STEMA Survey Services bv

New techniques to reveal crucial sub-bottom details
After working for eighteen years with the trailer department of a dredging company, Stef Mars started his own hydrographic survey company in 1985. Working on board of hopper trailer suction dredgers and later as hydrographic surveyor with project management he came across two main problems: a lack of reliable sub-bottom information, and the elusiveness of liquid sediment, or silt. Stema is known mostly as a hydrographic and geophysical survey company; it is less known as a manufacturer of software. However, we have developed our own tools that may be of interest to readers. The Company A team of geologists, hydrographers... (read more)
2008-01-01 01:00:00

How Google Explores the 10th Planet

About Mermaids and Sea Serpents
NASA has spent tens of billions of dollars exploring Planet Earth and the other eight planets of our solar system, yet there is one last great frontier that has gone almost completely unexplored – Planet Ocean. The disparity between our understanding of Planet Earth and Planet Ocean is highlighted by the computer program and image repository Google Earth. However, the ability to use Google Earth below sea level provides a new platform for scientists to exchange oceanographic information and also deliver research findings to the general public. Remote sensing satellites provide high-resolution imagery of all of Earth. Check out the... (read more)
2009-10-05 11:03:52

WESP: Water and Strand Profiler

Vehicle for bad-weather and wave-zone survey
The Netherlands is bordered in the north and west by the North Sea. Twenty-six percent of the country’s landmass lies below sea level. Global warming will bring slow rises in sea level, whilst extensive draining off in the west of The Netherlands is resulting in a fall in ground level. Given this background it is easy to understand why one of the main goals of the Dutch government is to protect the country against floods. Here knowledge and insight is required regarding several morphological processes pertaining to the Dutch coast. Such knowledge is acquired by means of coastal studies; quantitative... (read more)
2008-01-01 01:00:00

Promoting Safety for Surveyors?

The US$20 billion per annum market served by international offshore, marine and underwater engineering contractors is represented by the International Marine Contractors Association (IMCA). Its Offshore Survey Division is the most recently added division within the international trade association.<P> Formed in 1997, the Offshore Survey Division is concerned with all aspects of equipment, operations and personnel relating to offshore survey operation. The IMCA has over 420 member companies in 48 countries around the globe – nearly 80 of those companies are members of the Offshore Survey Division. By ‘survey’ in the IMCA, we mean such tasks as hydrographic survey of... (read more)
2007-11-27 12:00:00

Marine 3D Full Tensor Gravity Gradiometry

The first five years
3D Full Tensor Gradiometry (FTG) or high-precision moving platform gravity gradiometry measures the full gravity field in all directions. The technology was initially commercialised for the petroleum exploration industry to assist with defining complex salt structure/geometry, sub-salt play definition and the re-imaging of seismic data using techniques such as Pre and Post-Stack Depth Migration (PSDM). The scope of gradient data utility further ranges from prospect level to regional reconnaissance project evaluation. Integration with other geophysical datasets produces added value in the form of improved interpretation accuracy and risk reduction. FTG data contains critical directional information and greater resolution than does... (read more)
2008-01-01 01:00:00

The Laboratory Measurement

Salinity is one of the most measured parameters in oceanography. The importance of high quality salinity data has long been recognised in open ocean studies and more recently in coastal and estuarine processes. Much data is collected using in-situ instrumentation (e.g. CTD, multi-probes) but the measurement of salinity in the laboratory remains an important and widely used technique. This article describes developments made to allow the high precision, accurate measurement of Practical Salinity in the laboratory. In recent years salinity data has provided important information in the study of climate change. Large transects of the ocean using CTD profiles have... (read more)
2008-01-01 01:00:00

Discovering H.M.S. Ark Royal

In November 1941 the aircraft carrier H.M.S. Ark Royal was returning from Malta, when it was torpedoed and sunk by a German U-boat southeast of Gibraltar. Its destruction was a devastating blow to the Royal Navy's power in the Mediterranean theatre of war and to the morale of the British people. In October 2002, nearly sixty-one years after it was lost, the remains of the Ark Royal were identified on the bottom of the Mediterranean using C & C Technologies HUGIN 3000 AUV. In the autumn of 2002 the British Broadcasting Corporation (BBC) contracted C & C Technologies, Inc. (C... (read more)
2008-01-01 01:00:00

Benthic Habitat Mapping

Utilisation of Multi-beam Backscatter for Ecological Study of the Seafloor
The establishment of multi-beam echo sounders (MBES) as a mainstream tool in ocean mapping has revolutionised approaches towards nautical charting, seafloor geotechnical/geological surveys and benthic habitat mapping. The resolution of bathymetric and backscatter data collected by MBES has improved significantly in recent years through technological improvements of these acoustic systems. Furthermore, developments in data collection and processing of MBES backscatter have resulted in the increasing preferential use of multi-beam technology over conventional side-scan sonar or single beam sonar for these applications. This article explores some recent developments in the methods used to generate benthic habitat maps using multi-beam sonar systems.... (read more)
2012-07-26 02:55:45

Casualties of the Nautical Chart

What You See is Not Always What You Get
When ships run aground unexpectedly the initial presumption is that the vessel has struck an ‘uncharted’ feature. In practice this is rarely so. This article reviews a number of chart-related casualties. These demonstrate that while no charts are infallible, a better appreciation of their limitations might have averted disaster. New cruise ship itineraries in tropical seas and Polar Regions require especial vigilance. Ever deeper draught bulk cargo and crude carriers are transiting sparsely surveyed ocean areas and accessing remote locations in the continuing search for and exploitation of new mineral deposits. Are these accidents waiting to happen? Today’s navigators often venture... (read more)
2014-09-02 11:41:36

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
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