<b>Combustion / Diesel Engines</b> Even today, mostly inexpensive, unpurified diesel oil or heavy oil is used as fuel in large diesel engines. Due to resolutions of the IMO to reduce emissions from combustion engines, however, low-sulfur diesel fuels (“marine diesel”) are increasingly being used in order to make it possible to drive into the so-called Emission Control Areas (ECAs), in which only 1% sulfur is allowed in the fuel is; in EU ports even stricter requirements apply: 0.1% sulfur content in fuel. In particular, the larger marine diesel engines with an efficiency of up to 50% are designed for operation at low speeds. Four-stroke engines are used for small and medium outputs (up to 24 MW at 400 rpm to a maximum of 2000 rpm, so-called medium-speed motors) and for large and larger outputs, two-stroke engines (up to 100 MW per motor, rotation 60-250 rpm, so-called slow-speed motors ) used. High-speed runners with speeds of > 2000 rpm are particularly common in the sport and recreational boating sector, but are also used in the Fast Rescue Boats on board professional and naval vessels, although jet propulsion is already used and more and more prevalent for these boats . The term “diesel” is derived from the work process that takes place in the machine - not from the fuel. The engine developed by Rudolf Diesel (1893 - 1898) is the unequaled heat engine in terms of efficiency. The engine owes this to the high compression achieved during compression in the working area, which is made possible by the fact that, in contrast to the Otto engine, it compresses pure air and no air-fuel mixture; In the diesel process, the combustible mixture is only created at the end of compression by injecting the fuel into the cylinder. The injected fuel normally burns independently under the effect of the high compression temperature without a special ignition device. In this respect, the diesel engine is also referred to as a compression ignition engine. In contrast to this, in Otto engines, the fuel-air mixture is ignited by an externally controlled ignition device. Electrically operating spark plugs are generally used here, which ignite the intake mixture at the set point in time.