The effect of cleaning and repainting on the ship drag penalty

Although the hull of a recently dry-docked large ship is expected to be relatively smooth, surface scanning and experimentation reveal that it can exhibit an "orange-peel" roughness pattern with an equivalent sand-grain roughness height $$ = 0. 101 mm. Using the known $$ value and integral boundary layer evolution, a recently cleaned and coated full-scale ship was predicted to experience a significant increase in the average coefficient of friction $$ and total hydrodynamic resistance $$ during operation. Here the report also discusses two recently reported empirical estimations that can estimate k directly from measured surface topographical parameters, by-passing the need for experiments on replicated surfaces. The empirical estimations are found to have an accuracy of 4.5 - 5 percentage points in $$