A ballast tank is a compartment within a boat, ship or other floating structure that holds water, which is used as ballast to provide stability for a vessel. Using water in a tank allows for adjustment of weight than stone or iron ballast as was used in older vessels. It allows for ballast to be pumped out to reduce the draft of the vessel when required to enter shallower water. For example, in 1849 Abraham Lincoln, an Illinois attorney, in order to provide adequate stability to vessels at sea, ballast is used to weigh the ship down and lower its centre of gravity. International agreements under the Safety Of Life At Sea Convention require cargo vessels, the criteria specify the separation of compartments within the vessel and the subdivision of those compartments. The International agreements rely upon the states which have signed the agreement to implement the regulations within their waters, the ballast is generally seawater which is pumped into tanks known as ballast tanks. Depending on the type of vessel, the tanks can be double bottom and these ballast tanks are connected to pumps which can pump water in or out.
These tanks are filled in order to add weight to the ship once cargo has been discharged, in some extreme conditions, ballast water may be introduced to dedicated cargo spaces in order to add extra weight during heavy weather or to pass under low bridges. In submersibles and submarines, ballast tanks are used to control the buoyancy of the vessel, some submersibles, such as bathyscaphes, dive and re-surface solely by controlling their buoyancy. They flood ballast tanks to submerge, to either drop discardable ballast weights, or use stored compressed air to blow their ballast tanks clear of water. Submarines are larger, more sophisticated and have powerful underwater propulsion and they must travel horizontal distances submerged, require precise control of depth, yet do not descend so deeply, nor need to dive vertically on station. Their primary means of controlling depth are thus their diving planes, at the surface the ballast tanks are emptied to give positive buoyancy. When diving, the tanks are flooded to achieve neutral buoyancy.
The planes are adjusted together to drive the hull downwards, for a steeper dive, the stern planes may be reversed and used to pitch the hull downwards. Submerging is done by opening the vents in the top of the ballast tanks, in order for the submarine to surface, the vents in the top of the ballast tanks are shut, and compressed air is allowed into the tanks. The high-pressure air pocket pushes the water out through the valves and increases the vessels buoyancy. Ballast tanks are integral to the stability and operation of deepwater offshore oil platforms. The ballast facilitates hydrodynamic stability by moving the center-of-mass as low as possible, most wakeboard-specific inboard-engine boats have multiple integrated ballast tanks that are filled with ballast pumps controlled from the helm with rocker switches
The hull is the watertight body of a ship or boat. Above the hull is the superstructure and/or deckhouse, where present, the line where the hull meets the water surface is called the waterline. The structure of the hull varies depending on the vessel type, the uppermost continuous deck may be called the upper deck, weather deck, spar deck, main deck, or simply deck. The particular name given depends on the type of ship or boat. In a typical wooden sailboat, the hull is constructed of wooden planking, supported by transverse frames and bulkheads, often but not always there is a centerline longitudinal member called a keel. In fiberglass or composite hulls, the structure may resemble wooden or steel vessels to some extent, in many cases, composite hulls are built by sandwiching thin fiber-reinforced skins over a lightweight but reasonably rigid core of foam, balsa wood, impregnated paper honeycomb or other material. The shape of the hull is entirely dependent upon the needs of the design, shapes range from a nearly perfect box in the case of scow barges, to a needle-sharp surface of revolution in the case of a racing multihull sailboat.
Hulls come in varieties and can have composite shape, but are grouped primarily as follows. Examples are the flat-bottom, v-bottom, and multi-bottom hull and these types have at least one pronounced knuckle throughout all or most of their length. These hull shapes all have smooth curves, examples are the round bilge, semi-round bilge, and s-bottom hull. After this they can be categorized as, Displacement The hull is supported exclusively or predominantly by buoyancy, vessels that have this type of hull travel through the water at a limited rate that is defined by the waterline length. They are often, though not always, heavier than planing types, planing The planing hull form is configured to develop positive dynamic pressure so that its draft decreases with increasing speed. The dynamic lift reduces the surface and therefore the drag. They are sometimes flat-bottomed, sometimes V-bottomed and more rarely, round-bilged, the most common form is to have at least one chine, which makes for more efficient planing and can throw spray down.
