The advantage of producing energy via array of WECs and not via individual device has long been demonstrated [1]. The hydrodynamic analysis of wave energy converter arrays is relevant in productivity assessment. The goal of this work is to present an evaluation method of WECs’ dynamic response in array configuration and the analysis of the disturbed wave field. A boundary element method (BEM) [2] has been adopted in order to identify the hydrodynamic coefficients of the WECs and to study the interaction between the single devices. The point absorbers’ arrays have been widely studied and the interaction factor or q-factor has been introduced as performance index of the farm layout [3], [4]. In this study, the case of ISWEC device, Inertial Sea Wave Energy Converter [5], has been chosen. In order to compare the efficiency between an isolated device and a single device in a farm, the RAO on the pitch degree of freedom has been adopted as performance index. The linear approach, like BEM, has high limits of validity for the case of high amplitude oscillating systems. Therefore, a linearized pitch viscous damping term has been introduced in order to overcome the limits of the linear potential flow theory based methods.