessel ( 1 ) is further arranged for calculating and furnishing control signals ( 9 ) to said motors ( 5 a , 5 b ) for rotating said beam axis ( 3 a ) about said perpendicular axis ( 15 a ) and said base plane parallel axis ( 15 b ), in order for said beam axis ( 3 a ) to be directed towards said desired point ( 2 p ) on the sea while said vessel ( 1 ) is in movement.