Ballast

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Cross section of a vessel with a single ballast tank at the bottom Ballast tank boat cross section.png
Cross section of a vessel with a single ballast tank at the bottom

Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within a boat, ship, submarine, or other floating structure that holds water is called a ballast tank. Water should move in and out from the ballast tank to balance the ship. In a vessel that travels on the water, the ballast will remain below the water level, to counteract the effects of weight above the water level. [1] The ballast may be redistributed in the vessel or disposed of altogether to change its effects on the movement of the vessel.

Contents

History

The basic concept behind the ballast tank can be seen in many forms of aquatic life, such as the blowfish or members of the argonaut group of octopus. [2] The concept has been invented and reinvented many times by humans to serve a variety of purposes. In the fifteenth and sixteenth century, the ballast "did not consist entirely of leakage, but of urine, vomit, and various foul food leavings that lazy sailors discharged into the ballast contrary to orders, in the belief that the pumps would take care of it." [3] In the nineteenth century, cargo boats returning from Europe to North America would carry quarried stone as ballast, contributing to the architectural heritage of some east coast cities (for example Montreal), where this stone was used in building.

During World War 2 ships returning from Great Britain to America used rubble as ballast.[ citation needed ] The ballast would be dumped in New York and used for construction projects such as FDR Drive and an outcrop colloquially named Bristol Basin since it was made from rubble from bombed-out Bristol.[ citation needed ]

Uses

One of the functions of a yacht's keel is to provide ballast. Yacht keel.svg
One of the functions of a yacht's keel is to provide ballast.

Ballast takes many forms. The simplest form of ballast used in small day sailers is so-called "live ballast", or the weight of the crew. By sitting on the windward side of the hull, the heeling moment must lift the weight of the crew. On more advanced racing boats, a wire harness called a trapeze is used to allow the crew to hang completely over the side of the hull without falling out; this provides much larger amounts of righting moment due to the larger leverage of the crew's weight, but can be dangerous if the wind suddenly dies, as the sudden loss of heeling moment can dump the crew in the water. On larger modern vessels, the keel is made of or filled with a high density material, such as concrete, iron, or lead. By placing the weight as low as possible (often in a large bulb at the bottom of the keel) the maximum righting moment can be extracted from the given mass. Traditional forms of ballast carried inside the hull were stones or sand.

Sailing 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 then ballast of little or no value would be loaded to keep the vessel upright. Some or all of this ballast would then be discarded when cargo was loaded.

Ballast weight is also added to a race car to alter its performance. In most racing series, cars have a minimum allowable weight. Often, the actual weight of the car is lower, so ballast is used to bring it up to the minimum. The advantage is that the ballast can be positioned to affect the car's handling by changing its load distribution. This is near-universal in Formula 1. It is also common in other racing series that ballast may only be located in certain positions on the car. In some racing series, for example the British Touring Car Championship, ballast is used as a handicap, the leading drivers at the end of one race being given more ballast for the next race.

Ballast may also be carried aboard an aircraft. For example, in gliding it may be used to increase speed and/or adjust the aircraft's center of gravity, or in a balloon as a buoyancy compensator.

In commercial shipping

If a cargo vessel (such as a tanker, bulk carrier or container ship) wishes to travel empty or partially empty to collect a cargo, it must travel in ballast . This keeps the vessel in trim, and keeps the propeller and rudder submerged. Typically, being "in ballast" will mean flooding the ballast tanks with sea water. Serious problems arise when the ballast water is discharged, as water-borne organisms may create havoc when deposited in new environments.

In railways

Good quality track ballast is made of crushed stone. The sharp edges help the particles interlock with each other. Rails.and.ballast.bb.jpg
Good quality track ballast is made of crushed stone. The sharp edges help the particles interlock with each other.
Track ballast (close up) between railway sleepers and under railway track Close-up of railway track.jpg
Track ballast (close up) between railway sleepers and under railway track

Track ballast forms the trackbed upon which railroad ties (sleepers) are laid. It is packed between, below, and around the ties. [4] It is used to bear the load from the railroad ties, to facilitate drainage of water, and also to keep down vegetation that might interfere with the track structure. [4] Ballast also holds the track in place as the trains roll over it. A variety of materials have been used as track ballast, including crushed stone, washed gravel, bank run (unwashed) gravel, torpedo gravel (a mixture of coarse sand and small gravel), slag, chats, coal cinders, sand, [5] and burnt clay. [6] The term "ballast" comes from a nautical term for the stones used to stabilize a ship. [4] Not all types of railway tracks use ballast. [7]

Related Research Articles

Sailing Propulsion of a vehicle by wind power

Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the water, on ice (iceboat) or on land over a chosen course, which is often part of a larger plan of navigation.

Yacht Recreational boat or ship

A yacht is a sail or power vessel used for pleasure, cruising, or racing. There is no standard definition, so the term applies to such vessels that have a cabin with amenities that accommodate overnight use. To be termed a yacht, as opposed to a boat, such a pleasure vessel is likely to be at least 33 feet (10 m) in length and may have been judged to have good aesthetic qualities.

Sailboat Boat propelled partly or entirely by sails

A sailboat or sailing boat is a boat propelled partly or entirely by sails and is smaller than a sailing ship. Distinctions in what constitutes a sailing boat and ship vary by region and maritime culture.

Keel Lower centreline structural element of a ship or boat hull

The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in British and American shipbuilding traditions the construction is dated from this event.

Metacentric height

The metacentric height (GM) is a measurement of the initial static stability of a floating body. It is calculated as the distance between the centre of gravity of a ship and its metacentre. A larger metacentric height implies greater initial stability against overturning. The metacentric height also influences the natural period of rolling of a hull, with very large metacentric heights being associated with shorter periods of roll which are uncomfortable for passengers. Hence, a sufficiently, but not excessively, high metacentric height is considered ideal for passenger ships.

