This paper develops a semi-analytical solution of a water waves problem concerning the interaction between linear waves and an Oscillating Water Column (OWC) embedded into a circular platform. Unlike similar studies available in the literature, the proposed investigation concerns a realistic situation involving the use of an OWC having limited angular width. Such a configuration is likely to be employed in the arrangement of platforms in which the use of a large OWC is neither efficient nor feasible.The proposed solution is developed in the framework of the linear potential flow theory. The solution relies on the use of a domain decomposition approach involving eigen-function expansions of velocity potentials with unknown coefficients, which are calculated via a matching technique. The solution is utilized for conducting relevant parameter studies concerning the effects of the main geometrical parameters on the overall system performance and on the system hydrodynamic parameters.