When does the statical range of stability occur?

The statical range of stability occurs when the statical stability curve crosses the base line. This point represents the transition from a condition of righting stability to one where the vessel is either at equilibrium or potentially capsizing.

When analyzing a vessel's stability, the statical stability curve illustrates the relationship between the heel angle and the corresponding righting arm. This curve helps us visualize how the righting lever (the perpendicular distance from the center of gravity to the center of buoyancy) changes as the vessel is tilted. The range of stability is defined by the angles at which the vessel can right itself after being heeled due to external forces.

As the vessel heels, the righting arm initially increases until it reaches a maximum point. Beyond this angle, the righting arm begins to decrease, indicating reduced stability. Hence, the point where the stability curve crosses the base line is critical, as it signifies the limit of the vessel's ability to return to an upright position. Understanding this concept is essential for assessing a vessel's stability conditions and ensuring safety during operations.