Adding ballast to a vessel lowers its center of gravity, and increases the draft of the vessel. A ballast tank can be filled or emptied in order to adjust the amount of ballast force. Ships designed for carrying large amounts of cargo must take on ballast water for proper stability when travelling with light loads and discharge water when heavily laden with cargo.
On this geared bulk carrier an EchoSpan LU81 is measuring the level of ballast water in the upper ballast tank. As water is filled from outside the vessel the EchoSpan LU81, connected to a PLC, ensures that the ballasts are filled to optimum operating weight and evenly distributed to reduce stress on the hull structure.