Study of equipment of the transducer of the echo-sounder on the bottom of the wooden ship

Abstract

When the transducer of the echo-sounder is equipped on the bottom of the wooden ship, it is necessary to know the penetration loss of ultrasonic wave through all sorts of wooden boards. Now we report the result that we immersed a cryptomeria board and a pine board in water in the tank and measured the penetration loss of ultrasonic wave. And we studied its relation with the number of days of immersion. We found that the loss decreased conspicuously after about a week. And we stndied its relation with the thickness of a board and the frequency of ultrasonic wave.