q flag

License given to a ship to enter a port free from contagious disease
Pratique is the license given to a ship to enter a port free from contagious disease, indicating it is safe for entry.
Symbol for Request
A ship requests pratique by flying a solid yellow square-shaped flag known as the Q flag.
Consequences Without Pratique
If free pratique is not granted, the vessel will be held in quarantine until inspection and clearance.
The Q flag, also known as the "Quebec" flag in the International Code of Signals, is a solid yellow square flag used in maritime contexts to indicate a request for health clearance or "free pratique" when entering a port. Its primary purpose is to signal that the vessel is free from contagious diseases and requests permission to enter the port and conduct operations.

Key Points about the Q Flag

  • It is flown when a vessel arrives at a foreign port or returns to its home port after an international voyage.
  • It signals to port authorities that the vessel is "healthy" and requests clearance to enter and conduct operations (free pratique).
  • If clearance is granted, the Q flag is lowered, and the courtesy flag of the host nation is raised.
  • If clearance is denied due to health concerns, the vessel remains under quarantine until the issue is resolved, continuing to fly the Q flag.

Historical Usage

  • The yellow color has a long history of representing disease, previously used to mark infected houses before its maritime usage.
  • It was also used to mark cholera-infected ships and became associated with yellow fever, earning the nickname "Yellow Jack".
  • The letter "Q" likely derives from its initial use in signaling "quarantine".
In summary, the Q flag is an internationally recognized maritime signal flag used to request health clearance and free pratique when entering a port, indicating the vessel is free from contagious diseases.
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