Replacing the bucket with a drum cutter for excavators placed on floating platforms for dredging tasks is an effective option in construction. Dredging excavators used for channel opening have characteristics and working conditions that differ from conventional excavators such as high working depth, non-visible operating position. Therefore, controlling the drum cutter is a crucial task during equipment operation. In this paper, we will address the problem of inverse kinematics to determine the movements of the hydraulic cylinders to ensure the desired trajectory of the cutter is achieved. Several combined trajectories, both with and without transition points, will be studied to examine the system kinematic response of the system. The research results provide important information for controlling the drum cutter to optimize dredging activities for maritime channels, thereby improving efficiency and reducing energy consumption.