Underwater Positioning

Centimetric Accuracy Underwater-GPS
By Camille Béchaz, ACSA and Fran­­çois Boucquaert, Fugro-Topnav, France Fugro evaluated the accuracy of the GPS Intelligent Buoy (GIB-Lite) system for its possible use in shallow-water offshore underwater positioning applications. The trials proved that system accuracy could be brought up to centimetre level, the distance between two simultaneously tracked acoustic pingers having a standard deviation of 8cm. Additional works next to an offshore production platform are often required to increase oil recovery from an existing reservoir or to maintain its production rate over a longer period of time. The seabed near such a production platform typically shows pipelines, electric cables,... (read more)
2008-01-01 01:00:00

Satellite Positioning

Within the last twenty years Global Positioning System (GPS) receivers have revolutionised navigation. Integrated devices are capable of providing time, position, height, direction, heave and attitude to accuracies of a few nanoseconds time, 1cm position or 0.01 degree heading. All potentially displayed on a digital chart background with radar and auto-identification system overlays. In this first of two articles we look at current Satellite Positioning systems, how they work and how we can make them better. In a second article, to appear next month, we explore the future development of Satellite Positioning and the implications for navigation. How does Satellite... (read more)
2008-01-01 01:00:00

Indian Positioning Contracts

Four of India's leading DP vessel operators in Mumbai have each commissioned Veripos to provide medium to long-term high-precision GNSS positioning products and services for their respective domestic and international offshore operations.     The companies include Greatship India who have commissioned Veripos' Standard positioning service and LID3-G1 hardware on DP vessels, Greatship Amrita, Greatship Anjali, Greatship Dhriti, Greatship Disha, and Greatship Diya while a further four vessels are to be supplied with similar facilities later this year.  The company, which has recently had vessels operational in the Middle East, Mexico and South Africa as well as its domestic market in India, is currently engaged in... (read more)
2009-06-23 03:51:21

Guidelines for GNSS ­Positioning

A joint OGP & IMCA Revision of the 1994 UKOOA Guidelines
The original UKOOA Guidelines for the use of differential GPS in offshore surveying, published in 1994, were widely used within the offshore survey industry. In 2005, the International Oil & Gas Producers Association (OGP) took over the custodianship of the guidelines from Oil & Gas UK (formerly UKOOA). At that time it was recognised that the original guidelines needed updating in order to reflect the rapid technical advances in satellite navigation technology of recent years and to maintain the purpose and relevance of the original guidelines. OGP and the International Marine Contractors Association (IMCA) agreed to work together on the... (read more)
2013-01-18 02:14:13

Pipe-lay Positioning Support

Offshore survey company UTEC has consolidated its presence in the Middle East completing a significant contract for a major international pipelay contractor. The UAE (Dubai) project involved UTEC supporting the DP pipelay vessel in extremely shallow water providing enhanced USBL methodologies. The company also provided survey support services on two additional DP vessels which provided diver support and remedial services to the pipelay vessel. This is the second year in succession that UTEC has provided support to the contractor in the region. UTEC's Global Sales and Marketing director Trevor Hughes commented: “Based on our prior year’s performance the contractor as... (read more)
2013-01-31 10:19:36

Deepsea Positioning Accuracy

First NEMO Tower for Astrophysical Research
The Italian Istituto Nazionale di Fisica Nucleare (INFN) is developing a large underwater apparatus to investigate new frontiers in astrophysical research. The NEutrino Mediterranean Observatory, NEMO, consists of a 3D-array of optical sensors capable of detecting the primary source of extremely high-energy neutrinos. This article covers underwater positioning techniques: system architecture, technical, advanced and data processing aspects, and preliminary data analysis. The first prototype, NEMO Phase 1, was deployed in December 2006 off the coast of Catania. A set of synchronous acoustic beacons was installed in the sea at a depth of 2,000m to position a large number of optical... (read more)
2007-05-31 12:00:00

Subsea Positioning Transponders Order

Unique Systems (USA) has taken delivery of a major consignment of Compatt 5 subsea positioning transponders from Sonardyne. The order complements Unique's existing worldwide inventory of Sonardyne acoustic equipment which includes RovNav 5 Long BaseLine transceivers and Ranger Ultra-Short BaseLine systems.     Unique Systems is part of the Unique Group based in Sharjah (UAE), which is a major distributor and rental company for advanced marine and diving equipment. The Compatt 5 equipment will be made available to rent from their additional US office in Houston which opened a year ago to support clients and offshore projects throughout the Gulf... (read more)
2009-07-03 11:21:09

LBL Underwater Positioning

Long baseline (LBL) positioning has many applications both commercially and in research, from surveying a ship hull to positioning offshore platforms in deeper waters. The technique consistently provides accuracies in the order of decimetres over large areas, independent of depth. Recent advances include the integration with other acoustic techniques or with inertial navigation systems for greater levels of accuracy. Since navigation by GPS isbased on electromagnetic signals that cannot penetrate water, subsea positioning requires a different approach. As sounds waves travel through the sea they alternately compress and decompress the water molecules; these compressions/decompressions are detected as changes in pressure.... (read more)
2008-01-19 12:00:00

Geolab Extends Positioning Contract

Veripos has been awarded a further two-year general services contract by Naples-based GeoLab Srl, a turnkey offshore survey and construction support organisation. The contract extends the relationship between the two companies following an earlier three-year agreement. Under the new agreement Veripos will continue to supply its full range of GNSS positioning solutions in support of GeoLab's fleet of dedicated multi-role survey vessels. These operate worldwide on behalf of major offshore construction and telecommunications companies from GeoLab headquarters in Naples, Italy and other operating bases in Abu Dhabi, Houston, and Pointe Noire in the Congo, West Africa. The solutions cover a... (read more)
2011-03-14 11:02:12

Further Petrobras Positioning Contract

Veripos, UK, has been awarded a long-term contract by Petrobras, Brazil, for provision of positioning services in support of the Brazilian state-owned company‚Äôs BGL-1 pipeline installation barge operations.     Under the two-year contract, which includes an option for a further two years, Veripos will provide the 122-metre dynamically-positioned barge with continuous choice of its all-purpose Standard, Ultra and Differential Glonass positioning services supported by LD2-G2 mobile receiver equipment and Verify QC software for real-time position and quality control information.   The contract is the second to have recently been awarded to Veripos by Petrobras following an agreement last year... (read more)
2011-04-28 11:51:06
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