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128-697: Combined diesel or gas ( CODOG ) is a type of propulsion system for ships that need a maximum speed that is considerably faster than their cruise speed, particularly warships like modern frigates or corvettes . 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) For every propeller shaft there

256-442: 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

384-451: A Peloponnesian armada might win only when it fought near land in calm and confined waters, had the greater number of ships in a local theater, and if its better-trained marines on deck and hoplites on shore could turn a sea battle into a contest of infantry." In addition, compared to the high-finesse of the Athenian navy (superior oarsmen who could outflank and ram enemy triremes from the side),

512-409: A certain area may be more important than another depending on the purpose of the ship. The arrangement and number of oarsmen is the first deciding factor in the size of the ship. For a ship to travel at high speeds would require a high oar-gearing, which is the ratio between the outboard length of an oar and the inboard length; it is this arrangement of the oars which is unique and highly effective for

640-429: A decisive role in combat. The method for boarding was to brush alongside the enemy ship, with oars drawn in, in order to break the enemy's oars and render the ship immobile (which disables the enemy ship from simply getting away), then to board the ship and engage in hand-to-hand combat. Rams ( embola ) were fitted to the prows of warships, and were used to rupture the hull of the enemy ship. The preferred method of attack

768-520: A full stroke) and previous battle experience. The sailors were likely in their thirties and forties. In addition, there were ten sailors handling the masts and the sails. In the ancient navies, crews were composed not of galley slaves but of free men. In the Athenian case in particular, service in ships was the integral part of the military service provided by the lower classes, the thētai , although metics and hired foreigners were also accepted. Although it has been argued that slaves formed part of

896-767: 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

1024-403: A given day depended much on the weather. On a good day, the oarsmen, rowing for 6–8 hours, could propel the ship between 80–100 kilometres (50–62 mi). There were rare instances, however, when experienced crews and new ships were able to cover nearly twice that distance (Thucydides mentions a trireme travelling 300 kilometres in one day). The commanders of the triremes also had to stay aware of

1152-429: A great deal of upkeep in order to stay afloat, as references to the replacement of ropes, sails, rudders, oars and masts in the middle of campaigns suggest. They also would become waterlogged if left in the sea for too long. In order to prevent this from happening, ships would have to be pulled from the water during the night. The use of lightwoods meant that the ship could be carried ashore by as few as 140 men. Beaching

1280-410: A great financial burden, so that in the 4th century, it was often shared by two citizens, and after 397 BC it was assigned to special boards. The deck and command crew ( hypēresia ) was headed by the helmsman, the kybernētēs , who was always an experienced seaman and was often the commander of the vessel. These experienced sailors were to be found on the upper levels of the triremes. Other officers were

1408-421: A harbor, oarsmen would join the offensive and throw stones (from a stockpile aboard) to aid the marines in harassing/attacking other ships. Squadrons of triremes employed a variety of tactics. The periplous ( Gk. , "sailing around") involved outflanking or encircling the enemy so as to attack them in the vulnerable rear; the diekplous (Gk., "Sailing out through") involved a concentrated charge so as to break

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1536-426: A hole in the enemy line, allowing galleys to break through and then wheel to attack the enemy line from behind; and the kyklos (Gk., "circle") and the mēnoeidēs kyklos (Gk. "half-circle"; literally, "moon-shaped (i.e. crescent-shaped) circle"), were defensive tactics to be employed against these manoeuvres. In all of these manoeuvres, the ability to accelerate faster, row faster, and turn more sharply than one's enemy

1664-736: 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

1792-416: A maximum speed of 8 knots and a steady speed of 4 knots could be maintained, with half the crew resting at a time. Given the imperfect nature of the reconstructed ship, as well as the fact that it was manned by totally untrained modern men and women, it is reasonable to suggest that ancient triremes, expertly built and navigated by trained men, would attain higher speeds. The distance a trireme could cover in

