drone

In marine operations, a drone is a remotely operated vehicle (ROV) or autonomous underwater vehicle (AUV) deployed from a support vessel to perform inspection, repair, construction, or survey work at depth. Unlike surface craft, drones operate entirely submerged and transmit video, sonar, and sensor data back to operators aboard the host ship via tether or wireless link. Multiple drones are often launched simultaneously from the same vessel to accelerate work in deep water or confined spaces where human divers cannot safely or economically operate.

The distinction between ROV and AUV matters in practice. An ROV maintains a physical tether to the surface vessel, which supplies power and two-way communication; operators pilot it in real time using joysticks and camera feeds. An AUV is battery-powered and autonomous, following a pre-programmed path and returning to the surface or a waypoint, then uploading logged data. Both are called drones in shipyard vernacular, though ROVs dominate commercial offshore work because of their reliability and the operator's direct control. Larger ROVs weigh several tons and carry hydraulic arms rated for heavy tooling; smaller inspection drones may weigh under 100 kilograms and carry only lights and cameras.

In shipyards and offshore fields, drones handle hull inspection, valve actuation, pipeline repair, debris removal, and subsea cable laying. Their eyes (usually multiple HD cameras and sonar arrays) eliminate the need to haul vessels into dry dock or send human divers into dangerous conditions. A tether-managed ROV working at 300 meters depth can spend eight hours on station without fatigue, performing repetitive or high-precision tasks. Operators sit in a control room on the vessel, monitoring pressure gauges, compass headings, and live video feeds while maneuvering the drone with six degrees of freedom (surge, sway, heave, roll, pitch, yaw).

Common failure modes and limitations

Tether management is the primary operational constraint for ROVs. A tether can snag on wreckage, twist under current, or suffer abrasion where it passes through ship-mounted fairings. Operators must manage tether tension continuously and ensure umbilical slack does not tangle the vehicle. AUVs avoid this problem but trade away real-time control and power supply. Battery endurance typically limits AUV missions to four to twelve hours depending on survey speed and payload. Both types are vulnerable to strong currents, poor visibility from suspended sediment, and pressure ratings that cap their working depth.

The term "drone" in marine contexts is borrowed from military aviation and has largely replaced older jargon like "submersible" or "robot" in industry speech, though technical reports still prefer ROV or AUV for precision. Shipyard crews use drone generically to mean any unmanned subsea tool kit. The term carries no connotation of autonomy; a fully tethered, operator-piloted vehicle is still called a drone in daily use.