What does the term “critical angle of heel” refer to?

The concept of "critical angle of heel" is intrinsically linked to a vessel's stability and its ability to return to an upright position after being heeled over. When a vessel is heeled, it experiences a righting arm that helps it return to vertical; however, as the heel increases, this righting arm eventually reaches its maximum value. At this point, which is referred to as the critical angle of heel, the righting arm starts to decrease, indicating that the vessel is losing its ability to right itself effectively.

Understanding this angle is vital for safe navigation because it marks the threshold where the stability of the vessel declines. Beyond this angle, further heeling may result in the vessel being unable to recover, leading to potential capsizing. This defines the critical nature of this concept in terms of vessel stability management.