1920-482: 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. Trireme A trireme ( / ˈ t r aɪ r iː m / TRY -reem ; from Latin trirēmis  'with three banks of oars'; cf. Ancient Greek : τριήρης , romanized :  triḗrēs , lit.   'three-rower')

2048-435: 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,

2176-607: 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

2304-444: A port or with the use of an anchor. It was necessary to ride the triereis onto the shores because there simply was no time to anchor a ship during war and gaining control of enemy shores was crucial in the advancement of an invading army. (Petersen) The joints of the ship required finding wood that was capable of absorbing water but was not completely dried out to the point where no water absorption could occur. There would be gaps between

2432-413: 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

2560-513: A single piece. Making durable rope consisted of using both papyrus and white flax; the idea to use such materials is suggested by evidence to have originated in Egypt. In addition, ropes began being made from a variety of esparto grass in the later third century BC. The use of light woods meant that the ship could be carried ashore by as few as 140 men, but also that the hull soaked up water, which adversely affected its speed and maneuverability. But it

2688-399: 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

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2816-512: A single-banked boat), and of the bireme ( Ancient Greek : διήρης , diērēs ), a warship with two banks of oars, of Phoenician origin. The word dieres does not appear until the Roman period. According to Morrison and Williams, "It must be assumed the term pentekontor covered the two-level type". As a ship, it was fast and agile and was the dominant warship in the Mediterranean from the 7th to

2944-444: 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

3072-508: 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

3200-441: 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

3328-723: 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

3456-478: Is disputed by modern historians, and attributed to a confusion, since "triērēs" was by the 5th century used in the generic sense of "warship", regardless its type. The first definite reference to the use of triremes in naval combat dates to c.  525 BC , when, according to Herodotus , the tyrant Polycrates of Samos was able to contribute 40 triremes to a Persian invasion of Egypt ( Battle of Pelusium ). Thucydides meanwhile clearly states that in

3584-685: Is divided on the provenance of the trireme, Greece or Phoenicia , and the exact time it developed into the foremost ancient fighting ship. According to Thucydides , the trireme was introduced to Greece by the Corinthians in the late 8th century BC, and the Corinthian Ameinocles built four such ships for the Samians . This was interpreted by later writers, Pliny and Diodorus , to mean that triremes were invented in Corinth. Clement of Alexandria in

3712-421: Is one diesel engine for cruising speed and one geared gas turbine for high speed dashes. Both are connected to the shaft with clutches ; only one system is driving the ship, in contrast to combined diesel and gas (CODAG) systems that can use the combined power output of both. The advantage of CODOG is a simpler gearing compared to CODAG, but it needs either more powerful or additional gas turbines to achieve

3840-481: 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

3968-664: 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

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4096-419: The 2004 Olympic Torch Relay entered its final stages in the run-up to the 2004 Summer Olympics opening ceremony . The builders of the reconstruction project concluded that it effectively proved what had previously been in doubt, i.e., that Athenian triremes were arranged with the crew positioned in a staggered arrangement on three levels with one person per oar. This architecture would have made optimum use of

4224-660: The Battle of Salamis , each Athenian ship was recorded to have 14 hoplites and 4 archers (usually Scythian mercenaries) on board, but Herodotus narrates that the Chiots had 40 hoplites on board at Lade and that the Persian ships carried a similar number. This reflects the different practices between the Athenians and other, less professional navies. Whereas the Athenians relied on speed and maneuverability, where their highly trained crews had

4352-475: The Battle of Salamis . In the Peloponnesian War, after the Battle of Arginusae , six Athenian generals were executed for failing to rescue several hundred of their men clinging to wreckage in the water. If the men did not drown, they might be taken prisoner by the enemy. In the Peloponnesian War, "Sometimes captured crews were brought ashore and either cut down or maimed – often grotesquely, by cutting off

