Marine diesel engine is now the most used prime mover of modern ships. In the past, steam reciprocating engine was widely used with coal as the fuel. Steam reciprocating engine actually is a flexible engine in terms of the type of fuel it uses. When there is no coal around, ship crews could cut trees as fuel. This happened in the past, when a ship sailed to remote islands, ship crews would use wood as fuel if they ran out of coal.
Now most shipbuilders and ship designer choose marine diesel engine as the prime mover of ships that they build or design. Diesel engine is smaller, and compact compared to steam reciprocating engine. In addition, marine diesel engine does not need large room for storing coal. Fuel oil is stored in tanks usually at the double bottom of a ship and a smaller daily tank above the engine.
The improvements in engine design has made the operation of marine diesel engine both in small and large ships fully automatic. Unlike the steam engine which needs constant manning from ship crews to feed coal into the combustion room that heats up the boiler, the marine diesel engine is controlled by ship crews only by several touching buttons or moving levers.
In the future, marine diesel engine will continue to be used with expectation that the engine will be more efficient, and emit less CO2 gas and with lower vibration. by Charles Roring in Manokwari of West Papua - Indonesia. Also read: Design constraints of propeller diameter and Propeller and ship's hull