Remotely operated underwater vehicle (ROV) is the commonly accepted name for tethered underwater robots in the offshore industry. ROVs are unoccupied, highly maneuverable and operated by a person aboard a vessel. They are linked to the ship by a tether (sometimes referred to as an umbilical cable), which consists of a group of cables that carry electrical power, video and data signals back and forth between the operator and the vehicle. High power applications will often use hydraulics in addition to electrical cabling. Most ROVs are equipped with at least a video camera and lights. Additional equipment is commonly added to expand the vehicle’s capabilities. These may include sonars, magnetometers, a still camera, a manipulator or cutting arm, water samplers, and instruments that measure water clarity, light penetration and temperature.
The US Navy funded most of the early ROV technology development in the 1960s. This created the capability to perform deep-sea rescue operations and recover objects from the ocean floor. Building on this technology base; the offshore oil & gas industry created the work class ROVs to assist in the development of offshore oil fields. More than a decade after they were first introduced, ROVs became essential in the 1980s, when much of the new offshore development exceeded the depths reachable by human divers. Since then, technological development in the ROV industry has accelerated, and today ROVs perform numerous tasks in many fields. Those tasks range from simple inspection of subsea structures, pipelines, and platforms, to connecting pipelines and placing underwater manifolds. Submersible ROVs have been used to locate many historic shipwrecks, including that of the RMS Titanic, the Bismarck, USS Yorktown, and SS Central America. In some cases, such as the SS Central America, ROVs have been used to recover material from the sea floor and bring it to the surface.
If a valuable shipwreck is located in over 200 feet of water, you will most likely need to utilize ROVs for the salvage operation. The cost of the ROVs and the required support vessel has come down in the past years, but it is still extremely expensive compared to shallow water salvage. As you can imagine, the support vessel must maintain a fixed position, without the use of anchors, in order to control the ROV below it on the tether. This is an expensive and specialized capability, not available in most standard ships. The economical and/or historical value of the shipwreck must justify the use of such equipment.