Master thesis : Numerical Simulation of Installation Ship's Dynamics by Crane's Cargo Loss

Abstract

Crane load lifting failures in the past have raised some serious concerns about the safety of offshore operations. Numerous efforts are being made to make the large offshore wind turbine installation operation safe and reliable. A vessel is being designed by Neptun Ship Design (NSD) to carry out offshore wind turbine installation operation in deep sea. The purpose of master thesis is to carry out a time domain simulation of installation vessel in roll, pitch, and heave motion due to sudden load loss. A comparative study of corresponding rules of classification societies (DNV, BV, and ABS) have been documented and followed. Based on the classification recommendations, corresponding mathematical modelling is designed and time domain simulation in case of sudden loss of crane load is carried out and analysed in single degree of freedom and coupled motion. An estimation of added mass, damping and restoring coefficient is made on the bases of literature review, analytical approximation and using contrikov’s method. A sensitivity analysis of added mass is carried out to check the response of the vessel especially maximum heel angle. Moreover, the ship ability to minimize the roll angle by discharging of ballast water is analysed and its practical implementation is accessed.