| 摘要 |
A retractable thruster (5) is connected to a lifting device for retracting the thruster in two stages, the lifting device in the first stage lifting the thruster to a level at or near the keel (7) of the vessel, the second stage including lifting the thruster to an access level (13), located above the first level. The lifting device may be formed by a rack (3,3') which can be constructed on deck level, or by hydraulic cylinders. Preferably the frame (6) which carries the thruster is formed by a closed container having buoyancy, the drive motor, gearbox and rotational drive unit being placed in the container.
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