Shipbuilding

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Image:Pizarroshipbuilding.jpg
Men from Francisco de Orellana's expedition building a small brigantine, the San Pedro, to be used in the search for food

Shipbuilding is the construction of ships. It normally takes place in a specialized facility known as a shipyard. Shipbuilders, originally called shipwrights, follow a specialized occupation that traces its roots to before recorded history.

Shipbuilding and ship repairs, both commercial and military, are referred to as the "naval sector". The dismantling of ships is called ship breaking. The construction of boats is a similar activity called boat building.

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[edit] History

Archaeological evidence indicates that humans arrived on New Guinea at least 60,000 years ago, probably by sea from Southeast Asia during an ice age period when the sea was lower and distances between islands shorter. (See History of Papua New Guinea.) The ancestors of Australian Aborigines and New Guineans went across the Lombok Strait to Sahul by boat over 50,000 years ago.

Evidence from ancient Egypt shows that the early Egyptians already knew how to assemble planks of wood into a watertight hull, using treenails to fasten them together, and pitch for caulking the seams. The "Khufu ship", a 43.6 m long vessel sealed into a pit in the Giza pyramid complex at the foot of the Great Pyramid of Giza in the Fourth Dynasty around 2,500 BC, is a full-size surviving example which may have fulfilled the symbolic function of a solar barque. The ships of the Eighteenth Dynasty were typically about 25 meters (80 ft) in length, and had a single mast, sometimes consisting of two poles lashed together at the top making an "A" shape. They mounted a single square sail on a yard, with an additional spar along the bottom of the sail. These ships could also be oar propelled.

The ships of Phoenicia seems to have been of a similar design. The Greeks and probably others introduced the use of multiple banks of oars for additional speed, and the ships were of a light construction, for speed and so they could be carried ashore.

Viking longships developed from an alternate tradition of clinker-built hulls fastened with leather thongs. Sometime around the 12th century, northern European ships began to be built with a straight sternpost, enabling the mounting of a rudder, which was much more durable than a steering oar held over the side. Development in the Middle Ages favored "round ships", with a broad beam and heavily curved at both ends.

The introduction of cannons onto ships encouraged the development of tumblehome, the inward slant of the abovewater hull, for additional stability, as well as techniques for strengthening the internal frame. This kind of considerations, as well as the demand for ships capable of operating safely in the open ocean, led to the documentation of design and construction practice in what had previously been a secretive trade, and ultimately the field of naval architecture. Even so, construction techniques changed only very gradually; the ships of the Spanish Armada were internally very similar to those of the Napoleonic Wars over two centuries later.

Iron was gradually adopted in ship construction, initially in small areas needing greater strength, then throughout, although initially copying wooden construction. Isambard Brunel's Great Britain of 1843 was the first radical new design; built entirely of iron, using stringers for strength, inner and outer hulls, and bulkheads to form multiple watertight compartments. Despite her success, many yards only went so far to use composite construction, with wooden timbers laid over an iron frame (the Cutty Sark is so constructed). Steel supplanted wrought iron when it became readily available in the latter half of the 19th century. Wood continued to be favored for the decks, and is still the rule as deckcovering for modern cruise ships.

[edit] Shipwrights in England

Image:John Constable 006.jpg
Shipbuilding in Flatford, John Constable, 1815.

During the 16th century Shipwrights in England were so few in number as to be granted direct employment by the Crown. The first list of ‘Master Shipwrights’ appointed ‘by Patent’ was issued by Henry VIII and included ‘John Smyth, Robert Holborn, Richard Bull and James Baker’ (father of Mathew Baker). Peter Pett the son of John was summoned from his place of residence, then at Harwich to work on the King’s Ships at Portsmouth, and in 1543 was granted a wage and fee for life (vadium et feodum). The authority for the letters patent not being by the usual Writ of Privy Seal, but ‘Per Ipsum Regent’, i.e, by ‘direct motion of the King’, Henry VIII.

On the 23 April 1548 Robert Holborn, Smyth and Bull received similar Patents, the very fact of which should be considered of some significance, and it was added as Shipwrights they should instruct others, by reason of their long and good service.

[edit] Modern shipbuilding

Image:USShipbuilding1943.gif
Shipbuilding for the United States effort in WWII (1943)

Design work, also called naval architecture, may be conducted using a ship model basin.

Modern ships, since roughly 1940, have been produced almost exclusively of welded steel. Early welded steel ships used steels with inadequate fracture toughness, which resulted in some ships suffering catastrophic brittle fracture structural cracks (see Liberty ship#Problems). Since roughly 1950, specialized steels such as ABS Steels with good properties for ship construction have been used.

Modern shipbuilding makes considerable use of prefabricated sections; entire multi-deck segments of the hull or superstructure will be built elsewhere in the yard, transported to the building dock or slipway, then lifted into place. This is known as Block Construction. The most modern shipyards pre-install equipment, pipes, electrical cables, and any other components within the blocks, to minimize the effort needed to assemble or install components deep within the hull once it is welded together.

Shipbuilding (which encompasses the shipyards, the marine equipment manufacturers and a large number of service and knowledge providers) is an important and strategic industry in a number of countries around the world. This importance stems from:

  • The large number of trade persons required directly by the shipyard and also by the supporting industries such as steel mills, engine manufacturers, etc.
  • A nation's need to manufacture and repair its own Navy and vessels that support its primary industries.

Historically, the industry has suffered from the absence of global rules and a tendency of (state-supported) over-investment due to the fact that shipyards offer a wide range of technologies, employ a significant number of workers and generate foreign currency income (as the shipbuilding market is dollar-based and a global one). Shipbuilding is therefore an attractive industry for developing nations. Japan used shipbuilding in the 1950s and 1960s to rebuild its industrial structure, Korea made shipbuilding a strategic industry in the 1970s and China is now in the process to repeat these models with large state-supported investments in this industry. As a result the world shipbuilding market suffers from over-capacities, depressed prices (although the industry experienced a price increase in the period 2003-2005 due to strong demand for new ships which was in excess of actual cost increases), low profit margins, trade distortions and wide-spread subsidisation. All efforts to address the problems in the OECD have so far failed, with the 1994 international shipbuilding agreement never entering into force and the 2003-2005 round of negotiations being suspended in October 2005 after no agreement was possible.

[edit] See also

[edit] External links

el:Ναυπήγηση es:Construcción naval fr:Construction navale id:Pembuatan kapal it:Ingegneria navale nl:Scheepsbouw ja:造船 nds:Schippbu pl:Okrętownictwo pt:Engenharia naval e oceânica ru:Судостроение tr:Gemi mühendisliği zh:造船

Shipbuilding

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