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91-466: Vickers Shipbuilding and Engineering Limited ( VSEL ) was a shipbuilding company based at Barrow-in-Furness , England that built warships, civilian ships, submarines and armaments. The company was historically the Naval Construction Works of Vickers Armstrongs and has a heritage of building large naval warships and armaments. Through a complicated history the company's shipbuilding division

182-826: A ripsaw has a tooth set that is similar to the angle used on a chisel , so that it rips or tears the material apart. A "flush-cutting saw" has no set on one side, so that the saw can be laid flat on a surface and cut along that surface without scratching it. The set of the blade's teeth can be adjusted with a tool called a saw set . An abrasive saw has a powered circular blade designed to cut through metal or ceramic. Saws were at first serrated materials such as flint, obsidian, sea shells and shark teeth. Serrated tools with indications that they were used to cut wood were found at Pech-de-l'Azé cave IV in France. These tools date to 90,000-30,000 years BCE. In ancient Egypt, open (unframed) pull saws made of copper are documented as early as

273-601: A solar barque . Early Egyptians also knew how to fasten the planks of this ship together with mortise and tenon joints. The oldest known tidal dock in the world 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

364-426: A broad beam and heavily curved at both ends. Another important ship type was the galley, which was constructed with both sails and oars. The first extant treatise on shipbuilding was written c.  1436 by Michael of Rhodes, a man who began his career as an oarsman on a Venetian galley in 1401 and worked his way up into officer positions. He wrote and illustrated a book that contains a treatise on shipbuilding,

455-410: A curved, progressive joint could not be achieved. One study finds that there were considerable improvements in ship speed from 1750 to 1850: "we find that average sailing speeds of British ships in moderate to strong winds rose by nearly a third. Driving this steady progress seems to be the continuous evolution of sails and rigging, and improved hulls that allowed a greater area of sail to be set safely in

546-408: A die, the size varying with the size of the saw. The teeth were sharpened with a triangular file of appropriate size, and set with a hammer or a wrest. By the mid 18th century rolling the metal was usual, the power for the rolls being supplied first by water, and increasingly by the early 19th century by steam engines. The industry gradually mechanized all the processes, including the important grinding

637-407: A fore and aft sail on the mizzen. Ship-building then saw a steady improvement in design techniques and introduction of new materials. Iron was used for more than fastenings ( nails and bolts ) as structural components such as iron knees were introduced, with examples existing in the mid-18th century and from the mid-19th century onwards. This was partly led by the shortage of "compass timber",

728-573: A given wind. By contrast, looking at every voyage between the Netherlands and East Indies undertaken by the Dutch East India Company from 1595 to 1795, we find that journey time fell only by 10 percent, with no improvement in the heavy mortality, averaging six percent per voyage, of those aboard." Initially copying wooden construction traditions with a frame over which the hull was fastened, Isambard Kingdom Brunel 's Great Britain of 1843

819-547: A group of 14 ships discovered in Abydos that 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

910-478: A handle on each end or a frame saw . A pit-saw was also sometimes known as a whipsaw . It took 2-4 people to operate. A "pit-man" stood in the pit, a "top-man" stood outside the pit, and they worked together to make cuts, guide the saw, and raise it. Pit-saw workers were among the most highly paid laborers in early colonial North America. Hand saws typically have a relatively thick blade to make them stiff enough to cut through material. (The pull stroke also reduces

1001-413: A hard toothed edge. The cut is made by placing the toothed edge against the material and moving it back and forth, or continuously forward. This force may be applied by hand , or powered by steam , water , electricity or other power source. The most common measurement of the frequency of teeth on a saw blade is point per inch (25 mm ). It is taken by setting the tip (or point ) of one tooth at

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1092-499: A high degree of commercialization and an increase in trade. Large numbers of ships were built to meet the demand. The Ming voyages were large in size, numbering as many as 300 ships and 28,000 men. The shipbuilders were brought from different places in China to the shipyard in Nanjing , including Zhejiang , Jiangxi , Fujian , and Huguang (now the provinces of Hubei and Hunan ). One of

