Abstract: A hand held, self-contained depth finding device is immersible into water for transmitting and receiving sonic impulses in the direction the device is aimed. The device includes a hand grip carrying a battery cartridge and an external trigger for operating a power switch within the waterproof interior. A liquid crystal display registers the measured depth in feet.

Abstract: Marine detection apparatus includes a sound transducer mounted below the water line of a vessel for emitting and receiving sound signals and imperviously sealed within a transducer housing together with a temperature detector for sensing the temperature of the water. A display is provided capable of displaying water depth and water temperature. The water depth reading is proportional to the elapsed time between the transmission and the reception of the sound waves, and the temperature reading is proportional to an elapsed time determined by a timing circuit in which the resistance value of the temperature sensor operates to determine the charging time of a capacitor. The display is of a circular, dial type using lighted spots and a lighted arcuate shaped column to display the depth and temperature.

Abstract: Marine detection apparatus includes a sound transducer mounted below the water line of a vessel for emitting and receiving sound signals and imperviously sealed within a transducer housing together with a temperature detector for sensing the temperature of the water. A display is provided capable of displaying water depth and water temperature. The water depth reading is proportional to the elapsed time between the transmission and the reception of the sound waves, and the temperature reading is proportional to an elapsed time determined by a timing circuit in which the resistance value of the temperature sensor operates to determine the charging time of a capacitor. The display is of a circular, dial type using lighted spots and a lighted arcuate shaped column to display the depth and temperature.