Integration of Added Resistance Evaluations in a Ship Synthesis Model

In this paper, the impact of integrating a direct numerical evaluation of the added resistance in waves into the design process is illustrated. The increased power required to the ship advancing in waves for each combination of significant wave height and average period is computed by means of the PDStrip freeware software. The total power needed is then compared with the total installed power. The adverse meteo-marine conditions reflects into an increase in the consumption and possibly in a decrease of the average attainable speed in comparison to the nominal (calm water) values. A long term averaging, based on the wave scatter diagrams for the sea zones interested by the trade, provides the expected values for the increase in annual operating costs and for the reduction in the annual average speed. The latter implies also a decrease in the actual quantity of cargo delivered in a year. These outputs of seakeeping computations are integrated into the design process loop in order to seek the optimal solution.