Planing hulls are more efficient at speeds, although they still require more energy to achieve these speeds. An effective planing hull must be as light as possible with flat surfaces that are consistent with sea keeping. Sail boats that plane must sail efficiently in displacement mode in light winds, semi-displacement, or semi-planing The hull form is capable of developing a moderate amount of dynamic lift, most of the vessels weight is still supported through buoyancy. At present, the most widely used form is the round bilge hull, in the inverted bell shape of the hull, with a smaller payload the waterline cross-section is less, hence the resistance is less and the speed is higher
Draft determines the minimum depth of water a ship or boat can safely navigate. The draft can be used to determine the weight of the cargo on board by calculating the displacement of water. A table made by the shows the water displacement for each draft. The density of the water and the content of the bunkers has to be taken into account. The closely related term trim is defined as the difference between the forward and aft drafts, the draft aft is measured in the perpendicular of the stern. The draft forward is measured in the perpendicular of the bow, the scale may use traditional English units or metric units. If the English system is used, the bottom of each marking is the draft in feet, in metric marking schemes, the bottom of each draft mark is the draft in decimeters and each mark is one decimeter high. Larger ships try to maintain a water draft when they are light, in order to make a better sea crossing. In order to achieve this they use sailing ballasts to stabilize the ship, the water draft of a large ship has little direct link with its stability because stability depends solely on the respective positions of the metacenter of the hull and the center of gravity.
It is however, that a light ship has quite high stability which can lead to implying too much rolling of the ship. A fully laden ship can have either a strong or weak stability, the draft of ships can be increased when the ship is in motion in shallow water, a phenomenon known as squat. Draft is a significant factor limiting navigable waterways, especially for large vessels, of course this includes many shallow coastal waters and reefs, but some major shipping lanes. Panamax class ships—the largest ships able to transit the Panama Canal—do have a limit but are usually limited by beam, or sometimes length overall. However, in the much wider Suez Canal, the factor for Suezmax ships is draft. Some supertankers are able to transit the Suez Canal when unladen or partially laden, canals are not the only draft-limited shipping lanes. A Malaccamax ship has the deepest draft able to transit the very busy, there are only a few ships of this size. A small draft allows pleasure boats to navigate through shallower water and this makes it possible for these boats to access smaller ports, to travel along rivers and even to beach the boat. A large draft ensures a level of stability in strong wind
In fluid dynamics, wind waves, or wind-generated waves, are surface waves that occur on the free surface of bodies of water. They result from the wind blowing over an area of fluid surface, Waves in the oceans can travel thousands of miles before reaching land. Wind waves on Earth range in size from small ripples, to waves over 100 ft high, when directly generated and affected by local winds, a wind wave system is called a wind sea. After the wind ceases to blow, wind waves are called swells, more generally, a swell consists of wind-generated waves that are not significantly affected by the local wind at that time. They have been generated elsewhere or some time ago, wind waves in the ocean are called ocean surface waves. Wind waves have an amount of randomness, subsequent waves differ in height, duration. The key statistics of wind waves in evolving sea states can be predicted with wind wave models, although waves are usually considered in the water seas of Earth, the hydrocarbon seas of Titan may have wind-driven waves.
The great majority of large breakers seen at a result from distant winds. Water depth All of these work together to determine the size of wind waves. Further exposure to that wind could only cause a dissipation of energy due to the breaking of wave tops. Waves in an area typically have a range of heights. For weather reporting and for analysis of wind wave statistics. This figure represents an average height of the highest one-third of the waves in a time period. The significant wave height is the value a trained observer would estimate from visual observation of a sea state, given the variability of wave height, the largest individual waves are likely to be somewhat less than twice the reported significant wave height for a particular day or storm. Wave formation on a flat water surface by wind is started by a random distribution of normal pressure of turbulent wind flow over the water. This pressure fluctuation produces normal and tangential stresses in the surface water and it is assumed that, The water is originally at rest.
