Marine salvage

Marine salvage is the process of recovering a ship and its cargo after a shipwreck or other maritime casualty. Salvage may encompass towing, re-floating a vessel, or effecting repairs to a ship. Today, protecting the coastal environment from spillage of oil or other contaminants is a high priority. Before the invention of radio, salvage services would be given to a stricken vessel by any ship that happened to be passing by. Nowadays, most salvage is carried out by specialist salvage firms with dedicated crew and equipment.Flotation airbagDiving helmetUnderwater cutting equipmentHydraulic salvage pumpAir compressorHydraulic winch Marine salvage is the process of recovering a ship and its cargo after a shipwreck or other maritime casualty. Salvage may encompass towing, re-floating a vessel, or effecting repairs to a ship. Today, protecting the coastal environment from spillage of oil or other contaminants is a high priority. Before the invention of radio, salvage services would be given to a stricken vessel by any ship that happened to be passing by. Nowadays, most salvage is carried out by specialist salvage firms with dedicated crew and equipment. The legal significance of salvage is that a successful salvor is entitled to a reward, which is a proportion of the total value of the ship and its cargo. The amount of the award is determined subsequently at a 'hearing on the merits' by a maritime court in accordance with Articles 13 and 14 of the International Salvage Convention of 1989. The common law concept of salvage was established by the English Admiralty Court, and is defined as 'a voluntary successful service provided in order to save maritime property in danger at sea, entitling the salvor to a reward'; and this definition has been further refined by the 1989 Convention. Originally, a 'successful' salvage was one where at least some of the ship or cargo was saved, otherwise the principle of 'No Cure, No Pay' meant that the salvor would get nothing. In the 1970s, a number of marine casualties of single-skin-hull tankers led to serious oil spills. Such casualties were unattractive to salvors, so the Lloyd's Open Form (LOF) made provision that a salvor who acts to try to prevent environmental damage will be paid, even if unsuccessful. This Lloyd's initiative proved so advantageous that it was incorporated into the 1989 Convention. All vessels have an international duty to give reasonable assistance to other ships in distress in order to save life, but there is no obligation to try to salve the vessel. Any offer of salvage assistance may be refused; but if it is accepted a contract automatically arises to give the successful salvor the right to a reward under the 1989 Convention. Typically, the ship and the salvor will sign up to an LOF agreement so that the terms of salvage are clear. Since 2000, it has become standard to append a SCOPIC ('Special Compensation - P&I Clubs') clause to the LOF, so as to circumvent the limitations of the 'Special Compensation' provisions of the 1989 Convention (pursuant to the case of the Nagasaki Spirit). In 219 BC, the Chinese Emperor Qin Shihuang (r. 221–210 BC) assembled an expedition consisting of a thousand people for the salvage of the Nine Tripod Cauldrons. The tripods were considered important artifacts, Chinese legends credit a Xia dynasty emperor with their construction. The tripods were lost in Sishui River in present-day Anhui Province. The salvage attempt was ultimately unsuccessful. Carvings in Han Dynasty tombs depict the salvage attempt. In the 11th century AD, a successful underwater salvage operation in Song China (960–1279) would employ the use of buoyancy. The Chinese understood the concept of buoyancy by at least the 3rd century AD; the short-lived child prodigy Cao Chong (196–208) weighed a large elephant by placing it on a boat in a pond and measuring the rise of the water level, then matching this weight with a boat loaded with numerous heavy objects which could be measured separately. Between 1064 and 1067, the Puchin Bridge near Puchow, a floating bridge built some 350 years earlier across the Yellow River, was destroyed in a flood. This bridge was made of boats secured by iron chains which were attached to eight different cast iron statues located on each river bank, cast in the shape of recumbent oxen. The flood pulled the oxen from the sandy banks into the river, where they sunk to the bottom; after this loss, the local officials issued a proclamation for submission of ideas on how to recover the statues. The plan of the Buddhist monk Huaibing was accepted, which is described in the text Liang Chi Man Chih of 1192, 'he used two huge boats filled with earth, cables from them being made fast to the oxen in the river bed (by the drivers). Hooks and a huge counterweight lever were also used. Then the earth in the boats was gradually taken away so that the boats floated much higher and the oxen were lifted off the river bottom.' In the Early Modern Period, diving bells were often used for salvage work. In 1658, Albrecht von Treileben was contracted by King Gustavus Adolphus of Sweden to salvage the warship Vasa, which sank in Stockholm harbor on its maiden voyage in 1628. Between 1663-1665 von Treileben's divers were successful in raising most of the cannon, working from a diving bell. In 1687, Sir William Phipps used an inverted container to recover £200,000-worth of treasure from a Spanish ship sunk off the coast of San Domingo. The era of modern salvage operations was inaugurated with the development of the first surface supplied diving helmets by the inventors, Charles and John Deane and Augustus Siebe, in the 1830s. Royal George, a 100-gun first-rate ship of the line of the Royal Navy, sank undergoing routine maintenance work in 1782, and the Deane brothers were commissioned to perform salvage work on the wreck. Using their new air-pumped diving helmets, they managed to recover about two dozen cannons. Following on from this success, Colonel of the Royal Engineers Charles Pasley commenced the first large scale salvage operation in 1839. His plan was to break up the wreck of Royal George with gunpowder charges and then salvage as much as possible using divers. Pasley's diving salvage operation set many diving milestones, including the first recorded use of the buddy system in diving, when he ordered that his divers operate in pairs. In addition, the first emergency swimming ascent was made by a diver after his air line became tangled and he had to cut it free. A less fortunate milestone was the first medical account of a diver squeeze suffered by a Private Williams: the early diving helmets used had no non-return valves; this meant that if a hose became severed, the high-pressure air around the diver's head rapidly evacuated the helmet causing tremendous negative pressure that caused extreme and sometimes life-threatening effects. At the British Association for the Advancement of Science meeting in 1842, Sir John Richardson described the diving apparatus and treatment of diver Roderick Cameron following an injury that occurred on 14 October 1841 during the salvage operations.