This section provides some history and general background information on ROVs as well as the current state of ROVs.
Background and History
The first step in understanding any technology is to understand why it exists. In the case of ROV technology the answer is quite simple. There is no other practical, safe and economically feasible way to perform deep underwater intervention.
History tells us that humans have been doing everything from gathering food to salvaging cannons and performing other tasks underwater for several centuries. The first attempts to improve diving efficiencies were recorded in the mid sixteenth century, when the first diving "helmet" was used. A drawing of this device provides evidence that is was some sort of a greased leather bag with an extension tube to the surface. From that early technology to the record 2,250-foot simulated dive made at Duke University in 1981, we witnessed an incredible evolution in humans' ability to work underwater. Open water dives have been made to nearly 2,000 feet and commercial dives have been done to 1,750 feet, but these instances are very rare, involve high risk, and are not economically feasible.
Human occupied vehicles (HOV), formally called manned submersibles, appeared to be the solution to conquering the deep for a short time in history. The problem was they suffered many of the same disadvantages as hyperbaric diving. Between the mid nineteen-sixties and mid-nineteen-seventies it looked like HOVs would allow deeper work for longer periods of time. The problem was that HOVs required substantial dedicated support vessels and still put humans at risk underwater. They also were slow to launch and recover and had limited bottom time, rendering them economically ineffective. The introduction of commercial ROVs in the mid-seventies has relegated HOVs to limited use in science and the tourist industry.
Exactly who to credit with developing the first ROV will probably remain clouded. However, there are two who deserve credit. The PUV (Programmed Underwater Vehicle) was a torpedo developed by Luppis-Whitehead Automobile in Austria in 1864, but, the first tethered ROV, named POODLE, was developed by Dimitri Rebikoff in 1953.
The United States Navy is credited with advancing the technology to an operational state in its quest to develop robots to recover underwater ordnance lost during at-sea tests. ROVs gained in fame when US Navy CURV (Cable Controlled Underwater Recovery Vehicle) systems recovered an atomic bomb lost off Palomares, Spain in an aircraft accident in 1966, and then saved the pilots of the sunken submersible Pisces off Cork, Ireland in 1973, with only minutes of air remaining in the submersible.
The next step in advancing the technology was performed by commercial firms that saw the future in ROV support of offshore oil operations. The transition from military use to the commercial world was rather rapid. Manufacturing companies like International Submarine Engineering in British Columbia, Perry Oceanographic in Riviera Beach, Florida, and Hydro Products and Ametek Strata in San Diego, California were quick to begin commercial activity based on work done for the military.
Commercial diving companies like Seaway (a small company in Norway), Martech (a small independent Gulf of Mexico company), and Taylor Diving and Salvage (a Halliburton subsidiary) were anxious to extend their capabilities with this new technology. It often became a case of "beware of what you wish for." Factory acceptance tests and sea trials, scheduled for just a few days, often became ordeals lasting weeks. Once at the work site, the operators were happy if they got the vehicle back, and were really happy if they got more than 4 hours of productive time per 24-hour day. Some of the people, like Drew Michel, Wade Abadie, Kevin Peterson and Charles Royce, who suffered through those early long days and nights are still around.
From that very "humbling" beginning, the technology and industry of today has evolved. The following paragraphs attempt to provide a synopsis of the ROV world now.
What is an "ROV"
Two publications, the MTS ROV Committee's "Operational Guidelines for ROVs" (1984) and the National Research Council Committee's "Undersea Vehicles and National Needs" (1996), describe a Remotely Operated Vehicle (ROV) as an underwater robot that allows the vehicle's operator to remain in a comfortable environment while the ROV performs the work underwater. An umbilical, or tether, carries power and command and control signals to the vehicle and the status and sensory data back to the operators topside. In larger systems, a subsea garage and tether management system (TMS) are often included.
ROVs can vary in size from small vehicles fitted with one TV camera, like the three shown below that are used for simple observation, up to complex work systems that can have several dexterous manipulators, video cameras, mechanical tools and other equipment. They are generally free flying, but some are bottom-founded on tracks. Towed bodies, such as those used to deploy side scan sonar, are not considered ROVs. Lifting and rock dumping devices employing thrusters for lateral motion only are also not normally included in listings of ROV systems.
Small (Electric) Vehicles
Many small or "flying eyeball" ROVs, some as small as a breadbox, are in use today. The exact number of them has become simply too large to track. The best guess is that more than one thousand of these vehicles are at work worldwide. This small vehicle class includes the majority of "low-cost" vehicles, most of which are typically all electric and operate above 984 feet (300 meters) water depth. These vehicles are used primarily for inspection and observation tasks. There has been a recent surge in the development of small vehicles, due primarily to the improvement in technology for electrically powered systems. These improvements have resulted in an increase of capability, performance and depth not previously achieved.
Costs for these small ROVs range from around $10,000 to $100,000. The low-end products have been classified for Marine Recreational Use, while the more expensive systems have been used for inland water inspection projects and coastal offshore inspection and observation tasks. Some of the earlier systems were simply video camera housings with thrusters. Today's low-cost ROVs are used widely for many tasks including science, search and rescue, dam, waterway and port inspection, training, shipping and nuclear inspection.
High Capability Electric ROVs
Although ROVs like the infamous Perry RECON vehicle have been around for some time, they are limited in both depth and performance. A new class of electric ROVs, represented by the Schilling Quest vehicle shown below, was born recently which features the latest in technology from Brushless DC motors (thrusters) to PC-based control systems and fiber optic telemetry systems. Electrically operated vehicles can be made to go 20,000 feet (6,096 meters) with much less power required to operate them at depth. The ability to do heavy work is still not possible with the electric ROVs, which are primarily limited by the required electro-hydraulic design of modern manipulator and work systems, but they can still perform many tasks at a much lower cost.
