As the ship heels, the metacenter moves relative to the center of buoyancy and center of gravity in which manner?

• A. It moves opposite to the center of buoyancy and slower than the center of gravity
• B. It moves with the center of buoyancy and faster than the center of gravity
• C. It remains fixed
• D. It moves unpredictably

Answer: (A)

The key idea is stability geometry. When a vessel heels, the center of buoyancy shifts toward the lower side of the hull because the submerged shape changes. The metacenter, however, is a fixed point defined by the hull geometry and the waterline for small heel angles. The center of gravity stays in its position relative to the hull unless ballast or cargo moves.

So, as you heel, the buoyant force moves, but the metacenter stays essentially in the same place (relative to the hull) for small tilts. The stability is then described by GM, the distance between the center of gravity and this fixed metacenter. The notion that the metacenter moves opposite to the center of buoyancy (or moves with it) isn’t accurate for typical small-tilt conditions.