4480-533: 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

4608-417: The Peloponnesian War , the beached Athenian fleet was caught unawares on more than one occasion, while out looking for food ( Battle of Syracuse and Battle of Aegospotami ). Cities visited, which suddenly found themselves needing to provide for large numbers of sailors, usually did not mind the extra business, though those in charge of the fleet had to be careful not to deplete them of resources. In Athens,

4736-687: The dromon developed. In 1985–1987 a shipbuilder in Piraeus , financed by Frank Welsh (an author, Suffolk banker, writer and trireme enthusiast), advised by historian J. S. Morrison and naval architect John F. Coates (who with Welsh founded the Trireme Trust that initiated and managed the project), and informed by evidence from underwater archaeology, built an Athenian-style trireme, Olympias . Crewed by 170 volunteer oarsmen, Olympias in 1988 achieved 9 knots (17 km/h or 10.5 mph). These results, achieved with inexperienced crew, suggest that

4864-429: The hupozomata ." Excavations of the ship sheds ( neōsoikoi , νεώσοικοι) at the harbour of Zea in Piraeus , which was the main war harbour of ancient Athens, were first carried out by Dragatsis and Wilhelm Dörpfeld in the 1880s. These have provided us with a general outline of the Athenian trireme. The sheds were ca. 40 m long and just 6 m wide. These dimensions are corroborated by the evidence of Vitruvius , whereby

4992-546: The parexeiresia (the outriggers , see below), are common in 8th century BC and later vases and pottery fragments, and it is at the end of that century that the first references to three-banked ships are found. Fragments from an 8th-century relief at the Assyrian capital of Nineveh depicting the fleets of Tyre and Sidon show ships with rams , and fitted with oars pivoted at two levels. They have been interpreted as two-decked warships, and also as triremes. Modern scholarship

5120-541: 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

5248-452: The 170 oars ( kōpai ), arranged in three rows, with one man per oar. Evidence for this is provided by Thucydides, who records that the Corinthian oarsmen carried "each his oar, cushion ( hypersion ) and oarloop". The ship also had two masts, a main ( histos megas ) and a small foremast ( histos akateios ), with square sails, while steering was provided by two steering oars at the stern (one at

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5376-415: The 170 – the zygitai and thalamitai ), due to the design of the ship, were unable to see the water and therefore, rowed blindly, therefore coordinating the rowing required great skill and practice. It is not known exactly how this was done, but there are literary and visual references to the use of gestures and pipe playing to convey orders to rowers. In the sea trials of the reconstruction Olympias , it

5504-500: 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

5632-423: 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

5760-728: The 2nd century, drawing on earlier works, explicitly attributes the invention of the trireme ( trikrotos naus , "three-banked ship") to the Sidonians the possibility remains that the earliest three-banked warships originated in Phoenicia . Herodotus mentions that the Egyptian pharaoh Necho II (610–595 BC) built triremes on the Nile , for service in the Mediterranean, and in the Red Sea , but this reference

5888-536: The 4th centuries BC, after which it was largely superseded by the larger quadriremes and quinqueremes . Triremes played a vital role in the Persian Wars , the creation of the Athenian maritime empire and its downfall during the Peloponnesian War . Medieval and early modern galleys with three files of oarsmen per side are sometimes referred to as triremes. Depictions of two-banked ships ( biremes ), with or without

6016-592: The Aegean Sea and the loyalty of her allies, but also safeguarded the trade routes and the grain shipments from the Black Sea, which fed the city's burgeoning population. In addition, as it provided permanent employment for the city's poorer citizens, the fleet played an important role in maintaining and promoting the radical Athenian form of democracy . Athenian maritime power is the first example of thalassocracy in world history. Aside from Athens, other major naval powers of

6144-408: The Athenian navy, the crews enjoyed long practice in peacetime, becoming skilled professionals and ensuring Athens' supremacy in naval warfare. The rowers were divided according to their positions in the ship into thranitai , zygitai , and thalamitai . According to the excavated Naval Inventories, lists of ships' equipment compiled by the Athenian naval boards, there were: Most of the rowers (108 of

