VIDEO: The Largest Ship Engine in the World

VIDEO: The Largest Ship Engine in the World

The Largest Ship Engine in the World

The Wärtsilä RT-flex96C: The Largest Ship Engine in the World


The Wärtsilä RT-flex96C, a colossal creation by Finnish manufacturer Wärtsilä, is a two-stroke turbocharged low-speed diesel engine, specifically designed to power large container ships operating on heavy fuel oil. This engine is a marvel of marine engineering, holding the title of the world’s largest reciprocating engine. The 14-cylinder version of this engine, weighing over 2,300 tonnes, stands 13.5 meters high and 26.59 meters long and is capable of producing a staggering 80.08 megawatts of power.

Historical Context and Deployment

The 14-cylinder version of the Wärtsilä RT-flex96C made its commercial debut in September 2006, serving as the powerhouse for the Emma Mærsk. This engine is a refined version of the older RTA96C, incorporating advanced common rail technology, which replaces the traditional camshaft, chain gear, fuel pump, and hydraulic actuator systems. This innovation allows for enhanced performance at lower revolutions per minute (rpm), facilitating reduced fuel consumption and minimized emissions of harmful substances.

Innovative Design and Functionality

The engine is meticulously designed with crosshead bearings, ensuring that the piston rods are always vertical, creating a tight seal under the pistons. This intricate design allows for split lubrication; the cylinders and the crankcase use different specialized lubricants. The cylinders are lubricated by continuous timed injection of consumable lubricant, designed to protect against wear and neutralize acids formed during the combustion of high-sulfur fuels.

The crosshead design is crucial as it significantly reduces sideways forces on the piston, maintaining diametral cylinder liner wear to about 30 μm per 1,000 hours. As a piston descends, it compresses incoming combustion air for adjacent cylinders, cushioning the piston as it approaches bottom dead center and alleviating some load from the bearings. The engine employs uniflow scavenging through exhaust valves operated by electronically controlled hydraulics, eliminating the need for a camshaft.

Technical Proficiency and Specifications

The Wärtsilä RT-flex96C is a technical masterpiece, with specifications that are nothing short of impressive:

  • Configuration: Turbocharged two-stroke diesel straight engine, available in 6 to 14 cylinders.
  • Bore: 960 mm.
  • Stroke: 2,500 mm.
  • Displacement: 1,828.7 liters per cylinder.
  • Engine Speed: 15–102 RPM.
  • Power Output: Up to 5,720 kW per cylinder, with a total of 34,320–80,080 kW (46,020–107,390 bhp) for the 14-cylinder version.
  • Torque: Up to 7,603,850 N⋅m @ 102 rpm.
  • Fuel Consumption: The engine can consume up to 250 tons of fuel per day, with a brake-specific fuel consumption of 171 g/(kW·h).

Massive Components and Reliability

The components of the Wärtsilä RT-flex96C are as massive as the engine itself. The crankshaft alone weighs 300 tonnes, and each piston weighs 5.5 tonnes and has a height of 6 meters. As of 2006, over 300 RT-flex96C and older RTA96C engines were either in service or on order, highlighting the engine’s popularity and reliability in the marine industry.

Environmental Consideration and Impact

While the Wärtsilä RT-flex96C is a marvel of engineering, it also brings forth environmental considerations. The engine, designed to run on heavy fuel oil, emits significant amounts of sulfur oxides, nitrogen oxides, and particulate matter. However, the incorporation of common rail technology and other innovations aim to reduce these emissions and make the engine more environmentally friendly. The advancements in marine propulsion technology represented by engines like the Wärtsilä RT-flex96C are crucial in the ongoing efforts to mitigate the environmental impact of maritime activities.


The Wärtsilä RT-flex96C is a symbol of human ingenuity and a pinnacle of marine propulsion technology. Its intricate design, immense power, and efficiency have set new benchmarks in the marine industry, enabling large container ships to traverse the oceans more effectively and sustainably. The engine is not just a mechanical creation; it is a masterpiece that powers the giants of the sea, connecting continents and facilitating global trade and commerce.

The continuous innovations and advancements in marine engineering promise a future where such colossal engines will be even more efficient, eco-friendly, and integral to global maritime operations. The Wärtsilä RT-flex96C stands as a testament to the possibilities of engineering and the human spirit to create solutions that drive progress and connect the world in more sustainable ways.

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