What configuration indicates that a vessel is not making way?

A vessel that is not making way through the water typically indicates its status with two vertically disposed red lights. This configuration serves as a crucial signal to other vessels that the vessel is anchored, aground, or stopped in the water, effectively communicating its inability to maneuver.

The use of two red lights, positioned vertically one above the other, is standardized in maritime navigation rules to ensure consistency and clarity among vessels, helping to prevent collisions and enhance safety. This light configuration can be easily recognized by other mariners, allowing them to take the necessary precautions while navigating around the stationary vessel.

The other options provide signals associated with different operational states or maneuvers that do not relate to a vessel's inability to move through the water. For instance, white lights typically indicate restricted visibility or may be used in specific signaling situations, while green lights are often used by vessels to indicate starboard side navigation. An all-round red light usually signifies a vessel engaged in fishing or at anchor but does not exclusively indicate that it is not making way. Hence, the use of two vertically disposed red lights specifically communicates the status of a vessel that is not making way.