6272-463: The Greek words for the oarsmen in, respectively the lowest, middle, and uppermost files of the triereis. The holes were pins that acted as fulcrums to the oars that allowed them to move. The center of gravity of the ship is low because of the overlapping formation of the files that allow the ports to remain closer to the ships walls. A lower center of gravity would provide adequate stability. The trireme

6400-768: 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

6528-409: The Peloponnesian War there were 4 or 5 archers and 10 or so marines. These few troops were peripherally effective in an offensive sense, but critical in providing defense for the oarsmen. Should the crew of another trireme board, the marines were all that stood between the enemy troops and the slaughter of the men below. It has also been recorded that if a battle were to take place in the calmer water of

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6656-417: The Peloponnesian War. Naval battles were far more of a spectacle than the hoplite battles on land. Sometimes the battles raging at sea were watched by thousands of spectators on shore. Along with this greater spectacle, came greater consequences for the outcome of any given battle. Whereas the average percentage of fatalities from a land battle were between 10 and 15%, in a sea battle, the forces engaged ran

6784-599: The Spartans (as well as their allies and other enemies of Athens) would focus mainly on ramming Athenian triremes head on. It would be these tactics, in combination with those outlined by Brasidas, that led to the defeat of the Athenian fleet at the Second Battle of Syracuse during the Sicilian Expedition . Once a naval battle was under way, for the men involved, there were numerous ways for them to meet their end. Drowning

6912-568: 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

7040-614: 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

7168-520: The advantage, other states favored boarding, in a situation that closely mirrored the one that developed during the First Punic War . Grappling hooks would be used both as a weapon and for towing damaged ships (ally or enemy) back to shore. When the triremes were alongside each other, marines would either spear the enemy or jump across and cut the enemy down with their swords. As the presence of too many heavily armed hoplites on deck tended to destabilize

7296-467: The ancient writers were not exaggerating about straight-line performance. In addition, Olympias was able to execute a 180 degree turn in one minute and in an arc no wider than two and one half (2.5) ship-lengths. Additional sea trials took place in 1987, 1990, 1992 and 1994. In 2004 Olympias was used ceremonially to transport the Olympic Flame from the port of Keratsini to the main port of Piraeus as

7424-416: The available internal dimensions. However, since modern humans are on average approximately 6 cm (2 inches) taller than Ancient Greeks (and the same relative dimensions can be presumed for oarsmen and other athletes), the construction of a craft which followed the precise dimensions of the ancient vessel led to cramped rowing conditions and consequent restrictions on the modern crew's ability to propel

7552-419: The bow lookout ( prōreus or prōratēs ), the boatswain ( keleustēs ), the quartermaster ( pentēkontarchos ), the shipwright ( naupēgos ), the piper ( aulētēs ) who gave the rowers' rhythm and two superintendents ( toicharchoi ), in charge of the rowers on each side of the ship. What constituted these sailors' experience was a combination of superior rowing skill (physical stamina and/or consistency in hitting with

7680-435: 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

7808-413: 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

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7936-411: The condition of their men. They had to keep their crews comfortably paced, so as not to exhaust them before battle. The total complement ( plērōma ) of the ship was about 200. These were divided into the 170 rowers ( eretai ), who provided the ship's motive power, the deck crew headed by the trierarch and a marine detachment. The trierarch would be situated in the rear of the ship, and relay orders to

8064-404: The design of the trireme most likely pushed the technological limits of the ancient world. After gathering the proper timbers and materials it was time to consider the fundamentals of the trireme design. These fundamentals included accommodations, propulsion, weight and waterline, centre of gravity and stability, strength, and feasibility. All of these variables are dependent on one another; however

