In this article, smoothed particle hydrodynamics method is applied in order to study the free surface flow generated by two-dimensional planing flat plate. For this purpose, a two-dimensional smoothed particle hydrodynamics code is developed and validated by the well-known dam breaking problem. Four trim angles and three different velocities are considered to perform a parametric study to examine their physical effects. The obtained results from smoothed particle hydrodynamics are compared against the corresponding Reynolds-averaged Navier Stokes solutions. It is observed that at lower velocities, there exists a good agreement between the smoothed particle hydrodynamics and Reynolds-averaged Navier Stokes solutions, while at higher velocities, some inconsistency is observed. A brief discussion is presented to clarify the physical reasons behind the increase of the velocity and the height of the spray with the trim angle. Some formulas have also been derived to examine the variation of the ratio between the final wetted length of the flat plate and the initial wetted length at different velocities and trim angles.