Semaphore Flag

What is Semaphore?

Semaphore is a visual signaling system that uses flags held in different positions to represent letters and numbers. Developed for naval communication, semaphore allows messages to be transmitted over long distances without electronic equipment.

How Semaphore Works

The signaler holds two flags (typically red and yellow) and positions their arms at specific angles to represent each letter. There are 8 basic arm positions, arranged like clock positions:

• Position 1: Up-right diagonal (45°)
• Position 2: Horizontal right (0°)
• Position 3: Down-right diagonal (-45°)
• Position 4: Straight down (-90°)
• Position 5: Down-left diagonal (-135°)
• Position 6: Horizontal left (180°)
• Position 7: Up-left diagonal (135°)
• Position 8: Straight up (90°)

Semaphore in Geocaching

Semaphore appears in geocaching puzzles because:

• Visual clues: Images can show flag positions
• Nautical themes: Perfect for maritime-themed caches
• Physical puzzles: Actual flags or statues at waypoints
• Position numbers: The numeric positions can encode coordinates

Recognizing Semaphore

Look for these clues:

• Stick figures: With arms at various angles
• Flag imagery: Red/yellow or colored flags
• Naval references: Ships, sailors, maritime themes
• Paired numbers: Two numbers representing arm positions

Special Signals

• Rest/Space: Both arms down (6-6)
• Attention: Signal before starting
• Error: Multiple flag movements to restart
• Numeric: Special position indicates numbers follow

History

Semaphore was developed in the early 19th century for ship-to-ship and ship-to-shore communication. The system was widely used by navies around the world. While largely replaced by radio, semaphore is still taught for emergency backup communication.

Related Signaling Systems

• Morse Code: Dots and dashes for telegraphy
• Flag hoists: Colored flags for naval signals
• Heliograph: Signaling with reflected sunlight