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57-404: A Z-drive is a type of marine propulsion unit. Specifically, it is an azimuth thruster . The pod can rotate 360 degrees allowing for rapid changes in thrust direction and thus vessel direction. This eliminates the need for a conventional rudder . The Z-drive is so named because of the appearance (in cross section ) of the mechanical driveshaft or transmission configuration used to connect

114-442: A diesel-electric propulsion plant in 1986. Most new-build ships with steam turbines are specialist vessels such as nuclear-powered vessels, and certain merchant vessels (notably Liquefied Natural Gas (LNG) and coal carriers) where the cargo can be used as bunker fuel . Steam powers two types of engine, reciprocating (with steam driving pistons connected to a crankshaft) and turbine (with steam driving blades attached radially to

171-552: A cold head rather than swage fittings. This process requires a different, expensive machine but yields a more durable end fitting. Rod-type stays fail suddenly (rather than strand by strand as a cable would), often where the rod bends around a spreader . Bending can induce unseen stress fractures. Most fore-and-aft rigged vessels have the following types of standing rigging: a forestay , a backstay , and upper and lower shrouds (side stays). Less common rigging configurations are diamond stays and jumpers. Both of these are used to keep

228-767: A gearbox. Where more than one engine is geared to a single shaft, each engine will most likely drive through a clutch, allowing engines not being used to be disconnected from the gearbox while others keep running. This arrangement lets maintenance be carried out while under way, even far from port. Combined diesel or gas (CODOG) Combined diesel and gas (CODAG) Combined diesel-electric and diesel (CODLAD) Combined diesel–electric and gas (CODLAG) Combined diesel and diesel (CODAD) Combined steam and gas (COSAG) Combined gas or gas (COGOG) Combined gas and gas (COGAG) Combined gas and steam (COGAS) Combined nuclear and steam propulsion (CONAS) Integrated electric propulsion (IEP or IFEP) Many warships built since

285-736: A longer, lower engine room than that needed for two-stroke diesel engines. Multiple engine installations also give redundancy in the event of mechanical failure of one or more engines, and the potential for greater efficiency over a wider range of operating conditions. As modern ships' propellers are at their most efficient at the operating speed of most slow speed diesel engines, ships with these engines do not generally need gearboxes. Usually such propulsion systems consist of either one or two propeller shafts each with its own direct drive engine. Ships propelled by medium or high speed diesel engines may have one or two (sometimes more) propellers, commonly with one or more engines driving each propeller shaft through

342-429: A nozzle to direct its flow out, generating momentum, and in most cases, employing thrust vectoring to steer the craft. Pump-jets are found on personal watercraft , shallow-draft river boats, and torpedoes. Standing rigging Standing rigging comprises the fixed lines, wires, or rods, which support each mast or bowsprit on a sailing vessel and reinforce those spars against wind loads transferred from

399-435: A nuclear powerplant. In 2019, nuclear propulsion is rare except in some Navy and specialist vessels such as icebreakers . In large aircraft carriers , the space formerly used for ship's bunkerage is used instead to bunker aviation fuel. In submarines , the ability to run submerged at high speed and in relative quiet for long periods holds obvious advantages. A few naval cruisers have also employed nuclear power; as of 2006,

456-607: A number of small submarines in order to run as quietly as possible. 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. Merchant ships predominantly used sail, but during periods when naval warfare depended on ships closing to ram or to fight hand-to-hand, galley were preferred for their manoeuvrability and speed. The Greek navies that fought in

513-413: A reciprocating diesel engine as their prime mover, due to their operating simplicity, robustness and fuel economy compared to most other prime mover mechanisms. The rotating crankshaft can be directly coupled to the propeller with slow speed engines, via a reduction gearbox for medium and high speed engines, or via an alternator and electric motor in diesel-electric vessels. The rotation of the crankshaft

570-399: A single screw, even very large ships such as tankers, container ships and bulk carriers may have single screws for reasons of fuel efficiency. Other vessels may have twin, triple or quadruple screws. Power is transmitted from the engine to the screw by way of a propeller shaft, which may be connected to a gearbox. The propeller then moves the vessel by creating thrust. When the propeller rotates

