The purpose of this paper is to calculate the hydrodynamic performance of a ducted propeller (hereafter Duct_P) at oblique flows. e numerical code based on the solution of the Reynolds-averaged Navier– Stokes equations (RANSE) applies to the Kaplan propeller with 19A duct. e shear-stress transport (SST)-k-ω turbulence model is used for the present results. Open-water hydrodynamic results are compared with experimental data showing a relatively acceptable agreement. Two oblique flow angles selected to analyze in this paper are 10 and 20 degrees. Numerical results of the pressure distribution and hydrodynamic performance are presented and discussed.