What light arrangement is used for a vessel not under command and not making way?

The arrangement of lights for a vessel that is not under command and not making way is characterized by two red lights displayed vertically over another red light. This specific configuration is mandated by the International Regulations for Preventing Collisions at Sea (COLREGs) to indicate to other vessels that the ship is unable to maneuver and is therefore restricted in its ability to carry out its navigation.

This three-light arrangement helps ensure that other vessels recognize the situation and can take appropriate actions to avoid a collision, maintaining safe distances from the vessel that is not under command. The use of red lights in this indication signifies distress or a danger to navigation, thereby serving one of the critical safety functions in maritime operations.

Understanding the arrangement of navigation lights is crucial for safe maritime navigation, as it allows vessels to communicate their status effectively and ensures that all parties are aware of potential hazards on the water.