Ship Raising

a series of measures for raising a sunken ship from the bottom and partially or completely removing the vessel from the water. Ship raising is used to salvage ships, clear harbors, roads, and channels, and recover scrap metal, valuables, and documents. It is also used to establish the causes of shipwrecks and to rescue the crews of sunken submarines.

The buoyancy of a sunken ship can be restored by pumping water from the compartments or by using compressed air or gases, polyurethane foam, or soft inflatable pontoons to expel water. Ships can also be raised by attaching inflatable pontoons to the hull of the ship, by using cranes, keel lighters, or other devices, and by using a winch to drag the ship to shore. Raising a ship from the bottom is sometimes simplified if the ship is broken into sections with explosives or underwater cutting torches.

Before a ship is raised, its location is established by means of sonar, echo sounders, magnetic metal detectors, television equipment, and other devices. Underwater equipment fitted with manipulators can be used for work at great depths. In the USSR ship raising is the responsibility of the Sovsudopod”em All-Union Association.