What is the usual effect of moving weight from low in the vessel to above the main deck?

Correct Answer: Option B — The stability is decreased.

Moving weight upward raises the vessel's center of gravity (KG). Since metacentric height (GM) is the distance between the center of gravity and the metacenter (KM), raising the center of gravity reduces GM, thereby decreasing the vessel's initial transverse stability and its ability to right itself after an inclination.