627-444: A spinning shaft). The shaft power from each can either go directly to the propeller, pump jet or other mechanism, or it goes through some form of transmission; mechanical, electrical or hydraulic. In the 1800s, steam was one of the main power sources for marine propulsion. In 1869 there was a large influx of steam ships as the steam engine underwent large advancements during the time period. The development of piston-engined steamships

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684-508: A steam turbine. In such combined cycles, thermal efficiency can be the same or slightly greater than that of diesel engines alone; however, the grade of fuel needed for these gas turbines is far more costly than that needed for the diesel engines, so the running costs are still higher. Some private yachts, such as the Aga Khan 's Alamshar , also have gas turbine propulsion (Pratt and Whitney ST40M), which enables top speeds of up to 70 knots, which

741-410: A thin mast in column especially under the load of a large down wind sail or in strong wind. Rigging parts include swageless terminals , swage terminals , shackle toggle terminals and fail-safe wire rigging insulators. Whereas 20th-century square-rigged vessels were constructed of steel with steel standing rigging, prior vessels used wood masts with hemp-fiber standing rigging. As rigs became taller by

798-441: Is a promising fuel, it has a few disadvantages. Hydrogen is far more flammable than other fuels such as diesel, so precautions must be taken. It is also not very energy dense, so it has to be heavily compressed to increase its energy density enough for it to be practical, similar to methane and LNG. Hydrogen can have its power extracted either by use of a fuel cell system or it can be burned in an internal combustion engine, similar to

855-416: Is comparatively easy to recognize wear and stress as individual strands (normally 19) break often near a swage fitting , and can be inspected while standing. Solid rod stainless steel is more aerodynamic so is often used in extreme racing yachts but it is difficult to see stress as this requires professional inspection such as dye penetrate testing or x-raying . Rod rigging is strongest when terminated with

912-723: Is connected to the camshaft or a hydraulic pump on an intelligent diesel . The reciprocating marine diesel engine first came into use in 1903 when the diesel electric rivertanker Vandal was put into service by Branobel . Diesel engines soon offered greater efficiency than the steam turbine, but for many years had an inferior power-to-space ratio. The advent of turbocharging however hastened their adoption, by permitting greater power densities. Diesel engines today are broadly classified according to Most modern larger merchant ships use either slow speed, two stroke, crosshead engines, or medium speed, four stroke, trunk engines. Some smaller vessels may use high speed diesel engines. The size of

969-481: Is the most efficient of fuels, although limited access to LNG fueling stations limits the production of such engines. Vessels providing services in the LNG industry have been retrofitted with dual-fuel engines, and have been proved to be extremely effective. Benefits of dual-fuel engines include fuel and operational flexibility, high efficiency, low emissions, and operational cost advantages. Liquefied natural gas engines offer

1026-664: Is unique for a 50-meter yacht. Shipping companies are required to comply with the International Maritime Organization (IMO) and the International Convention for the Prevention of Pollution from Ships emissions rules. Dual fuel engines are fueled by either marine grade diesel, heavy fuel oil, or liquefied natural gas (LNG). A Marine LNG Engine has multiple fuel options, allowing vessels to transit without relying on one type of fuel. Studies show that LNG

1083-581: The Peloponnesian War used triremes , as did the Romans at the Battle of Actium . The development of naval gunnery from the 16th century onward vaulted broadside weight ahead of maneuverability; this led to the dominance of the sail-powered warship over the following three centuries. In modern times, human propulsion is found mainly on small boats or as auxiliary propulsion on sailboats. Human propulsion includes

1140-664: The Voith-Schneider marine propulsion system (also mechanically linked), which can also quickly change the direction of thrust, as the Z-drive uses a shrouded conventional screw that pivots or rotates the propeller, unlike the variable-geometry blades of the Voith-Schneider. The Z-drive transmission was invented in 1950 by Joseph Becker, the founder of Schottel, and used in the first azimuth thrusters built by Schottel GmbH in Germany in

1197-445: The sails . This term is used in contrast to running rigging , which represents the moveable elements of rigging which adjust the position and shape of the sails. Early sailing vessels used rope of hemp or other fibers, which gave way to wire ropes of various types. Galvanized steel was common for the first half of the 20th century, continuing as an inexpensive option to its 1960s successor material—stainless steel cables and rods. In

