What action should you take when overtaken by a vessel not under command?

When overtaken by a vessel not under command, the appropriate action is to stand on with caution. This means you should maintain your course and speed while being vigilant about the movements of the overtaking vessel, as it may not be able to maneuver appropriately due to its situation. The COLREGs (International Regulations for Preventing Collisions at Sea) provide a framework for understanding the responsibilities of vessels in various situations, and when encountering a vessel that is not under command, the safest approach is to continue on your course but be prepared to take action if necessary.

Standing on with caution allows you to assess the situation while maintaining your own navigational safety. Conversely, changing course immediately or adjusting speed might complicate the situation or create additional hazards. Giving way to a vessel not under command is unnecessary since they are unable to comply with navigation rules, and increasing speed could lead to dangerous interactions with the overtaking vessel. Thus, remaining cautious while standing on is the most prudent response in this scenario.