Reducing ship emissions: A review of potential practical improvements in the propulsive efficiency of future ships

Environmental issues such as the emission of greenhouse gases, pollution, wash and noise are having an increasing impact on the design and operation of ships. These environmental issues together with economic factors, such as rising fuel costs, all ultimately lead to the need to minimise ship propulsive power. Various methods and devices for reducing propulsive power are reviewed and discussed. The most favourable methods, from a feasible and practical point of view, are identified and quantified. It is found that potential reductions in the resistance of existing good hull forms are relatively small, but optimising hull-propeller-rudder interaction offers very promising prospects for improvement. The biggest potential savings in power arise from optimised operational strategies such as the use of optimum trim, speed and weather routeing. Potential conflicts of interest when considering both economic and environmental requirements are investigated and discussed. Suitable design methodologies and procedures, taking into account economic and environmental factors, are suggested for the design of future ships.