What does the "GZ curve" in stability assessments illustrate?

The GZ curve is a critical tool in stability assessments as it illustrates the righting arm for various angles of heel. The righting arm, denoted as 'GZ', is the horizontal distance between the center of gravity (G) of the vessel and the center of buoyancy (B) when the vessel is heeled over at an angle. This measurement is crucial because it directly indicates the ability of the vessel to return to an upright position after being heeled by external forces, such as wind or waves.

As the angle of heel increases, the GZ value will change, which is represented graphically in the GZ curve. A larger righting arm suggests a greater ability for the vessel to right itself, which is essential for maintaining stability and safety at sea. The shape and characteristics of the GZ curve help mariners evaluate the stability of the vessel at various angles and understand at what points the vessel may become optimistic or lose its stability.

Understanding the GZ curve helps ensure that the vessel is seaworthy and capable of managing the forces experienced during operation, contributing significantly to the safety of navigation and vessel performance.