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

When trying to prevent a collision at sea, making a series of small alterations to course and speed may not be effective in ensuring a clear passage. Such minor adjustments might confuse other vessels about your intentions, leading to uncertainty and increasing the risk of a collision. Clarity of action is paramount in collision avoidance; significant and decisive maneuvers provide a clear and predictable response which other vessels can easily interpret.

In contrast, maintaining a steady course allows other vessels to understand your path and anticipate your movements, which is essential in busy waterways. Taking action based on the other vessel's trajectory is critical in assessing potential collision risks, and making significant alterations to course and speed can be a decisive response when a risk is detected. The emphasis lies on providing clear and effective navigation maneuvers that all nearby vessels can understand and respond to appropriately, thus enhancing overall maritime safety.