In this paper, we deal with a operation scheduling scheme for the process after a ship is launched from docks in shipbuilding industry. After a ship is launched, almost works are performed while the ship is on the berth at quay. Since the number of quays is limited, ships have to move from a quay to another quay until all works are finished in the process. And sometimes they are anchored in the sea because of lack of quays. Thus, general project management schemes like PERT/CPM are not fit for this process as a scheduling algorithm. In this paper, we propose a practical scheduling procedure which consists of 3 steps. In the first step, we can make initial work schedule for each ship using PERT/CPM scheme. In the second step, we perform quay assignment to ships. In this step, we formulate a mathematical problem to implement an efficient quay assignment algorithm. In the last step, the final work schedule for each ship is made using modified PERT/CPM scheme. Through computing simulation, we show that the proposed scheme can provide a good performance.