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Deadweight Tonnage
Deadweight tonnage (also known as deadweight; abbreviated to DWT, D.W.T., d.w.t., or dwt) or tons deadweight (DWT) is a measure of how much weight a ship can carry. It is the sum of the weights of cargo, fuel, fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salt (chemistry), salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include ..., ballast water, provisions, passengers, and crew. DWT is often used to specify a ship's maximum permissible deadweight (i.e. when it is fully loaded so that its Plimsoll line is at water level), although it may also denote the actual DWT of a ship not loaded to capacity. Definition Deadweight tonnage is a measure of a vessel's weight carrying capacity, not including the empty weight of the ship. It is distinct from the displacement (weight of water displaced), which includes the ship's own weight, or the ...
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Displacement (ship)
The displacement or displacement tonnage of a ship is its weight. As the term indicates, it is measured indirectly, using Archimedes' principle, by first calculating the volume of water displaced by the ship, then converting that value into weight. Traditionally, various measurement rules have been in use, giving various measures in long tons. Today, tonnes are more commonly used. Ship displacement varies by a vessel's degree of load, from its empty weight as designed (known as "lightweight tonnage") to its maximum load. Numerous specific terms are used to describe varying levels of load and trim, detailed below. Ship displacement should not be confused with measurements of volume or capacity typically used for commercial vessels and measured by tonnage: net tonnage and gross tonnage. Calculation The process of determining a vessel's displacement begins with measuring its draft.George, 2005. p. 5. This is accomplished by means of its "draft marks". A merchant vessel has t ...
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Long Ton
The long ton, also known as the imperial ton, displacement ton,Dictionary.com - ''"a unit for measuring the displacement of a vessel, equal to a long ton of 2240 pounds (about 1016 kg) or 35 cu. ft. (1 cu. m) of seawater."'' or British ton, is a measurement unit equal to 2,240 pounds (1,016.0 kg). It is the name for the unit called the " ton" in the avoirdupois system of weights or Imperial system of measurements. It was standardised in the 13th century. It is used in the United States for bulk commodities. It is not to be confused with the short ton, a unit of weight equal to used in the United States, and Canada before metrication, also referred to simply as a "ton". Unit definition A long ton is defined as exactly 2,240 pounds. The long ton arises from the traditional British measurement system: A long ton is 20 long hundredweight (cwt), each of which is 8 stone Thus, a long ton is Unit equivalences A long ton, also called the weight ton (W/T), imperial ton, or d ...
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Nautical Terminology
Seamanship is the skill, art, competence (human resources), competence, and knowledge of operating a ship, boat or other craft on water. The'' Oxford Dictionary of English, Oxford Dictionary'' states that seamanship is "The skill, techniques, or practice of handling a ship or boat at sea." It involves topics and development of specialised skills, including navigation and international Admiralty law, maritime law and regulatory knowledge; weather, meteorology and forecasting; watchkeeping; ship-handling and small boat handling; operation of deck equipment, anchors and cables; ropework and line handling; communications; sailing; engines; execution of evolutions such as towing; cargo handling equipment, dangerous cargoes and cargo storage; dealing with emergencies; survival at sea and search and rescue; and fire fighting. The degree of knowledge needed within these areas is dependent upon the nature of the work and the type of vessel employed by a sailor, seafarer. History Shi ...
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TK Bremen
''TK Bremen'' was a Maltese-flagged cargo ship that ran aground on December 16, 2011, at Erdeven, on the coast of southern Brittany in France, generating extensive media coverage and much controversy. Built in 1982 at a shipyard in Busan, South Korea, the modest-sized bulk carrier was owned by a succession of shipowners since its launch, sometimes changing flag. Regularly inspected, it did not present any major safety defects at the time of grounding. On December 15, the ship left the port of Lorient, where it had just unloaded its cargo, as storm Cyclone Joachim, Joachim was forecast. The captain decided to anchor in the shelter of the island of Groix, opposite Lorient, to allow the storm to pass. During the gale, the ship was unable to hold on to its anchor, and after several attempts to reach a sheltered anchorage, it ran aground on the south coast of Morbihan on the night of December 16, causing moderate pollution but no casualties. Too damaged to be repaired, it was dismantled ...