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1254-541: The 100-foot (30 m) Turbinia at the Spithead Naval Review in 1897. 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. In the early 20th century, heavy fuel oil came into more general use and began to replace coal as the fuel of choice in steamships. Its great advantages were convenience, reduced manpower by removal of

1311-500: The 1960s have used gas turbines for propulsion, as have a few passenger ships, like the jetfoil . Gas turbines are commonly used in combination with other types of engine. Most recently, RMS  Queen Mary 2 has had gas turbines installed in addition to diesel engines . Because of their poor thermal efficiency at low power (cruising) output, it is common for ships using them to have diesel engines for cruising, with gas turbines reserved for when higher speeds are needed. However, in

1368-629: The 1960s under the Schottel brand name and referred to as RudderPropeller ever since. Joseph Becker was awarded the Elmer A. Sperry Award for this invention as a major contribution to the improvement of transportation worldwide. Marine propulsion Human-powered paddles and oars, and later, sails were the first forms of marine propulsion. Rowed galleys , some equipped with sail, played an important early role in early human seafaring and warfares . The first advanced mechanical means of marine propulsion

1425-423: The 1970s. The Savannah also suffered from an inefficient design, being partly for passengers and partly for cargo. In recent times, there is some renewed interest in commercial nuclear shipping. Fuel oil prices are now much higher. Nuclear-powered cargo ships could lower costs associated with carbon dioxide emissions and travel at higher cruise speeds than conventional diesel powered vessels. Most modern ships use

1482-768: The International Maritime Organization's (IMO) standards. Company profits from tax cuts and operational cost advantages has led to the gradual growth of LNG fuel use in engines. LPG Engines As environmental sustainability becomes a paramount concern, the maritime industry is exploring cleaner propulsion technologies. LPG (Liquid Petroleum Gas) is another fuel alternative that brings operational, economics and environmental benefits. Studies have shown that using LPG reduces sulfur oxide emissions by 97% and particulate matter by 90%. Similar to LNG, many LPG vessels have been retrofitted with dual-fuel engines which are extremely effective. Using LPG as fuel also makes

1539-568: The Stirling engine's operation. The engines are currently used on submarines of the Gotland and Södermanland classes and the Japanese Sōryū -class submarine. These are the first submarines to feature Stirling air-independent propulsion (AIP), which extends the underwater endurance from a few days to several weeks. The heat sink of a Stirling engine is typically the ambient air temperature. In

1596-614: The adoption of this system by the U.S. Navy , followed by the British Royal Navy . To expand the range and duration of the submarine during World War II the German Kriegsmarine developed a snorkel system, which allowed the diesel-electric system to be utilized while the submarine was all but completely submerged. Finally, in 1952, the USS Nautilus was launched, the world's first nuclear powered submarine, which eliminated

1653-435: The case of medium to high power Stirling engines, a radiator is generally required to transfer the heat from the engine to the ambient air. Stirling marine engines have the advantage of using the ambient temperature water. Placing the cooling radiator section in seawater rather than ambient air allows for the radiator to be smaller. The engine's cooling water may be used directly or indirectly for heating and cooling purposes of

1710-413: 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. Some warships, and a few modern cruise ships have also used steam turbines to improve the efficiency of their gas turbines in a combined cycle , where waste heat from a gas turbine exhaust is utilized to boil water and create steam for driving

1767-498: The diesel engines presently used in the maritime industry. Battery-electric propulsion first appeared in the latter part of the 19th century, powering small lake boats. These relied entirely on lead-acid batteries for electric current to power their propellers. 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 . In

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1824-448: The different types of engines is an important factor in selecting what will be installed in a new ship. Slow speed two-stroke engines are much taller, but the footprint required is smaller than that needed for equivalently rated four-stroke medium speed diesel engines. As space above the waterline is at a premium in passenger ships and ferries (especially ones with a car deck), these ships tend to use multiple medium speed engines resulting in

1881-543: The early part of the 20th century electric propulsion was adapted to use in submarines . As underwater propulsion driven exclusively by heavy batteries was both slow and of limited range and timespan, rechargeable battery banks were developed. Submarines were primarily powered by combined diesel-electric systems on the surface, which were much faster and allowed for dramatically expanded range, charging their battery systems as necessary for still limited subsurface action and duration. The experimental Holland V submarine led to