Electric vehicles have gained popularity with the military and science markets due primarily to their quiet operation. In addition, the work requirements for military and science are, in most cases, not as complex when compared to ROVs used for oil and gas operations.
Work Class Vehicles
This class of ROV refers to electro-hydraulic vehicles ranging from 50-100 horsepower typically, which can only carry moderate payloads and have limited through-frame lift capability. These ROVs range in weight from 2,205-4,410 lbs (1,000-2,200 kg) with typical payload capacities in the 220-600 lb (100-272 kg) range. Most carry a seven function rate manipulator and a five function grabber. Some have the capability of through-frame lift of over 1,000 lbs (454 kg). These vehicles comprise the most widely used ROV class, which evolved from the early "eye ball" systems that were used to observe divers working or to perform routine inspections. Typical tasks for this class are drilling support (where most are deployed), light construction support, pipeline inspection and general "call out" work.
Heavy Work Class Vehicles
This represents the class of ROVs being used for current deepwater operations to 10,000 feet (3,000 meters) ranging from 100-250 horsepower and having through-frame lift capabilities to 11,025 lbs (5,000 kg).
With new requirements to perform subsea tie-in operations on deepwater installations and to carry very large diverless intervention systems, this class of ROV is becoming increasingly large, powerful and capable of carrying and lifting large loads- thus the term "heavy work class vehicle" has been adopted by the industry. These vehicles can weight more than ten thousand pounds and resemble a minivan in size. Three-thousand meter depth capable systems are now commonplace, with at least one system capable of six thousand meters. A cable and flow line burial system powered by four electro hydraulic units totaling one thousand horsepower is in use today, and at least one ROV that can lift and maneuver sixteen hundred pounds has been built. Cameras, lights, sonars and other sensors necessary to operate at great depths are readily available. Manipulators capable of lifting hundreds of pounds are commonly installed on these vehicles.
The latest estimate (March 2004) is that approximately 435 work- and heavy work-class ROV systems are active in the world today. The best guess is that this represents over $1.5 billion in capital assets. Seven major commercial operators own the majority of these systems with a total of approximately 405 listed in their respective inventories. Smaller companies, academia, and other non-commercial organizations operate another 30 systems. This total count does not include mine-hunting and other specialized military equipment.
Work Class ROV systems operating worldwide
Oceaneering International, Inc. 152
Subsea 7 (Halliburton/Subsea) 78
Stolt (Stolt/Comex/Seaway) 35
Sonsub (Saipem) 59
Fugro (ex Racal/Thales) 36
Canyon (Cal Dive) 23
Technip-Coflexip 22
Others- Approximate number of specialty systems, plus systems operated by smaller companies.
(Source: Drew Michel interviewing contractors March 2004) 30
Total Systems
435
The fortunes of the ROV industry track the level of activity in the offshore oil and gas industry. Companies that produce hydrocarbon reserves from the depths of our oceans, to supply us with the heat, light and mobility we rely on for our every day existence, employ the vast majority of the world's work class ROV systems. The second most significant market for ROV technology is in support of installing and maintaining undersea cable systems. The split of use in support of hydrocarbon production and undersea cables is hard to define because of the dual use of many systems, but a fairly accurate estimate of use of the approximately 400 commercial systems deployed worldwide is about 85 percent hydrocarbon production and 15 percent undersea cable support.
The next step in the underwater intervention evolution is to Autonomous Underwater Vehicles (AUV). A few AUVs are being used by the military, for science, and in the commercial world for survey work. AUVs that actually perform heavy physical tasks are in development. The primary limitation is the power the AUV can carry. Rather than making quantum leaps to AUV technology, ROV systems will evolve to hybrid systems. Control and feedback will continue to be provided through thin fiber umbilicals, with power carried on board and charged by stations on the seafloor. They will be deployed to maintain subsea production systems and the associated pipeline manifolds. Undersea observatories will use a similar approach. Picture an AUV that swims from docking station to docking station to dump data and recharge. For more on this subject look for the MTS AUV Committee website coming soon.
For more details from a CD entitled "Operational Effectiveness of Unmanned Underwater Systems" click here and the CD is available for purchase here.
http://www.rov.org/info.cfm
Tuesday, September 23, 2008
DSV Alvin
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Alvin (DSV-2) is a 16-ton, manned deep-ocean research submersible owned by the United States Navy and operated by the Woods Hole Oceanographic Institution (WHOI) in Woods Hole, Massachusetts. The craft was built by General Mills' Electronics Group[1] in the same factory used to manufacture breakfast cereal-producing machinery in Minneapolis, Minnesota. Named to honor the prime mover and creative inspiration for the vehicle, Allyn Vine, Alvin was commissioned on June 5, 1964.
The submersible is launched from the deep submergence support vessel Atlantis, which is also owned by the U.S. Navy and operated by WHOI. The submersible has taken 12,000 people on over 4,000 dives to observe the lifeforms that must cope with super-pressures and move about in total darkness. It is said that research conducted by Alvin has been featured in nearly 2,000 scientific papers.
Alvin was designed as a replacement for bathyscaphes and other less maneuverable oceanographic vehicles. Its more nimble design was made possible in part by the development of syntactic foam, which is buoyant and yet strong enough to serve as a structural material at great depths. The three-person vessel allows for two scientists and one pilot to dive for up to nine hours at 4500 meters (15,000 ft). The submersible features two robotic arms and can be fitted with mission-specific
sampling and experimental gear. The hatch of the vessel is 0.6 meters (two feet) thick[citation needed], and held in place by the pressure of the water above it (it is tapered, narrower inward).
History
[edit] Early career
Alvin, first of its class of Deep Submergence Vehicle (DSV), was built to dive to 2440 meters (8000 ft). Each of the Alvin-class DSVs have different depth capabilities. However Alvin is the only one seconded to the National Oceanic and Atmospheric Administration (NOAA), with the others staying with the United States Navy. On March 17, 1966, Alvin was used to locate a submerged 1.45-megaton hydrogen bomb lost in a United States Air Force refueling accident over Palomares, Spain. The bomb, found resting nearly 910 meters (3000 ft) deep, was raised intact on April 7.
