Where is the metacentric height measured from?

Metacentric height is an important concept in naval architecture that helps determine the stability of a floating body, such as a ship. It is defined as the distance between the center of gravity and the metacenter, which is a point where the buoyant force acts when the vessel is tilted.

The correct answer, which states that metacentric height is measured vertically above the center of buoyancy, highlights how this measurement directly corresponds to the inherent stability of the vessel. When a vessel tilts, the center of buoyancy shifts, and the metacenter is established at the point where the vertical line drawn from the center of buoyancy intersects the centerline of the vessel. By measuring the distance from the center of buoyancy to the metacenter, we can assess how efficiently the vessel will return to an upright position after being tilted.

The other options do not accurately describe this critical measurement. The measurement taken horizontally from the center of gravity does not reflect how stability functions while the vessel is heeling (tilting). Similarly, measuring along the keel of the vessel or at the waterline would not yield the relevant vertical distance needed to determine stability and how effectively a vessel can right itself.