This study describes a detailed procedure for design of marine screw propellers in combination with stators, also known as fixed guide vanes or pre/post swirl devices, based on lifting line theory. The design procedure presented here involves the realistic representation of the propeller slipstream, which is contracted form of helical vortices. The slipstream shape is allowed to deform and to align with the direction of local velocity that is the sum of the inflow wake velocity and induced velocity. As the slipstream deformation is the key parameter in the design of reaction type performance improvement devices, the design methodology is applied to a stator device behind the propeller, and then the hydrodynamic performance of the combined propulsor is analyzed. Furthermore a CFD analysis based on Finite Volume Method is applied. The results from both methods are compared and discussed. (C) 2006 Elsevier Ltd. All rights reserved.