We first derive a dynamical model for the control of a flexible rotary crane which carries out three kinds of motion (rotation, load hoisting, and boom hoisting) simultaneously. Only the joint between the boom and the jib is assumed to be flexible. The goal is to transfer a load to a desired place in such a way that at the end of the transfer the swing of the load decays as quickly as possible. We first apply an open-loop control input to the system such that the state of the system can be transferred to a neighbourhood of the equilibrium state. Then we apply a feedback control signal so that the stale of the system approaches the equilibrium state as quickly as possible.