Kongsberg EM 712 Multibeam Echosounder The EM 712 multibeam echo sounder is a high to very high-resolution seabed mapping system capable of meeting all relevant survey standards. The minimum acquisition depth is from less than 3 m below its transducers, to a maximum of 3600m dependent upon array size. Across track coverage (swath width) is up to 5.5 times water depth, with a maximum of up to 4400 m, which is almost double the range performance of the EM710.