Cranes employed for load transfer are large volume machines and can be designed to accomplish linear, planar or spatial motions depending on the intended use. Understanding the dynamic behavior of these systems, which have a load-carrying capacity of hundreds of tonnes, is highly noteworthy for system design, control, and work safety. In this study, a theoretical model of a spatially actuated telescopic rotary crane is obtained with provided assumptions using Bond Graph techniques. Following the modeling of an actuation system and of a main structure, unification of these two is accomplished. Since the overall system consists of high nonlinearity originating from geometric nonlinearity, gyroscopic forces, hydraulic compressibility, and elastic boom structure, the resulting derivative causality problem caused by rigidly coupled inertia elements is addressed for this highly nonlinear system and consequential system state-space equations are presented.