What must a vessel be able to do to navigate safely under the rules?

A vessel must be capable of all the listed actions to ensure safe navigation under the rules. Following traffic patterns is crucial because these patterns are designed to promote safety and efficiency on the water, helping vessels to avoid each other and manage crossings in a structured manner. Maintaining a steady heading is equally important, as it allows the operator to control the vessel's direction accurately, making it predictable to other boaters. Finally, the ability to avoid collisions is essential; this encompasses awareness of surroundings, understanding navigation rules, and making necessary adjustments in speed or course to steer clear of other vessels and obstacles. Each of these components plays a critical role in nautical safety, and together they enable a vessel to navigate safely in various marine environments. Therefore, the answer encompasses all necessary aspects of safe navigation.