Effect of barnacle fouling on ship resistance and powering

Predictions of added resistances and effective powers of ships were made for varying barnacle fouling conditions. A series of towing tests were carried out using flat plates covered with artificial barnacles. The tests were designed to allow the examination of the effects of barnacle height and percent coverage on the resistance and effective power of ships. The drag coefficients and roughness function values were evaluated for the flat plates. Roughness effects of the fouling conditions on the ship frictional resistances were predicted. Added resistance diagrams were then plotted using these predictions, and powering penalties of these ships were calculated using the generated diagrams. The results indicate that the effect of barnacle size is significant, since 10% of the coverage of barnacles, which are 5mm in height, causes a similar level of added power requirements as 50% of the coverage of barnacles, which are 1.25 mm in height.