Bill Diedrich: High-speed sonar

Improved data-processing speed has allowed quality sonar graph units to display images on the screen at speeds well over 20 miles per hour. Speed changes sonar images. The slowly sloping valley between two sunken humps will look like a "V" on the screen. Stalks of cabbage will look like sticks growing from the bottom, and fish arches will look like compressed arches or sticks. Proper high-speed transducer installation is necessary to get a good high-speed reading.