Field Testing Of A New Deep Water Multibeam Echo Sounder

SUMMARY The SIMRAD EM12 multibeam echo sounder is available as a single 90' system with 81 beams, or as a dual 150' system with 162 beams. All beams are roll and pitch stabilized. The single system has a coverage of two times the water depth to about 7000 m, and up to 15 km is expected at 11000 m water depth. The dual system has a coverage of 15-20 km from 2500 to 11000 m water depth and usually 7.4 times the water depth in shallower areas. Sea trials of both system versions were carried out last year, and showed that the instrumental accuracy of the echo sounder including sound velocity refraction corrections is in the 'order of 0.1% of water depth in all beams with accepted soundings. In areas with rough seabed, where positioning, gyrocompass, vertical reference unit, and weather will influence the accuracy of the soundings, the sea trials showed that an accuracy in the order of 0.2-0.3% (lo) of water depth was achieved.