|
|
|
|
Shipbuilding
|
| |
|
| |
- See also Shipbuilding (song).
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".
Discussion
Ask a question about 'Shipbuilding' Start a new discussion about 'Shipbuilding' Answer questions from other users |
Encyclopedia
- See also Shipbuilding (song).
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 construction of boats is a similar activity called boat building.
The dismantling of ships is called ship breaking.
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 ship hull as early as 3000 BC. The Archaeological Institute of America reports that the oldest ships yet unearthed, a group of 14 discovered in Abydos, were constructed of wooden planks which were "sewn" together. Discovered by Egyptologist David O'Connor of New York University, woven straps were found to have been used to lash the planks together, and reeds or grass stuffed between the planks helped to seal the seams. Because the ships are all buried together and near a mortuary belonging to Pharaoh Khasekhemwy, originally they were all thought to have belonged to him, but one of the 14 ships dates to 3000 BC, and the associated pottery jars buried with the vessels also suggest earlier dating. The ship dating to 3000 BC was 75 feet long and is now thought to perhaps have belonged to an earlier pharaoh. According to professor O'Connor, the 5,000-year-old ship may have even belonged to Pharaoh Aha.
Early Egyptians also knew how to assemble planks of wood with treenails to fasten them together, using pitch for caulking the seams. The "Khufu ship", a 43.6-meter vessel sealed into a pit in the Giza pyramid complex at the foot of the Great Pyramid of Giza in the Fourth Dynasty around 2500 BC, is a full-size surviving example which may have fulfilled the symbolic function of a solar barque. Early Egyptians also knew how to fasten the planks of this ship together with mortise and tenon joints.
The ships of Ancient Egypt's 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.
The world's first tidal dock was built around 2500 BC during the Harappan civilisation at Lothal near the present day Mangrol harbour on the Gujarat coast in India. Other ports were probably at Balakot and Dwarka. However, it is probable that many small-scale ports, and not massive ports, were used for the Harappan maritime trade. Ships from the harbour at these ancient port cities established trade with Mesopotamia. Shipbuilding and boatmaking may have been prosperous industries in ancient India. Native labourers may have manufactured the flotilla of boats used by Alexander the Great to navigate across the Hydaspes and even the Indus, under Nearchos. The Indians also exported teak for shipbuilding to ancient Persia. Other references to Indian timber used for shipbuilding is noted in the works of Ibn Jubayr.
The naval history of China stems back to the Spring and Autumn Period (722 BC–481 BC) of the ancient Chinese Zhou Dynasty. The Chinese built large rectangular barges known as 'castle ships', essentially floating fortresses complete with multiple decks with guarded ramparts. They also built ramming vessels as in the Greco-Roman tradition of the trireme, although oar-steered ships in China lost their favor very early on since it was in 1st century China that the stern-mounted rudder was first developed. This was dually met with the introduction of the Han Dynasty junk ship design in the same century. The shipbuilding industry in Imperial China reached its height during the Song Dynasty, Yuan Dynasty, and early Ming Dynasty. During the Song period (960–1279 AD), the establishment of China's first official standing navy in 1132 AD and the enormous increase in maritime trade abroad (from Heian Japan to Fatimid Egypt) allowed the shipbuilding industry in provinces like Fujian to thrive like never before. Some of the largest seaports in the world existed in China during this era, including Guangzhou, Quanzhou, and Xiamen.
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.
These 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.
Modern shipbuilding
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 problems of the Liberty ship). Since roughly 1950, specialized steels such as ABS Steels with good properties for ship construction have been used. Although it is commonly accepted that modern steel has eliminated brittle fracture in ships, some controversy still exists. Brittle fracture of modern vessels continues to occur from time to time as the use of grade A and grade B steel of unknown toughness or fracture appearance transition temperature (FATT) in way of ships' side shells can be less than adequate for all ambient conditions.
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 and engine manufacturers; and
- 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 of repeating 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 paused in September 2005 after no agreement was possible.
Where state subsidies have been removed and domestic policies do not provide support, in high-cost nations shipbuilding has usually gone into steady, if not rapid, decline. The British shipbuilding industry is one of many examples of this. From a position in the early 1970s where British yards could still build the largest types of sophisticated merchant ships, British shipbuilders today have been reduced to a handful specialising in defence contracts and repair work. In the U.S.A., the Jones Act (which places restrictions on the ships that can be used for moving domestic cargoes) has meant that merchant shipbuilding has continued, but such protection has failed to penalise shipbuilding inefficiencies. The consequence of this is contract prices that are far higher than those of any other nation building oceangoing ships.
Thanks to the productivity of its shipyards, South Korea is the world's largest shipbuilding nation in terms of tonnage and numbers of vessels built, in spite of high labour costs. South Korea's "big three" shipbuilders, Hyundai Heavy Industries, Samsung Heavy Industries and Daewoo Shipbuilding & Marine Engineering, dominate global shipbuilding, with Hanjin Heavy Industries also being a significant presence. China is currently the third largest shipbuilding country and poised to overtake Japan in the near future. The three East Asian countries produce significantly more ships than any other countries and are marked in bold.
| World shipbuilding completions by countries (2005) | | Rank | Country | No. of ships | 1,000 GT | % |
|---|
| 1 | South Korea | 326 | 17,689 | 37.7% | | 2 | Japan | 469 | 16,434 | 35.0% | | 3 | China | 420 | 6,466 | 13.8% | | 4 | Germany | 67 | 1,236 | 2.6% | | 5 | Poland | 55 | 787 | 1.7% | | 6 | Taiwan | 19 | 629 | 1.3% | | 7 | Croatia | 24 | 546 | 1.2% | | 8 | Denmark | 7 | 493 | 1.0% | | 9 | United States | 46 | 431 | 0.9% | | 10 | Italy | 18 | 356 | 0.8% |
See also
External links
- — interactive history of Liverpool docks
- — extensive information about the U.S. shipbuilding industry, including over 500 pages of U.S. shipyard construction records
- United States — from GlobalSecurity.org
-
-
-
-
|
| |
|
|