1183-667: A merger with a larger company to reduce its exposure to cycles in warship production, particularly following the Options for Change defence review after the end of the Cold War . Both bids were referred to the Monopolies & Mergers Commission (MMC) which issued its conclusions and advice to government in May 1995. BAe's bid was approved, while the MMC concluded (with two of six members dissenting) that GEC's bid

1274-406: A range of sailing rigs that included the crab claw sail . The origins of this technology is difficult to date, relying largely on linguistics (studying the words for parts of boats), the written comments of people from other cultures, including the observations of European explorers at the time of first contact and the later more systematic ethnographic observations of the types of craft in use. There

1365-412: A significant number of workers, and generate income as the shipbuilding market is global . Saw#Mechanically powered saws A saw is a tool consisting of a tough blade , wire , or chain with a hard toothed edge used to cut through material . Various terms are used to describe toothed and abrasive saws . Saws began as serrated materials, and when mankind learned how to use iron, it became

1456-863: A similar design. Austronesians established the Austronesian maritime trade network at around 1000 to 600 BC, linking Southeast Asia with East Asia, South Asia, the Middle East, and later East Africa. The route later became part of the Spice trade network and the Maritime Silk Road . 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", which were essentially floating fortresses complete with multiple decks with guarded ramparts . However,

1547-411: A single piece of hollowed-out log. At the sides were two planks, and two horseshoe-shaped wood pieces formed the prow and stern . These were fitted tightly together edge-to-edge with dowels inserted into holes in between, and then lashed to each other with ropes (made from rattan or fiber) wrapped around protruding lugs on the planks. This characteristic and ancient Austronesian boatbuilding practice

1638-518: A treatise on mathematics, much material on astrology, and other materials. His treatise on shipbuilding treats three kinds of galleys and two kinds of round ships. Shipbuilders in the Ming dynasty (1368~1644) were not the same as the shipbuilders in other Chinese dynasties, due to hundreds of years of accumulated experiences and rapid changes in the Ming dynasty. Shipbuilders in the Ming dynasty primarily worked for

1729-467: Is a famous example). Later Great Britain ' s iron hull was sheathed in wood to enable it to carry a copper-based sheathing . Brunel's Great Eastern represented the next great development in shipbuilding. Built-in association with John Scott Russell , it used longitudinal stringers for strength, inner and outer hulls, and bulkheads to form multiple watertight compartments. Steel also supplanted wrought iron when it became readily available in

1820-654: Is a possibility that they may have reached the Americas . After the 11th century, a new type of ship called djong or jong was recorded in Java and Bali. This type of ship was built using wooden dowels and treenails, unlike the kunlun bo which used vegetal fibres for lashings. The empire of Majapahit used jong, built in northern Java, for transporting troops overseas. The jongs were transport ships which could carry 100–2000 tons of cargo and 50–1000 people, 28.99–88.56 meter in length. The exact number of jong fielded by Majapahit

1911-600: Is known as the " lashed-lug " technique. They were commonly caulked with pastes made from various plants as well as tapa bark and fibres which would expand when wet, further tightening joints and making the hull watertight. They formed the shell of the boat, which was then reinforced by horizontal ribs. Shipwrecks of Austronesian ships can be identified from this construction as well as the absence of metal nails. Austronesian ships traditionally had no central rudders but were instead steered using an oar on one side. Austronesians traditionally made their sails from woven mats of

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2002-571: Is noted in the works of Ibn Jubayr . 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 ocean- and sea-going ships of Ancient Egypt were constructed with cedar wood, most likely hailing from Lebanon. The ships of Phoenicia seem to have been of

2093-683: Is now BAE Systems Submarine Solutions and the armaments division is now part of BAE Systems Land & Armaments . The company was founded in 1871 by James Ramsden as the Iron Shipbuilding Company , but its name was soon changed to Barrow Shipbuilding Company . In 1897, Vickers & Sons bought the Barrow Shipbuilding Company and its subsidiary the Maxim Nordenfelt Guns and Ammunition Company , becoming Vickers, Sons and Maxim Limited. The shipyard at Barrow became

