PURPOSE: To save expense required for cleaning the hull and sufficiently hold effect of reducing the resistance of the hull by cleaning only the shell plating below the load water line for the range as far as it is approximately one fourth of the ship's length from the bow end on which fouling to the hull's shell plating greatly contributes to the increase in the resistance of the hull.

CONSTITUTION: Cleaning is done only on the surface of the shell plating below the load water line for the range 2 as far as it is approximately one fourth of the ship's length from the bow end which is part of the hull recognized as that fouling to the hull's shell plating greatly contributes to the increase in the resistance of the hull, and the cleaning is not applied for other hull's parts. Thus, necessary expenses for applying the cleaning can be widely reduced to approximately one fourth, and approximately half of the increase in the resistance of the hull can be restrained. Further, as to the range not alone at the bow part but also as far as it is approximately one fourth from the stern, if the cleaning is applied, the increase in the resistance of the hull can be reduced as much as approximately 70%.