[edit] Sinking
The Alvin, aboard the NOAA tender ship Lulu, was lost as it was being transported in October 1968. The Lulu, a vessel created from a pair of decommissioned US Navy pontoons with a support structure added on, carried Alvin on a steel cable. The cable snapped with three crewmembers aboard and the hatch open. Situated between the pontoons with no deck underneath, the Alvin hit the water and rapidly started to sink. The three crewmembers managed to escape, but the sub sank in 1500 meters (5000 ft) of water.
Ten months later, in September 1969, the Aluminaut, another US Navy DSV owned by Reynolds Metals Aluminum Company, secured a line on the Alvin, and it was hauled up. It was so intact that lunches left on board were soggy but edible. This incident led to a more comprehensive understanding that near-freezing temperatures and the lack of decaying oxygen at depth aided preservation. Notwithstanding the preserved food aboard, the Alvin required a major overhaul after the incident.
[edit] Post-sinking career
In 1973, Alvin's pressure hull was replaced by a newer titanium pressure hull. The new hull extended the submersible's maximum depth to 4000 meters (15,000 ft).
[edit] Black smokers
In 1977, during an expedition led by Robert Ballard and sponsored by the National Oceanic and Atmospheric Administration (NOAA), Alvin discovered and documented the existence of black smokers around the Galapagos Islands. Existing at a depth of more than 2000 meters, black smokers emit a strong flow of black, smoky water, superheated to over 400 °C (750 °F). Alvin was able to sample the water from a black smoker, discovering that the pH is roughly 2.8, or equal to the acidity of household vinegar.
[edit] Exploration of RMS Titanic
Most famously, Alvin was involved in the exploration of the wreckage of RMS Titanic in 1986. Launched from her support ship R/V Atlantis II, she carried Dr. Robert Ballard and two companions to the wreckage of the great liner. RMS Titanic sank in 1912 after striking an iceberg while crossing the North Atlantic Ocean on her maiden voyage.
Alvin, accompanied by a small remotely operated vehicle (ROV) named Jason Jr., was able to conduct detailed photographic surveys and inspections of the Titanic's wreckage. Many of the photographs of the expedition have been published in the magazine of the National Geographic Society which was a major sponsor of the expedition.
Of note, the Woods Hole Oceanographic Institute team involved in the Titanic expedition also managed to locate the wreck of the USS Scorpion (SSN-589), a nuclear armed Skipjack class submarine which sank off the coast of the Azores in 1968. The Alvin was able to obtain photographic and other environmental monitoring data off of the remains of the Scorpion.
[edit] Recent overhauls
Over the years, the Alvin has undergone many overhauls to improve its equipment and extend its lifetime. The most recent overhaul was during 2001 in which, among other equipment, motor controllers and computer systems were added. The current Alvin is the same as the original vessel in name and general design only. All components of the vessel including the frame and personnel sphere have been replaced at least once.
[edit] A possible replacement
On August 6, 2004, the National Science Foundation announced the creation of a new Human Occupied Vehicle (HOV) to replace the aging Alvin. The new vehicle is being designed to dive deeper up to 6500 meters (21,000 ft) as opposed to Alvin's 4500 meters and use new scientific equipment. The personnel sphere will be larger, it is expected that the battery capacity will be greatly increased (longer bottom times). The new deep sea submarine is in the preliminary manufacturing phases and is expected to be completed as early as the end of 2011. Some components of the current Alvin are anticipated to be used in the new Alvin replacement vehicle. Due to export laws, the vehicle cannot be sold to parties outside of the United States. The fate of the Alvin when this new submersible arrives is unknown, but due to the limited market for sale and stripping of components for use on the new vehicle, it will likely be placed in a museum.
Lockheed Martin is designing the Alvin replacement vehicle as a nonclassified project and classing the vehicle to American Bureau of Shipping Rules.
Contrary to a BBC article published in October 2004 [2], the Alvin has not yet been retired from service.
Jump to: navigation, search
Alvin (DSV-2) is a 16-ton, manned deep-ocean research submersible owned by the United States Navy and operated by the Woods Hole Oceanographic Institution (WHOI) in Woods Hole, Massachusetts. The craft was built by General Mills' Electronics Group[1] in the same factory used to manufacture breakfast cereal-producing machinery in Minneapolis, Minnesota. Named to honor the prime mover and creative inspiration for the vehicle, Allyn Vine, Alvin was commissioned on June 5, 1964.
The submersible is launched from the deep submergence support vessel Atlantis, which is also owned by the U.S. Navy and operated by WHOI. The submersible has taken 12,000 people on over 4,000 dives to observe the lifeforms that must cope with super-pressures and move about in total darkness. It is said that research conducted by Alvin has been featured in nearly 2,000 scientific papers.
Alvin was designed as a replacement for bathyscaphes and other less maneuverable oceanographic vehicles. Its more nimble design was made possible in part by the development of syntactic foam, which is buoyant and yet strong enough to serve as a structural material at great depths. The three-person vessel allows for two scientists and one pilot to dive for up to nine hours at 4500 meters (15,000 ft). The submersible features two robotic arms and can be fitted with mission-specific
sampling and experimental gear. The hatch of the vessel is 0.6 meters (two feet) thick[citation needed], and held in place by the pressure of the water above it (it is tapered, narrower inward).
History
[edit] Early career
Alvin, first of its class of Deep Submergence Vehicle (DSV), was built to dive to 2440 meters (8000 ft). Each of the Alvin-class DSVs have different depth capabilities. However Alvin is the only one seconded to the National Oceanic and Atmospheric Administration (NOAA), with the others staying with the United States Navy. On March 17, 1966, Alvin was used to locate a submerged 1.45-megaton hydrogen bomb lost in a United States Air Force refueling accident over Palomares, Spain. The bomb, found resting nearly 910 meters (3000 ft) deep, was raised intact on April 7.
