The dynamics of ship propulsion unit-large hull-water interactions

This paper developed a generalised theory to model the dynamics of an integrated ship propulsion unit-large hull-water interaction system. The engine shaft unit, the hull structure are considered as two substructures and the water as a subdomain, of which the motions of each subsystem are governed by the fundamental laws in continuum mechanics, and on their interfaces, kinematical and dynamical conditions are satisfied. The integrated variational formulation is given, based on which the numerical equation is derived by using the mode summation approach. The shaft frequency and deformation factors are defined to study on its interactions with large hull and water in order to provide a mean for safety propulsion unit design in large ships. An example is given to illustrate the applications of the general theory presented in the paper. Some guidelines which are useful in preliminary design stage for dynamical designs of large ship hull - propulsion system are suggested.