An experimental study was carried out to compare the drag characteristics of a tin-free self-polishing co-polymer (SPC) and a foul release coating. Rotor measurements were carried out using different cylinders coated with both paint types. The experiments showed that the frictional resistance for the foul release test cylinders was lower than for the tin-free SPC cylinders. The drag characteristics were related to the roughness parameters of the tested surfaces measured with an optical measurement system. The measurements indicated that the texture of the foul release surface was significantly different from SPC systems. The findings show that the drag of a foul release coating will only correlate with a characteristic roughness measure that takes both the amplitude and the texture of the surface into account, and that is calculated at bandwidth parameters which depend on the degree of roughness.