8192-498: 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

8320-448: 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

8448-543: 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

8576-547: The entirety of the Mediterranean and thus the need to maintain a powerful navy was minimal, as the only enemy they would be facing is pirates. As a result, the fleet was relatively small and had mostly political influence, controlling the grain supply and fighting pirates, who usually employed light biremes and liburnians. But instead of the successful liburnians of the Greek Civil War, it was again centred around light triremes, but still with many marines. Out of this type of ship,

8704-443: The era included Syracuse , Corfu and Corinth . In the subsequent Peloponnesian War, naval battles fought by triremes were crucial in the power balance between Athens and Sparta. Despite numerous land engagements, Athens was finally defeated through the destruction of her fleet during the Sicilian Expedition , and finally, at the Battle of Aegospotami , at the hands of Sparta and her allies. Based on all archeological evidence,

8832-437: The front of the ship. In the case of Athens, since most of the fleet's triremes were paid for by wealthy citizens, there was a natural sense of competition among the patricians to create the "most impressive" trireme, both to intimidate the enemy and to attract the best oarsmen. Of all military expenditure, triremes were the most labor- and (in terms of men and money) investment-intensive. The ship's primary propulsion came from

8960-488: The funds necessary to construct the new naval fleets necessary to combat the Athenians. Sparta was able to build fleet after fleet, eventually destroying the Athenian fleet at the Battle of Aegospotami . The Spartan General Brasidas summed up the difference in approach to naval warfare between the Spartans and the Athenians: "Athenians relied on speed and maneuverability on the open seas to ram at will clumsier ships; in contrast,

9088-447: The individual space allotted to each rower was 2 cubits . With the Doric cubit of 0.49 m, this results in an overall ship length of just under 37 m. The height of the sheds' interior was established as 4.026 metres, leading to estimates that the height of the hull above the water surface was ca. 2.15 metres. Its draught was relatively shallow, about 1 metre, which, in addition to

9216-472: The keel and stretched by means of windlasses. Hence the triremes were often called "girded" when in commission. The materials from which the trireme was constructed were an important aspect of its design. The three principal timbers included fir, pine, and cedar. Primarily the choice in timber depended on where the construction took place. For example, in Syria and Phoenicia, triereis were made of cedar, because pine

9344-399: 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

9472-583: The mainstay of all smaller navies. While the Hellenistic kingdoms did develop the quinquereme and even larger ships, most navies of the Greek homeland and the smaller colonies could only afford triremes. They were used by the Diadochi Empires and sea powers like Syracuse , Carthage and later Rome . The difference to the classical 5th century Athenian ships was that they were armoured against ramming and carried significantly more marines. Lightened versions of

9600-551: The majority of the crews were either killed, captured or lost. During the Hellenistic period , the light trireme was supplanted by larger warships in dominant navies, especially the pentere/ quinquereme . The maximum practical number of oar banks a ship could have was three. So the number in the type name did not refer to the banks of oars any more (as for biremes and triremes), but to the number of rowers per vertical section, with several men on each oar. The reason for this development

9728-514: 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

9856-472: 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

9984-518: The middle line of the hull just under the main beams and tensioned to 13.5 tonnes force. The hypozomata were considered important and secret: their export from Athens was a capital offense. This cable would act as a stretched tendon straight down the middle of the hull, and would have prevented hogging . Additionally, hull plank butts would remain in compression in all but the most severe sea conditions, reducing working of joints and consequent leakage. The hypozomata would also have significantly braced

10112-474: The mounting Persian preparations, in 483/2 BC the Athenian statesman Themistocles used his political skills and influence to persuade the Athenian assembly to start the construction of 200 triremes, using the income of the newly discovered silver mines at Laurion . The first clash with the Persian navy was at the Battle of Artemisium , where both sides suffered great casualties. However, the decisive naval clash occurred at Salamis , where Xerxes' invasion fleet

10240-403: 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

10368-571: 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

10496-690: 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

10624-503: The planks of the hull when the ship was new, but, once submerged, the planks would absorb the water and expand, thus forming a watertight hull. Problems would occur, for example, when shipbuilders would use green wood for the hull; when green timber is allowed to dry, it loses moisture, which causes cracks in the wood that could cause catastrophic damage to the ship. The sailyards and masts were preferably made from fir, because fir trees were naturally tall, and provided these parts in usually

