What is the significance of the righting arm in stability analysis?

The righting arm is a critical concept in stability analysis as it measures the vessel's resistance to tipping, particularly when it is heeled or tilted. The righting arm is the horizontal distance between the center of gravity and the center of buoyancy when the vessel is heeled. A larger righting arm means that the vessel has a greater ability to return to an upright position after being tilted by external forces, such as wind or waves. This resistance to tipping is vital for ensuring the safety and stability of the vessel during various conditions at sea.

In the context of the other options, the degree of list relates to the angle at which the vessel is already leaning, which is not the same as the righting arm measurement. The vessel's speed is determined by factors like engine power and hull design rather than by the righting arm. The amount of cargo a vessel can safely carry is influenced by stability but is not directly indicated by the righting arm itself; it encompasses a broader analysis involving overall stability criteria, loading conditions, and trim. Thus, the significance of the righting arm lies primarily in its crucial role in indicating a vessel's stability and its ability to recover from heeling.