Environmentalists outside of the marine industry might like to see all ships powered by wind or solar and make engines of any description a thing of the past but more practically minded people will recognise that while such power sources can make a small contribution, an engine of some type is an essential element of a safe and efficient ship.
There may one day come a time when ships are fitted with a power source that is not an internal combustion engine but for the foreseeable future the power needed for propulsion and other ship systems is almost certain to come from a marine diesel engine running on either oil or a liquid gas fuel.
Regulation of ships’ power and propulsion systems is a comparatively recent thing except of course for fire and safety aspects of engine rooms and machinery spaces and a requirement for emergency steering. The power source itself is effectively only regulated by MARPOL Annex VI and the EEDI regulations and there is little if any direct regulation of propulsors beyond that set down in classification society rules. The question of lubricant choices for propeller shafts and rudders can be a matter of regulation if the lubricant is not considered environmentally acceptable.
Despite the growing list of regulations aimed at the emissions aspect of power generation on board, modern ships’ systems have advanced significantly primarily because of owners’ demands for more reliable, more efficient and less thirsty vessels. Almost all designers and manufacturers involved have reacted to those demands with innovative measures and evolved technology that has involved massive R&D expenditure only sometimes aided by grant funded research such as the HERCULES engine research project.
Because the basics of internal combustion engines and ship propulsion are still much as they were a century ago there should be no doubt that the advances made over that time have been significant. It has been some time since a single advance has had the same degree of effect as say turbochargers did in the 1960s and 70s and it is accepted that future improvements come in much smaller increments and at greater research cost.
Nevertheless equipment makers and others are not deterred and the variety of options available to shipowners is increasing at a faster pace than at any time in the history of powered navigation.