Margin plate

The margin plate is the outermost strake of the inner bottom (tank-top) plating in a double-bottom ship, running along each side where the inner bottom meets the bilge and turns down to the shell. It closes the double-bottom space at the turn of the bilge and forms the inboard boundary of the bilge well or duct keel margin. In older riveted and many welded designs the margin plate is set at an angle from the floors down to the shell, transferring floor loads into the side shell and bracketing the floors to the frames. It defines the outboard edge of the double-bottom tanks.