9 MARINE APPARATUS AND INSTRUMENTS FOR COMMUNICATIONS AND SIGNALLING, NAVIGATION, MARINE LIFE DETECTION, AND ENVIRONMENTAL CONDITIONS MEASUREMENTS, NAMELY, DIRECTION FINDERS, FISH FINDERS, DEPTH FINDERS, ELECTRO-OPTICAL FISH INDICATING UNITS, WATER TEMPERATURE INDICATORS, TELEPHONE AND RADIO UNITS, CHART RECORDERS, DEPTH COMPUTERS, HAILERS, MEGAPHONES, FUME DETECTORS, AND PARTS THEREOF; BATTERY CHARGERS