The extreme wave oscillations during seasonal weather causes difficulty in maritime transport system i.e., the process of unloading and loading of a moored ship and disturbs it’s six modes of oscillations. In this work, a mathematical model is presented that uses 3-D Boundary Element Method (BEM) to examine the six-modes of oscillations of moored ship in Pohang New Harbor (PNH) considering resonance condition. The domain of fluid is partitioned into three domains namely port domain, ship domain and the open sea domain, Laplace equation is used to obtain the wave oscillations in the port domain and ship domain while the Helmholtz equation is utilized in the open sea domain including the partially reflecting port’s wall and variable water depth. The present model is well validated from the available studies and to attain numerical accuracy convergence analysis are presented. Further, the damping coefficient and added mass of six modes of oscillations of the motion of moored ship is analyzed in order to investigate the hydrodynamic forces imposing on the moored ship.