Question 2481 Deck Safety

The correct answer is B) 9.45 feet. The reduction to GM (metacentric height) due to free surface effect is calculated using the formula: Reduction to GM = (Free Surface Moment / Displacement) / GM. In this case, the free surface moment is the weight of the water (80 tons) multiplied by the transverse distance between the centerline and the center of gravity of the water on the after deck (65'/2 = 32.5 feet). Plugging in the values, the reduction to GM is (80 * 32.5) / 968 / GM, which equals 9.45 feet. The other answer choices are incorrect because they do not accurately apply the free surface effect formula given the provided vessel dimensions and water weight.