International Maritime Signal Flags

A system of flags ships use to communicate messages, signals, or important information visually. Flags often represent letters, numbers, or specific meanings.

International maritime signal flags are a standardised set of flags used globally in the marine industry to facilitate communication between vessels, ships, and shore stations. Each flag represents a letter of the alphabet, a numeral, or a specific meaning when flown individually or in combination. The system, governed by the International Code of Signals, allows vessels to convey critical information, such as navigational warnings, distress signals, or operational intentions, even when language barriers or radio silence are in effect. For example, the “A” flag signifies “I have a diver down; keep well clear at slow speed,” while the “Q” flag indicates “My vessel is healthy, and I request free pratique” (clearance to enter port). 

These flags are typically hoisted on a ship’s halyards and are designed with bold colours and patterns to ensure visibility at a distance. They are particularly valuable when electronic communication is unavailable or impractical, such as during emergencies or in remote areas. Additionally, combinations of flags can spell words or convey more complex messages, though this is less common in modern maritime practice due to radio and satellite communication advancements. Despite technological progress, international maritime signal flags remain essential for the marine world’s safety, tradition, and ceremonial purposes.