High retraction marine thruster

A high retraction steerable thruster for a floating structure which defines a downwardly open, substantially vertical passage in which the thruster is movable to and from a deployed position relative to the structure in which a thruster propeller is submerged below an exterior surface of the structure, characterized in that the passage is defined to enable the thruster to be moved substantially only vertically from its deployed position to a second position at which the propeller is above the floating waterline of the floating structure.

A floating marine structure which includes a steerable retractable thruster which is movable in the structure between a lower deployed position in which a propeller of the thruster is disposed below adjacent submerged surfaces of the structure and an upper retracted position in which the propeller is within the structure in a submerged state below the floating waterline of the structure, characterized by a more elevated service position of the thruster in the structure in which the thruster propeller is located above said floating waterline.

A floating marine structure, such as an offshore drilling facility, having a hull in which there is a retractable steerable thruster, the thruster having a propeller carried by and below a vertically movable enclosure which includes a driver for the propeller, the floating structure including, among other components, a vertical trunk in the hull in which the thruster driver enclosure is vertically movable, the trunk extending from a submerged lower open end to a level in the hull above the floating waterline of the structure at which at least one wall of the trunk opens to a thruster service space, and a thruster vertical travel system effectively coupled between the structure and the thruster and operable for moving the thruster vertically between a deployed position of the thruster in which the propeller is below the trunk lower end and an elevated position in which the propeller is above said level.