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A remotely operated underwater vehicle, commonly referred to as an ROV, is a tethered underwater vehicle. They are common in deep water industries such as offshore hydrocarbon extraction. While the traditional abbreviation "ROV" stands for remotely operated vehicle, one must distinguish it from remote control vehicles operating on land or in the air. ROVs are unoccupied, highly maneuverable, and operated by a crew aboard a vessel. They are linked to the ship by either a neutrally buoyant tether or, often when working in rough conditions or in deeper water, a load-carrying umbilical cable is used along with a tether management system (TMS). The TMS is either a garage-like device which contains the ROV during lowering through the splash zone or, on larger work-class ROVs, a separate assembly which sits on top of the ROV. The purpose of the TMS is to lengthen and shorten the tether so the effect of cable drag where there are underwater currents is minimized. The umbilical cable is an armored cable that contains a group of electrical conductors and fiber optics that carry electrical power, video, and data signals between the operator and the TMS. Where used, the TMS then relays the signals and power for the ROV down the tether cable. Once at the ROV, the electrical power is distributed between the components of the ROV. However, in high-power applications, most of the electrical power drives a high-power electrical motor which drives a hydraulic pump. The hydraulic pump is then used for propulsion and to power equipment such as torque tools and manipulator arms where electrical motors would be too difficult to implement subsea. 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, water temperature, water density, sound velocity, light penetration, and temperature.
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In the 1970s and '80s the Royal Navy used "Cutlet", a remotely operated submersible, to recover practice torpedoes and mines. RCA (Noise) maintained the "Cutlet 02" System based at BUTEC ranges, whilst the "03" system was based at the submarine base on the Clyde and was operated and maintained by RN personnel.
The US Navy funded most of the early ROV technology development in the 1960s into what was then named a "Cable-Controlled Underwater Recovery Vehicle" (CURV). This created the capability to perform deep-sea rescue operation and recover objects from the ocean floor, such as a nuclear bomb lost in the Mediterranean Sea after the 1966 Palomares B-52 crash. 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 reach of human divers. During the mid-1980s the marine ROV industry suffered from serious stagnation in technological development caused in part by a drop in the price of oil and a global economic recession. Since then, technological development in the ROV industry has accelerated and today ROVs perform numerous tasks in many fields. Their tasks range from simple inspection of subsea structures, pipelines, and platforms, to connecting pipelines and placing underwater manifolds. They are used extensively both in the initial construction of a sub-sea development and the subsequent repair and maintenance.
Submersible ROVs have been used to locate many historic shipwrecks, including 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.
While the oil and gas industry uses the majority of ROVs, other applications include science, military, and salvage. The military uses ROV for tasks such as mine clearing and inspection. Science usage is discussed below.
Work-class ROVs are built with a large flotation pack on top of an aluminium chassis to provide the necessary buoyancy to perform a variety of tasks. Syntactic foam is often used for the flotation material. A tooling skid may be fitted at the bottom of the system to accommodate a variety of sensors or tooling packages. By placing the light components on the top and the heavy components on the bottom, the overall system has a large separation between the center of buoyancy and the center of gravity: this provides stability and the stiffness to do work underwater.
Electrical components can be in oil-filled water tight compartments or one-atmosphere compartments to protect them from corrosion in seawater and being crushed by the extreme pressure exerted on the ROV while working deep. Thrusters are usually in a vectored configuration to provide the most precise control as possible. The ROV will be fitted with cameras, lights and manipulators to perform basic work. Additional sensors and tools can be fitted as needed for specific tasks.
The majority of the work-class ROVs are built as described above; however, this is not the only style in ROV building method. Specifically, the smaller ROVs can have very different designs, each geared towards its own task.
In October 2008 the U.S. Navy began to replace its manned rescue systems, based on the Mystic DSRV and support craft, with a modular system, the SRDRS based on a tethered, unmanned ROV called a pressurized rescue module (PRM). This followed years of tests and exercises with submarines from the fleets of several nations.
The US Navy also uses an ROV called AN/SLQ-48 Mine Neutralization Vehicle (MNV) for mine warfare. It can go 1000 yards away from the ship, and can reach 2000 feet deep. The mission packages available for the MNV are known as MP1, MP2, and MP3.
The charges are detonated by acoustic signal from the ship.
The AN/BLQ-11 autonomous Unmanned Undersea Vehicle (UUV) is designed for covert mine countermeasure capability and can be launched from certain submarines.
The ROVs are only on Avenger-class mine countermeasures ships. There are currently 13 ships, operating mostly off the coast of Japan and California, and there are always four US minesweepers in the Persian Gulf: USS Ardent (MCM-12), USS Dextrous (MCM-13), USS Scout (MCM-8) and USS Gladiator (MCM-11).
During August 19, 2011, a Boeing-made robotic submarine dubbed Echo Ranger was being tested for possible use by the U.S. military to stalk enemy waters, patrol local harbors for national security threats and scour ocean floors to detect environmental hazards.
As their capabilities grow smaller ROVs are also increasingly being adopted by navies, coast guards, and port authorities around the globe, including the U.S. Coast Guard and U.S. Navy, Royal Netherlands Navy, the Norwegian Navy, the Royal Navy and the Saudi Border Guard. They have also been widely adopted by police departments and search and recovery teams. Useful for a variety of underwater inspection tasks such as explosive ordnance disposal (EOD), meteorology, port security, mine countermeasures (MCM), and maritime ISR (Intelligence, Surveillance, Reconnaissance).