There is a distribution of normal pressure to the water surface from the turbulent wind. Correlations between air and water motions are neglected, the second mechanism involves wind shear forces on the water surface
A plimsoll shoe, plimsole or pumps is a type of athletic shoe with a canvas upper and rubber sole developed as beachwear in the 1830s by the Liverpool Rubber Company. Plimsolls had solid rubber soles about 8 or 9mm thick, to which the canvas was glued without coming up the sides, the effect when running was not dissimilar to running without shoes. The shoe was originally, and often still is in parts of the United Kingdom, called a sand shoe, in the UK plimsolls are commonly worn for schools indoor physical education lessons. Regional terms are common, in Northern Ireland and central Scotland they are known as gutties, sannies is used in Scotland. In parts of the West Country and Wales they are known as daps or dappers, in London, the home counties, much of the West Midlands, the West Riding of Yorkshire and north west of England they are known as pumps. There is a belief that daps is taken from a factory sign – Dunlop Athletic Plimsoles which was called the DAP factory. Plimsolls were issued to the British military until replaced by trainers in the mid-80s, if white they required hours of application of shoe whitener, if black they were required to be polished until they gleamed.
As it was used for corporal punishment in the British Commonwealth. The brown version is used by most police and military units as a gym training shoe, Ireland – called Penneys shoes/recession shoes if bought in Penneys. Occasionally called rubber dollies, especially in County Cork, trade mark Wamba became a household name, producing a universal unlaced indigo blue canvas shoe, worn by adults and children alike. Still today any kind of shoe is known as Wambas in some parts of the country. United States – sneakers, tennis shoes or chucks Gibraltar – Kung-Fu Shoes Italy – Superga or Converse like the name of the famous brands
Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers to its solid state or its gaseous state. It occurs in nature as snow, ice packs and icebergs, fog, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are chemically combined or adsorbed in hydrated minerals.
Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, lakes, large quantities of water and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life.
Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
Seawater, or salt water, is water from a sea or ocean. On average, seawater in the oceans has a salinity of about 3. 5% This means that every kilogram of seawater has approximately 35 grams of dissolved salts. Average density at the surface is 1.025 kg/l, seawater is denser than both fresh water and pure water 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 −2 °C. The coldest seawater ever recorded was in 2010, in a stream under an Antarctic glacier, 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, although the vast majority of seawater has a salinity of between 31 g/kg and 38 g/kg, seawater is not uniformly saline throughout the world. Where mixing occurs with fresh water runoff from river mouths, near melting glaciers or vast amounts precipitation, the most saline open sea is the Red Sea, where high rates of evaporation, low precipitation and low river run-off, and confined circulation result in unusually salty water.
The salinity in isolated bodies of water can be considerably greater still, several salinity scales were used to approximate the absolute salinity of seawater. A popular scale was the Practical Salinity Scale where salinity was measured in practical salinity units, the current standard for salinity is the Reference Salinity scale with the salinity expressed in units of g/kg. The density of surface seawater ranges from about 1020 to 1029 kg/m3, depending on the temperature, at a temperature of 25 °C, salinity of 35 g/kg and 1 atm pressure, the density of seawater is 1023.6 kg/m3. Deep in the ocean, under pressure, seawater can reach a density of 1050 kg/m3 or higher. The density of seawater changes with salinity, brines generated by seawater desalination plants can have salinities up to 120 g/kg. The density of typical seawater brine of 120 g/kg salinity at 25 °C, seawater pH is limited to the range 7.5 to 8.4. The speed of sound in seawater is about 1,500 m/s, and varies with temperature, salinity.
