How is the swing circle defined in navigation?

The swing circle in navigation is defined as the area that a vessel will move in while at anchor, essentially encompassing the full extent of its potential movement due to changes in wind, tide, or current. This swing circle is calculated by taking the radius equal to the length of the ship plus the length of the anchor chain that has been veered out.

When a ship is anchored, it will pivot around the anchor point. The more chain that is let out, the greater the radius of the swing circle. This ensures that other vessels and objects in the water are within a safe distance from the anchored vessel. If the swing circle were only defined by the ship's length or any of the other provided options, it would not adequately account for the dynamic movement facilitated by the veered-out chain, which is crucial for safe navigation and mooring decisions.