[edit] Sinking
The Alvin, aboard the NOAA tender ship Lulu, was lost as it was being transported in October 1968. The Lulu, a vessel created from a pair of decommissioned US Navy pontoons with a support structure added on, carried Alvin on a steel cable. The cable snapped with three crewmembers aboard and the hatch open. Situated between the pontoons with no deck underneath, the Alvin hit the water and rapidly started to sink. The three crewmembers managed to escape, but the sub sank in 1500 meters (5000 ft) of water.
Ten months later, in September 1969, the Aluminaut, another US Navy DSV owned by Reynolds Metals Aluminum Company, secured a line on the Alvin, and it was hauled up. It was so intact that lunches left on board were soggy but edible. This incident led to a more comprehensive understanding that near-freezing temperatures and the lack of decaying oxygen at depth aided preservation. Notwithstanding the preserved food aboard, the Alvin required a major overhaul after the incident.
[edit] Post-sinking career
In 1973, Alvin's pressure hull was replaced by a newer titanium pressure hull. The new hull extended the submersible's maximum depth to 4000 meters (15,000 ft).
[edit] Black smokers
In 1977, during an expedition led by Robert Ballard and sponsored by the National Oceanic and Atmospheric Administration (NOAA), Alvin discovered and documented the existence of black smokers around the Galapagos Islands. Existing at a depth of more than 2000 meters, black smokers emit a strong flow of black, smoky water, superheated to over 400 °C (750 °F). Alvin was able to sample the water from a black smoker, discovering that the pH is roughly 2.8, or equal to the acidity of household vinegar.
[edit] Exploration of RMS Titanic
Most famously, Alvin was involved in the exploration of the wreckage of RMS Titanic in 1986. Launched from her support ship R/V Atlantis II, she carried Dr. Robert Ballard and two companions to the wreckage of the great liner. RMS Titanic sank in 1912 after striking an iceberg while crossing the North Atlantic Ocean on her maiden voyage.
Alvin, accompanied by a small remotely operated vehicle (ROV) named Jason Jr., was able to conduct detailed photographic surveys and inspections of the Titanic's wreckage. Many of the photographs of the expedition have been published in the magazine of the National Geographic Society which was a major sponsor of the expedition.
Of note, the Woods Hole Oceanographic Institute team involved in the Titanic expedition also managed to locate the wreck of the USS Scorpion (SSN-589), a nuclear armed Skipjack class submarine which sank off the coast of the Azores in 1968. The Alvin was able to obtain photographic and other environmental monitoring data off of the remains of the Scorpion.
[edit] Recent overhauls
Over the years, the Alvin has undergone many overhauls to improve its equipment and extend its lifetime. The most recent overhaul was during 2001 in which, among other equipment, motor controllers and computer systems were added. The current Alvin is the same as the original vessel in name and general design only. All components of the vessel including the frame and personnel sphere have been replaced at least once.
[edit] A possible replacement
On August 6, 2004, the National Science Foundation announced the creation of a new Human Occupied Vehicle (HOV) to replace the aging Alvin. The new vehicle is being designed to dive deeper up to 6500 meters (21,000 ft) as opposed to Alvin's 4500 meters and use new scientific equipment. The personnel sphere will be larger, it is expected that the battery capacity will be greatly increased (longer bottom times). The new deep sea submarine is in the preliminary manufacturing phases and is expected to be completed as early as the end of 2011. Some components of the current Alvin are anticipated to be used in the new Alvin replacement vehicle. Due to export laws, the vehicle cannot be sold to parties outside of the United States. The fate of the Alvin when this new submersible arrives is unknown, but due to the limited market for sale and stripping of components for use on the new vehicle, it will likely be placed in a museum.
Lockheed Martin is designing the Alvin replacement vehicle as a nonclassified project and classing the vehicle to American Bureau of Shipping Rules.
Contrary to a BBC article published in October 2004 [2], the Alvin has not yet been retired from service.
Competence Assurance and Assessment in the ROV Sector
The IMCA guidance on competence assurance and assessment assists contractors in ensuring and demonstrating the competence of personnel working offshore in safety critical positions.
In the ROV sector, guidance currently extends to the following positions:
* ROV supervisor
* ROV senior pilot/technician
* ROV pilot/technician Grade I
* ROV pilot/technician Grade II
For each job, entry level qualifications and acceptance criteria are listed. For example, an ROV supervisor must have a valid offshore medical, a valid certificate from an offshore survival course for the relevant geographic work area, competence as a Senior Pilot/Technician and at least one year’s experience as a Senior Pilot/Technician.
Various subjects are then given for competence assessment. Accompanying each of these is a summary of the knowledge required, a way to demonstrate competence, and acceptance criteria. For example, a supervisor would need to be competent in safety awareness. For this it is necessary, for example, to know how to organise and manage the safety of a team and how to make an accident report. Competence in this case should be assessed within an organisation’s competence scheme by a suitable assessor and recorded in the relevant logbook.
With much of the sector’s workforce employed through agencies, IMCA’s contractor members have been keen to involve such organisations in the development and implementation of the guidance framework. A number of successful workshops have been held, with valuable feedback taken onboard, a dedicated membership category to enable better information and dialogue, and an extensive freelance competence information pack to assist in development of individual portfolios of work records and competence assessments.
For full details on IMCA’s work and guidance on competence assurance assessment, please visit our TCPC competence pages.
In the ROV sector, guidance currently extends to the following positions:
* ROV supervisor
* ROV senior pilot/technician
* ROV pilot/technician Grade I
* ROV pilot/technician Grade II
For each job, entry level qualifications and acceptance criteria are listed. For example, an ROV supervisor must have a valid offshore medical, a valid certificate from an offshore survival course for the relevant geographic work area, competence as a Senior Pilot/Technician and at least one year’s experience as a Senior Pilot/Technician.
