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This work addresses the numerical study of wave-piercing planing hull and related hydrodynamic performance as the appendages. From the half century ago, the interest in high-speed planing crafts has been advanced toward maintaining performance stably. The main reasons to make it hard are instability motion occurring from porpoising and wave condition. Porpoising is mainly due to overlap the heaving and pitching motion with certain period, which is caused by instable pressure distribution and changing longitudinal location of center of gravity. In addition, in wave condition, encountering wave disturbs going into planing mode. This paper presents numerical results of wave-piercing planing hull in porpoising and wave condition. Numerical simulation is conducted via Reynolds Averaged Navier-stokes (RANS) with moving mesh techniques (overset grid), performed at different wave condition. The numerical results reveal motion characteristics overlapping porpoising and wave condition. At first, motions on low wavelength region show resonance on this condition, and some appendages enhance the motion amplitude larger than original values. Finally, this resonance was suppressed by stern appendages. However, momentum generated from stern appendages increases motions in high wavelength region. This effective motion corresponds with vertical accelerations from CG.