The thermal conductivity of seawater is 0.6 W/mK at 25 °C, the thermal conductivity decreases with increasing salinity and increases with increasing temperature. Seawater contains more dissolved ions than all types of freshwater, the ratios of solutes differ dramatically. Bicarbonate ions constitute 48% of river water solutes but only 0. 14% of all seawater ions, differences like these are due to the varying residence times of seawater solutes and chlorine have very long residence times, while calcium tends to precipitate much more quickly. The most abundant dissolved ions in seawater are sodium, magnesium and its osmolarity is about 1000 mOsm/l
The Atlantic Ocean is the second largest of the worlds oceans with a total area of about 106,460,000 square kilometres. It covers approximately 20 percent of the Earths surface and about 29 percent of its surface area. It separates the Old World from the New World, the Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Eurasia and Africa to the east, and the Americas to the west. The Equatorial Counter Current subdivides it into the North Atlantic Ocean, in contrast, the term Atlantic originally referred specifically to the Atlas Mountains in Morocco and the sea off the Strait of Gibraltar and the North African coast. The Greek word thalassa has been reused by scientists for the huge Panthalassa ocean that surrounded the supercontinent Pangaea hundreds of years ago. The term Aethiopian Ocean, derived from Ancient Ethiopia, was applied to the Southern Atlantic as late as the mid-19th century, many Irish or British people refer to the United States and Canada as across the pond, and vice versa.
The Black Atlantic refers to the role of ocean in shaping black peoples history. Irish migration to the US is meant when the term The Green Atlantic is used, the term Red Atlantic has been used in reference to the Marxian concept of an Atlantic working class, as well as to the Atlantic experience of indigenous Americans. Correspondingly, the extent and number of oceans and seas varies, the Atlantic Ocean is bounded on the west by North and South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea, to the east, the boundaries of the ocean proper are Europe, the Strait of Gibraltar and Africa. In the southeast, the Atlantic merges into the Indian Ocean, the 20° East meridian, running south from Cape Agulhas to Antarctica defines its border. In the 1953 definition it extends south to Antarctica, while in maps it is bounded at the 60° parallel by the Southern Ocean, the Atlantic has irregular coasts indented by numerous bays and seas. Including these marginal seas the coast line of the Atlantic measures 111,866 km compared to 135,663 km for the Pacific.
Including its marginal seas, the Atlantic covers an area of 106,460,000 km2 or 23. 5% of the ocean and has a volume of 310,410,900 km3 or 23. 3%. Excluding its marginal seas, the Atlantic covers 81,760,000 km2 and has a volume of 305,811,900 km3, the North Atlantic covers 41,490,000 km2 and the South Atlantic 40,270,000 km2. The average depth is 3,646 m and the maximum depth, the bathymetry of the Atlantic is dominated by a submarine mountain range called the Mid-Atlantic Ridge. It runs from 87°N or 300 km south of the North Pole to the subantarctic Bouvet Island at 42°S, the MAR divides the Atlantic longitudinally into two halves, in each of which a series of basins are delimited by secondary, transverse ridges. The MAR reaches above 2000 m along most of its length, the MAR is a barrier for bottom water, but at these two transform faults deep water currents can pass from one side to the other
Ballast is used in sailboats to provide moment to resist the lateral forces on the sail. Insufficiently ballasted boats will tend to tip, or heel, excessively in high winds, too much heel may result in the boat capsizing. If a sailing vessel should need to voyage without cargo ballast of little or no value would be loaded to keep the vessel upright, some or all of this ballast would be discarded when cargo was loaded. The simplest form of ballast used in small day sailers is so-called live ballast, by sitting on the windward side of the hull, the heeling moment must lift the weight of the crew. On larger modern vessels, the keel is made of or filled with a high density material, such as concrete, iron, by placing the weight as low as possible the maximum righting moment can be extracted from the given mass. Traditional forms of ballast carried inside the hull were stones or sand, there are disadvantages to using high-density ballast. The first is the mass of the boat, a heavier boat sits lower in the water, increasing drag when it moves. A heavier boat is more difficult to put on a trailer.
