This paper presents numerical study of the surface curvature effects on the performance of a 3D lab scale tidal turbine (E387) using Eppler 387 airfoil. The prescribed surface curvature distribution blade design method is used to remove the surface curvature discontinuity of E387 turbine and the redesigned turbine is denoted as A7 turbine. The two turbines are analysed using in-house BEM code and CFD RANS. The performance of E387 turbine obtained from BEM and RANS match well with the experimental results from reported literature. The A7 turbine has a mildly better performance at low tip speed ratios (1–4.25) where the rotor is deviated from the designed operating TSR and the blade is partly or fully stalled.