10752-413: The port side, one to starboard). Classical sources indicate that the trireme was capable of sustained speeds of ca. 6 knots at relatively leisurely oaring. There is also a reference by Xenophon of a single day's voyage from Byzantium to Heraclea Pontica , which translates as an average speed of 7.37 knots. These figures seem to be corroborated by the tests conducted with the reconstructed Olympias :

10880-518: The possible rollover. If the center of gravity were placed any higher, the additional beams needed to restore stability would have resulted in the exclusion of the Thalamian the holes due to the reduced hull space. The purpose of the area just below the center of gravity and the waterline known as the hypozomata (ὑποζώματα) was to allow bending of the hull when faced with up to 90 kN of force. The calculations of forces that could have been absorbed by

11008-400: 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

11136-457: 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

11264-749: 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

11392-422: The relatively flat keel and low weight, allowed it to be beached easily. Construction of the trireme differed from modern practice. The construction of a trireme was expensive and required around 6,000 man-days of labour to complete. The ancient Mediterranean practice was to build the outer hull first, and the ribs afterwards. To secure and add strength to the hull, cables ( hypozōmata ) were employed, fitted in

11520-479: 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

11648-414: The rest of the crew via the rowmaster. For the crew of Athenian triremes, the ships were an extension of their democratic beliefs. Rich and poor rowed alongside each other. Victor Davis Hanson argues that this "served the larger civic interest of acculturating thousands as they worked together in cramped conditions and under dire circumstances." During the Peloponnesian War, there were a few variations to

11776-418: 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

11904-429: The right hand or thumb to guarantee that they could never row again." The image found on an early-5th-century black-figure , depicting prisoners bound and thrown into the sea being pushed and prodded under water with poles and spears, shows that enemy treatment of captured sailors in the Peloponnesian War was often brutal. Being speared amid the wreckage of destroyed ships was likely a common cause of death for sailors in

12032-462: The risk of losing their entire fleet. The number of ships and men in battles was sometimes very high. At the Battle of Arginusae for example, 263 ships were involved, making for a total of 55,000 men, and at the Battle of Aegospotami more than 300 ships and 60,000 seamen were involved. In Battle of Aegospotami , the city-state of Athens lost what was left of its navy: the once 'invincible' thalassocracy lost 170 ships (costing some 400 talents), and

12160-655: 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

12288-508: The rowing crew in the Sicilian Expedition , a typical Athenian trireme crew during the Peloponnesian War consisted of 80 citizens, 60 metics and 60 foreign hands. Indeed, in the few emergency cases where slaves were used to crew ships, these were deliberately set free , usually before being employed. For instance, the tyrant Dionysius I of Syracuse once set all slaves of Syracuse free to man his galleys, employing thus freedmen, but otherwise relied on citizens and foreigners as oarsmen. In

12416-427: The same maximum power output. The disadvantage of CODOG is that the fuel consumption at high speed is poor compared to CODAG. 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

12544-471: 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

12672-400: The ship are arguable because there is not enough evidence to confirm the exact process of jointing used in ancient times. In a modern reconstruction of the ship, a polysulphide sealant was used to compare to the caulking that evidence suggests was used; however this is also contentious because there is simply not enough evidence to authentically reproduce the triereis seams. Triremes required

12800-401: The ship's patron was known as the trierarch ( triērarchos ). He was a wealthy Athenian citizen (usually from the class of the pentakosiomedimnoi ), responsible for manning, fitting out and maintaining the ship for his liturgical year at least; the ship itself belonged to Athens. The triērarchia was one of the liturgies of ancient Athens; although it afforded great prestige, it constituted