Secondly, since the ballast needs to be as low as possible, it is placed into a centerboard or retracting keel. The simplest solution is to use a fixed ballasted keel, but that makes the boat nearly incapable of sailing in shallow water. While prohibited by most class racing rules, some cutting-edge boats use a bulb of ballast on a long and this lets the ballast be placed on the windward side, providing a far greater righting moment with a lower angle of heel. A common type of ballast for small boats that avoids many of the problems of high-density ballast is water ballast, while it seems counter-intuitive that placing water in the hull would add any stability, adding water ballast below the vertical center of gravity increases stability. The water ballast does not need to be lifted above the waterline to affect stability and it is the relationship between centre of gravity and centre of buoyancy that dictates the righting moment. The advantage of water ballast is that the tanks can be emptied, reducing draft or the weight of the boat and water added back in after the boat is launched or cargo unloaded.
Pumps can be used to empty the leeward ballast tank and fill the tank as the boat tacks. On empty cargo vessels water is added to ballast tanks to increase propeller immersion, to improve steering, a disadvantage of water ballast is that water is not very dense and therefore the tanks required take up more space than other forms of ballast. Some manufacturers offer flexible ballast bags that are mounted outboard of the hull on both sides, and pumps that use the speed through the water for power. When under way, the pump can be used to fill the windward side and this system, while not very attractive, does allow significant gains in righting force with no modifications to the hull
American Bureau of Shipping
At the end of 2012, ABS was the second largest class society with a classed fleet of nearly 12,000 commercial vessels and offshore facilities. ABS core service is the provision of services through the development of standards called ABS Rules. These Rules form the basis for assessing the design and construction of new vessels, ABS was first chartered in the state of New York in 1862, to certify ship captains. It has been involved in the development and improvement of safety standards, born out of a need for industry self-regulation, ABS published its first technical standards, Rules for Survey and Classing Wooden Vessels, in 1870. When the era of wooden ships gave way to iron, ABS established standards for structures, published as Rules for Survey. Similarly, when iron gave way to steel, ABS Rules for Building and Classing Steel Vessels were established and published in 1890 and these Steel Vessel Rules continue to be revised and published annually. ABS has been organized as a not-for-profit since its founding in 1862, ABS has been commissioned by the US government and the US Coast Guard to act in many maritime matters and has hired several former officers from the Coast Guard. ABS is required under US law to maintain its status as a organization in order to maintain its role as the agent of the US government on matters of government vessel classification.
The world headquarters as well as the ABS Americas Division headquarters for ABS are located in Houston, the divisional headquarters for Europe is located in London and the divisional headquarters for Asia Pacific is located in Singapore. ABS has more than 5,500 employees worldwide and is divided into 2 groups, Engineering review. ABS Engineers work in buildings in Houston, Hong Kong, London, Busan, Yokohama. Surveyors are employed in ports and shipyards worldwide to verify that ships are according to the drawings. Classification itself does not judge the economic viability of a vessel, neither is the society in a position to judge whether a vessel is ultimately employed according to the stated intended purpose for which it was classed. The classification society records and recommends in accordance with what it has seen at the time of a vessels construction and subsequent surveys. If a vessel is not to comply with the Rules. Rules are derived from principles of architecture, marine engineering.
