Which of the following actions should be avoided when trying to prevent a collision?

Making a series of small alterations to course and speed is generally not advisable when trying to prevent a collision. This approach can create confusion for other vessels and can make it difficult for them to predict your intentions. In high-pressure scenarios, such as when a collision appears imminent, larger, more decisive actions are typically more effective. These significant alterations can clearly signal to other vessels your intended course and speed, allowing for better coordination between both parties and helping to prevent misunderstandings that could lead to a collision.

Maintaining a steady course can be part of a safe navigation strategy, especially in high-traffic areas or when you have the right of way. However, it’s essential to assess the situation continually. If another vessel's trajectory indicates a risk of collision, then action must be taken promptly, which often involves making more significant adjustments rather than a series of small changes. In contrast, making adjustments based on another vessel's trajectory is crucial for avoiding collisions, as this suggests an understanding of the situation and proactive measures to mitigate risk.