The interaction of the free surface with either lifting and non lifting, submerged, bodies moving beneath it is of primary interest in naval architecture. Indeed, there are many examples of possible applications such as rudders, stabilizer fins, hydrofoils among the others. The hydrodynamic problem of a submerged lifting body moving close to a free surface presents several complexities that need to be properly addressed in order to achieve a reliable solution. The problem is studied in the framework of a potential flow theory and solved by using an ad-hoc developed Vortex Lattice Method (VLM). The developed method is described and validated by comparison against available data on a flat plate. The analysis then focuses on the convergence properties of the method, especially with respect to the panel dimensions used for the free surface discretization, and on a sensitivity with respect to some peculiar operating parameters such as the depth of the body with respect to the free surface and the angle of attack with respect to the incoming flow.