What action should you take if you see a stand-on vessel failing to maintain its course?

When observing a stand-on vessel that is failing to maintain its course, the appropriate action is to alter your course to avoid a potential collision. The stand-on vessel is expected to maintain its course and speed in accordance with the "Rules of the Road." If it is not doing so, and you notice signs that it may not be following the rules properly or is in danger of collision, taking action to avoid the situation becomes necessary.

Altering your course helps prevent a dangerous scenario where both vessels might be on a collision path. This action emphasizes the principle of safe navigation, which is crucial for ensuring the safety of all vessels in the area. Maneuvering to avoid the vessel is the most responsible choice, as it prioritizes safety and adherence to navigational rules.

Maintaining your course and speed could lead to a collision if the stand-on vessel continues to deviate from its expected path. Sounding your horn might be useful for alerting the other vessel; however, it does not contribute to immediate avoidance. Reporting the situation is sometimes necessary, but it does not address the urgent need to prevent a collision in real-time.