12928-478: The ship, the epibatai were normally seated, only rising to carry out any boarding action. The hoplites belonged to the middle social classes, so that they came immediately next to the trierarch in status aboard the ship. In the ancient world, naval combat relied on two methods: boarding and ramming . Artillery in the form of ballistas and catapults was widespread, especially in later centuries, but its inherent technical limitations meant that it could not play

13056-436: 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

13184-475: The ships at night, however, would leave the troops vulnerable to surprise attacks. While well-maintained triremes would last up to 25 years, during the Peloponnesian War, Athens had to build nearly 20 triremes a year to maintain their fleet of 300. The Athenian trireme had two great cables of about 47 mm in diameter and twice the ship's length called hypozomata (undergirding), and carried two spares. They were possibly rigged fore and aft from end to end along

13312-490: The structure of the trireme against the stresses of ramming, giving it an important advantage in combat. According to material scientist J.E. Gordon : "The hupozoma was therefore an essential part of the hulls of these ships; they were unable to fight, or even to go to sea at all, without it. Just as it used to be the practice to disarm modern warships by removing the breech-blocks from the guns, so, in classical times, disarmament commissioners used to disarm triremes by removing

13440-469: The time of the Persian Wars , the majority of the Greek navies consisted of (probably two-tiered) penteconters and ploia makrá ("long ships"). In any case, by the early 5th century, the trireme was becoming the dominant warship type of the eastern Mediterranean, with minor differences between the "Greek" and "Phoenician" types, as literary references and depictions of the ships on coins make clear. The first large-scale naval battle where triremes participated

13568-435: The trireme and smaller vessels were often used as auxiliaries, and still performed quite effectively against the heavier ships, thanks to their greater manoeuvrability. With the rise of Rome the biggest fleet of quinqueremes temporarily ruled the Mediterranean , but during the civil wars after Caesar's death the fleet was on the wrong side and a new warfare with light liburnas was developed. By Imperial times, Rome controlled

13696-510: The trireme. The ports would house the oarsmen with a minimal waste of space. There would be three files of oarsmen on each side tightly but workably packed by placing each man outboard of, and in height overlapping, the one below, provided that thalamian tholes were set inboard and their ports enlarged to allow oar movement. Thalamian, zygian, and thranite are the English terms for thalamios (θαλάμιος), zygios (ζύγιος), and thranites (θρανίτης),

13824-409: The typical crew layout of a trireme. One was a drastically reduced number of oarsmen, so as to use the ship as a troop transport. The thranites would row from the top benches while the rest of the space, below, would be filled with hoplites . In another variation, the Athenians used 10 or so trireme for transporting horses. Such triremes had 60 oarsmen, and rest of the ship was for horses. The trireme

13952-538: 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

14080-400: 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

14208-421: 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

14336-511: 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

14464-518: Was an ancient vessel and a type of galley that was used by the ancient maritime civilizations of the Mediterranean Sea , especially the Phoenicians , ancient Greeks and Romans . The trireme derives its name from its three rows of oars , manned with one man per oar. The early trireme was a development of the penteconter , an ancient warship with a single row of 25 oars on each side (i.e.,

14592-424: Was constructed to maximize all traits of the ship to the point where if any changes were made the design would be compromised. Speed was maximized to the point where any less weight would have resulted in considerable losses to the ship's integrity. The center of gravity was placed at the lowest possible position where the Thalamian tholes were just above the waterline which retained the ship's resistance to waves and

14720-567: Was decisively defeated. After Salamis and another Greek victory over the Persian fleet at Mycale , the Ionian cities were freed, and the Delian League was formed under the aegis of Athens. Gradually, the predominance of Athens turned the League effectively into an Athenian Empire. The source and foundation of Athens' power was her strong fleet, composed of over 200 triremes. It not only secured control of

14848-516: Was designed for day-long journeys, with no capacity to stay at sea overnight, or to carry the provisions needed to sustain its crew overnight. Each crewman required 2 gallons (7.6 l) of fresh drinking water to stay hydrated each day, but it is unknown quite how this was stored and distributed. This meant that all those aboard were dependent upon the land and peoples of wherever they landed each night for supplies. Sometimes this would entail traveling up to eighty kilometres in order to procure provisions. In