2184-499: Is only a small body of archaeological evidence available. Since Island Southeast Asia contained effective maritime transport between its very large number of islands long before Austronesian seafaring, it is argued that Austronesians adopted an existing maritime technology from the existing inhabitants of this region. Austronesian ships varied from simple canoes to large multihull ships. The simplest form of all ancestral Austronesian boats had five parts. The bottom part consists of

2275-413: Is the degree to which the teeth are bent out sideways away from the blade, usually in both directions. In most modern serrated saws, the teeth are set, so that the kerf (the width of the cut) will be wider than the blade itself. This allows the blade to move through the cut easily without binding (getting stuck). The set may be different depending on the kind of cut the saw is intended to make. For example,

2366-411: Is unknown, but the largest number of jong deployed in an expedition is about 400 jongs, when Majapahit attacked Pasai, in 1350. Until recently, Viking longships were seen as marking an advance on traditional clinker -built hulls where leather thongs were used to join plank boards. This consensus has recently been challenged. Haywood has argued that earlier Frankish and Anglo-Saxon nautical practice

2457-571: The ghe mành . 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

2548-579: The k'un-lun po or kunlun bo ("ship of the k'un-lun [dark-skinned southern people]"). These ships used two types of sail of their invention, the junk sail and tanja sail . Large ships are about 50–60 metres (164–197 ft) long, had 5.2–7.8 metres (17–26 ft) tall freeboard , each carrying provisions enough for a year, and could carry 200–1000 people. The Chinese recorded that these Southeast Asian ships were hired for passage to South Asia by Chinese Buddhist pilgrims and travelers, because they did not build seaworthy ships of their own until around

2639-702: The Abbasid period. Mughal Empire had a large shipbuilding industry, which was largely centred in the Bengal Subah . Economic historian Indrajit Ray estimates shipbuilding output of Bengal during the sixteenth and seventeenth centuries at 223,250 tons annually, compared with 23,061 tons produced in nineteen colonies in North America from 1769 to 1771. He also assesses ship repairing as very advanced in Bengal. Documents from 1506, for example, refer to watercraft on

2730-467: The Early Dynastic Period , c.  3,100 –2,686 BC. Many copper saws were found in tomb No. 3471 dating to the reign of Djer in the 31st century BC. Saws were used for cutting a variety of materials, including humans ( death by sawing ), and models of saws were used in many contexts throughout Egyptian history. Particularly useful are tomb wall illustrations of carpenters at work that show

2821-648: The London Stock Exchange in December 1986. In 1988, a mistake by senior management and changing shipbuilding methods meant that the Vickers shipyard in Barrow-in-Furness accidentally welded part of HMS  Triumph (a nuclear submarine ) in an upside-down position. In 1994 VSEL was subject to two takeover proposals, one from GEC and another from British Aerospace (BAe). VSEL was willing to participate in

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2912-533: The Napoleonic Wars were still built more or less to the same basic plan as those of the Spanish Armada of two centuries earlier, although there had been numerous subtle improvements in ship design and construction throughout this period. For instance, the introduction of tumblehome , adjustments to the shapes of sails and hulls, the introduction of the wheel, the introduction of hardened copper fastenings below

3003-463: The Persian Gulf . Evidence from Ancient Egypt shows that the early Egyptians knew how to assemble planks of wood into a ship hull as early as 3100 BC. Egyptian pottery as old as 4000 BC shows designs of early fluvial boats or other means for navigation. The Archaeological Institute of America reports that some of the oldest ships yet unearthed are known as the Abydos boats . These are

3094-453: The Sierra Leone river carrying 120 men. Others refer to Guinea coast peoples using war canoes of varying sizes – some 70 feet in length, 7–8 feet broad, with sharp pointed ends, rowing benches on the side, and quarterdecks or forecastles build of reeds. The watercraft included miscellaneous facilities, such as cooking hearths, and storage spaces for the crew's sleeping mats. From