Various subjects are then given for competence assessment. Accompanying each of these is a summary of the knowledge required, a way to demonstrate competence, and acceptance criteria. For example, a supervisor would need to be competent in safety awareness. For this it is necessary, for example, to know how to organise and manage the safety of a team and how to make an accident report. Competence in this case should be assessed within an organisation’s competence scheme by a suitable assessor and recorded in the relevant logbook.
With much of the sector’s workforce employed through agencies, IMCA’s contractor members have been keen to involve such organisations in the development and implementation of the guidance framework. A number of successful workshops have been held, with valuable feedback taken onboard, a dedicated membership category to enable better information and dialogue, and an extensive freelance competence information pack to assist in development of individual portfolios of work records and competence assessments.
For full details on IMCA’s work and guidance on competence assurance assessment, please visit our TCPC competence pages.
THE 21st CENTURY ROV, TRITON® XLX
Luke R Briant
Perry Slingsby Systems
821 Jupiter Park Drive
Jupiter, Florida 33458, USA
ABSTRACT
This paper will describe the latest work class ROV designed and developed by Perry Slingsby Systems Inc. The paper will focus on the technical improvements to the modern Work Class ROV System. One major improvement is the new “ICE”
Integrated Controls Engine and User Interface (UI), with modern ergonomic features utilizing advanced graphical displays, familiar user interface functions,
data logging, diagnostics and networking. The paper will also illustrate the improvements of a modular system which has increased deck space and overall
performance and reliability. The improved hydraulic control, increased user interface options and commonality of parts will also be discussed.
BACKGROUND
The Triton® XLX is the latest evolution of the very successful and industry known Triton series of work class ROV. Perry Slingsby Systems (PSS) industry
recognized Triton design has proven itself to be a reliable system with over 150 delivered units.
The main objectives of the design of the XL “X” was to further increase reliability and enhance the already “best in class” technologies of PSS ROV Systems.
This included the following:
• Develop and implement PSS next generation control system.
• Increase capability for Tooling and Survey systems.
• Develop a common design for 3 or 4. Kilometer applications.
• Increase overall deck space on the ROV for user equipment.
The one key driving factor was to develop a new controls solution that would accommodate varying control applications. With this in mind ICE™ was born.
Along with this improvement, the vehicle dynamics,which includes its payload distribution and flying characteristics, hydraulic and electrical user interfaces and overall positioning of modules to increase deck “real estate” for tooling packages and equipment. This aspect has proven to be invaluable
from an operator’s point of view. The consoles were also modernized with increased communication bandwidth and ergonomically designed user controls.
CONTROL SYSTEM
The ICE™ system architecture consists of four (4) primary computer nodes: (See Figure 1)
• Two Surface Windows® based Human Machine Interface (HMI) PC nodes
• One Surface real-time Controller node
• One Subsea real-time Controller node
The two redundant HMI nodes provide the Graphical User Interface (GUI) and the two Controller nodes perform the mission critical real-time control
functions for ROV operation. The HMI’s are completely independent of each other; if one fails the second is not affected and the system can continue with normal operations with a single HMI.
The four nodes communicate with one another via an Ethernet network integrated with a fiber optic telemetry system.
The subsea control system is a distributed system which disperses I/O functionality from the control can to individual nodes, via a serial bus wiring scheme called ICENet™. The subsea control system consists of one small control can containing the
Subsea Controller computer and an instrument junction box (Core J-Box) containing ICENet™ boards.
There is also a survey junction box which contains ICENet™ boards for additional survey capability. All the necessary boards for processing I/O, controls, and
telemetry are distributed within the system in the junction boxes and the control can.
ICENET™ BOARDS- LOCAL MICRO CONTROLLERS
The ICENet™ boards are local micro controller boards which are a proprietary all-in-one solution, with onboard processing, data communication, sensor
circuits, diagnostics, and power regulation. The board is designed to operate in oil under ambient pressures eliminating the need for complex pressure vessel
assemblies. Every board is factory tested, operating at a pressure equivalent to 5000m water depth (7290psi). The ICENet™ boards have electrical fault protection limiting the effects of reverse polarity,
over-voltage, over-current, and short circuits. The ICENet™ board will protect itself in the majority of fault conditions and revert to normal operations when
the fault has cleared. The ICENet™ board is fuse free with no operator intervention required.
The ICENet™ boards also have environmental protection limiting the effects of any water ingress into oil filled positive compensated enclosures for increased
reliability.
The TMS control system is made up of a subset of the same ICENet™ boards installed on the ROV.
The ICENet™ board serial connections are brought to the surface via the fiber optic system.
There is no control can on the TMS. For I/O control on both the ROV and TMS, the
ICE™ system consists of a complement of proprietary “ICENet™” boards. The ICENet™ board types are:
• LVC – Local Valve Controller Board for valve control in the manifolds
• LAM – Local Alarms Monitor Board for GFD and water detects
• LCI – Local Camera Interface Board for camera and light control
• LPD – Local Power Controller Board – DC for DC power control
• LPA – Local Power Controller Board – AC for AC power control
• LSI – Local Serial Isolator Board for RS-232 to RS-485 conversion and optical isolation The I/O on the surface is also distributed using Commercial Off-The-Shelf (COTS) Ethernet I/O devices contained in each hardware control panel.
Each Ethernet I/O device plugs into the surface Ethernet switch and each device is polled by the Surface Controller.
The distributed I/O systems surface and subsea allow for less overall system hardware, wiring looms and the ability to allow modularization of the system.
This enabled PSS to increase the payload distribution and deck space, providing the end user the maximum amount of additional space for mounting and integrating future peripheral sensors and equipment, thus offering the end user a superior Work Class
ROV.
The subsea controller gives an ROV system a degree of protection when telemetry to the vehicle is lost.
