Which action should you take if you see another vessel in your path and it's changing course slowly?

The appropriate action to take when encountering another vessel that is changing course slowly is to alter your own course to avoid a collision. This decision is based on the responsibilities of mariners under navigation rules, which emphasize safety on the water. When a vessel is in your path, especially one that is moving unpredictably, it is crucial to take proactive measures to avoid any potential accidents.

Altering your course ensures that you create a safe distance between your vessel and the other, reducing the risk of misunderstanding or misjudgment about the other vessel's intentions. Floating on your current course or merely monitoring the situation without taking action can lead to an unsafe situation, especially if the other vessel’s movements become more erratic or if visibility conditions change. Sounding a horn signal can be used as a communication method but does not inherently provide a solution for preventing possible collisions. Therefore, the most prudent choice is to take action by steering your vessel to ensure safety.