Commercial interests now demand a close awareness of fuel consumption, which is one of the major costs in vessel operation. This paper outlines one shipping operator's attempts to monitor and improve economic performance as indicated by fuel consumption alone. The authors are well aware that some aspects of operation, such as main engine performance variables, are closely and easily monitored whilst others such as environmental effects are not. They have therefore adopted a ‘macro-economic’ approach to the analysis and advice on Fleet operation in this instance, attempting to monitor the vessel operation system as a whole. Thus fuel consumption is used as a yardstick and it is this particular variable which is the subject of management focus. Although many of the inputs to the complete economic equation are necessarily unquantifiable in precise terms, it is considered that a valid determination of performance is attainable from a scientifically based overview.