What lights should be displayed by vessels at anchor at night?

Vessels at anchor at night are required to display an all-round white light. This is crucial for navigation safety, as the all-round white light makes the vessel visible to other boats in the area. It indicates the position of the stationary vessel to other operators, helping to prevent collisions in low-light conditions.

Displaying an all-round white light is part of the International Regulations for Preventing Collisions at Sea, which aim to ensure that all vessels maintain safe navigation practices. This requirement is in place to signal to other vessels that the anchored vessel is not under way, allowing sufficient time for other operators to adjust their course or speed accordingly.

The other options do not comply with the standards set for vessels at anchor. Using two all-round green lights could mislead other vessels into thinking the anchored vessel is under way. Not displaying any lights could create a hazard, as the vessel would become virtually invisible during night operations. A combination of a red and green light typically signifies a vessel under way, navigating, and not applicable to vessels at anchor.