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Late in 2008 we were requested to carry out a CFD study of alternative rudders. The client now often uses the flap-rudder concept to generate the high side forces required. These flap rudders however are relatively expensive and require more maintenance than rudders without moving parts. Our work commenced by carrying out CFD calculations of alternative foil shapes as are used for marine rudders and, subsequently, by CFD calculations to analyse different rudder concepts in 3D. The results of this work were used to develop a new rudder concept with the promise of considerably higher side forces. This concept is presently being investigated in detail.