3185-419: The axe , adz , chisel , and saw were clearly established more than 4,000 years ago." Once mankind had learned how to use iron, it became the preferred material for saw blades of all kinds; some cultures learned how to harden the surface ("case hardening" or "steeling"), prolonging the blade's life and sharpness. Steel , made of iron with moderate carbon content and hardened by quenching hot steel in water,

3276-461: 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 about 75 feet (23 m) 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 . The Austronesian expansion , which began c.  3000 BC with migration from Taiwan to

3367-536: The 17th century, some kingdoms added brass or iron cannons to their vessels. By the 18th century, however, the use of swivel cannons on war canoes accelerated. The city-state of Lagos , for instance, deployed war canoes armed with swivel cannons. With the development of the carrack , the west moved into a new era of ship construction by building the first regular oceangoing vessels. In a relatively short time, these ships grew to an unprecedented size, complexity, and cost. Shipyards became large industrial complexes, and

3458-590: The 8–9th century AD. Austronesians (especially from western Island Southeast Asia ) were trading in the Indian Ocean as far as Africa during this period. By around 50 to 500 AD, a group of Austronesians, believed to be from the southeastern coasts of Borneo (possibly a mixed group related to the modern Ma'anyan , Banjar , and/or the Dayak people ) crossed the Indian Ocean and colonized Madagascar . This resulted in

3549-731: The Admiral Zheng He . Six voyages were conducted under the Yongle Emperor's reign, the last of which returned to China in 1422. After the Yongle Emperor's death in 1424, his successor the Hongxi Emperor ordered the suspension of the voyages. The seventh and final voyage began in 1430, sent by the Xuande Emperor . Although the Hongxi and Xuande Emperors did not emphasize sailing as much as the Yongle Emperor, they were not against it. This led to

3640-499: The Chinese vessels during this era were essentially fluvial (riverine). True ocean-going Chinese fleets did not appear until the 10th century Song dynasty . There is considerable knowledge regarding shipbuilding and seafaring in the ancient Mediterranean. Large multi-masted seafaring ships of Southeast Asian Austronesians first started appearing in Chinese records during the Han dynasty as

3731-648: The Chinese, from the Old Javanese parahu , Javanese prau , or Malay perahu – large ship. Southern Chinese junks showed characteristics of Austronesian ships that they are made using timbers of tropical origin, with keeled, V-shaped hull. This is different from northern Chinese junks, which are developed from flat-bottomed riverine boats. The northern Chinese junks were primarily built of pine or fir wood, had flat bottoms with no keel, water-tight bulkheads with no frames, transom (squared) stern and stem, and have their planks fastened with iron nails or clamps. It

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3822-561: The Han dynasty junk ship design in the same century. The Chinese were using square sails during the Han dynasty and adopted the Austronesian junk sail later in the 12th century. Iconographic remains show that Chinese ships before the 12th century used square sails, and the junk rig of Chinese ships is believed to be developed from tilted sails . Southern Chinese junks were based on keeled and multi-planked Austronesian ship known as po by

3913-695: 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

4004-563: The Naval Construction & Armaments Company. In 1911 the company was renamed Vickers Limited, and in 1927 became Vickers Armstrongs Limited after a merger with Armstrong Whitworth , whose shipyard at High Walker on the River Tyne became the "Naval Yard". In 1955 the name of the shipbuilding division changed to Vickers Armstrongs Shipbuilders, Ltd and changed again in 1968 to Vickers Limited Shipbuilding Group. The shipbuilding group

4095-484: The United States in a 15-year period just before the war was a grand total of two. During the war, thousands of Liberty ships and Victory ships were built, many of them in shipyards that did not exist before the war. And, they were built by a workforce consisting largely of women and other inexperienced workers who had never seen a ship before (or even the ocean). After World War II , shipbuilding (which encompasses

4186-445: The amount of stiffness required.) Thin-bladed handsaws are made stiff enough either by holding them in tension in a frame, or by backing them with a folded strip of steel (formerly iron) or brass (on account of which the latter are called "back saws.") Some examples of hand saws are: "Back saws" which have a thin blade backed with steel or brass to maintain rigidity, are a subset of hand saws. Back saws have different names depending on

