Two major flaws present themselves in the paper Thakker, A. and Elhemry, M. A. (2007). 3-D CFD Analysis on Effect of Hub-to-Tip Ratio on Performance of Impulse Turbine for Wave Energy Conversion, THERMAL SCIENCE: Vol. 11 (2007), No. 4, pp. 157-170. The first is the form of the non-dimensional performance parameters. These are at odds with the accepted performance parameters for turbomachinery published in textbooks, Massey, 1971 and the literature, Curran et al., 1998, Thakker et al., 2001. Also the presence of multiple geometric parameters in the definition of the non-dimensional performance parameters invalidates the assumption of geometric similarity and also renders the comparison of geometrically dissimilar turbines impossible.