The book presents a broadscope analysis of piezoelectric electromechanical transducers and the related aspects of practical transducer design for underwater applications. It uses an energy method for analyzing transducer problems that provide the physical insight important for the understanding of electromechanical devices. Application of the method is first illustrated with transducer examples that can be modeled as systems with a single degree of freedom such as spheres short cylinders bars and flexural disks and plates made of piezoelectric ceramics. Thereupon transducers are modeled as devices with multiple degrees of freedom. In all these cases results of modeling are presented in the form of equivalent electromechanical circuits convenient for the calculation of the transducers operational characteristics. Special focus is made on the effects of coupled vibrations in mechanical systems on transducer performance. The book also provides extensive coverage of acoustic radiation including acoustic interaction between the transducers.Part III considers calculating transducers of various configurations cylindrical spherical plates and beams vibrating in flexure and the length expander bars.Part IV is focused on the transducers designing related issues such asampnbsphydrostatic pressure compensation matching projectors with acoustic load receivers noise immunity and combining analytical methods with FEA for treating the transducers.ampnbspampnbsp