4277-516: The bottom planking of cogs . The north-European and Mediterranean traditions merged in the late 15th century, with carvel construction being adopted in the North and the centre-line mounted rudder replacing the quarter rudder of the Mediterranean. These changes broadly coincided with improvements in sailing rigs, with the three masted ship becoming common, with square sails on the fore and main masts, and

4368-454: The century, due to superior mechanisation, better marketing, a large domestic market, and the imposition of high tariffs on imports. Highly productive industries continued in Germany and France. Early European saws were made from a heated sheet of iron or steel, produced by flattening by several men simultaneously hammering on an anvil. After cooling, the teeth were punched out one at a time with

4459-564: The development beyond that raft technology occurred in the "nursery" areas of the Mediterranean and in Maritime Southeast Asia . Favoured by warmer waters and a number of inter-visible islands, boats (and, later, ships) with water-tight hulls (unlike the "flow through" structure of a raft) could be developed. The ships of ancient Egypt were built by joining the hull planks together, edge to edge, with tenons set in mortices cut in

4550-495: The end of the Ming dynasty in 1644. During this period, Chinese navigation technology did not make any progress and even declined in some aspect. In the Islamic world, shipbuilding thrived at Basra and Alexandria . The dhow , felucca , baghlah , and the sambuk became symbols of successful maritime trade around the Indian Ocean from the ports of East Africa to Southeast Asia and the ports of Sindh and Hind (India) during

4641-575: The government, under command of the Ministry of Public Works . During the early years of the Ming dynasty, the Ming government maintained an open policy towards sailing. Between 1405 and 1433, the government conducted seven diplomatic Ming treasure voyages to over thirty countries in Southeast Asia, India, the Middle East and Eastern Africa. The voyages were initiated by the Yongle Emperor , and led by

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4732-507: The infrastructure required to transport the trees from their point of origin to the shipyards. Shipbuilders were usually divided into different groups and had separate jobs. Some were responsible for fixing old ships; some were responsible for making the keel and some were responsible for building the helm. After 1477, the Ming government reversed its open maritime policies, enacting a series of isolationist policies in response to piracy . The policies, called Haijin (sea ban), lasted until

4823-524: The introduction of outrigger canoe technology to non-Austronesian cultures in the East African coast. The ancient Chinese also built fluvial ramming vessels as in the Greco-Roman tradition of the trireme , although oar-steered ships in China lost favor very early on since it was in the 1st century China that the stern -mounted rudder was first developed. This was dually met with the introduction of

4914-525: The island of Luzon in the Philippines , spread across Island Southeast Asia . Then, between 1500 BC and 1500 AD they settled uninhabited islands of the Pacific, and also sailed westward to Madagascar. This is associated with distinctive maritime technology: lashed lug construction techniques (both in outrigger canoes and in large planked sailing vessels), various types of outrigger and twin-hulled canoes and

5005-485: The keel, the hull was made by overlapping nine strakes on either side with rivets fastening the oaken planks together. It could hold upwards of thirty men. 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

5096-405: The kerf from all the cuts. The kerf depends on several factors: the width of the saw blade; the set of the blade's teeth; the amount of wobble created during cutting; and the amount of material pulled out of the sides of the cut. Although the term "kerf" is often used informally, to refer simply to the thickness of the saw blade, or to the width of the set, this can be misleading, because blades with

5187-470: The latter half of the 19th century, providing great savings when compared with iron in cost and weight. Wood continued to be favored for the decks. During World War II , the need for cargo ships was so great that construction time for Liberty ships went from initially eight months or longer, down to weeks or even days. They employed production line and prefabrication techniques such as those used in shipyards today. The total number of dry-cargo ships built in

5278-478: The mating edges. A similar technique, but with the tenons being pinned in position by dowels, was used in the Mediterranean for most of classical antiquity . Both these variants are "shell first" techniques, where any reinforcing frames are inserted after assembly of the planking has defined the hull shape. Carvel construction then took over in the Mediterranean. Northern Europe used clinker construction , but with some flush-planked ship-building in, for instance,

