In port, what flag is flown by the ship having the ready duty?

The flag flown by a ship having the ready duty in port is the Romeo flag. This flag is specifically designated for communicating that a vessel is ready to conduct operations. When the Romeo flag is displayed, it signals to other vessels and personnel in the vicinity that the ship is prepared to execute tasks or respond to emergencies.

In maritime operations, proper flag signaling is crucial for conveying information quickly and effectively, especially in busy port environments. The Romeo flag serves a distinct purpose, emphasizing the ship's readiness status.

Other flags mentioned, such as Golf, Echo, and Baker, represent different messages and situations. While they each have their respective meanings—such as indicating specific types of operations, communicating safety statuses, or alerting to medical emergencies—they do not pertain to a vessel's readiness for duty in port. Hence, the use of the Romeo flag in this context is both appropriate and essential.