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HOW IT WORKS
How Do ROVs Work?
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Remotely Operated Vehicles, or ROVs, are underwater robots that allow the controller to be located above the water. ROVs are connected to the topside via an umbilical link that houses communications cables, an energy source and information transfer.

All ROVs contain some sort of visual device, such as a camera, to see under the water, and additional tools vary according to what type of ROV is being used. For example, some ROVs have multiple manipulators to carry out myriad operational functions at water depths up to 10,000 feet.

Bottom-Founded Perry Trenching ROV
Bottom-Founded Perry Trenching ROVSource: ROV Technology Committee...

As ROV technologies and capabilities have improved, the offshore oil and gas industry has come to rely on ROVs for drilling support and subsea construction services to enable deepwater exploration and development projects worldwide.

History of the ROV

Human divers can only submerge to certain depths, and the skill and danger involved makes deepwater diving unrealistic. Developed to overcome the limitations of human subsea divers, ROVs have become an indispensable tool to the offshore oil and gas industry.

The first iteration of the robotic diving concept was the Human Occupied Vehicle, or HOV, which was developed in the mid-1960s. While somewhat successful, HOVs were limited by human frailties and unable to achieve the water depths needed.

While Dimitri Rebikoff is credited with building the first tethered ROV in 1953, the US military expanded on the technology to retrieve equipment lost at sea. In 1966, the US Navy recovered an atomic bomb lost in a plane crash offshore Spain using an ROV, and in 1973, an ROV was used to save sailors in a sunken submersible offshore Ireland.

The commercial world quickly began manufacturing preliminary versions of ROVs for the offshore oil and gas industry. Although these products were not as successful initially, the technology has come a long way, and now ROVs are regularly used offshore for petroleum developments and drilling, military and science efforts, as well as underwater cable endeavors.

Types of ROVs

ROVs can vary in size from that of a bread box to a large van. The functions ROVs perform can range from simply carrying a camera to observe subsea environments to housing multiple agile arms to perform numerous functions subsea.

Used primarily for observation and inspection operations, Small Electric Vehicles are the tiniest version of ROVs. These robots simply carry a single camera and are deployed in waters no greater than 984 feet (300 meters) deep.

High Capability Electric ROVs are larger versions of their Small Electric Vehicle cousins. These ROVs are able to dive to depths up to 20,000 feet (6,096 meters), but they are still only equipped with video cameras and are unable to perform many other tasks because their electricity supply limits them. Primarily used by the science and military industries, High Capability Electric ROVs are unable to perform any heavy tasks typically required by the oil and gas industry.

The next iteration of ROV, the Work Class Vehicle is powered electrically and hydraulically, enabling some more serious work subsea. Although payload and lift capabilities are restricted, the Work Class Vehicle ROV does generally include a seven-function manipulator and a five-function grabber. Most of this class of ROV is deployed in the drilling and construction support sector, as well as pipeline inspection.

Schilling Robotics RigMaster Grabber Arm
Schilling Robotics RigMaster Grabber ArmSource: ROV Technology Committee...

The most advanced version of ROV is the Heavy Work Class Vehicle ROV. This kind of ROV is capable of working in waters measuring up to 10,000 feet (3,000 meters) deep. Aptly named, the Heavy Work Class Vehicle boasts horsepower ranging from 100 to 250 and has lift capabilities up to 11,025 pounds. Additionally, these ROVs house multiple manipulators and grabbers capable of performing subsea tie-ins and deepwater installations.

Although the military is testing preliminary versions, Autonomous Underwater Vehicles (AUVs) are the next step in ROV technology and are not yet available in the consumer market. Most likely the next commercial ROV technology will be a hybrid between the AUV and ROV, with less umbilicals needed to connect the subsea robot to its above-water controller.

As the oil and gas industry moves to a more subsea environment, ROVs will become an even more important tool in drilling, development and repair offshore. In fact, some ROVs are being built to work on specific subsea developments, with manipulators and tools designed for work on equipment in a precise field. In this case, as the subsea architecture is being designed, the ROV that will handle the subsea work is taken into account, as well, ensuring that all tasks at hand can be managed by the ROV.