When sailing internationally, vessels are expected to fly certain flags based on their registry, ownership, and status. Here’s a breakdown of the key flags and their meanings:

1. National (Ensign) Flag – “Ship’s Flag”

• This is the primary flag that identifies the vessel’s country of registration (also called the “flag state”).
• It must be flown at the stern (back) of the boat.
• Required in most territorial waters and while entering/leaving ports.
• Different countries have specific maritime ensigns.
• Read about the history of blue vs red ensign…

2. Courtesy Flag – “Visiting Country’s Flag”

• Flown on the starboard spreader of a sailboat or on a mast/hardtop for powerboats.
• Signals respect to the country whose waters you’re in.
• Hoisted after clearing customs and replacing the quarantine flag (“Q” flag).
• Must be in good condition—a tattered flag can be seen as disrespectful.
• Read more about courtesy flags.

3. Quarantine Flag (“Q” Flag) – Entering a New Country

• A solid yellow flag, indicating the boat has not yet cleared customs and immigration.
• Flown at the starboard spreader before entering port.
• Replaced by the courtesy flag once clearance is granted.

4. Owner’s or Private Signal Flag

• Some yacht owners have personal house flags or private signals, flown from the mainmast or bow staff.
• Often used in yacht clubs or by distinguished owners.
• Not required but adds a personal touch to a vessel.

5. Club or Association Burgee

• Small triangular flags that show yacht club membership.
• Flown from the masthead or bow staff.
• Not required, but a tradition among sailors.

6. Racing Flags

• Special pennants are flown when participating in regattas or official races.
• Each event has its own flag rules.

Flag Etiquette & Rules

• The national ensign should be the largest and most prominent.
• Flags should be taken down at sunset unless the boat is underway.
• Tattered or dirty flags should be replaced.
• Never fly a courtesy flag higher than your national ensign.

As an aside, a ship ‘wears’ the flag, whereas the owner of the ship ‘flies’ the flag. Also, rather than saying ‘raising’ the colours, one says the colours are ‘made’.