3-D sonar imaging system helps lay undersea cable

Engineers at Deep BV Hydrography and Geophysics (Amsterdam, The Netherlands) have deployed a 3-D phased array sonar system from CodaOctopus (Edinburgh, UK) to assist with the installation of a power cable at Thornton Bank, an offshore wind farm 28 km off the Belgian coast in water ranging from 12 to 27 meters deep.

According to CodaOctopus, this is the first time that their Echoscope sonar system has been used to monitor the touchdown of a cable into a trench on the seabed. Using the Echoscope system, the operator was able to visualize in real time the cable's catenary and touchdown point in three dimensions as it was being laid.

Using CodaOctopus' proprietary USE (Underwater Survey Explorer) software, it was also possible to overlay a computer generated image of the planned site of the cable onto the sonar view to enable the engineers at Deep BV to confirm that it was being laid on target.

"By ensuring the correct siting of the cable and by making necessary adjustments as it is being laid, we were able to work continuously without having to stop to check its position. We therefore avoided having to go back and take remedial action," says Jurgen Beerens, Commercial Manager at Deep BV.

The image above shows a 3-D view of a section of cable being laid into a trench on the seafloor.

-- Dave Wilson, Senior Editor, Vision Systems Design