Question 2499 Deck Safety

The correct answer is B. The reduction in GM (metacentric height) due to free surface effect is calculated using the formula: Δ(GM) = (IL / Δ), where I is the moment of inertia of the free surface and L is the longitudinal distance between the center of gravity of the liquid and the center of gravity of the ship. Given the vessel's dimensions of 135'L by 34'B, the moment of inertia of the free surface (I) can be calculated as (135^3 * 34) / 12 = 696,075 ft^4. With a displacement of 696 tons, the reduction in GM is (696,075 / 696) = 1 ft. The other options are incorrect because they do not correctly apply the formula to calculate the reduction in GM due to the free surface effect.