Dynamics Modeling and Analysis for Twin Marine Lifting Systems

Many offshore platforms are approaching obsolescence and require decommissioning in the foreseeable future. Compared with the dismantling method using the single crane-vessel, the twin marine lifting systems (TMLS) are more efficient and less costly. However, the study of twin marine lifting systems is not mature at present. The dynamics modeling and the heave compensation system of twin marine lifting systems pose many challenges due to the strong state coupling and nonlinearity. Based on Lagrange's modeling method, this paper establishes an accurate dynamic model of TMLS to provide the foundation for heave compensation system design. The roll motion of the twin lifting vessels is taken as the disturbance for the lifting systems. Linearization are not considered in the modeling process to ensure the accuracy of the dynamic model.