Research On Collocation Of DP Thrusters Of Pipelay Crane Vessel

The pipelay crane vessel is a very significant equipment to the offshore oil technology nowadays. It charged with the task of laying pipes onto the seabed. So its performance directly affects the development of petroleum industry. But the environment on the ocean is variable, so the Dynamic Positioning System (DPS) which could automatically maintain the ship's position and heading is indispensable.In this paper, the method of collocation thrusters of DPS was researched. A deepwater pipelay crane vessel was Chosen as the research object. After analyzed the various elements which could influence the performance of thruster system, the project of collocation thrusters for the vessel had achieved eventually.At the beginning of the study, the external load of vessel had analyzed, including selection of utmost marine environment, the selection of work condition, the calculation of environmental forces, and the calculation of work forces. The chose environment and work condition were the state which influences the DPS remarkably. Environmental forces were calculated by non-dimension coefficients which came from reduced scale wind tunnel experiment. Then, the selection of thrusters, the interference factors to thruster efficiency had discussed, including comparison of thrusters'performance between different species and control modes, the prescript of DP rules for thruster system, and the environmental disturbances to thrusters. These works had established a firm foundation for next researches.During design process of the dynamic positioning thruster system, needs to analyze the forces of thrusters and the capabilities of DPS's. Therefore, two programs were designed to achieve the computer simulation. One could simulate the forces of thrusters, and the other one could simulate the capability of DPS to maintain the ship's position and heading in the range of 360 degrees.During the research process of collocate DPS thrusters, the states of the vessel's basic motion had analyzed, and had found the relevant laws of arrangement. Then summed up a set of practical process for collocate DP thruster system. On this basis, the arrangement work of pipelay crane vessel's thruster system had finished. The dynamic positioning capability plot showed that the thruster system fully satisfied the DP-2 dynamic positioning Requirements. This work can serve as practical engineering design of dynamic positioning thruster system.