Cassette assembly, waterborne vessel and method of servicing a water-accessible structure

A cassette assembly (200) is attachable to an end portion (102) of a waterborne vessel (100). The cassette assembly (200) includes a cassette section (210) to bear against an external structure (300) in use. The cassette section (210) is movable relative to the vessel (100) in a direction towards an opposite end of the vessel (100). A resilient buffer system (250) counters movement of the cassette section (210) when the vessel (100) is moved towards the external structure (300), wherein the resilient buffer system (250) includes a buffer (251) including a plurality of resiliently compressible elements (253) arranged in series. A waterborne vessel (100) includes a receiving portion (120) for receiving the cassette assembly (200), and can be used to service a water-accessible structure (300) such as a wind turbine.