Landing craft

Landing craft are small and medium seagoing watercraft, such as boats and barges, used to convey a landing force from the sea to the shore during an amphibious assault. The term excludes landing ships, which are larger. Production of landing craft peaked during World War II, with a significant number of different designs produced in large quantities by the United Kingdom and United States.

A monohull is a type of boat having only one hull, unlike multihulled boats which can have two or more individual hulls connected to one another.

This is a glossary of nautical terms; some remain current, while many date from the 17th to 19th centuries. See also Wiktionary's nautical terms, Category:Nautical terms, and Nautical metaphors in English. See the Further reading section for additional words and references.

Capsizing Action where a vessel turns on to its side or is upside down

Capsizing or keeling over occurs when a boat or ship is turned on its side or it is upside down in the water. The act of reversing a capsized vessel is called righting.

Leeboard

A leeboard is a form of pivoting keel used by a sailboat in lieu of a fixed keel. Typically mounted in pairs on each side of a hull, leeboards function much like a centreboard, allowing shallow draft craft to ply waters fixed keel boats cannot. Only one, however, the leeward, is used at a time, as it does not get lifted from the water when the boat heels under the force of the wind.

Ballast is used in ships to provide moment to resist the lateral forces on the hull. Insufficiently ballasted boats tend to tip or heel excessively in high winds. Too much heel may result in the boat/ship capsizing. If a sailing vessel should need to voyage without cargo then ballast of little or no value would be loaded to keep the vessel upright. Some or all of this ballast would then be discarded when cargo was loaded.

Ballast tank

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 provides easier weight adjustment than the stone or iron ballast used in older vessels. It also makes it easy for the crew to reduce a vessel's draft when they enter shallower water, by temporarily pumping out ballast. Airships use ballast tanks for similar advantages.

The Stability conditions of watercraft are the various standard loading configurations to which a ship, boat, or offshore platform may be subjected. They are recognized by classification societies such as Det Norske Veritas, Lloyd's Register and American Bureau of Shipping (ABS). Classification societies follow rules and guidelines laid down by International Convention for the Safety of Life at Sea (SOLAS) conventions, the International Maritime Organization and laws of the country under which the vessel is flagged, such as the Code of Federal Regulations.

Ship stability is an area of naval architecture and ship design that deals with how a ship behaves at sea, both in still water and in waves, whether intact or damaged. Stability calculations focus on centers of gravity, centers of buoyancy, the metacenters of vessels, and on how these interact.

Sailing yacht Private sailing vessel with overnight accommodations

A sailing yacht, is a leisure craft that uses sails as its primary means of propulsion. A yacht may be a sail or power vessel used for pleasure, cruising, or racing. There is no standard definition, so the term applies here to sailing vessels that have a cabin with amenities that accommodate overnight use. To be termed a "yacht", as opposed to a "boat", such a vessel is likely to be at least 33 feet (10 m) in length and have been judged to have good aesthetic qualities. Sailboats that do not accommodate overnight use or are smaller than 30 feet (9.1 m) are not universally called yachts. Sailing yachts in excess of 130 feet (40 m) are generally considered to be superyachts.

<i>Ictíneo I</i> Pioneering submarine constructed in Barcelona, Spain in 1858–1859

Ictíneo I was a pioneering submarine constructed in Barcelona, Spain in 1858–1859 by engineer Narcís Monturiol.

Esse 850

The Esse 850 is an 8.5 metre long racing sportboat designed by Umberto Felci and built by Josef Schuchter Sportboats of Stafa, Switzerland. The first hull was sold in 2004 and the Esse 850 International Class Association was begun in 2005 in Europe.

Ship measurements consist of a multitude of terms and definitions specifically related to ships and measuring or defining their characteristics.

Maagan Michael Ship

The Ma'agan Michael Ship is a well-preserved 5th-century BCE boat discovered off the coast of Kibbutz Ma'agan Michael, Israel, in 1985. The ship was excavated and its timber immersed in preservation tanks at the University of Haifa, undergoing a seven-year process of impregnation by heated polyethylene glycol (PEG). In March 1999, the boat was reassembled and transferred to a dedicated wing built at the Hecht Museum, on the grounds of the university. The boat has provided researchers with insights into ancient methods of shipbuilding and the evolution of anchors.

Dismasting

Dismasting, also spelled demasting, occurs to a sailing ship when one or more of the masts responsible for hoisting the sails that propel the vessel breaks. Dismasting usually occurs as the result of high winds during a storm acting upon masts, sails, rigging, and spars. Over compression of the mast owing to tightening the rigger too much and g-forces as a consequence of wave action and the boat swinging back and forth can also be result in a dismasting. Dismasting does not necessarily impair the vessel's ability to stay afloat, but rather its ability to move under sail power. Frequently, the hull of the vessel remains intact, upright and seaworthy.

References

  1. Edward Spon, Oliver Byrne, Ernest Spon, Francis N. Spon, Spons' dictionary of engineering, civil, mechanical, military, and Naval, Volume 2 (1874), p. 1205.
  2. Discovery Blog: Scientists solve millennia-old mystery about the argonaut octopus
  3. Morison, Samuel Eliot (1971). The European Discovery of America. U.S.A.: Oxford University Press. p. 135. LCCN   71-129637.
  4. 1 2 3 Solomon (2001), p. 18.
  5. Kellogg, H. W. (1946). "Selection and Maintenance of Ballast" (PDF). American Railway Engineering and Maintenance-of-Way Association. Retrieved 27 March 2021.
  6. Beyer, S. W.; Williams, I. A. (1904). The Geology of Clays. pp. 534–537.
  7. Tubular Modular Track