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

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