What does one long blast from a boat horn indicate?

One long blast from a boat horn is a recognized sound signal that serves as a warning to other vessels. This signaling is part of the international rules for preventing collisions at sea, which are also applicable in many local boating regulations, including those in Maryland. The long blast communicates to nearby vessels that the signaling vessel is about to take action or change its course, ensuring that other operators are aware and can take appropriate measures to avoid a potential collision.

Understanding these sound signals is crucial for safe navigation, as they facilitate communication between vessels in situations where visibility may be compromised, such as fog or heavy rain. It’s important for boaters to familiarize themselves with these signals to enhance safety on the water. In contrast, the other choices misrepresent the purpose of a long blast, as it does not indicate a signal for docking, a command to come closer, or a cue to leave.