shipbuilding

shipbuilding. Transport over water is a necessity in most parts of the world. Since time immemorial ships have been constructed in any place with a suitable shoreline, easily procured supplies of timber, and an available workforce. The improvement in ship design and construction has been a process of evolution, slow at first, but gathering speed over the centuries, leading ultimately to the sophisticated ships of the 21st century. It is interesting to compare the simplest dugouts still to be found in less developed parts of the world and to appreciate that the design of even these humble craft has variations brought about by experience in operation. Following on from carved logs, dugouts, and similar craft, early shipbuilders in many Middle Eastern lands produced vessels constructed with papyrus, and elsewhere craft, like the coracle and the kayak, were formed of animal skins stretched over timber framework.

Wooden Shipbuilding.

Well over 1,500 years ago, the skill of building ships with wooden planks was developed, a method that continued until the middle of the 19th century for commercial ships and which is still in use today for smaller vessels. Methods of construction have altered little over a thousand years: The shape of the ship is constrained by frames (or ribs) covered with a shell of thinner planks, the plank edges being secured and caulked to prevent leakage. The ship has a spine, or keel, on which the frames are set up and which in turn support the beams, longitudinals, and other parts. Timber is a flexible material, able to yield and adapt to complex shapes, and with centuries of experience, methods of construction have become fairly standard throughout the world.

The western tradition of shipbuilding evolved over a period of about 500 years. During it the sailing ship became a fairly efficient vehicle, but also one in which the layout and rigging have a form which is constrained by conventions understandable to multilingual, international crews. Hence, over the years, improvements and developments were accepted on a worldwide scale.

For several reasons, wooden vessels cannot be constructed in the traditional way with a waterline length much in excess of 80 metres (260 ft). As the ratios of the various dimensions, such as length to breadth, are fairly constant, this length limitation made it difficult to improve cargo-carrying capacity, and a plateau in efficiency was reached. Any small improvements came about by manipulation of the key proportions of ships. This often made them unseaworthy, a situation exacerbated by the elementary knowledge of naval architecture at that time. Also wooden ships often had a fairly short lifespan if maintenance was lacking, or if they were laid up for lengthy periods. A further problem came through demand for timber outstripping supply in many countries during the 18th century. At this time, industrial shipyards were being created in Europe, and for the first time there came an appreciation that shipbuilding was an assembly business requiring detailed planning, material control, ample manpower, and safe access to water. The stage was set for iron.

Iron and Steel Shipbuilding.

The introduction of iron into shipbuilding was the industry's most dramatic change ever. In Britain the Vulcan was the first vessel to be built in it and Brunel's Great Britain was the first large iron-built ocean liner. The form of a ship's construction altered little, but the methods changed overnight. From a technical point of view there was practically no limit to the length, speed, and carrying capacity of a ship, its size being limited only by its ports of call. In addition, the basic principle that doubling a ship's length increased its carrying capacity eightfold made iron ships highly profitable, while improved hull strength enabled the fitting of heavy steam machinery, with adequately sized coal bunkers. As iron is a tough and unyielding material, the shipyards had to retool to enable them to produce component parts to the highest precision standards. New engineering techniques had to be introduced and shipyards were equipped with rollers, shears, punches, and frame-bending furnaces, while lofting departments became dedicated to the making of accurate full-scale templates for construction. Design and drawing offices were introduced as were specialist ordering departments for the procurement of all necessary materials. The tasks within a shipyard also had to be redefined and new trades, like plater, riveter, and driller, introduced and integrated into the labour force—not always an easy task.

For a short time in the mid-19th century, some owners ordered vessels of composite construction. This led to slightly longer hulls and to ones which did not ‘sweat’ in the tropics. This method was used to build many clipper ships during the 1850s and 1860s, and remained in use to a limited extent in yachtbuilding into the early 20th century.

In the 1860s there was another change in material that was as significant as had been the one from wood to iron. This was the introduction of steel, an alloy of iron, which, though much more vulnerable to corrosion than iron, was stronger and lighter and it increased a ship's cargo capacity by as much as 10%. Such an improvement in earning power more than outweighed any increase in production costs, with the further benefit that the machine tools and systems for iron could be adapted to it. The Rotomahana, built at Dumbarton by William Denny in 1879, is credited with being the first large merchant ship to be built in mild steel and was the first steel ocean-going ship. Initially, steel was extremely expensive but by the 1880s a number of ships had been built in it, and by 1890 it was being used in every British shipyard. Europe and North America made the changeover somewhat later, completing it by 1900.

Ship Manufacture.

Despite the introduction of new processes, new materials, and advanced ship designs, the traditional processes of a shipyard have altered little over the years.

First, the design settles the dimensions and overall appearance of the ship, and from this the detailed plans are generated. After careful investigation of the suppliers, and their ability to meet stipulated dates and costs, materials have to be ordered. Some, like steel, are ordered in bulk; others, like machinery, as individual items. The plans have to be submitted to a Classification Society, like Lloyd's Register, for acceptance, and also to statutory bodies like the UK's Maritime and Coastguard Agency or the US Coast Guard. Their approval of a design is mandatory and there must also be a plan for an ongoing inspection during construction, and then for the lifetime of the ship. Most countries of the world have accepted a new concept, known as State Port Control, where their maritime authorities can carry out random inspections of any ship and detain it if it fails to meet international standards laid down by the International Maritime Organization.