ABS engineers review the plans to verify that the structural and mechanical details conform to the Rule requirements and they survey the building and testing of the structural and principal mechanical and electrical systems. When completed, a vessel undergoes sea trials attended by an ABS field surveyor, the Classification Committee is composed of ABS Members drawn from the maritime industry, United States Coast Guard and ABS officers
The organisation dates back to 1760. Its stated aims are to enhance the safety of life, historically, as Lloyds Register of Shipping, it was a specifically maritime organisation. During the late 20th century, it diversified into other industries including oil and gas, process industries, Lloyds Register is unaffiliated with Lloyds of London. The organisations name came from the 17th-century coffee house in London frequented by merchants, marine underwriters, the coffee house owner, Edward Lloyd, helped them to exchange information by circulating a printed sheet of all the news he heard. In 1760, the Register Society was formed by the customers of the house who assembled the Register of Shipping. Between 1800 and 1833, a dispute between shipowners and underwriters caused them to publish a list each—the Red Book and the Green Book and this brought both parties to the verge of bankruptcy. Agreement was reached in 1834 when they united to form Lloyd’s Register of British and Foreign Shipping, establishing a General Committee, in 1914, with an increasingly international outlook, the organisation changed its name to Lloyds Register of Shipping.
Thus the best classification A1, from which the expression A1 or A1 at Lloyds is derived, the Register, with information on all seagoing, self-propelled merchant ships of 100 gross tonnes or greater, is published annually. A vessel remains registered with Lloyds Register until she is sunk, hulked, Lloyds Register sold its share of the venture to IHS in 2009. Lloyds Register provides quality assurance and certification for ships, offshore structures, LRs Rules for Ships are derived from principles of naval architecture and marine engineering, and govern safety and operational standards for numerous merchant and privately owned vessels. A ship is known as being in class if she meets all the requirements of LRs Rules. Class can be withdrawn from a ship if she is in violation of any regulations, exceptional circumstances may warrant special dispensation from Lloyds Register. Any alteration to the vessel, whether it is an alteration or machinery. Ships are inspected on a basis by a team of Lloyds Register surveyors.
Such a survey includes an inspection of the hull to make sure that the line has not been altered. Numerous other inspections such as the condition of hatch and door seals, safety barriers, upon completion the ship is allowed to be operated for another year, and is issued a Load Line Certificate. Lloyd’s Register provide a list of rules and regulations to the public, Lloyds Register maintains other offices globally, including Hong Kong and Houston, Texas. In 1833 the Österreichischer Lloyd company was formed in the port city of Trieste, consciously modeling itself on the British company
The displacement or displacement tonnage of a ship is the ships weight. The name reflects the fact that it is measured indirectly, by first calculating the volume of water displaced by the ship, by Archimedes principle, this is the weight of the ship. Displacement should not be confused with other measurements of volume or capacity typically used for vessels such as net tonnage, gross tonnage. The process of determining a vessels displacement begins with measuring its draft This is accomplished by means of its draft marks, a merchant vessel has three matching sets, one mark each on the port and starboard sides forward and astern. These marks allow a ships displacement to be determined to an accuracy of 0. 5%, the draft observed at each set of marks is averaged to find a mean draft. The ships hydrostatic tables show the corresponding volume displaced, to calculate the weight of the displaced water, it is necessary to know its density. Seawater is more dense than water, so a ship will ride higher in salt water than in fresh.
The density of water varies with temperature. Devices akin to slide rules have been available since the 1950s to aid in these calculations and it is done today with computers. Displacement is usually measured in units of tonnes or long tons and these bring the ship down to its load draft, colloquially known as the waterline. Full load displacement and loaded displacement have almost identical definitions, full load is defined as the displacement of a vessel when floating at its greatest allowable draft as established by classification societies. Warships have arbitrary full load condition established, deep load condition means full ammunition and stores, with most available fuel capacity used. Light displacement is defined as the weight of the ship excluding cargo, water, stores, crew, normal displacement is the ships displacement with all outfit, and two-thirds supply of stores, etc. on board. Standard displacement, known as Washington displacement, is a term defined by the Washington Naval Treaty of 1922.
Naval architecture Hull Hydrodynamics Tonnage Dear, I. C. B, oxford Companion to Ships and the Sea. George, William E. Stability & Trim for the Ships Officer, Edward A. McEwen, William A. Trim and Stability Information for Drydocking Calculations, conference on the Limitation of Armament,1922. Papers Relating to the Foreign Relations of the United States,1922, proceedings of the United States Naval Institute