What lights should a pilot vessel exhibit when it is not engaged in pilotage duty?

When a pilot vessel is not engaged in pilotage duty, it must exhibit two all-round white lights. This configuration serves to indicate its status clearly and ensures that other vessels can identify its role when it is not performing its primary function of pilotage. The use of two all-round white lights signifies that the vessel is at anchor or in a position where it is not currently active in providing pilot services.

The requirement to display these specific lights aligns with the COLREGs (International Regulations for Preventing Collisions at Sea) standards, which govern the navigation and identification of various types of vessels based on their activities. It is essential for maintaining safe navigation and avoiding collisions by ensuring that vessels can easily recognize the operational state of other vessels on the water.

In contrast, the other options present configurations that do not meet the requirements for a pilot vessel not engaged in pilotage, as they either signify different types of vessels or operational scenarios.