In recent years merchant marine propulsion has been dominated by the diesel engine (primarily the slow speed type) with fuel costs being the principal factor in favour of their selection. Fuel costs, however, constitute but one of the major constraints entering the design and operation of the marine power plant.
Following a systems approach, the design problem of the marine power plant (within the framework of the overall ship design and seaborne transport systems) is considered, with the view to properly identify and classify the complete set of machinery constraints and their interactions, in relation to different ship applications.
On this basis, the gas turbine is compared with its internal combustion rival by considering the most significant constraints, but with due reference to other factors (of a lesser importance), where appropriate. It is shown that, in this way, the predominance of one type of prime mover over the other, in different applications can be easily explained.
Finally, consideration is given to future developments in terms of high-speed marine transportation demands, possible legislation requirements for environmental protection and potential advances in prime movers themselves. It is concluded that the gas turbine could well assume a more prominent role in marine propulsion, in the near or distant future.