The steelwork plans have to be transferred to some form of templates, or, as is now current practice, to computer-controlled machine tools. All parts are sub-assembled and then placed in assembly units, which can be as large as 500 tonnes, with most of the piping, wiring, and other small parts included. When these are moved to the erection berth or building dock they should require little work apart from assembly and the testing of the systems, and final paintwork. The Classification Society inspections continue throughout and all watertight compartments must be tested under a head of water.

The task of final outfitting includes placing main machinery aboard and then testing in dock conditions. Following float out or the traditional launching, the ship is prepared for exhaustive full-scale trials, often lasting several days. Indeed in many large ships a small team of test engineers will remain aboard for the first voyage to ensure all contractual obligations are fulfilled.

Modern Systems of Production.

The number of people employed in a shipyard has fallen significantly and large portions of the traditional shipbuilding tasks are subcontracted out. A current example, from a north German shipyard, is that steel is sourced from another country and brought to the yard for primary cutting. It is then sent to another European country for machining and preparation, before being returned to the yard for painting and assembly. Almost every other task in the establishment is by subcontracted labour, and all parts, including the main engines, are brought to the shipyard by sea or land.

The computer has entered every field in shipbuilding and a very small group of people can plan and control the complex tasks of a ship's construction, from design and materials ordered, through to construction and delivery. The time scales required for construction have been greatly reduced, although the ‘gestation period’, when the design concepts are evaluated, has risen. This is because lengthy periods of planning and analysis are required for a ship that may be constructed in just a few months, something which adds weight to the commercial advantage of repeat orders and standardized ships.

Geographical Disposition of Shipyards.

In the years up to the introduction of iron, shipyards were found in all places blessed with readily available timber supplies and adequate water for launching. Labour requirements were less problematical as from time immemorial shipyards could depend on groups of itinerant shipwrights, something that continues to this day in the replica ship market. Shipbuilding sites were to be found on every part of the European coast and later in North America and Russia, all countries with an abundance of timber. With the demise of wooden shipbuilding, such sites became few and far between, although some are found still in Indonesia and other parts of South-East Asia.

The introduction of iron made it economical to set up of shipyards near iron suppliers, and therefore in areas adjacent to coalfields. Examples include the River Clyde—which saw the founding of nearly 400 shipyards in a mere 200 years—and those based in the north-east of England on the Tyne, Wear, and Tees rivers. Despite the reduction in the use of coal, and the gradual centralization of iron and then steel smelting, European shipyards remained viable until the end of the Second World War (1939–45). Since then rationalization in Europe and North America has led to a vast reduction in shipbuilding sites in these areas, while, at the same time, they increased elsewhere, particularly in the Far East.

With modern methods of production and good transport infrastructures, the need to be near raw material supplies has vanished and shipyards now survive on their technical and commercial competence.

Worldwide Production.

During the 19th century timber ships continued to be built but on an ever-decreasing scale, and by 1900 even the large North American yards were in decline. Britain enjoyed a head start in iron shipbuilding, and then with the changeover to steel, so that by 1913 British shipyards were the dominant force in the world. In that year, when British shipbuilding was at its peak, the industry produced 61% of the world's ships, with the River Clyde alone producing an amazing 23%. In that year the Clyde delivered more than one new ship every day of the year. The First World War (1914–18) ensured that the shipyards of both the United States and the United Kingdom were working at full stretch. During this period many of Britain's former customers, unable to obtain tonnage quickly in the profitable wartime market place, set up new shipyards themselves and even started to compete for Britain's former customers. Despite the Depression years, when shipyards throughout the world were struggling to survive, some wonderful ocean liners, including the Empress of Britain, Normandie, Queen Mary, and Queen Elizabeth, were produced for the passenger trades. However, closures—mostly of small and undercapitalized yards—were commonplace and when hostilities began again in 1939 the shipbuilding industry was poorly placed to produce what was required. As in the First World War, both the British and the American shipbuilding industries contributed in a superb manner to the Allied cause with the Americans, as they had during the First World War, concentrating on mass-produced war-standard cargo ships such as the Liberty and Victory ships, as well as on standard tankers, known as T2s, producing them in astonishing numbers. Untrammelled by tradition, they capitalized on the known but under-utilized processes of welding and prefabrication-processes which are now accepted in every shipyard in the world.

In 2001, the number of merchant vessels completed was around 1,700 worldwide: totally 31 million gross tonnes. The largest shipbuilders are now in the Far East, with the People's Republic of China growing fast, the Republic of Korea producing 37% of the world's production, and Japan 38%.

New Techniques, New Types of Ship.

Construction techniques, ship design, and construction materials developed dramatically in the final decades of the 20th century, allowing for a great increase in the size of existing vessels and the introduction of new types of ship. The greatest increase in size has been in the tanker trade, with ships now being built which can carry over 500,000 tonnes of crude oil. Container ships are also increasing in size, but the most interesting statistics come from cruise liners. Here, not only have passenger numbers increased, but the amount of space for each passenger has increased more than twofold.

In the area of new designs, two in particular stand out. The first, the underwater vehicle, has given access to the deepest parts of the ocean. Whether manned or unmanned, it has opened up new avenues of research for scientists in oceanography, marine archaeology, and the offshore oil and gas industry. The second is the continuing development of the surface effect ship.

See also moulding; mould-loft; moulds.

Fred M. Walker