The PSS standard “Failsafe Mode” has been maintained with Triton® XLX. The subsea controller enables this function if downlink data communication between the Surface Controller and the Subsea Controller fails.
When this occurs all horizontal thruster commands are set to zero, the ROV is put into auto depth control mode, all other automatic control modes are turned
off, and other commands are maintained as they were prior to losing communications. This is a key function for the user and invaluable when in offshore operational conditions.
Simulating Subsea Scenarios
Simulating Subsea Scenarios
by Dr. Jason Tisdall
CEO, General Robotics Limited
Just a generation ago subsea oil deposits were being discovered and exploited at depths of around 300 metres. Today, as readily accessible oil becomes exhausted, attention is being transferred to oil reservoirs at depths of 3,000 metres and beyond. This presents a range of challenges which require the use of autonomous and remotely controlled equipment and techniques. To an ever increasing extent Visualisation and Simulation technologies are playing a key role in the remote operation of subsea and ocean floor equipment.
Visualisation and Simulation are distinct technologies with different but complementary applications. Visualisation ranges from a simple graphic model of a field to a complex graphic model in which objects can be moved around relative to each other by an operator, and can be both 2D and 3D. Visualisations can show live data input, so GPS and USBL inputs give the position of a support vessel and its ROV or a pipelay barge and its anchor lines. This allows operations to be shown in real-time such as tracking an ROV's manoeuvres near a subsea structure, or monitoring touchdown during cable or pipeline deployment.
Simulation, rather than just showing inputs, incorporates a physics engine so objects move in response to their environment (e.g. complex water currents and swell) and may also include user interactive inputs in parallel.
A pilot training simulator should reproduce the actual subsea conditions that an ROV pilot has to work with. Hydrodynamic modelling of objects in the water is important, so that the ROV simulator responds to the controls just like its real counterpart, with behaviour based on actual physical properties like: mass, density, drag, taking account of currents and ROV speed and the resultant forces acting on the tether and the ROV. Different visibility conditions can also be simulated, with varying light levels, water fogging and suspended particles together with an accurate sonar system to provide realistic support data. An ROV trainer simulates the subsea environment which pilots must “fly” through interactively and presents complex situations where the pilot’s decisions directly affect the success of a mission.
Subsea services providers like Sonsub and DeepOcean AS are increasingly making use of simulators. DeepOcean uses a simulator to train pilots for its KystDesign Installer and Supporter ROVs, working from ships and oil platforms in the North Sea and the Mediterranean.
DeepOcean used to recruit experienced ROV pilots and then cross-train them on the ROVs offshore, but as the volume of work grew, on-the-job training became too slow and expensive. It takes a new pilot, with no prior ROV experience, around two years of training to gain DeepOcean's certificate of competence. Using the simulator, pupils can notch up the training hours far more quickly and cheaply than using the ROVs at sea; in addition, a real work environment is not the best place to train new pilots.
"We believe the simulator is paying for itself - more qualified pilots can be deployed more flexibly, which is making our offshore operations more efficient," said Sven Storesund, Superintendent ROV/Survey at DeepOcean. "We can now give existing pilots refresher and scenario training on-shore. A unique aspect of the simulator is that you can play around with new techniques which would be prohibitively expensive, and possibly dangerous, using the ROV for real."
Sonsub expects its ROV operators to be able to take the machines apart offshore, change components and reassemble them. As a result simulator training also involves learning to troubleshoot problems using diagnostics software included in the simulator, which replicates hardware failures offshore so trainees can practise fault finding.
An important benefit of a simulator integrated with an ROV is the capacity to rehearse subsea projects down to the level of individual tasks. Sonsub’s project teams can prepare a complete 3D virtual scene of the subsea facility, and pilots and other offshore personnel are given a chance to perform the planned operations in a simulated environment. This gives an invaluable opportunity to practise the best way of carrying out the planned tasks, exposing possible problems and allowing alternative strategies to be developed before going offshore.
There is a clear trend towards using visualisation and simulation tools in ROV and other offshore operations, for both task planning and crew training. In the future, engineering tools and planning tools will continue to converge, so not only will the deployment of equipment to the seabed be visualised taking in live inputs, but control and simulation will come together to allow the operator to respond to events and drive what happens in the real world. Such developments promise huge benefits not just in improved training and reduced operation timescales but in greater operational predictability and reliability, leading in turn to improved safety, lower costs and lower environmental impact in all offshore tasks.
Dr. Jason Tisdall is CEO of UK-based General Robotics Limited, a leading and vastly experienced provider of subsea visualisation and simulation systems since 1988. To contact Tisdall, email jason-tisdall@generalrobotics.co.uk.
by Dr. Jason Tisdall
CEO, General Robotics Limited
Just a generation ago subsea oil deposits were being discovered and exploited at depths of around 300 metres. Today, as readily accessible oil becomes exhausted, attention is being transferred to oil reservoirs at depths of 3,000 metres and beyond. This presents a range of challenges which require the use of autonomous and remotely controlled equipment and techniques. To an ever increasing extent Visualisation and Simulation technologies are playing a key role in the remote operation of subsea and ocean floor equipment.
Visualisation and Simulation are distinct technologies with different but complementary applications. Visualisation ranges from a simple graphic model of a field to a complex graphic model in which objects can be moved around relative to each other by an operator, and can be both 2D and 3D. Visualisations can show live data input, so GPS and USBL inputs give the position of a support vessel and its ROV or a pipelay barge and its anchor lines. This allows operations to be shown in real-time such as tracking an ROV's manoeuvres near a subsea structure, or monitoring touchdown during cable or pipeline deployment.
Simulation, rather than just showing inputs, incorporates a physics engine so objects move in response to their environment (e.g. complex water currents and swell) and may also include user interactive inputs in parallel.
