What does two short blasts mean when navigating?

Two short blasts of a vessel's whistle or horn signal an intention to alter course to port when navigating in restricted visibility or in situations where sound signals are necessary to communicate with other vessels. This sound signal is widely recognized in maritime navigation rules, specifically Rule 34 of the International Regulations for Preventing Collisions at Sea (COLREGs). The purpose of these sound signals is to ensure that other vessels are aware of your intentions and can take appropriate actions to avoid collisions.

In contrast, other options refer to different actions that are not accurately represented by the two short blasts. For example, going to starboard is indicated by one short blast rather than two, and proceeding straight does not require any blast signaling at all. Similarly, changing direction could encompass a variety of maneuvers but is not specifically defined by the two short blasts required for signaling a turn to port. Understanding these signals is crucial for safe navigation and effective communication between mariners.