Frictional resistance contributes up to 80-90% of the total resistance for commercial vessels. An increase in resistance results in higher fuel consumption, harmful greenhouse gas emissions and higher (engine) maintenance – ultimately higher cost for ship owners and operators.
Therefore, much attention has always been paid to understanding and predicting frictional resistance of a ship in the design phase. To make such predictions, detailed knowledge of the frictional resistance coefficient of the wetted surface area of the ship is required. This frictional resistance coefficient depends largely on the roughness and texture of the wetted surface area. Effects of physical roughness parameters on the friction coefficient were established long ago in towing tank experiments and are well documented.1 Thereafter, other studies were published on the relationship between surface roughness of non-fouled hull coatings and friction drag performance. At that time, so-called self-polishing antifouling paints (based on TBT) gained a strong market position due to their advanced binder technology, resulting in a smooth surface on which minimal fouling could settle. Further investigations into friction drag consequences of changes in hull roughness due to paint polishing have been reported by Townsin et al.1 and Grigson.2