The shell, including bottom and bow plating, keel, stern, sternframe and rudder; parts of the structure particularly liable to excessive corrosion or deterioration due to chafing or lying aground, and any undue unfairness of bottom plating; clearances in rudder bearings; sea connections and overboard discharge valves and their attachments; propulsion pods; propellers, sternbush and sea connection fastenings; gratings at sea inlets; clearance in the sternbush or efficiency of the oil glands.