Preliminary modelling methodology of a coupled payload-vessel system for offshore lifts of light and heavyweight objects

This paper presents the concept of the modelling methodology of a payload-vessel system allowing for a comprehensive investigation of mutual interactions of the system dynamics for lifting in the air. The proposed model consists of six degrees of freedom (6-DoF) vessel and three degrees of freedom (3-DoF) lifting model that can replace the industrial practice based on a simplified approach adopted for light lifts. Utilising the response amplitude operators (RAOs) processing methodology provides the ability to incorporate the excitation functions at the vessel crane tip as a kinematic and analyse a wide spectrum of lifted object weights on a basis of regular wave excitation. The analytical model is presented in detail and its solution in a form of numerical simulation results are provided and discussed within the article. The proposed model exposes the disadvantages of the models encountered in engineering practice and literature and proposes a novel approach enabling efficient studies addressing a lack of access to reliable modelling tools in terms of coupled models for offshore lifting operations planning.