The bilge of a vessel with double bottom tanks is a triangular channel on both sides formed by the margin plate of a double bottom, the curvature of the outer skin of the vessel and the blige ceiling. The bilge ceiling can be regarded as a continutaion of the ceiling on the tank top. More simply, the redius part of the shell plating joining the bottom and the side shell is the "bilge". It is actually the area where the surplus liquids from ships are collected.