A shipyard (also called a dockyard) is a place where ships are built and repaired. These can be yachts, military vessels, cruise liners or other cargo or passenger ships. Dockyards are sometimes more associated with maintenance and basing activities than shipyards, which are sometimes associated more with initial construction. The terms are routinely used interchangeably, in part because the evolution of dockyards and shipyards has often caused them to change or merge roles.
Most shipbuilders in the United States are privately owned, the largest being Colonna's Shipyard in Norfolk, VA. The publicly owned shipyards in the US are Naval facilities providing basing, support and repair.
Shipyards are constructed nearby the sea or tidal rivers to allow easy access for their ships. In the United Kingdom, for example, shipyards were established on the Rivers Thames (King Henry VIII founded yards at Woolwich and Deptford in 1512 and 1513 respectively), Mersey, Tees, Tyne, Wear, and Clyde – the latter growing to be the World's pre-eminent shipbuilding centre.
The site of a large shipyard will contain many specialised cranes, dry docks, slipways, dust-free warehouses, painting facilities and extremely large areas for fabrication of the ships. After a ship's useful life is over, it makes its final voyage to a shipbreaking yard, often on a beach in South Asia. Historically shipbreaking was carried on in drydock in developed countries, but high wages and environmental regulations have resulted in movement of the industry to developing regions.
Having shipyards that have been operational for a long time could lead to serious pollution to the environment as years pass by. There have been many different studies that have shown that welding, sandblasting, paint, and maintenance are some of the many factors that contribute pollution to the environment. It is common for a ship to have a hull made of steel, but this process must go through many layers of anti-fouling or anti-corrosion paint to ensure that the metal doesn't corrode and prevent organisms from attaching to the surface. The painting process is inevitable but will it be at nearly every shipyard there is, and two of the most common ways to paint a ship is by airtight spraying and thermal spraying. Many studies have shown that painting is what generates almost half dangerous waste at a shipyard due to using high-pressure equipment to wash or remove any unwanted material that is on it like rust. Which will eventually make its way to the water and creates water pollution to the environment. Once these have compromised the surface of the hull the ship must go to the shipyard for maintenance. In a study in 2011 samples of sediments were collected from two sites in coastal marine area of Yongho Bay, one from the shipyard yard and the other 500m away. These results had analyzed that both samples contained metals that included Al, Fe, Li, V, Cr, Mn, Ni, Cu, Zn, As, Cd, Sn, and Pb. In addition, it had been confirmed that the concentration was higher in the first sample that was by the shipyard then the sample taking 500m away and was due to paint fragments applied to the steel ship hulls.
After a ship has been used it is then scrapped at a shipyard, but in the process can release excessive amounts of pollution. In paint used for hulls of the ship, they are anti-fouling based paint. Over time weathering from ships will eventually sink to the bottom of the seabed and the most common component that is toxic in paint used in shipyards is triphenyl (TPT) and can be treated by using dolomitic sorbents. In 2005, there was a study that show the high level of toxicity of TBT compounds to organisms in the ocean and what can be done to reduce the pollution by using dolomitic sorbents. In the study, a sample of shipyard water was used in the experiment in a period over 14 days. At the end the experiment it was concluded that dolomitic and dolomite were successful in reducing the contaminants from the shipyard wastewater.
Welding is the most important factor in ship building and should be performed by qualified welders in order to protect the ship structure. It is achieved by heating the surfaces to the point of melting using oxy-acetylene, electric arc, or other means, and uniting them by pressing, hammering, etc. But in shipyards, there are times when the welder has to crawl into a confined space and weld. Welding can produce toxic fumes such as Nitric Oxide, Nitrogen Dioxide, Carbon Monoxide, Phosgene, Hydrogen Fluoride, Carbon Dioxide can also result in serious damage to human health or death if ventilation is not present. A case study was performed to see where would be most effective place to exhaust the hull cells on the bulkhead in between two spaces using an air horn versus air with an electric blower. They used welders who were employees of the shipyard and asked them to weld in a specific space. One that had shipyard dilution ventilation(DV) and the other had local exhaust ventilation(LEV) then recorded to see which typed of ventilation worked the best. In the results, they found that local exhaust ventilation reduced particulate concentrations but also the efficiency of either method depended on equipment maintenance and their own work practices because everyone has a different way of getting things done.