Bilge. 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 bilge ceiling.
The bilge ceiling can be regarded as a continuation of the ceiling on the tank top. More simply, the radius part of the shell plating joining the bottom and the side shell is the “bilge”.
The water collected in the ship’s bilges can be pumped out by suction pipes running through both bilges.