<p>Although a variety of wave energy conversion devices have been developed globally, standalone systems often face economic challenges. A practical solution is integrating wave energy converters (WECs) with existing marine infrastructure, such as breakwaters, to serve as multifunctional structures. Breakwaters are primarily constructed to facilitate the development of harbours for maritime trade. When detached and positioned parallel to the shoreline at a distance, they have also been proven effective as a measure to protect against coastal erosion. By incorporating WECs into these structures, installation and maintenance costs can be shared between coastal protection and energy generation, improving the overall economic viability. Among different WEC technologies, the oscillating water column (OWC) has proven particularly effective. This study investigates the hydrodynamic performance characteristics of OWCs integrated with semi-circular breakwaters (SCBWs), which, when installed as detached offshore structures serve both as coastal defense and energy harvesting systems. The configuration consists of three identical OWCs, each of which is integrated with a detached SCBW. Each SCBW has a width five times that of the OWC, and the gap between adjacent integrated SCBWs is varied from one to four times the OWC width to assess its impact on performance. The study evaluates the impact of this gap on both the hydrodynamic efficiency of the OWCs and the wave transmission behind the structure. Numerical simulations are carried out using OpenFOAM, validated against experimental data. Results indicate that the gap of three times the OWC width between integrated SCBWs yields good performance.</p>