When two vessels are approaching one another, what should they do to avoid a collision?

The correct answer highlights the importance of both vessels altering their course to starboard when approaching each other. According to the Navigation Rules, specifically the International Collision Regulations (COLREGs), vessels are required to take measures to avoid collisions by following established protocols.

When two power-driven vessels approach each other, they must determine their action based on the situation. The rule that applies here specifies that each vessel should turn to starboard, or right, to pass each other with a safe margin. This maneuver reduces the risk of collision as it promotes a predictable movement that helps both vessels navigate safely past one another.

In some situations, maintaining course and speed or having one vessel stop might seem appropriate, but these actions can lead to confusion or increased risk of collision if the movements of the vessels are not clear. Sounding the horn is a communication tool typically used to signal intentions or alert other vessels, but it does not contribute to physically avoiding a collision on its own. Hence, the most effective action, as described, is to alter course to starboard for both vessels.