The book discusses gyroscopic compasses; gyro horizon compasses and integrated navigation systems; magnetic compasses and magnetic horizontal compasses; navigation gyrotachometers; ship (lag) speed meters of different operating principles; radio sonar, as well as navigation echo sounders. In addition, information about the flight data recording system is provided. The handbook is intended mainly for boaters of all levels; it will also be useful for hydrographs and specialists in the field of marine electronics.