GIS Analysis Tools in Submarine Cable Planning

While the advantages of Geographic Information Systems (GIS) for storing and displaying spatial data are widely recognised, the analytic capabilities are less well known outside the GIS community. Extensions to core GIS software make possible new information, insights and better understanding of spatial relationships. GIS analysis functions can identify locations that meet a set of criteria, reclassify data to a common class-scale, weight datasets and combine these to analyse suitability or adherence to a given set of rules. GIS provides the framework for solving complicated problems. The output can be displayed on a map, where relationships are apparent and solutions... (read more)
2008-01-01 01:00:00

GPS for Global Tidal Measurements

Recent data analysis heralds applications for hydrography
Hydrographers require accurate three-dimensional positions of the survey vessel and typically use differing methods for resolving the horizontal and vertical components. GNSS, such as the Navstar Global Positioning System (GPS), have become the dominant horizontal positioning system for hydrographic operations, whereas tidal estimation is the foremost method used in determining vertical positioning. The tidal estimation method integrates a water level measurement at a remote location with a predicted propagation of the tidal wave, to establish a sea surface level at the desired location. This paper investigates a new method using GNSS as an aid in improving these water level estimates... (read more)
2008-01-01 01:00:00

AUV-based 3D Chirp Sub-bottom Profiling

Offshore Diamond Mining Applications
During the 1990s De Beers Marine identified a major business opportunity in radically improving its geological modelling capability. It set up a project to deliver the necessary geophysical systems and the team soon saw potential in integrating the company’s future development ideas for Chirp sub-bottom profiling sonar and sediment characterisation with the stability and accuracy of AUVs. The result was an ultra-high-resolution, 3D-volume imaging sub-bottom profiling system capable of low-cost, large-scale, deep-water (600m) mapping from a low-specification survey support vessel. Since 2001 De Beers Marine (DBM) has been routinely operating an Autonomous Underwater Vehicle (AUV) as its principle, ultra-high-resolution geosurvey... (read more)
2008-01-01 01:00:00

AEM Bathymetry

Using geophysical exploration techniques to map shallow seawater depths
Airborne Electro Magnetic Bathymetric (AEMB) mapping is useful in turbid and surf-zone waters where lidar systems are not fully effective. Coastal areas of hydrographic importance containing turbidity, shoals and channels have been surveyed. This article describes AEM systems, gives highlights from surveys in Sydney Harbour and mentions refinements that would improve bathymetric accuracy. For several decades geophysicists have been using a transmitter loop fixed to an aircraft or towed by a helicopter to emit a magnetic field into the ground to search for mineral deposits. Currents thus induced in the ground generate a return magnetic field that can be detected... (read more)
2008-01-01 01:00:00

Hydrographic Societies

  Australian Hydrographic Society Australasian Awards for Hydrography The patron of the AHS, vice admiral Chris Ritchie, AO, RAN (retd), has been pleased to approve the following awards for 2009: Corporate Achievement – Training A. McNeill Maritime Safety Achievement (Individual) J. Kunda Maritime Safety Achievement (Group) National Maritime Safety Authority RAN Hydrographic Service – PNG Section L3-Nautronix – PNG Team Literary Achievement W. Richardson Education Award M.J. Lindsay The patron’s and president’s Letter of Appreciation (LoA) awards for government agencies, corporations and individuals will be advised separately. Presentations were made at various events in Australia and New Zealand coinciding with... (read more)
2009-09-02 12:00:00

e-Navigation for Increasing Safety

Hydro International Interviews Gurpreet Singhota
Gurpreet Singhota is Deputy Director/Head of the Operational Safety Section within the Maritime Safety Division of the International Maritime Organisation (IMO) and will therefore play a key role in directing the concept of e-navigation in the years to come. Singhota calls on industry, port authorities and shipping navigation to discuss their needs and requirements with the IMO. What do you think of the progress made on e-Navigation so far?The work is progressing quite well. The lead body is the Sub-Committee on Safety of Navigation, which will next meet from 2 to 6 July 2012. The e-Navigation concept is being developed... (read more)
2012-05-02 04:20:16

Sandwave Migration

Seabed mobility and shallow-water swathe sounding
The use of swathe systems in a highly mobile, shallow-water environment poses significant problems for the hydrographic surveyor. Several physical factors encountered when gathering swathe data are introduced and described as contributing to degradation of the accuracy model. The extent of influence by physical/environmental characteristics and the tidal solution on bathymetry must be understood so that methods to obtain accurate bathymetry suitable for safe navigation, seabed migration modelling and future research projects can be employed by the surveyor in real time. Lack of space prevents detailed discussion of such factors here, but this by no means reduces their importance, briefly... (read more)
2008-01-01 01:00:00

Geosurvey Techniques in Offshore Diamond Mining

De Beers Marine routinely acquires ultra high-resolution geophysical data in support of its offshore mining and exploration programmes for diamondiferous placer deposits situated on the continental shelf off the West Coast of southern Africa. Geosurveys are conducted over a wide range of water depths, each with a unique geological seabed terrain and associated survey requirements. Detailed mapping of complex and varied geological terrain demands the use of leading-edge survey technology. To this end, we have for the past four years been routinely operating an AUV (Autonomous Underwater Vehicle) as our principal ultra-high resolution geophysical survey platform. The continental shelf off... (read more)
2008-01-01 01:00:00

Dynamic Calibration of ­Navigation Sensors Using GNSS Technology

New on the move approach of calibration for vessel navigation sensors
Over the years there has been a requirement to calibrate navigation (heading and motion) sensors and verify DGNSS systems on vessels working in the offshore oil industry. These calibrations are a requirement of oil companies and need to be undertaken prior to commencement of a project and/or at regular intervals throughout a project. This article covers the techniques and accuracies related to applying GNSS technology to vessel sensor calibration and verification. Historically, vessel sensor calibrations have been undertaken in port using traditional land survey techniques, where the vessel is moored alongside a quay. The current advances made in GNSS technology... (read more)
2013-09-06 03:37:40

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
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