The Department of the Navy maintains a vigorous science and technology (S&T, ) research program in those areas that are critically important to ensuring U.S. naval superiority in the maritime environment. A number of these areas depend largely on sustained Navy Department investments for their health, strength, and growth. One such area is naval hydromechanics, that is, the study of the hydrodynamic and hydroacoustic performance of Navy ships, submarines, underwater vehicles, and weapons. A fundamental understanding of naval hydromechanics provides direct benefits to naval warfighting capabilities through improvements in the speed, maneuverability, and stealth of naval platforms and weapons. An Assessment of Naval Hydromechanics Science and Technology is an assessment of S&T, research in the area of naval hydromechanics. This report assesses the Navy's research effort in the area of hydromechanics, identifies non-Navy-sponsored research and development efforts that might facilitate progress in the area, and provides recommendations on how the scope of the Navy's research program should be focused to meet future objectives.