Jan De Nul Group
Swathe Services continue to provide GeoSwath Plus operation and training on board the ‘mega-dredger’ Vasco Da Gama. She has been engaged in deep-dredging off the coast of Namibia since January, working in water depths of up to 130m.
The onboard GeoSwath Plus system, which is deployed through a moon pool for ease of maintenance, is a low-frequency version (125kHz) for use in deep water and has been producing excellent results. Because GeoSwath is a bathymetric sonar rather than a multi-beam echosounder, and works on side scan sonar priciples, it also records true, co-registered side-scan data. This mosaiced and then draped over the digital bathymetric model. Because they are co-registered, the drapes have in many cases been seamless. All models have been binned successfully at a resolution of 1m. Accuracy has been confirmed by comparison with high-resolution AUV data. Repeatability is confirmed by surveying in an un-dredged area in both the pre and post-dredge surveys.
Jan De Nul Group has won several more deep-dredge contracts and Swathe Services will be providing continuing support for the next six months on these projects.
