Cranes employed for load transfer are large volume machines and canbe designed to accomplish linear, planar or spatial motions dependingon the intended use. Understanding the dynamic behavior of thesesystems, which have a load-carrying capacity of hundreds of tonnes, ishighly noteworthy for system design, control, and work safety. Inthis study, a theoretical model of a spatially actuated telescopic rotarycrane 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 consistsof high nonlinearity originating from geometric nonlinearity, gyroscopicforces, hydraulic compressibility, and elastic boom structure, the resultingderivative causality problem caused by rigidly coupled inertia elementsis addressed for this highly nonlinear system and consequential systemstate-space equations are presented.