You sight another power-driven vessel dead-ahead showing both the red and green sidelights. The required action to take would be to __________.

When you sight another power-driven vessel displaying both red and green sidelights directly ahead, this indicates that the other vessel is operating in a restricted manner, often suggesting that it could be a vessel that is not making way or is stationary. The appropriate action to take in this situation is to alter your course to starboard.

By turning to starboard, you position yourself to pass the other vessel safely on its port side, in accordance with maritime navigation rules. This ensures that you avoid a potential collision with the other vessel. The rules of the road emphasize the importance of keeping a safe distance and being aware of other vessels' orientations to navigate effectively.

In navigating safely in a well-trafficked area, this response is critical to ensuring that both vessels can continue on their intended courses without incident.