By the 1950s, even cargo liners and tankers were routinely fitted with steam turbines. Reliable, compact and smooth-running, turbines seemed to be the engine of choice for the owner who wanted high performance.

However, turbine machinery needs high boiler pressures if it is to be efficient. Achieving high boiler pressures is expensive in terms of fuel, and requires high standards of maintenance. In recent years, and especially with high oil prices, the marine diesel has grown so efficient that it has become first choice for almost every type of ship. Indeed, large passenger ships like the Queen Elizabeth 2 and France have had their turbines replaced with diesels. Some regret the demise of the turbine, as no other type of engine can propel a ship quickly with such smoothness or quietness.

The gas turbine: a promise unfulfilled

For a time, it looked like the gas turbine might take over from the steam turbine. This form of engine burns fuel to produce hot gases which drive the blades of a turbine. Several merchant ships have been propelled by gas turbines, including tankers, ore carriers and container ships. However, none of these have proved commercially successful. Gas turbines have been very successfully applied to warships, where their ability to produce large power outputs and to do so very quickly from ‘cold’ have been important factors.