What should a power-driven vessel do when on a collision course with a sailing vessel on her port side?

When a power-driven vessel is on a collision course with a sailing vessel on its port side, the power-driven vessel has the responsibility to keep clear. This action is consistent with the navigation rules that prioritize the safety of both vessels. In this scenario, the power-driven vessel must take measures to avoid a collision and ensure safe passage.

Keeping clear means that the power-driven vessel should pass at a safe distance, allowing the sailing vessel to continue on its course without danger. It is important to foster safe navigation practices, as the sailing vessel under these circumstances has the right of way due to its sailing status and the specific rules that apply to interactions between power-driven and sailing vessels.

While altering course to starboard could be a possible maneuver to avoid the situation, it is essential that the power-driven vessel's path does not compromise the sailing vessel's safety. Maintaining speed and course or simply signaling the other vessel would not adequately address the imminent risk of collision. Thus, the safest and most responsible action is for the power-driven vessel to keep clear of the sailing vessel, as indicated in the correct answer.