A pilot training simulator should reproduce the actual subsea conditions that an ROV pilot has to work with. Hydrodynamic modelling of objects in the water is important, so that the ROV simulator responds to the controls just like its real counterpart, with behaviour based on actual physical properties like: mass, density, drag, taking account of currents and ROV speed and the resultant forces acting on the tether and the ROV. Different visibility conditions can also be simulated, with varying light levels, water fogging and suspended particles together with an accurate sonar system to provide realistic support data. An ROV trainer simulates the subsea environment which pilots must “fly” through interactively and presents complex situations where the pilot’s decisions directly affect the success of a mission.
Subsea services providers like Sonsub and DeepOcean AS are increasingly making use of simulators. DeepOcean uses a simulator to train pilots for its KystDesign Installer and Supporter ROVs, working from ships and oil platforms in the North Sea and the Mediterranean.
DeepOcean used to recruit experienced ROV pilots and then cross-train them on the ROVs offshore, but as the volume of work grew, on-the-job training became too slow and expensive. It takes a new pilot, with no prior ROV experience, around two years of training to gain DeepOcean's certificate of competence. Using the simulator, pupils can notch up the training hours far more quickly and cheaply than using the ROVs at sea; in addition, a real work environment is not the best place to train new pilots.
"We believe the simulator is paying for itself - more qualified pilots can be deployed more flexibly, which is making our offshore operations more efficient," said Sven Storesund, Superintendent ROV/Survey at DeepOcean. "We can now give existing pilots refresher and scenario training on-shore. A unique aspect of the simulator is that you can play around with new techniques which would be prohibitively expensive, and possibly dangerous, using the ROV for real."
Sonsub expects its ROV operators to be able to take the machines apart offshore, change components and reassemble them. As a result simulator training also involves learning to troubleshoot problems using diagnostics software included in the simulator, which replicates hardware failures offshore so trainees can practise fault finding.
An important benefit of a simulator integrated with an ROV is the capacity to rehearse subsea projects down to the level of individual tasks. Sonsub’s project teams can prepare a complete 3D virtual scene of the subsea facility, and pilots and other offshore personnel are given a chance to perform the planned operations in a simulated environment. This gives an invaluable opportunity to practise the best way of carrying out the planned tasks, exposing possible problems and allowing alternative strategies to be developed before going offshore.
There is a clear trend towards using visualisation and simulation tools in ROV and other offshore operations, for both task planning and crew training. In the future, engineering tools and planning tools will continue to converge, so not only will the deployment of equipment to the seabed be visualised taking in live inputs, but control and simulation will come together to allow the operator to respond to events and drive what happens in the real world. Such developments promise huge benefits not just in improved training and reduced operation timescales but in greater operational predictability and reliability, leading in turn to improved safety, lower costs and lower environmental impact in all offshore tasks.
Dr. Jason Tisdall is CEO of UK-based General Robotics Limited, a leading and vastly experienced provider of subsea visualisation and simulation systems since 1988. To contact Tisdall, email jason-tisdall@generalrobotics.co.uk.
Remotely operated underwater vehicles (ROVs
Remotely operated underwater vehicles (ROVs) is the common 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), 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.
History
ROV at work in an underwater Oil& Gas field. The ROV manipulator is about to operate a lever on the subsea structure.
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 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, pipeline 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.
ROV on its way to work
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.
However, there is a lot of work that remains to be done. More than half of the earth’s ocean is deeper than 3000 meters, which is the current working depth of most of the ROV technology. As of the writing of this article, the deeper half of the ocean has never been explored. This vast area has the potential to meet much of humanity’s needs for raw materials. As the industry advances to meet these challenges, we will undoubtedly see further improvements in these complicated robots.
While the oil & gas industry uses the majority of ROVs; other applications include science, military and salvage. Science usage is discussed below, the military uses ROV for tasks such as mine clearing and inspection. Approximately a dozen times per year ROVs are used in marine salvage operations of downed planes and sunken ships.
Construction
Conventional ROVs are constructed with a large flotation pack on top of a steel or alloy chassis, to provide the necessary buoyancy. Syntactic foam is often used for the flotation. A tool sled may be fitted at the bottom of the system and can accommodate a variety of sensors. 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 cables may be run inside oil-filled tubing to protect them from corrosion in seawater. Thrusters are usually located in all three axes to provide full control. Cameras, lights and manipulators are on the front of the ROV or occasionally in the rear for assistance in maneuvering.
The majority of the work class ROVs are constructed as described above, however this is not the only style in ROV building. Specifically the smaller ROVs can have very different designs each geared towards their own task. One company's ROV even has wings that allow the vehicle to move more efficiently, while being towed and/or operating on thruster power in high currents.
Science ROVs
Image taken by a ROV under the ice of Antarctica. In the spring krill can scrape off the green lawn of ice algae from the underside of the pack ice in Antarctica. In this image most krill swim in an upside down position directly under the ice. Only one animal (in the middle) is hovering in the open water.
Image taken by a ROV under the ice of Antarctica. In the spring krill can scrape off the green lawn of ice algae from the underside of the pack ice in Antarctica. In this image most krill swim in an upside down position directly under the ice. Only one animal (in the middle) is hovering in the open water.
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), and the University of Rhode Island / Institute for Exploration (URI/IFE). The picture to the right shows a 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.
A science ROV being launched from an oceanographic research vessel.
A science ROV being launched from an oceanographic research vessel.
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.
Classification
Submersible ROVs are normally classified into categories based on their size, weight, ability or power. Some common ratings are:
* Micro - typically Micro class ROVs are very small in size and weight. Today’s Micro Class ROVs can weigh less than 3 kg. These ROVs are used as an alternative to a diver, specifically in places where a diver might not be able to physically enter such as a sewer, pipeline or small cavity.
* Mini - typically Mini Class ROVs weigh in around 15 kg. Mini Class ROVs are also used as a diver alternative. One person may be able to transport the complete ROV system out with them on a small boat, deploy it and complete the job without outside help. Occasionally both Micro and Mini classes are referred to as "eyeball" class to differentiate them from ROVs that may be able to perform intervention tasks.