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Light Displacement
The displacement or displacement tonnage of a ship is its weight. As the term indicates, it is measured indirectly, using Archimedes' principle, by first calculating the volume of water displaced by the ship, then converting that value into weight. Traditionally, various measurement rules have been in use, giving various measures in long tons. Today, tonnes are more commonly used. Ship displacement varies by a vessel's degree of load, from its empty weight as designed (known as "lightweight tonnage") to its maximum load. Numerous specific terms are used to describe varying levels of load and trim, detailed below. Ship displacement should not be confused with measurements of volume or capacity typically used for commercial vessels and measured by tonnage: net tonnage and gross tonnage. Calculation The process of determining a vessel's displacement begins with measuring its draft.George, 2005. p. 5. This is accomplished by means of its "draft marks". A merchant vessel has three ...
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Draft (hull)
The draft or draught of a ship is a determined depth of the vessel below the waterline, measured vertically to its hull's lowest—its propellers, or keel, or other reference point. Draft varies according to the loaded condition of the ship. A deeper draft means the ship will have greater vertical depth below the waterline. Draft is used in under keel clearance calculations, where the draft is calculated with the available depth of water (from Electronic navigational charts) to ensure the ship can navigate safely, without grounding. Navigators can determine their draught by calculation or by visual observation (of the ship's painted load lines). Related terminology A ship's draft/draught is the "depth of the vessel below the waterline measured vertically to the lowest part of the hull, propellers, or other reference point". That is, the draft or draught is the maximum depth of any part of the vessel, including appendages such as rudders, propellers and drop keels if de ...
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Sea Water
Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximately of dissolved salts (predominantly sodium () and chloride () ions). The average density at the surface is 1.025 kg/L. Seawater is denser than both fresh water and pure water (density 1.0 kg/L at ) because the dissolved salts increase the mass by a larger proportion than the volume. The freezing point of seawater decreases as salt concentration increases. At typical salinity, it freezes at about . The coldest seawater still in the liquid state ever recorded was found in 2010, in a stream under an Antarctic glacier: the measured temperature was . Seawater pH is typically limited to a range between 7.5 and 8.4. However, there is no universally accepted reference pH-scale for seawater and the difference between measurements b ...
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Specific Gravity
Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nearly always measured with respect to water at its densest (at ); for gases, the reference is air at room temperature (). The term "relative density" (abbreviated r.d. or RD) is preferred in SI, whereas the term "specific gravity" is gradually being abandoned. If a substance's relative density is less than 1 then it is less dense than the reference; if greater than 1 then it is denser than the reference. If the relative density is exactly 1 then the densities are equal; that is, equal volumes of the two substances have the same mass. If the reference material is water, then a substance with a relative density (or specific gravity) less than 1 will float in water. For example, an ice cube, with a relative density of about 0.91, will float. ...
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MARPOL 73/78
The International Convention for the Prevention of Pollution from Ships, 1973 as modified by the Protocol of 1978, or "MARPOL 73/78" (short for "marine pollution") is one of the most important international marine environmental conventions. It was developed by the International Maritime Organization with an objective to minimize pollution of the oceans and seas, including dumpingoil and air pollution The original MARPOL was signed on 17 February 1973, but did not come into force at the signing date. The current convention is a combination of 1973 Convention and the 1978 Protocol, which entered into force on 2 October 1983. As of January 2018, 156 states are parties to the convention, being flag states of 99.42% of the world's shipping tonnage. All ships flagged under countries that are signatories to MARPOL are subject to its requirements, regardless of where they sail, and member nations are responsible for vessels registered on their national ship registry. Provisions MA ...
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SOLAS Convention
The International Convention for the Safety of Life at Sea (SOLAS) is an international maritime treaty which sets out minimum safety standards in the construction, equipment and operation of merchant ships. The International Maritime Organization convention requires signatory flag states to ensure that ships flagged by them comply with at least these standards. Initially prompted by the sinking of the Titanic, the current version of SOLAS is the 1974 version, known as SOLAS 1974, which came into force on 25 May 1980, and has been amended several times. , SOLAS 1974 has 167 contracting states, which flag about 99% of merchant ships around the world in terms of gross tonnage. SOLAS in its successive forms is generally regarded as the most important of all international treaties concerning the safety of merchant ships. Signatories The non-parties to SOLAS 1974 include numerous landlocked countries, as well as El Salvador, Micronesia and East Timor. Some others including Bolivi ...
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Tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1,000  kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton in the United States to distinguish it from the non-metric units of the short ton ( United States customary units) and the long ton ( British imperial units). It is equivalent to approximately 2,204.6 pounds, 1.102 short tons, and 0.984 long tons. The official SI unit is the megagram (Mg), a less common way to express the same amount. Symbol and abbreviations The BIPM symbol for the tonne is t, adopted at the same time as the unit in 1879.Table 6
. BIPM. Retrieved on 2011-07-10.
Its use is also official for the metric ton in the United States, having been adopted by the United States