Robotic Vehicles Gain In Favor

The great expense of operating manned submersibles led inevitably to the development of cheaper and simpler alternatives. One is the remote-operated vehicle (ROV). An ROV is powered by an electrical cable from a mother ship on the surface and is piloted by an operator on the ship. ROV's can be equipped with every type of instrument a manned submersible carries. Video cameras on the ROV transmit images of the ocean bottom to screens in the control room. ROV's are smaller than manned submersibles, so they can explore places like small caves and narrow crevices. And, unlike manned submersibles, they can be operated for extended periods, because they are powered by generators on the mother ship and because the operator is not confined inside the vehicle. ROV's are also much cheaper to build because—since they do not carry a crew—they do not need a costly, heavy pressure hull. They need only compact pressure cases to protect their instruments.

Some ROV's are carried partway down to the bottom by an underwater launcher that is towed by a ship on the surface. The launcher is equipped with video cameras and sonar that scan the sea floor as the ship cruises along. When the launcher detects a site of potential interest, the operator releases the ROV, which then examines the site in detail. This two-stage procedure enables oceanographers to explore a much larger area of the sea floor than they can with an ROV alone.