* General - typically less than 5 HP (propulsion); occasionally small three finger manipulators grippers have been installed, such as on the very early RCV 225. These ROVs may be able to carry a sonar unit and are usually used on light survey applications. Typically the maximum working depth is less than 1,000 metres though one has been developed to go as deep as 7,000 m.
* Light Workclass - typically less than 50 hp (propulsion). These ROVs may be able to carry some manipulators. Their chassis may be made from polymers such as polyethylene rather than the conventional stainless steel or aluminium alloys. They typically have a maximum working depth less than 2000 m.
* Heavy Workclass - typically less than 220 hp (propulsion) with an ability to carry at least two manipulators. They have a working depth up to 3500 m.
* Trenching/Burial - typically more than 200 hp (propulsion) and not usually greater than 500 hp (while some do exceed that) with an ability to carry a cable laying sled and work at depths up to 6000 m in some cases.
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.
Naming Conventions
ROVs that are manufactured following a standardised design are commonly named by a brand name followed by a number indicating the order of manufacture. Examples would be Sealion 1 or Scorpio 17. The design of a series of ROVs may have changed significantly over the life of an ROV series, however an ROV pilot will often be familiar with the idiosyncrasies of a particular vehicle by name.
ROVs that are one off or unique designs may be given a unique name similar to the style used for ships. ROVs are not normally referred to in the female gender as ships may be, but in the neutral gender.
History
ROV at work in an underwater Oil& Gas field. The ROV manipulator is about to operate a lever on the subsea structure.
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 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, pipeline 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.
ROV on its way to work
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.
However, there is a lot of work that remains to be done. More than half of the earth’s ocean is deeper than 3000 meters, which is the current working depth of most of the ROV technology. As of the writing of this article, the deeper half of the ocean has never been explored. This vast area has the potential to meet much of humanity’s needs for raw materials. As the industry advances to meet these challenges, we will undoubtedly see further improvements in these complicated robots.
While the oil & gas industry uses the majority of ROVs; other applications include science, military and salvage. Science usage is discussed below, the military uses ROV for tasks such as mine clearing and inspection. Approximately a dozen times per year ROVs are used in marine salvage operations of downed planes and sunken ships.
Construction
Conventional ROVs are constructed with a large flotation pack on top of a steel or alloy chassis, to provide the necessary buoyancy. Syntactic foam is often used for the flotation. A tool sled may be fitted at the bottom of the system and can accommodate a variety of sensors. 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 cables may be run inside oil-filled tubing to protect them from corrosion in seawater. Thrusters are usually located in all three axes to provide full control. Cameras, lights and manipulators are on the front of the ROV or occasionally in the rear for assistance in maneuvering.
The majority of the work class ROVs are constructed as described above, however this is not the only style in ROV building. Specifically the smaller ROVs can have very different designs each geared towards their own task. One company's ROV even has wings that allow the vehicle to move more efficiently, while being towed and/or operating on thruster power in high currents.
Science ROVs
Image taken by a ROV under the ice of Antarctica. In the spring krill can scrape off the green lawn of ice algae from the underside of the pack ice in Antarctica. In this image most krill swim in an upside down position directly under the ice. Only one animal (in the middle) is hovering in the open water.
Image taken by a ROV under the ice of Antarctica. In the spring krill can scrape off the green lawn of ice algae from the underside of the pack ice in Antarctica. In this image most krill swim in an upside down position directly under the ice. Only one animal (in the middle) is hovering in the open water.
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), and the University of Rhode Island / Institute for Exploration (URI/IFE). The picture to the right shows a 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.
A science ROV being launched from an oceanographic research vessel.
A science ROV being launched from an oceanographic research vessel.
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.
Classification
Submersible ROVs are normally classified into categories based on their size, weight, ability or power. Some common ratings are:
* Micro - typically Micro class ROVs are very small in size and weight. Today’s Micro Class ROVs can weigh less than 3 kg. These ROVs are used as an alternative to a diver, specifically in places where a diver might not be able to physically enter such as a sewer, pipeline or small cavity.
* Mini - typically Mini Class ROVs weigh in around 15 kg. Mini Class ROVs are also used as a diver alternative. One person may be able to transport the complete ROV system out with them on a small boat, deploy it and complete the job without outside help. Occasionally both Micro and Mini classes are referred to as "eyeball" class to differentiate them from ROVs that may be able to perform intervention tasks.
* General - typically less than 5 HP (propulsion); occasionally small three finger manipulators grippers have been installed, such as on the very early RCV 225. These ROVs may be able to carry a sonar unit and are usually used on light survey applications. Typically the maximum working depth is less than 1,000 metres though one has been developed to go as deep as 7,000 m.
* Light Workclass - typically less than 50 hp (propulsion). These ROVs may be able to carry some manipulators. Their chassis may be made from polymers such as polyethylene rather than the conventional stainless steel or aluminium alloys. They typically have a maximum working depth less than 2000 m.
* Heavy Workclass - typically less than 220 hp (propulsion) with an ability to carry at least two manipulators. They have a working depth up to 3500 m.
* Trenching/Burial - typically more than 200 hp (propulsion) and not usually greater than 500 hp (while some do exceed that) with an ability to carry a cable laying sled and work at depths up to 6000 m in some cases.
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.
Naming Conventions
ROVs that are manufactured following a standardised design are commonly named by a brand name followed by a number indicating the order of manufacture. Examples would be Sealion 1 or Scorpio 17. The design of a series of ROVs may have changed significantly over the life of an ROV series, however an ROV pilot will often be familiar with the idiosyncrasies of a particular vehicle by name.
ROVs that are one off or unique designs may be given a unique name similar to the style used for ships. ROVs are not normally referred to in the female gender as ships may be, but in the neutral gender.
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