If you are overtaking another vessel at night, what light must you show?

When overtaking another vessel at night, displaying an all-round white light is necessary to comply with the Rules of the Road. This light serves to indicate to other vessels that you are engaged in an overtaking maneuver without obscuring your navigation status or creating confusion regarding your intentions.

The all-round white light is visible to all directions, which is crucial when overtaking because it ensures that the vessel being overtaken, as well as any vessels nearby, can clearly identify your presence and the nature of your maneuver. This helps maintain safety on the water by reducing the risk of collisions.

In contrast, the other options lack the necessary visibility or do not adequately convey the message that you are overtaking. A single white light forward, for example, may not provide sufficient indication to other vessels. Two masthead lights are typically used by power-driven vessels in motion but do not convey the information required in an overtaking situation. A sternlight by itself does not communicate the overtaking status effectively and primarily indicates a vessel’s presence when it’s docked or at rest.

Hence, using the all-round white light while overtaking is essential for safe navigation and adherence to maritime regulations, ensuring that your vessel's actions are clearly understood by others on the water.