Which area under the curve is required to not be less than 0.090m.radians for a regular vessel?

The area under the curve from 0 to 40 degrees is significant because it represents the total righting lever, or GZ, of a vessel as it heals from an upright position to a specified angle. This area quantifies the vessel's ability to return to an upright position, which is a critical consideration in stability assessments.

For a regular vessel, the requirement that this area should not be less than 0.090 m.radians is a safety standard that ensures adequate stability under various loading conditions. By analyzing the area from the upright position to 40 degrees heel, we capture the range of angles where the vessel experiences significant righting moment, which is essential for preventing capsizing.

Additionally, the 40 degrees heel is often considered a practical limit for operating conditions, as it reflects a realistic scenario that vessels may encounter. The area from 0 to 40 degrees thus encompasses not only the vessel's initial stability but also its stability performance as it approaches these critical angles.

In this context, areas under the curve calculated for smaller ranges (such as 0 to 30 degrees or 30 to 40 degrees) do not suffice to meet the stability criteria, because they do not cover the full extent necessary to ensure that the total righting