Identifying a ship's means of propulsion is usually indicated by its name. The MV preceding the name indicates what kind of ship it is, as in the case of a motor vessel. General speaking, at the beginning of the 21st century, around 97 % of all large ships are motor vessels that can also be reliably operated against the wind. The largest ship diesel engines generate more than 100,000 hp.
Nicolaus August Otto presumably had no conception of these dimensions when he patented the internal combustion engine in 1876. According to the inventor's idea, the first four-stroke engine with spark ignition was merely supposed to serve as a small drive to supplement steam engines. It was only when Gottlieb Daimler and Wilhelm Maybach further developed the idea into quick-running internal combustion engines in 1886 that a breakthrough took place â for the engine and thus for motorised shipping as well. When Hamburg's Freeport was opened in 1888, Gottlieb Daimler took advantage of the opportunity to present his first motor boat there. The seven-metre-long wooden boat with a 2 hp engine met with great approval. It became the prototype for the Hamburg harbour launch boat and was built for many years.
Motorisation of merchant shipping
Motor vessels driven with petrol or kerosene did not develop into high-performance propulsion units for merchant shipping, however, until it became possible to design a reversing device. After the motor drive gained acceptance in small watercraft and the spark ignition engine was also used as auxiliary propulsion for sailing vessels, replacing the steam engine on large sailing ships, the triumphal advance of the diesel engine as means of ship propulsion kicked off at the beginning of the 20th century. Particularly convincing features were its high thermal efficiency of 35-46 %, whereas steam engines only exploited approximately 15 % of the fuel energy, as well as the spatial gain due to elimination of the boiler unit and coal bunker, the easy fuel supply and less need of engine personnel.
Further development into a power plant
As of the 1950s, diesel motor vessels dominated in ship's newbuilding because they had higher efficiency, the above mentioned lower spatial requirements and lower material expenditures. The big diesel engines enabled fuel utilisation of 50 %. Different engine designs with direct injection, swirl chamber and precombustion chamber engines primarily served to provide propulsion for ships. At the beginning of the 1960s the output of a ship's diesel engine was around 25,000 hp, which was achieved in part by means of an exhaust-driven turbocharger. The introduction of the container as the standardised means of transportation that considerably increased the efficiency and productivity of maritime traffic, required even higher power performance because of the increasing size of ships with greater load capacities. The introduction of electronics contributed to the next jump in diesel engine performance. Common rail technology enabled electronically controlled injection and thus powerful diesel engines generating about 100,000 hp.
And today?
Low fuel consumption, high power density and simple operation were the advantages of internal combustion engines, which were consequently able to replace all other engines. Meanwhile another criterion for sustainable power has been added: reduction of pollutant emissions. At the beginning of 2011 a five-year process started with the aim of reducing the pollutant emissions of ships' engines specified by the IMO by up to 80 %. The enormous success in motorised shipping since 1886 has made the most economical means of cargo transport by far. Now it is ushering in the launch of a new era with regard to the expected advancements in environmental protection, performance and efficiency as well as improved flexibility in engine operation.