In stability theory, what does the term "heel" refer to?

In stability theory, "heel" specifically refers to the angle of tilt from the vertical that a vessel achieves when subjected to external forces, such as wind or waves. This tilt occurs as the center of gravity and center of buoyancy shift in response to these forces. When a vessel heels, it affects the stability of the vessel by changing the metacentric height and ultimately influencing its ability to right itself when the external force is removed. Understanding heel is crucial for determining the ship's stability, particularly when navigating through conditions that may cause the vessel to lean to one side. This concept is fundamental in ensuring the safety and operational efficiency of maritime operations.