1938-432: The end of the 19th century, masts relied more heavily on successive spars, stepped one atop the other to form the whole, from bottom to top: the lower mast , top mast , and topgallant mast . This construction relied heavily on support by a complex array of stays and shrouds. Each stay in either the fore-and-aft or athwartships direction had a corresponding one in the opposite direction providing counter-tension. Fore-and-aft

1995-399: The late 19th century. These engines exhausted steam from a high pressure cylinder to a lower pressure cylinder, giving a large increase in efficiency. Steam turbines were fueled by coal or, later, fuel oil or nuclear power . The marine steam turbine developed by Sir Charles Algernon Parsons raised the power-to-weight ratio . He achieved publicity by demonstrating it unofficially in

2052-457: The late 20th Century, racing yachts adopted composite fiber lines for standing rigging, with the goal of reducing weight and windage aloft. On modern yachts, standing rigging is often stainless steel wire , Nitronic-50 stainless steel rod or synthetic fiber . Semi-rigid stainless steel wire is by far the most common as it combines extreme strength, relative ease of assembling and rigging with reliability. Unlike rigid stainless steel rod, it

2109-514: 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. Construction of NB 1376 will be completed in 2013. According to Viking Line, vessel NB 1376 will primarily be fueled by liquefied natural gas. Vessel NB 1376 nitrogen oxide emissions will be almost zero, and sulphur oxide emissions will be at least 80% below

2166-472: The mechanical energy of a turbine (steam or gas) into electric energy and electric motors to convert it back into mechanical energy to power the driveshafts. 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. It can also provide electricity for other electrical systems, such as lighting, computers, radar, and communications equipment. To transmit

2223-449: The mechanically supplied driving energy to the Z-drive azimuth thruster device. This form of power transmission is called a Z-drive because the rotary motion has to make two right angle turns, thus resembling the letter "Z". This name is used to differentiate the arrangement of drive to that of the L-drive . It does not refer to an electric motor in a rotating pod. The device is different from

2280-403: The need for trimmers and stokers, and reduced space needed for fuel bunkers. In these vessels, the nuclear reactor heats water to create steam to drive the turbines. When first developed, very low prices of diesel oil limited nuclear propulsion's commercial attraction. The advantages of its fuel-price security, greater safety and low emissions were unable to overcome the higher initial costs of

2337-571: The only ones remaining in service are the Russian Kirov class . An example of a non-military ship with nuclear marine propulsion is the Arktika -class icebreaker with 75,000 shaft horsepower (55,930  kW ). In an ice-breaker, an advantage is fuel security and safety in demanding arctic conditions. The commercial experiment of the NS ; Savannah ended before the dramatic fuel price increases of

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2394-690: The paddle wheel produces thrust , forward or backward as required. More advanced paddle wheel designs have featured feathering methods that keep each paddle blade oriented closer to vertical while it is in the water; this increases efficiency. The upper part of a paddle wheel is normally enclosed in a paddle box to minimize splashing. Paddle wheels have been superseded by screws, which are a much more efficient form of propulsion. Nevertheless, paddle wheels have two advantages over screws, making them suitable for vessels in shallow rivers and constrained waters: first, they are less likely to be clogged by obstacles and debris; and secondly, when contra-rotating, they allow

2451-400: The pressure in front of the propeller is lower than the pressure behind the propeller. The force from the pressure difference propels the propeller forward. The paddle wheel is a large wheel, generally built of a steel framework , upon the outer edge of which are fitted numerous paddle blades (called floats or buckets ). The bottom quarter or so of the wheel travels underwater. Rotation of

2508-457: The process of transporting LPG easier. First, LPG deck tanks are filled together with the LPG cargo tanks using the cargo system during loading. LPG is then drawn from the deck tanks into a fuel gas supply system and piped to the engine. This increases operational and economic efficiency, especially during long-haul shipping. In 2020, BW LPG pioneered the world’s first Very Large Gas Carrier (VLGC) that

2565-749: The push pole, rowing, and pedals. Propulsion by sail generally consists of a sail hoisted on an erect mast, supported by stays , and controlled by lines made of rope . Sails were the dominant form of commercial propulsion until the late nineteenth century, and continued to be used well into the twentieth century on routes where wind was assured and coal was not available, such as in the South American nitrate trade . 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. In

