Precise RTK GPS Water Levels

Incline plane models in geoid-ellipsoid separation calibration
As more people adopt RTK GPS technology for measuring water levels, the issue of ellipsoid-geoid separation is increasingly being discussed. This article outlines various projects undertaken to calibrate this separation, and presents information to consider when using RTK GPS for measuring relative to an orthometric (geoid) datum. RTK GPS is increasingly being used for measuring water-level corrections during hydrographic survey, as for water levels in general. Measuring this third vertical dimension usually requires local site calibration to correct for separation between WGS84 ellipsoidal height and geoidal elevation, enabling conversion of WGS84 heights to orthometric heights such as mean seal level... (read more)
2008-01-01 01:00:00

Live On-water Ixsea Demonstration

Industry professionals could familiarise themselves with the latest technology available in the Ixsea underwater acoustic and navigation equipment range during Ocean Business 2011 in Southampton, UK.   Directly after departure, the Ixsea Echoes 5000 was launched, a range of wide-band chirp sub-bottom profilers capable of generating from very low frequencies and deep penetrations up to very high resolution frequencies. The system is based on more than ten years of sub-bottom experience. The Echoes sub-bottom profiler was mounted on the towed body, but could also be mounted on a pole if required.   During the survey Ixsea representatives also demonstrated the... (read more)
2011-04-07 10:15:50

Mapping Cold Water Coral Reef

In recent trials off Trondheim, Norway, the GeoSwath Plus swath bathymetry and side scan system was used for the first time on a remotely operated vehicle (ROV) to map cold water coral reefs. The objective of the survey was to test how effective the GeoSwath was as a ROV mounted sonar for identifying cold-water coral colonies. At 60m deep the Tautra ridge in Trondheim Fjord is home to world’s shallowest known cold-water coral reef, and was an ideal site for initial system trials. The corals seen there usually thrive in much deeper waters.  The GeoSwath was deployed on a Minerva... (read more)
2007-02-12 09:24:28

Navigating Through Land and Water

This year the Geodetic Institute of Slovenia is celebrating its 55th anniversary. As a public institution, the work of the Institute was and remains dedicated to geodesy, photogrammetry, cartography, geomatics and property. Its experts in different fields of the profession are also the lecturers at the University of Ljubljana and, in this way, they transfer their knowledge to younger generations. About 10 years ago, the Institute started hydrographic activities as official support to the Slovenian Hydrographic Office.<P> The Institute for Geodesy and Photogrammetry (IGF) was established on 14 December 1953 as a research institute at the University of Ljubljana. The... (read more)
2009-01-05 12:00:00

Cable Tracking in Shallow Water

Tailoring Systems for Inshore Operations
Whilst there has been an increased effort to resolve the issues of supporting deepwater construction operations, issues specific to shallow-water operations seem to have been largely overlooked, the attitude being that standard equipment packages would be perfectly adequate. What makes this all the more surprising is that the majority of offshore developments have some sort of shallow-water requirement associated with beach landing points. As always, the other factor driving all developments is cost. Whilst the high price of oil has produced a boom in oil-construction support, the laws of supply and demand have increased vessel and service provision rates to... (read more)
2007-05-31 12:00:00

Object Identification in Turbid Water

Near video-quality Images from Acoustic Systems
Working underwater requires visual feedback to prevent work slowing or even coming to a halt. Acoustic systems make images in turbid water, but not always with the required detail provided by optical systems. This article reviews technology that provides near-optical-quality acoustic images, allowing work to continue in zero-visibility water. Problem Overview A significant amount of underwater work takes place in seas, rivers and coastal areas where visibility is minimal and optical systems generate blank screens. Conventional sonar provides images under these conditions, but the detail generally does not come close to the optical detail needed for identification, inspection and manipulation... (read more)
2008-01-01 01:00:00

Hottest Water on Earth Discovered

At over 3 kilometres beneath the surface, sitting atop what could be a huge bubble of magma, it's the hottest water ever found on Earth. The fluid is in a "supercritical" state that has never before been seen in nature. The fluid spews out of two black smokers called Two Boats and Sisters Peak. Koschinsky, from Jacobs University in Bremen, Germany, says it is somewhere between a gas and a liquid. She thinks it could offer a first glimpse at how essential minerals and nutrients like gold, copper and iron are leached out of the entrails of the Earth and... (read more)
2008-08-05 10:58:58

Deep-water Black-box Retrieval

A Game of Hunt-the-pinger Against the Clock
Restricted operating life, limited range and bearing ambiguity in deep water are the known limitations of current locator beacons mounted on aircraft. These problems raise important questions: what is the best method of locating existing pingers and what can replace them? In deep water, pinger detection equipment could be installed on a submarine. Alternatively, a transponder beacon can provide both range and bearing information, as well as demonstrate a significantly longer listening life. Although heavier and therefore not suitable for light aircraft, commercial aircraft could easily accommodate such beacons allowing easier retrieval of the aircraft black boxes. In the July/August... (read more)
2009-12-04 03:49:14

World Water Depth Drill Record

The new world water depth drilling record set by Transocean drillship Discoverer Deep Seas was accomplished using a Sonardyne dual redundant subsea acoustic positioning system. The record was set last November when the vessel spudded a well in 10,011 feet (3,051 metres) of water in the Gulf of Mexico. The Discoverer Deep Seas has been equipped with a dual Sonardyne Long and Ultra-Short BaseLine (LUSBL) system since December 2002 and uses it as a highly accurate position reference for its DP system. The system is particularly suited to deepwater applications as it combines the performance derived from Long BaseLine (LBL)... (read more)
2004-03-03 12:00:00

Multibeam Echosounder for Medium to Deep Water

The RESON SeaBat 7160 multibeam echosounder has been developed for marine exploration, seafloor habitat mapping and hydrographic charting in medium to deep water (3 to 3,000m). Equipped with X-Range, it provides improved system immunity to external noise. The system can operate in water depths of between 3 to 3,000 metres, offering up to 512 high-density equidistant beams with a selection of coverage modes including features such as variable and steerable swath, together with real-time pitch and roll stabilisation maximising useable swath and performance. The SeaBat 7160 also provides the collection of high-density water-column data all wrapped up in a processing... (read more)
2013-01-18 10:17:57
Search Filter