sentences:  The vessels are fitted with a C-Tech CMAS 36/39 hull-mounted high-frequency active sonar.In addition, the ships carry an Atlas Fansweep-20 multibeam echo sounder and an Atlas Hydrographic Deso single-beam echo sounder, and a Klein 2000 towed sidescan sonar array.The sonars and echo sounders allow the vessels to chart waters up to deep.