Question 10General Subjects - Assistant Engineer

The correct answer is D) Filling a salt water ballast tank located below the waterline. This is because a ballast tank located below the waterline can be filled by hydrostatic pressure, without the need for a ballast pump. The water pressure outside the hull will naturally force the water into the lower ballast tank, causing it to fill. The other options are incorrect because: A) Filling an above-waterline tank would require a pump to overcome gravity, B) Draining an above-waterline tank would also require a pump, and C) Draining a below-waterline tank would require a pump to overcome the hydrostatic pressure.