ROVs are also used extensively by the science community to study the ocean. A number of deep sea animals and plants have been discovered or studied in their natural environment through the use of ROVs: examples include the jellyfish Bumpy and the eel-like halosaurs. In the USA, cutting edge work is done at several public and private oceanographic institutions, including the Monterey Bay Aquarium Research Institute (MBARI), the Woods Hole Oceanographic Institution (WHOI) (with Nereus), and the University of Rhode Island / Institute for Exploration (URI/IFE). The picture to the right shows the behavior and microdistribution of krill under the ice of Antarctica.
Science ROVs take many shapes and sizes. Since good video footage is a core component of most deep-sea scientific research, research ROVs tend to be outfitted with high-output lighting systems and broadcast quality cameras. Depending on the research being conducted, a science ROV will be equipped with various sampling devices and sensors. Many of these devices are one-of-a-kind, state-of-the-art experimental components that have been configured to work in the extreme environment of the deep ocean. Science ROVs also incorporate a good deal of technology that has been developed for the commercial ROV sector, such as hydraulic manipulators and highly accurate subsea navigation systems.
While there are many interesting and unique science ROVs, there are a few larger high-end systems that are worth taking a look at. MBARI's Tiburon vehicle cost over $6 million US dollars to develop and is used primarily for midwater and hydrothermal research on the West Coast of the US. WHOI's Jason system has made many significant contributions to deep-sea oceanographic research and continues to work all over the globe. URI/IFE's Hercules ROV is one of the first science ROVs to fully incorporate a hydraulic propulsion system and is uniquely outfitted to survey and excavate ancient and modern shipwrecks. The Canadian Scientific Submersible Facility ROPOS system is continually used by several leading ocean sciences institutions and universities for challenging tasks such as deep-sea vents recovery and exploration to the maintenance and deployment of ocean observatories.
The SeaPerch Remotely Operated Underwater Vehicle (ROV) educational program is an educational tool and kit that allows elementary, middle, and high-school students to construct a simple, remotely operated underwater vehicle, from polyvinyl chloride (PVC) pipe and other readily made materials. The SeaPerch program teaches students basic skills in ship and submarine design and encourages students to explore naval architecture and marine and ocean engineering concepts. SeaPerch is sponsored by the Office of Naval Research, as part of the National Naval Responsibility for Naval Engineering (NNRNE), and the program is managed by the Society of Naval Architects and Marine Engineers.
The Marine Advanced Technology Education (MATE) Center uses ROVs to teach middle school, high school, community college, and university students about ocean-related careers and help them improve their science, technology, engineering, and math skills. MATE’s annual student ROV competition challenges student teams from all over the world to compete with ROVs that they design and build. The competition uses realistic ROV-based missions that simulate a high-performance workplace environment, focusing on a different theme that exposes students to many different aspects of marine-related technical skills and occupations. The ROV competition is organized by MATE and the Marine Technology Society's ROV Committee and funded by organizations such as the National Aeronautics and Space Administration (NASA), National Oceanic and Atmospheric Administration (NOAA), and Oceaneering, and many other organizations that recognize the value of highly trained students with technology skills such as ROV designing, engineering, and piloting. MATE was established with funding from the National Science Foundation and is headquartered at Monterey Peninsula College in Monterey, California.
As cameras and sensors have evolved and vehicles have become more agile and simple-to-pilot ROVs have become popular particularly with documentary filmmakers due to their ability to access deep, dangerous, and confined areas unattainable by divers. There is no limit to how long an ROV can be submerged and capturing footage which allows for previously unseen perspectives to be gained. ROVs have been used in the filming of several documentaries including Nat Geo's Shark Men and The Dark Secrets of the Lusitania and the BBC Wildlife Special Spy in the Huddle.
With an increased interest in the ocean by many people, both young and old, and the increased availability of once expensive and non-commercially available equipment, ROVs have become a popular hobby amongst many. This hobby involves the construction of small ROVs that generally are made out of PVC piping and often can dive to depths between 50 to 100 feet but some have managed to get to 300 feet. This new interest in ROVs has led to the formation of many competitions, including MATE (Marine Advanced Technology Education) and NURC (National Underwater Robotics Challenge). These are competitions in which competitors, most commonly schools and other organizations, compete against each other in a series of tasks using ROVs that they have built. Most hobby ROVs are tested in swimming pools and lakes where the water is calm, however some have tested their own personal ROVs in the sea. Doing so, however, creates many difficulties due to waves and currents that can cause the ROV to stray off course or struggle to push through the surf due to the small size of engines that are fitted to most hobby ROVs.
Submersible ROVs are normally classified into categories based on their size, weight, ability or power. Some common ratings are:
Submersible ROVs may be "free swimming" where they operate neutrally buoyant on a tether from the launch ship or platform, or they may be "garaged" where they operate from a submersible "garage" or "tophat" on a tether attached to the heavy garage that is lowered from the ship or platform. Both techniques have their pros and cons; however very deep work is normally done with a garage.
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