Abstract: An underwater detection system for displaying underwater conditions over a large area around a ship comprises a linear array type transducer, a transducer training mechanism for rotating the transducer stepwise in a horizontal plane, a receiver which forms a receiving beam for scanning a fan-like vertical cross-sectional area by giving specified time delays or phase differences to echo signals received by the transducer, an image memory for storing echo signal data picked up by the receiving beam in addresses defined by horizontal directions relative to the ship and depths, a sampling circuit for reading out data of one vertical line after another in a downward direction from the image memory and determining a bottom depth in each vertical line, a seabed data memory for storing bottom depths, a PPI image generator for producing a fractional PPI image depicting the bottom based on bottom depth data read from the seabed data memory, and an indicator for presenting search results in the form of a plan view cover

Abstract: The present invention provides flexibility in the shape and material of the cleaning vessel, enables high-power transmission of ultrasonic waves, and reduces audible noise generation. An ultrasonic cleaning machine according to the invention comprises an acoustic lens mounted above an ultrasonic transducer which is immersed in oil held within an external tank as well as a cleaning vessel holding a cleaning liquid further above the acoustic lens so that ultrasonic waves produced by the ultrasonic transducer converge at a point within the cleaning liquid. In one form of the invention, the cleaning vessel is eliminated and the cleaning liquid is held directly in the external tank.