5369-455: The most advanced structure that the society building it could produce. Some key industrial advances were developed to support shipbuilding, for instance the sawing of timbers by mechanical saws propelled by windmills in Dutch shipyards during the first half of the 17th century. The design process saw the early adoption of the logarithm (invented in 1615) to generate the curves used to produce

5460-555: The most famous shipyards was Long Jiang Shipyard ( zh:龙江船厂 ), located in Nanjing near the Treasure Shipyard where the ocean-going ships were built. The shipbuilders could build 24 models of ships of varying sizes. Several types of ships were built for the voyages, including Shachuan (沙船), Fuchuan (福船) and Baochuan ( treasure ship ) (宝船). Zheng He's treasure ships were regarded as Shachuan types, mainly because they were made in

5551-538: The naturally curved timber that meant that shapes could be cut without weaknesses caused by cuts across the grain of the timber. Ultimately, whole ships were made of iron and, later, steel . The earliest known depictions (including paintings and models) of shallow-water sailing boats is from the 6th to 5th millennium BC of the Ubaid period of Mesopotamia . They were made from bundled reeds coated in bitumen and had bipod masts. They sailed in shallow coastal waters of

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5642-420: The preferred material for saw blades of all kind. There are numerous types of hands saws and mechanical saws, and different types of blades and cuts. A saw is a tool consisting of a tough blade , wire , or chain with a hard toothed edge. It is used to cut through material , very often wood , though sometimes metal or stone. A number of terms are used to describe saws. The narrow channel left behind by

5733-506: The preferred material, due to its hardness, ductility, springiness and ability to take a fine polish. A small saw industry survived in London and Birmingham, but by the 1820s the industry was growing rapidly and increasingly concentrated in Sheffield, which remained the largest centre of production, with over 50% of the nation's saw makers. The US industry began to overtake it in the last decades of

5824-416: The resilient and salt-resistant pandanus leaves. These sails allowed Austronesians to embark on long-distance voyaging. The ancient Champa of Vietnam also uniquely developed basket-hulled boats whose hulls were composed of woven and resin - caulked bamboo, either entirely or in conjunction with plank strakes . They range from small coracles (the o thúng ) to large ocean-going trading ships like

5915-456: The resulting company, BAE Systems as part of BAE Systems Marine . In 2003 it became an independent division known as BAE Systems Submarines after BAE systems split its ship and submarine building operations. This was renamed BAE Systems Submarine Solutions in January 2007. Shipbuilding Until recently, with the development of complex non-maritime technologies, a ship has often represented

6006-407: The same number of teeth per inch throughout their entire length, but the vast majority do. Those with more teeth per inch at the toe are described as having incremental teeth, in order to make starting the saw cut easier. An alternative measurement of the frequency of teeth on a saw blade is teeth per inch . Usually abbreviated TPI, as in, "a blade consisting of 18TPI." (cf. points per inch.) Set

6097-421: The same thickness and set may create different kerfs. For example, a too-thin blade can cause excessive wobble, creating a wider-than-expected kerf. The kerf created by a given blade can be changed by adjusting the set of its teeth with a tool called a saw tooth setter . The kerf left behind by a laser beam can be changed based on the laser's power and type of material being cut. A toothed saw or tooth saw has

6188-412: The saw and (relatedly) the measure of its width is known as the kerf . As such, it also refers to the wasted material that is turned into sawdust, and becomes a factor in measurements when making cuts. For example, cutting an 8 foot (2.4 meter) piece of wood into 1 foot (30 cm) sections, with 1/8 inch (3 mm) kerf will produce only seven sections, plus one that is 7/8 inch (21 mm) too short when factoring in

6279-403: The saw plate "thin to the back" by a fraction of an inch, which helped the saw to pass through the kerf without binding. The use of steel added the need to harden and temper the saw plate, to grind it flat, to smith it by hand hammering and ensure the springiness and resistance to bending deformity, and finally to polish it. Most hand saws are today entirely made without human intervention, with

