Ship hull and machinery optimization using physics-based design software

Ship design software is applied to the study of improving the design of an existing cruiser. The focus of this paper is on exploring machinery configuration options that could significantly reduce the overall fuel consumption and, consequently, reduce the total weight and operating cost of the ship. The prime movers, most likely gas turbines, of the majority of the naval ships today are usually designed for maximum speed, which is much higher than the ship's cruise speed. In the case of the CG47, the shaft power required at cruise speed is only 16% of that at maximum speed. Consequently, the specific fuel consumption is 64% higher at cruise speed because the gas turbines are delivering only a fraction of their rated power. In this paper, auxiliary engines are introduced and their overall impact on ship design are studied. Four different machinery configurations, namely, CODOG, CODAG, COGOG and COGAG, are examined. Results show that as much as 34% fuel savings could be achieved and the overall reduction in total ship weight could be as high as 9%.