How is the metacentric height (GM) calculated?

The metacentric height (GM) is a crucial measurement in marine stability, as it provides insight into the stability of a floating vessel. To calculate GM, the focus is on the vertical distance between the center of gravity (G) and the metacenter (M).

The metacenter is a point where the buoyant force acts when the vessel is tilted slightly. The center of gravity represents the point where the vessel's weight is concentrated. The vertical distance between these two points (G and M) gives us the metacentric height (GM). A higher GM typically indicates greater stability, meaning the vessel will return to an upright position more quickly after being tilted.

The other options do not accurately describe the concept of metacentric height. For example, measuring the distance between the keel and waterline is related to draft and displacement but not specifically to the calculation of GM. Similarly, the center of buoyancy to the waterline does not consider the relationship between G and M. Averaging the heights of the vessel's sides does not directly relate to stability calculations. Hence, understanding GM through its relationship with G and M is essential for assessing a vessel's stability.