On a vessel of 12,000 tons displacement, what is the reduction in metacentric height due to free surface when a tank 60 feet long and 60 feet wide is partially filled with water?

Correct Answer: Option D — 2.57 feet

Evaluating a 60 ft long by 60 ft wide slack tank on a 12,000-ton displacement vessel requires multiplying the tank's moment of inertia by the fluid density ratio, resulting in a substantial metacentric height reduction of 2.57 feet.