Partially overlapped plates submerged in water are of interest in some industrial applications such as in blade-adjustable hydraulic turbine runners, where the neighboring blades become closer and partially overlapped for certain operating conditions. To know the influence of partially overlapped structures on their dynamic behavior is of great importance to avoid resonances and therefore to extend their lifetime. In this paper, the dynamic behavior of two identical rectangular plates with a partially overlapped area in water has been studied experimentally and numerically. An experimental test rig has been constructed, which consists of two identical rectangular plates in a tank full of water. The distance and the overlapped area between the two plates can be changed to investigate their influence on the added mass, added damping and mode shapes. A finite element method model based on acoustic fluid-structure interaction was used to simulate the added mass effect of the plates from the surrounding water. A theoretical equation used to calculate the damping ratios of submerged structures has also been proposed. Theoretical, experimental and numerical results have been compared and analyzed.