2622-479: The rest of the 19th century. Notable developments include the steam surface condenser , which eliminated the use of sea water in the ship's boilers. This, along with improvements in boiler technology, permitted higher steam pressures, and thus the use of higher efficiency multiple expansion (compound) engines. As the means of transmitting the engine's power, paddle wheels gave way to more efficient screw propellers. Multiple expansion steam engines became widespread in

2679-418: The restrictions of both diesel fuel and limited duration battery propulsion. Several short-range ships are built as (or converted to) pure electric vessels . This includes some powered by batteries which are recharged from shore, and some shore-powered by electrical cables , either overhead or submerged (no batteries). On November 12, 2017 Guangzhou Shipyard International (GSI) launched what may be

2736-655: The rotational force of the shaft into thrust, propellers are most commonly used in today's merchant vessels. The developed thrust from the propeller is transferred to the hull via a thrust bearing. Numerous types of propulsion have been developed over time. These include: One of the oldest forms of marine propulsion, oars have been found dating back to 5000-4500 BCE. Oars are used in rowing sports such as rowing, kayaking, canoeing. Marine propellers are also known as "screws". There are many variations of marine screw systems, including twin, contra-rotating, controllable-pitch, and nozzle-style screws. While smaller vessels tend to have

2793-471: The second half of the 20th century, rising fuel costs almost led to the demise of the steam turbine. Most new ships since about 1960 have been built with diesel engines , both Four or two-Stroke. The last major passenger ship built with steam turbines was Fairsky , launched in 1984. Similarly, many steam ships were re-engined to improve fuel efficiency . One high-profile example was the 1968 built Queen Elizabeth 2 which had her steam turbines replaced with

2850-436: The ship. The Stirling engine has potential for surface-ship propulsion, as the engine's larger physical size is less of a concern. 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. While hydrogen

2907-477: The system of tensioning started with the stays that were anchored in front each mast. Shrouds were tensioned by pairs of deadeyes , circular blocks that had the large-diameter line run around them, whilst multiple holes allowed smaller line— lanyard —to pass multiple times between the two and thereby allow tensioning of the shroud. In addition to overlapping the mast below, the top mast and topgallant mast were supported laterally by shrouds that connected to either

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2964-538: 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 or reducing general vibrations by highly flexible couplings. Diesel-electric provides flexibility to assign power output to applications on board, other than propulsion. The first diesel electric ship was the Russian tanker Vandal , launched in 1903. Turbo-electric transmission uses electric generators to convert

3021-400: The vessel to spin around its own vertical axis. Some vessels had a single screw in addition to two paddle wheels, to gain the advantages of both types of propulsion. A pump-jet , hydrojet , water jet , or jet drive uses a ducted propeller ( axial-flow pump ), centrifugal pump , or mixed flow pump to create a jet of water for propulsion. These incorporate an intake for source water and

3078-421: The world's first all-electric, battery-powered inland coal carrier. The 2,000 dwt vessel will carry bulk cargo for up to 40 nautical miles per charge. The ship carries lithium ion batteries rated at 2,400 kilowatt-hours, about the same amount as 30 Tesla Model S electric sedans. The diesel-electric transmission of power from the engine to the propeller affords flexibility in distribution of machinery within

3135-511: Was a complex process. Early steamships were fueled by wood, later ones by coal or fuel oil. Early ships used stern or side paddle wheels , which gave way to screw propellers . 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. Steam propulsion progressed considerably over

3192-539: Was retrofitted with LPG dual-fuel propulsion technology and the company has the largest VLGC fleet that has been retrofitted with LPG dual fuel propulsion technology. This technology works towards reductions in emissions and a step closer to achieving carbon-neutral shipping. Since the late 1980s, Swedish shipbuilder Kockums has built a number of successful Stirling engine powered submarines. The submarines store compressed oxygen to allow more efficient and cleaner external fuel combustion when submerged, providing heat for

3249-761: Was the marine steam engine , introduced in the early 19th century. During the 20th century it was replaced by two-stroke or four-stroke diesel engines , outboard motors , and gas turbine engines on faster ships. 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. Electric motors using battery packs have been used for propulsion on submarines and electric boats and have been proposed for energy-efficient propulsion. Development in liquefied natural gas (LNG) fueled engines are gaining recognition for their low emissions and cost advantages. Stirling engines , which are quieter, smoother running, propel

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