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Note: MOPS

Abstract: Offshore wind farm vessels are oftentimes equipped with jack-up legs, to lift the hull above the water surface at the site of operation. The vessels´ harmonic motions in a seaway must be within defined limits during the initial contact of leg and seabed. This paper therefore presents the implementation of the legs´ hydrodynamic influence on the seakeeping behaviour in an existing seakeeping analysis method for application in the early design stage. It is based on a frequency domain, linear strip method providing response amplitude operators in a regular seaway. The legs´ hydrodynamic influence is included by a Morison approach. The presented method provides the possibility to quickly calculate the response motions of a jack-up vessel in a regular seaway during the jack-up process. It represents a fast computational tool for the early design stage to design the vessel especially for the environmental conditions of the site of operation.