Marine propulsion

Marine nuclear reactors, which appeared in the 1950s, produce steam to propel warships and icebreakers; commercial application, attempted late that decade, failed to catch on.

[1]Development in liquefied natural gas (LNG) fueled engines are gaining recognition for their low emissions and cost advantages.

Its design is not used in civilian marine application due to lower total efficiency than internal combustion engines or power turbines.

Until the application of the coal-fired steam engine to ships in the early 19th century, oars or the wind were the principal means of watercraft propulsion.

Sails are now generally used for recreation and racing, although innovative applications of kites/royals, turbosails, rotorsails, wingsails, windmills and SkySails's own kite buoy-system have been used on larger modern vessels for fuel savings.

The first commercial success accrued to Robert Fulton's North River Steamboat (often called Clermont) in US in 1807, followed in Europe by the 45-foot (14 m) Comet of 1812.

The marine steam turbine developed by Sir Charles Algernon Parsons[3] raised the power-to-weight ratio.

This facilitated a generation of high-speed liners in the first half of the 20th century, and rendered the reciprocating steam engine obsolete; first in warships, and later in merchant vessels.

The advantages of its fuel-price security, greater safety and low emissions were unable to overcome the higher initial costs of a nuclear powerplant.

In submarines, the ability to run submerged at high speed and in relative quiet for long periods holds obvious advantages.

Nuclear-powered cargo ships could lower costs associated with carbon dioxide emissions and travel at higher cruise speeds than conventional diesel powered vessels.

However, in the case of passenger ships the main reason for installing gas turbines has been to allow a reduction of emissions in sensitive environmental areas or while in port.

[8] Liquefied natural gas engines offer the marine transportation industry with an environmentally friendly alternative to provide power to vessels.

In 2010, STX Finland and Viking Line signed an agreement to begin construction on what would be the largest environmentally friendly cruise ferry.

[9] Company profits from tax cuts and operational cost advantages has led to the gradual growth of LNG fuel use in engines.

[10] LPG Engines As environmental sustainability becomes a paramount concern, the maritime industry is exploring cleaner propulsion technologies.

[14][15] The submarines store compressed oxygen to allow more efficient and cleaner external fuel combustion when submerged, providing heat for the Stirling engine's operation.

While currently not commonly used in the maritime industry, hydrogen as a fossil fuel alternative is an area with heavy investment.

As of 2018 the shipping company Maersk has pledged to be carbon free by 2050, a goal they plan to achieve partly by investing in hydrogen fuel technology.

Elco (the Electric Launch Company) evolved into the industry leader, later expanding into other forms of vessel, including the iconic World War II PT boat.

Finally, in 1952, the USS Nautilus was launched, the world's first nuclear powered submarine, which eliminated the restrictions of both diesel fuel and limited duration battery propulsion.

On November 12, 2017 Guangzhou Shipyard International (GSI) launched what may be the world's first all-electric, battery-powered inland coal carrier.

The ship carries lithium ion batteries rated at 2,400 kilowatt-hours, about the same amount as 30 Tesla Model S electric sedans.

[19][20] The diesel-electric transmission of power from the engine to the propeller affords flexibility in distribution of machinery within the vessel at a higher first cost than direct-drive propulsion.

It is a preferred solution for vessels that employ pod-mounted propellers for precision positioning[21] or reducing general vibrations by highly flexible couplings.

An advantage of turbo-electric transmission is that it allows the combination of high-speed turbines with slow turning propellers or wheels, without requiring a gearbox.

[citation needed][26] To transmit the rotational force of the shaft into thrust, propellers are most commonly used in today's merchant vessels.

These incorporate an intake for source water and a nozzle to direct its flow out, generating momentum, and in most cases, employing thrust vectoring to steer the craft.

This moved a series of paddles on chains along the bottom of the boat to propel it over the water and preceded the development of tracked vehicles.

[citation needed] In 1997, Gregory S. Ketterman patented a propulsion method of oscillating flappers driven by pedals.