What lights must a power-driven vessel underway display at night?

A power-driven vessel underway at night is required to display navigation lights in accordance with the International Regulations for Preventing Collisions at Sea (COLREGs). These lights serve critical purposes: they help indicate the vessel's presence, position, and safe navigation intentions to other vessels.

The navigation lights for a power-driven vessel include a white masthead light and side lights (red on the port side and green on the starboard side), and in many cases, a stern light as well. Displaying these lights is essential for the safety of all vessels, as it enables them to see each other and take necessary actions to avoid collisions.

In contrast, choices focusing on anchor lights, not displaying lights, or using deck lights do not fulfill the legal requirements for navigation and can jeopardize safety on the water. Anchor lights are designated for vessels that are at anchor, while deck lights are not intended for indicating the vessel's navigational status. Not displaying lights at all would create a significant hazard, as it would leave the vessel practically invisible to others. Therefore, navigation lights are necessary for any power-driven vessel that is underway at night.