Fundamentals of major electronic equipments on board ships are presented in this text prepared for naval officers in general. Basic radio principles are discussed in connection with various types of transmitters, receivers, antennas, couplers, transfer panels, remote-control units, frequency standard equipments, teletypewriters, and facsimile installations. Theoretical and practical analyses are made of radar and sonar equipments to show their capabilities and limitations. On the subject of electronic navigation, loran, shoran, omega, tacan, and satellite and ships' inertial navigation systems are presented. Also included are descriptions of digital computers, gun and missile weapon systems, direction finders, closed-circuit television sets, electronic countermeasures, communication console equipments, underwater telephones, intrared and meteorological setups, carrier control approach systems, radiac instruments, and target control installations. Illustrations for explanation purposes and a glossary of general terms are included. (CC)