3.2.2. Other external forces
Other external forces for the VLCC during the initial onset of the tsunami are wind forces, of which the velocity was about 4m/s NNE with beam wind on the ship׳s starboard side. Thus, the wind forces have been given for sway, roll and yaw, which are estimated as 83 kN (8.4 ton), 620 kN (63 tm), and 53 kNm (5 tm) respectively, referring to the OCIMF guidelines (Oil Companies International Marine Forum (OCIMF), 1994). The side wall effect between ship hull and quay wall during the tsunami is neglected due to the large stand-off distance between the VLCC and the quay wall. The drag forces from the tsunami currents, which are proportional to the current squared, have not been employed because the tsunami wave forces are already included in the superposition of linear wave forces.