Based on a small prototype of the McCabe wave pump device, this paper studies the optimal size of an interconnected pontoon system, where the power take-off systems attached to each barge are equipped with optimal linear passive dampers. To this end, an optimization procedure is developed, where the objective is to maximize the extracted energy of the device under given sea states. A multi-DOF mathematical model is presented to describe the device motion, and associated hydrodynamic parameters are computed using a boundary element model tool, based on linear potential flow theory. Numerical results, under regular and irregular waves, are presented. Simulation results show that the optimal dimension of the device, under given sea states, can be found using the developed methodology. In addition, it is found that the three-body hinge-barge device tends to perform like a two-body system under optimal control conditions. This indicates that a two-barge control system may be a better design solution in those situations, considering the high cost of power take-off systems.