Integrated System Analysis and Design of Podded Ship Propulsors

AlliedSignal has studied podded propulsion for surface combatants for the US Navy under a contract sponsored by DARPA. The integrated system analysis included mathematical models for the main components of a podded propulsor. The models addressed both performance and cost. Components modeled included the propulsor itself (single propeller, ducted propeller, etc.), bearings, coupling, gearbox, motor, and azimuthing system. Simplified, approximate methods, especially for propulsor sizing and performance, were used. Other information in the literature and product data from leading vendors was used to size the components and to estimate their efficiencies. In other sections of the model, life-cycle fuel costs and costs of reliability were computed. The model was used to size and estimate the total costs for different configurations for four surface ships. A conceptual design for each vessel was selected, and three-dimensional CAD renderings of four pods were prepared. Sensitivity studies were run to show the effects of variations in fuel cost and in the relative efficiencies of propulsor types. Subsequent to the naval program data on a typical cruise ship were obtained and the spreadsheet model was applied to that platform.