Abstract: The stern appendages of a surface ship have great effects not only on the resistance，but also on the nominal wake field. Taking a ship which installed four propellers and two rudders as example，numerical simulation of the 3D viscous flow field on the hull with appendages was carried out based on RANS without considering the free surface effect. The analysis focused on the effects of the twin shaft bracket section profile and installation angle on the viscous resistance and nominal wake field. The results show that the installation angle of shaft bracket can be determined by the direction of flow velocity vector.