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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, 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 volumetric measures of gross tonnage or net tonnage (and the legacy measures gross register tonnage and net register tonnage). Deadweight tonnage was historically expressed in long tonsOne long ton (LT) is but is now usually given internationally ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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" (or "load lines"). A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautical Terminology
This glossary of nautical terms is an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water (mostly though not necessarily on the sea). Some remain current, while many date from the 17th to 19th centuries. The word nautical derives from the Latin ''nauticus'', from Greek ''nautikos'', from ''nautēs'': "sailor", from ''naus'': "ship". Further information on nautical terminology may also be found at Nautical metaphors in English, and additional military terms are listed in the Multiservice tactical brevity code article. Terms used in other fields associated with bodies of water can be found at Glossary of fishery terms, Glossary of underwater diving terminology, Glossary of rowing terms, and Glossary of meteorology. This glossary is split into two articles: * terms starting with the letters A to L are at Glossary of nautical terms (A-L) * terms starting with the letters M to Z are at Glossary of nautical terms (M-Z) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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" (or "load lines"). A merc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Summer Draft
Summer draft is a naval term for the worst-case loaded draft Draft, The Draft, or Draught may refer to: Watercraft dimensions * Draft (hull), the distance from waterline to keel of a vessel * Draft (sail), degree of curvature in a sail * Air draft, distance from waterline to the highest point on a vesse ... a ship can have. This draft is corrected for the worst-case seasonal conditions. During summer, the water is warmer, thus expands slightly, losing density. This effect causes ships to float deeper in the water. Summer draft is the opposite of light ship condition. References * Navigation Ship measurements {{water-transport-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Draft (hull)
The draft or draught of a ship's hull is the vertical distance between the waterline and the bottom of the hull (keel). The draught of the vessel is the maximum depth of any part of the vessel, including appendages such as rudders, propellers and drop keels if deployed. Draft determines the minimum depth of water a ship or boat can safely navigate. The related term air draft is the maximum height of any part of the vessel above the water. The more heavily a vessel is loaded, the deeper it sinks into the water, and the greater its draft. After construction, the shipyard creates a table showing how much water the vessel displaces based on its draft and the density of the water (salt or fresh). The draft can also be used to determine the weight of cargo on board by calculating the total displacement of water, accounting for the content of the ship's bunkers, and using Archimedes' principle. The closely related term "trim" is defined as the difference between the forward and aft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Water
Seawater, or salt 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 measurement ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Specific Gravity
Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for 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" (often abbreviated r.d. or RD) is often preferred in scientific usage, whereas the term "specific gravity" is deprecated. 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. A substance with a relative density greater ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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" is one of the most important international marine environmental conventions. MARPOL 73/78, MARPOL is an amalgamation of the words "marine and pollution" in multiple languages and a short way to refer to the purpose of the convention. and 73/78 short for the years 1973 and 1978) It was developed by the International Maritime Organization with an objective to minimize pollution of the oceans and seas, including dumping, oil 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SOLAS Convention
The International Convention for the Safety of Life at Sea (SOLAS) is an international maritime treaty that sets 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. The current version of SOLAS is the 1974 version, known as SOLAS 1974, which came into force on 25 May 1980. , 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 (for obvious reasons), as well as El Salvador, Micronesia and East Timor. Some others including Bolivia, Lebanon and Sri Lanka, all considered flag of convenience states, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton 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 2204.6 pounds, 1.102 short tons, and 0.984 long tons. The official SI unit is the megagram (symbol: Mg), a less common way to express the same mass. 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 |
Net Register Tonnage
Net register tonnage (NRT, nrt, n.r.t.) is a ship's cargo volume capacity expressed in "register tons", one of which equals to a volume of . It is calculated by subtracting non-revenue-earning spaces i.e. spaces not available for carrying cargo, for example engine rooms, fuel tanks and crew quarters, from the ship's gross register tonnage.Units and Systems of Measurement Their Origin, Development, and Present Status . National Institute of Standards and Technology. Net tonnage is thus used in situations where a vessel's earning capacity is important, rather than its mere size. Net register tonnage is not a measure of the weight of the ship or its cargo, and should not be confused with terms such as |
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