Applying renewable energy could decrease the side effects of fossil fuels, therefore wave energy converters are crucial for implementing. This study focuses on the experimental investigation of an OWSC (1:8) by considering Caspian Sea for installation. After defining the significant hydrodynamic coefficients that impact the performance of the OWSC, including damping, pressure, and transmission coefficients, this study identified the parameters influencing these coefficients and investigated how these parameters affected them. The experiments were designed within the range of wave heights [0.04-0.1] m, wave frequency [0.4-0.63] Hz and water depths [0.8-1.5] m. Previous studies have shown that draft depth, wave height, and wave frequency are parameters affecting the performance of WEC. In this paper, the effect of these parameters on the hydrodynamic coefficients of the WEC was investigated. The results showed that increasing the wave height decreases the damping coefficient of the WEC, it was also shown that the effect of the dimensionless draft depth on the damping coefficient has a non-linear behavior and the WEC has the lowest damping coefficient at the optimal draft depth. An increase in the wave height leads to a decrease in the pressure coefficient (Cp), the Cp decreases by approximately 40% when the wave height changes from 0.04 to 0.1 m. The effect of the dimensionless wave frequency on the Cp is insignificant. Increasing the dimensionless draft depth leads to an increase in the transfer coefficient (Ct). Furthermore, the results of the correlation between parameters and Hydrodynamic coefficients indicate correlation of approximately -1 between wave height and Cp, close to -1 between wave height and Cd, and a close to 0 between wave height and Ct.