The wave-piercing tumblehome (WPTH) vessel has special geometric characteristics, its hull is inclined to suffer significant green water and corresponding hydrodynamic loads. The motions of a WPTH vessel in heading waves are simulated using commercial computational fluid dynamics (CFD) software. It is found that the typical green water process consists three stages: water collision above the bulbous, green water convergence, and green water jet flow impact. In stage 1, collision of two streams above the bulbous bow causes a high pressure area like a butterfly. The convergence of green water induces high pressure in stage 2, and the green water jet flow in stage 3 results high impact pressure on the superstructure. The vertical bending moments are calculated by introducing a field function. The green water and bow slamming have less effects on the vertical bending moment but cause considerable local hydrodynamic loads. •Typical green water of the wave-piercing tumblehome vessel consists three stages.•Collision of streams over the bulbous results a butterfly-shaped pressure zone.•Green water from broadsides converges and high pressure is induced on the deck.•An accelerated water jet impacts on the superstructure and causes high pressure.