The 3rd engineer on watch reports than the ship has an erratic rolling behavior and it does not appear to stabilize at an even keel position. As Chief Engineer, after consultation with the Chief Mate, what instruction would you give him?

Correct Answer: Option A — Add ballast to a center line double bottom tank.

Erratic rolling and failure to settle at an even keel indicate a dangerously low or negative metacentric height (GM) caused by excessive free surface or high vertical weight. Adding ballast to a centerline double bottom tank lowers the center of gravity and increases GM.