Maritime Signal Flags

What are Maritime Signal Flags?

International Maritime Signal Flags are a standardized system of flags used for communication at sea. Each flag represents a letter of the alphabet, a number, or has a specific meaning when flown alone or in combination.

The Flag Alphabet

There are 26 letter flags (A-Z) and 10 number pennants (0-9). Each flag has a specific design and colors, plus a phonetic name (Alfa, Bravo, Charlie, etc.) that corresponds to the NATO phonetic alphabet.

Single Flag Meanings

When flown alone, many flags have specific meanings:

• A (Alfa): Diver down; keep clear at slow speed
• B (Bravo): Taking on or discharging dangerous cargo
• N (November): No/Negative
• C (Charlie): Yes/Affirmative
• O (Oscar): Man overboard
• P (Papa): Blue Peter - vessel about to sail

Maritime Flags in Geocaching

Maritime signal flags appear in geocaching puzzles because:

• Nautical themes: Perfect for coastal or maritime caches
• Visual encoding: Colorful flags make engaging puzzles
• Layered meanings: Both letters and flag meanings can be clues
• Historical: Rich naval tradition and history

Recognizing Flag Puzzles

Look for:

• Colorful rectangular flags in images
• References to ships, navy, or sailing
• Flags hung on a line or arranged in sequence
• Phonetic alphabet names (Alfa, Bravo, etc.)

History

The International Code of Signals dates back to 1857 and has been revised several times. The current version was adopted in 1969. Before radio communication, signal flags were the primary method of ship-to-ship communication over distances.