What type of maneuver should be performed when a "MAN OVERBOARD" call is heard while underway in thick fog?

When a "MAN OVERBOARD" call is made while underway in thick fog, the Williamson Turn is the most appropriate maneuver to execute. This steep turn is designed specifically for recovering a person who has fallen overboard, allowing the vessel to safely and effectively return to the last known position of the person in the water.

The Williamson Turn involves turning the vessel 180 degrees while maintaining the same track, which is then followed by a straight course that takes the vessel back toward the person in the water. This maneuver is particularly advantageous in poor visibility conditions, such as fog, as it allows the crew to maintain awareness of the victim's location while minimizing the risk of losing sight of them.

In foggy conditions, options like the Circle Maneuver or Quick Stop Maneuver may not provide the same level of safety or precision needed for an effective recovery, as they could lead to longer recovery times or complications due to limited visibility. Steady Course Maintenance would also be ineffective, as failing to take action immediately could reduce the chances of safely recovering the individual. Therefore, the Williamson Turn is the best choice for managing a man overboard situation in thick fog.