Abstract: Various embodiments relate to a method and a harbour plant for mooring a floating body. The harbour plant includes a piled base structure provided with two upwards through sea level projecting sidewalls terminated above sea level and a laterally arranged bottom structure interconnecting the sidewalls, where a top surface of the bottom structure is arranged at a depth allowing the floating body to be floated in between the sidewalls, and where the floating body is arranged to be rigidly, but releasably supported by at least parts of the sidewalls. The method includes bringing the floating body into a position between the sidewalls and fixing rigidly the floating body to the vertical sidewalls of the base structure and still exposing the floating body more or less fully to buoyancy by allowing a water-filled gap at least between bottom of the floating body and a corresponding upper surface of the base structure.