Marine salvage

Marine salvage is the process of recovering a ship, its cargo, or other property after a shipwreck or other maritime casualty. Salvage may encompass towing, re-floating a sunken or grounded vessel, or patching or repairing a ship. Today, protecting the environment from cargoes such as oil or other contaminants is often considered a high priority.

"Salvors" are seamen and engineers who carry out salvage to vessels that they do not own, and who are not members of the vessel's original crew. When salving large ships, they may use cranes, floating dry docks and divers to lift and repair submerged or grounded ships, preparing them to be towed by a tugboat. The goal of the salvage may be to repair the vessel at a harbour or dry dock, or to clear a channel for navigation. Salvage operations may also aim to prevent pollution or damage to the marine environment. Additionally, the vessel or valuable parts of the vessel or its cargo may be recovered for resale, or for scrap.

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. The 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.

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