Increasingly boom cranes were used as harbor mobile cranes for container handling. In comparison to gantry cranes or overhead traveling cranes up until now there are only a few automation concepts for boom cranes, due to the dominant nonlinear plant behavior and the problem of measuring the rope angle, which the established methods can not be used. In this paper a trajectory tracking control for boom cranes is presented consisting of decentralized control modules and a trajectory generation module. Nonlinearities are compensated by a feedforward strategy and by gain scheduling adaptation of feedforward and feedback control. The rope angle is reconstructed out of gyroscope measurement signals by disturbance observers. The trajectory tracking control is realized on a harbor mobile crane LIEBHERR LHM 400. Measurement results show the efficiency of the presented control concept.