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

Positioning Contract for Veripos

Allseas, UK, has awarded Veripos (UK) a further three-year contract for continuing provision of specialist GNSS positioning services for its entire fleet of vessels headed by the world's largest pipelaying vessel, the 300m Solitaire. Other vessels concerned include companion DP pipelayers Audacia and Lorelay in addition to the DP trenching support and subsea installation vessel, Calamity Jane, the anchored pipelay barge, Tog Mor, and the ROSVs Highland Fortress, Highland Navigator and Highland Rover. Allseas expect to add to its fleet during the course of the contract what will be the world’s largest construction support vessel, the platform installation-decommissioning and pipelayer, Pieter Schelte, presently under construction at Daewoo Shipbuilding & Marine Engineering in... (read more)
2012-12-05 01:35:13

Geolab Positioning Contract

Veripos has been awarded a further three-year contract by Naples-based GeoLab Srl, one of Europe's leading turnkey offshore survey and construction support organisations, for provision of high-precision GNSS positioning services. The contract extends the relationship between the two companies following an earlier three-year agreement.   Under the new agreement, Veripos will continue to provide GeoLab with a full range of proprietary globalised satellite positioning facilities extending from its Standard GNSS augmentation service to its latest Ultra Precise Point Positioning (PPP) capability which ensures decimetre-level accuracies by minimising or removing all main GPS error sources.   Together with the supply of... (read more)
2008-05-07 08:44:42

GeoTag Underwater Positioning Solution

Sercel (France) has launched GeoTag, an acoustic positioning solution for seabed seismic acquisition. GeoTag can be used to accurately position all types of ocean bottom cable (obc), ocean bottom node and transition zone cable systems for seabed seismic surveys in water depths down to 500 metres. The GeoTag solution operates with the smallest acoustic positioning transponder available on the market, according to the supplier. The transponders are attached to the seabed seismic equipment and interrogated by a vessel-based transceiver. GeoTag’s design allows for rapid maintenance such as battery replacement for improved crew efficiency. The transponders can also be stored on... (read more)
2015-10-19 10:28:15

Brazilian Offshore Positioning Contracts

Veripos has been awarded a series of contracts in Brazil under which it is to provide high-precision GNSS positioning products and services to leading offshore operators, DOF Subsea, NorSkan Offshore and Companhia Brasileira de Offshore (CBO).     The DOF Subsea contract includes the provision of Veripos Ultra dual-beam precise-point positioning (PPP) service supported by two LD2-G2 integrated mobile demodulators and proprietary Verify QC processing software aboard the ROV support vessel, Skandi Chieftan.  Similar facilities have already been operational for some time aboard the company's other ROV vessels, Skandi Fluminense and Skandi Salvador.   Meanwhile, DOF Subsea's associate Brazilian concern, NorSkan Offshore, is to... (read more)
2009-08-19 03:45:48

Which Satellite Positioning Systems

The International Marine Contractors Association (IMCA, UK) has published new guidance on the selection of satellite positioning systems, warning that in recent years lower priority has been given to system selection than is wise. This is particularly the case when choosing a dynamic positioning (DP). The guide explains that the use of inappropriate systems has led to delays in project execution, vessel downtime and, in some circumstances, damage to assets. In the introduction to ‘Guidance on the Selection of Satellite Positioning Systems for Offshore Applications' (IMCA S 018) the association explains that the costs incurred during any of these incidents... (read more)
2011-07-08 12:00:00

Indonesian Positioning Contract

Veripos, headquartered in the UK, has been awarded a further contract for supply of precision services to PT Pageo Utama of Jakarta, one of Indonesia's leading independent offshore survey organisations.   The facilities involve supply of continuous positioning services aboard two Saipem construction support vessels, the derrick lay barge, Castoro Otto, and the diving support vessel, Eclipse, engaged on key offshore projects for Carigali-Triton Operating Company in Malaysia-Thailand and Premier Oil for the Indonesian Gajah Baru gas field project. Each vessel is being provided with Veripos's Ultra Precise Point Positioning (PPP) service for decimetre-level accuracies together with Verify QC software... (read more)
2011-07-18 11:28:41

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
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