What does the APPROACH SHIP flag hoist signal "PREP at the dip" indicate?

The "PREP at the dip" signal in naval flag hoisting indicates to the ships involved that they should prepare to disengage in 15 minutes. The phrase "at the dip" means that the flag is flown halfway down the halyard, signaling that the message is in progress or that the receiving ship should be on standby for the upcoming event. Therefore, when this signal is displayed, it is a clear indication that the crew should be ready for the actions leading toward disengagement from another vessel or for an operation that requires preparation.

This specific timing allows for coordination and ensures that all crew members are aware that preparations for disengagement should begin. Members of the crew can start completing their immediate tasks or organizing themselves for the next operational steps that will occur after the 15-minute period.