After working for eighteen years with the trailer department of a dredging company, Stef Mars started his own hydrographic survey company in 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 and a land surveyor form the core of our company. Their dedication and inspiration leads to continuing improvement in our products. We develop acoustic software that is combined with acoustic systems but we are not involved in acoustic hardware.
Apart from geophysical surveys for dredging, marine aggregate mining, land reclamation, and construction we also execute wreck detection, cable and pipeline route surveys. In we started with the development of a Windows version of the software.
One main objective of the acoustic reflection measurement software is to measure density variations in sub-bottom sediment and produce detailed geophysical information on seabed sediment. Penetration rates depend on the combination of the acoustic system used, frequency and water depth. The software currently consists of three modules: Module 1 for layer tracing in sub-bottom sediments Module 2 also includes density computation in liquid silt layers Module 3 for sub-bottom sediment classification, is currently in its testing phase The software is suitable for use with a wide range of acoustic sources, such as: dual frequency echosounders, sub-bottom profiler pinger , boomer see Figure 2 or sparker linear or non-linear.
The software operates in the frequency range between 1 to 40 kHz. Together with the development of the SILAS software, a tool for calibration and verification of the acoustic reflection recordings had to be developed for defining absolute density and rheological parameter values in areas with liquid sediments.