14976-425: Was evident that this was a difficult problem to solve, given the amount of noise that a full rowing crew generated. In Aristophanes ' play The Frogs two different rowing chants can be found: " ryppapai " and " o opop ", both corresponding quite well to the sound and motion of the oar going through its full cycle. A varying number of marines ( epibatai ), usually 10–20, were carried aboard for boarding actions. At

15104-448: Was in motion in the direction of the attacker, even less speed was required, and especially if the hit came amidships. The Athenians especially became masters in the art of ramming, using light, un- decked ( aphraktai ) triremes. In either case, the masts and railings of the ship were taken down prior to engagement to reduce the opportunities for opponents' grappling hooks . Unlike the naval warfare of other eras, boarding an enemy ship

15232-496: Was not readily available. Pine is stronger and more resistant to decay, but it is heavy, unlike fir, which was used because it was lightweight. The frame and internal structure would consist of pine and fir for a compromise between durability and weight. Another very strong type of timber is oak; this was primarily used for the hulls of triereis, to withstand the force of hauling ashore. Other ships would usually have their hulls made of pine, because they would usually come ashore via

15360-407: Was not the primary offensive action of triremes. Triremes' small size allowed for a limited number of marines to be carried aboard. During the 5th and 4th centuries, the trireme's strength was in its maneuverability and speed, not its armor or boarding force. That said, fleets less confident in their ability to ram were prone to load more marines onto their ships. On the deck of a typical trireme in

15488-409: Was perhaps the most common way for a crew member to perish. Once a trireme had been rammed, the ensuing panic that engulfed the men trapped below deck no doubt extended the amount of time it took the men to escape. Inclement weather would greatly decrease the crew's odds of survival, leading to a situation like that off Cape Athos in 411 (12 of 10,000 men were saved). An estimated 40,000 Persians died in

15616-539: 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

15744-411: Was still faster than other warships. Once the triremes were seaworthy, it is argued that they were highly decorated with, "eyes, nameplates, painted figureheads, and various ornaments". These decorations were used both to show the wealth of the patrician and to make the ship frightening to the enemy. The home port of each trireme was signaled by the wooden statue of a deity located above the bronze ram on

15872-522: Was the Battle of Lade during the Ionian Revolt , where the combined fleets of the Greek Ionian cities were defeated by the Persian fleet, composed of squadrons from their Phoenician, Carian , and Egyptian subjects. Athens was at that time embroiled in a conflict with the neighbouring island of Aegina , which possessed a formidable navy. In order to counter this, and possibly with an eye already at

16000-761: 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

16128-452: Was the increasing use of armour on the bows of warships against ramming attacks, which again required heavier ships for a successful attack. This increased the number of rowers per ship, and also made it possible to use less well-trained personnel for moving these new ships. This change was accompanied by an increased reliance on tactics like boarding , missile skirmishes and using warships as platforms for artillery . Triremes continued to be

16256-402: Was to come in from astern, with the aim not of creating a single hole, but of rupturing as big a length of the enemy vessel as possible. The speed necessary for a successful impact depended on the angle of attack; the greater the angle, the lesser the speed required. At 60 degrees, 4 knots was enough to penetrate the hull, while it increased to 8 knots at 30 degrees. If the target for some reason

16384-599: Was very important. Athens' strength in the Peloponnesian War came from its navy, whereas Sparta's came from its land-based Hoplite army. As the war progressed however the Spartans came to realize that if they were to undermine Pericles ' strategy of outlasting the Peloponnesians by remaining within the walls of Athens indefinitely (a strategy made possible by Athens' Long Walls and fortified port of Piraeus), they were going to have to do something about Athens superior naval force. Once Sparta gained Persia as an ally, they had

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