How should alterations to course or speed be made to avoid collision?

When navigating to avoid collision, making large alterations to course or speed that are readily apparent to other vessels is the most effective practice. This approach ensures that other operators clearly observe your intentions, allowing them to adjust their own navigation accordingly. Visibility of your intentions helps to prevent confusion and maintain safety among all vessels in the vicinity.

In busy marine environments, clear communication through navigation maneuvers is vital. If a vessel alters its course or speed in a subtle or minimal way, as suggested by other options, it may not be noticed by nearby vessels, potentially leading to misunderstandings and possible collisions. Therefore, making significant, easily observable changes not only promotes clarity but also aligns with the COLREGs guidelines that emphasize actions aimed at avoiding collisions should be obvious to all parties involved.

In summary, when faced with the need to avoid a collision, ensuring that the alterations are significant and observable promotes safer navigation practices for everyone on the water.