We present a conceptual design study to develop high power density High Temperature Superconducting (HTS) machines for two Navy applications: primary ship propulsion power generation and drive, and power generation modules (PGM). The objective of the study was to evaluate the design of a 36 MW, 3600 rpm generator, a 36 MW, 120 rpm propulsion motor, and a 4 MW, 7000 rpm power generation module. The generators are to be driven directly by the turbines without the benefit of clutch or gear. Several design concepts were evaluated, including iron core rotors and homopolar inductor alternator topologies. Engineering trade-offs make the re-introudction of ferromagnetic iron attractive for a number of reasons. High power density is obtained by the increased airgap flux density and armature loading, and, for high speed applications, the high tip velocity of the rotor.