An engineer stands on the crankshaft of a huge engine of a merchant ship. The largest ship cargo engines are up to 25 meters long, height 13-14 meters and weight 2.000-3.000 tons. Their strength is about 80.000-100.000 kW (107.000-135.000 BHP) and operate at low speeds of 60-100 RPM, which increases performance.

These engines burn heavy fuel oil (HFO) and consume 200-300 tons of fuel per day. An example is the Wärtsilä RT-flex96C engine, which weighs 2,300 tons, it has 14 cylinders and has an efficiency of 80.080 kW. The efficiency of these motors can reach up to 50%, making it possible to transport large cargoes across the oceans at low operating costs. Comparative, conventional car engines are 20-30% efficient, the most modern around 40%.