6370-556: The shape of a hull , especially when scaling up these curves accurately in the mould loft . Shipbuilding and ship repairs, both commercial and military, are referred to as naval engineering . The construction of boats is a similar activity called boat building . The dismantling of ships is called ship breaking . The earliest evidence of maritime transport by modern humans is the settlement of Australia between 50,000 and 60,000 years ago. This almost certainly involved rafts , possibly equipped with some sort of sail . Much of

6461-450: The shipbuilder learned the techniques of shipbuilding from his family and is very likely to earn a higher status in the shipyard. Additionally, the shipbuilder had access to business networking that could help to find clients. If a shipbuilder entered the occupation through an apprenticeship, the shipbuilder was likely a farmer before he was hired as a shipbuilder, or he was previously an experienced shipbuilder. Many shipbuilders working in

6552-429: The ships built were financed by consortia of investors. These considerations led to the documentation of design and construction practices in what had previously been a secretive trade run by master shipwrights and ultimately led to the field of naval architecture , in which professional designers and draftsmen played an increasingly important role. Even so, construction techniques changed only very gradually. The ships of

6643-422: The shipyard were forced into the occupation. The ships built for Zheng He's voyages needed to be waterproof, solid, safe, and have ample room to carry large amounts of trading goods. Therefore, due to the highly commercialized society that was being encouraged by the expeditions, trades, and government policies, the shipbuilders needed to acquire the skills to build ships that fulfil these requirements. Shipbuilding

6734-433: The shipyards, the marine equipment manufacturers, and many related service and knowledge providers) grew as an important and strategic industry in a number of countries around the world. This importance stems from: Historically, the industry has suffered from the absence of global rules and a tendency towards ( state - supported ) over-investment due to the fact that shipyards offer a wide range of technologies, employ

6825-649: The site of Portus in Rome revealed inscriptions in a shipyard constructed during the reign of Trajan (98–117) that indicated the existence of a shipbuilders guild . Roughly at this time is the last migration wave of the Austronesian expansion , when the Polynesian islands spread over vast distances across the Pacific Ocean were being colonized by the (Austronesian) Polynesians from Island Melanesia using double-hulled voyaging catamarans . At its furthest extent, there

6916-483: The sizes and use of different types of saws. Egyptian saws were at first serrated, hardened copper which may have cut on both pull and push strokes. As the saw developed, teeth were raked to cut only on the pull stroke and set with the teeth projecting only on one side, rather than in the modern fashion with an alternating set. Saws were also made of bronze and later iron. In the Iron Age , frame saws were developed holding

7007-400: The steel plate supplied ready rolled to thickness and tensioned before being cut to shape by laser. The teeth are shaped and sharpened by grinding and are flame hardened to obviate (and actually prevent) sharpening once they have become blunt. A large measure of hand finishing remains to this day for quality saws by the very few specialist makers reproducing the 19th century designs. A pit saw

7098-478: The stronger flushed deck design derived from Indian designs, and the increasing use of iron reinforcement. The flushed deck originated from the Bengal rice ships, with Bengal being famous for its shipbuilding industry at the time. Iron was gradually adopted in ship construction, initially to provide stronger joints in a wooden hull e.g. as deck knees, hanging knees, knee riders and the other sharp joints, ones in which

7189-509: The thin blades in tension. The earliest known sawmill is the Roman Hierapolis sawmill from the third century AD and was for sawing stone. According to Chinese legend, the saw was invented by Lu Ban . In Greek mythology , as recounted by Ovid , Talos , the nephew of Daedalus , invented the saw. In archeological reality, saws date back to prehistory and most probably evolved from Neolithic stone or bone tools . "[T]he identities of

7280-549: The treasure shipyard in Nanjing. Shachuan , or 'sand-ships', are ships used primarily for inland transport. However, in recent years, some researchers agree that the treasure ships were more of the Fuchuan type. It is said in vol. 176 of San Guo Bei Meng Hui Bian (三朝北盟汇编) that ships made in Fujian are the best ones. Therefore, the best shipbuilders and laborers were brought from these places to support Zheng He's expedition. The shipyard

