Question 2493 Deck Safety

The correct answer is D) 2.57 feet. The reduction in metacentric height due to free surface effect is determined by the formula: GM' = GM - (b^3 * l) / (12 * D), where GM' is the corrected metacentric height, GM is the original metacentric height, b is the breadth of the tank, l is the length of the tank, and D is the displacement of the vessel. Given the vessel's displacement of 12,000 tons and the tank dimensions of 60 feet long and 60 feet wide, the calculation yields a reduction in metacentric height of 2.57 feet, making option D the correct answer. The other options are incorrect as they do not accurately reflect the calculated value.