Nomoto-type manoeuvring mathematical models and their applicability to simulation tasks

Besides “full-size” mathematical models for ship manoeuvring based on the Euler equations for the free rigid body, it is possible to develop simplified input–output models describing the evolution of certain kinematical parameters of manoeuvring motion but not based directly on the principles of mechanics. A family of such models starting from the well-known Nomoto equations is reviewed and analysed. Also, the Nomoto equations augmented with nonlinear static characteristics are used for simulating turning and zigzag manoeuvres of a typical vessel with varying degrees of directional stability and the output is compared with that obtained from simulations carried out with the relatively full primary mathematical models. Conclusions about the adequacy of simplified input–output models and their applicability to simulation tasks are drawn.