A finite-volume method with the curvilinear grid system fitted to the hull surface is applied to the elucidation of the 3 D structure of the flow about a full hull form. After examining the grid effects with two different systems of which number of grid points are 1 × 105 and 4 × 105, the simulated flow field is carefully examined using a variety of drawings of the simulated flow. It is demonstrated that the grid dependency can not be fully removed with these number of grid points and that the Reynolds stress by the simulation with the finer grid system qualitatively agrees with the measurement. It is revealed that the stern flow about a full hull form is composed of complicated 3 D vortices. Both spanwise and streamwise vortices are included in the bilge vortices and the former plays an important role for the generation of the wake distortions.