Résumé : In this thesis, a novel smart inspection-ROV is described. The research addresses the need for a highly-capable ROV with abilities to carry out close-quarters inspections of marine renewable energy installations in their inherently challenging environments where strong waves, current and wind are the norm. The use of such an ROV can aid towards the reduction of levelised costs for generating electricity of these MRE devices through maintenance operations and support. The design, fabrication and integration of the inspection-class ROV (I-ROV) are detailed. To ensure that the ROV can operate within the challenging conditions associated with MRE sites it has been designed to be reconfigurable, with options to use different types of thrusters in different configurations. For robust control, the ROV combines a state-of-the-art navigational sensor suite with the enhanced OceanRINGS+ control system. The ROV has also been designed to incorporate fault-tolerant control through the use of active or passive thruster fault detection (FDI) subsystems. The development of all the subsystems within the ROV is documented along with the testing and validation of the full ROV in virtual (simulated) and real-world environments. The agile hardware-in-the-loop (HIL) development and testing of the thruster FDI subsystems are described, with results issued. The thesis concludes with a summary of the work conducted for the research and provides suggestions for future work.