7371-603: The waterline, the introduction of copper sheathing as a deterrent to shipworm and fouling, etc. In the early decades of the Industrial Revolution (1760 to 1825) western ship design remained largely based on its traditional pre-industrial designs and materials and yet greatly improved in safety as "the risk of being wrecked for Atlantic shipping fell by one-third, and of foundering by two thirds, reflecting improvements in seaworthiness and navigation respectively." The improvement in seaworthiness has been credited to adopting

7462-456: The zero point on a ruler, and then counting the number of points between the zero mark and the one-inch mark, inclusive (that is, including both the point at the zero mark and any point that lines up precisely with the one-inch mark). There is always one more point per inch than there are teeth per inch (e.g., a saw with 14 points per inch will have 13 teeth per inch, and a saw with 10 points per inch will have 9 teeth per inch). Some saws do not have

7553-574: Was nationalised under the Aircraft and Shipbuilding Industries Act in 1977 and subsumed into British Shipbuilders . The ex-Vickers yard at Barrow was the first shipyard of the British Shipbuilders group to return to the private sector. It was sold in March 1986 to an employee-led company, VSEL Consortium, which also included its Birkenhead -based subsidiary, Cammell Laird . The company was floated on

7644-516: Was a two-man ripsaw . In parts of early colonial North America, it was one of the principal tools used in shipyards and other industries where water-powered sawmills were not available. It was so-named because it was typically operated over a saw pit , either at ground level or on trestles across which logs that were to be cut into boards. The pit saw was "a strong steel cutting-plate, of great breadth, with large teeth, highly polished and thoroughly wrought, some eight or ten feet in length" with either

7735-454: Was likely to "operate against the public interest". However it was GEC's bid that was approved and accepted by VSEL, since Secretary of State Michael Heseltine did not accept the MMC's recommendation and allowed the bid to proceed. Following GEC's purchase VSEL became Marconi Marine (VSEL), part of the company's GEC-Marconi division. With the merger of British Aerospace and GEC's defence business – Marconi Electronic Systems – VSEL passed to

7826-525: Was much more accomplished than had been thought and has described the distribution of clinker vs. carvel construction in Western Europe (see map [1] ). An insight into shipbuilding in the North Sea/Baltic areas of the early medieval period was found at Sutton Hoo , England, where a ship was buried with a chieftain. The ship was 26 metres (85 ft) long and 4.3 metres (14 ft) wide. Upward from

7917-539: Was not the sole industry utilising Chinese lumber at that time; the new capital was being built in Beijing from approximately 1407 onwards, which required huge amounts of high-quality wood. These two ambitious projects commissioned by Emperor Yongle would have had enormous environmental and economic effects, even if the ships were half the dimensions given in the History of Ming . Considerable pressure would also have been placed on

8008-444: Was the first radical new design, being built entirely of wrought iron. Despite her success, and the great savings in cost and space provided by the iron hull, compared to a copper-sheathed counterpart, there remained problems with fouling due to the adherence of weeds and barnacles. As a result, composite construction remained the dominant approach where fast ships were required, with wooden timbers laid over an iron frame ( Cutty Sark

8099-426: Was under the command of Ministry of Public Works . The shipbuilders had no control over their lives. The builders, commoner's doctors, cooks and errands had lowest social status. The shipbuilders were forced to move away from their hometown to the shipyards. There were two major ways to enter the shipbuilder occupation: family tradition, or apprenticeship. If a shipbuilder entered the occupation due to family tradition,

8190-414: Was unknown when the Chinese people started adopting Southeast Asian (Austronesian) shipbuilding techniques. They may have been started as early as the 8th century, but the development was gradual and the true ocean-going Chinese junks did not appear suddenly. The word "po" survived in Chinese long after, referring to the large ocean-going junks. In September 2011, archeological investigations done at

8281-508: Was used as early as 1200 BC. By the end of the 17th century European manufacture centred on Germany, (the Bergisches Land) in London, and the Midlands of England. Most blades were made of steel (iron carbonised and re-forged by different methods). In the mid 18th century a superior form of completely melted steel ("crucible cast") began to be made in Sheffield, England, and this rapidly became

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