Why Flag Signals?
Flag-based encoding creates visually memorable puzzles that work great for:
- Coastal and harbour caches — Perfect thematic fit
- Military or Scout themes — Semaphore has historical significance
- Visual puzzles — Images can be placed in the field
- Multi-stage adventures — Flags work well at waypoints
Flag Signalling Systems
Semaphore Flags
Arm positions with handheld flags represent letters and numbers. Each letter uses a unique combination of arm angles.
Best for: Scout themes, historical caches, physical puzzles
International Maritime Signal Flags
26 flags for letters, 10 for numbers, plus special signals. Each flag has distinct colours and patterns.
Best for: Harbour/coastal caches, sailing themes
NATO Flag Signals
Same as maritime flags but with standardised meanings for military communication.
Best for: Military themes, aviation
Racing/Motorsport Flags
Chequered, yellow, red, green—each has specific meanings in racing.
Best for: Racing circuit caches, motorsport themes
Creating Semaphore Puzzles
Semaphore is the most accessible flag system for puzzles. Each letter is shown by arm positions at 45° intervals:
Presentation Methods
- Images: Create or use semaphore diagrams in your listing
- Physical: Place actual flag positions at waypoints
- Descriptive: "Arms at 10 o'clock and 4 o'clock"
- Clock positions: Use clock face analogy for positions
Tool: Use our Semaphore Flags tool to generate visual diagrams and verify your encoding.
Creating Maritime Flag Puzzles
Maritime signal flags are colourful and distinctive. Key flags for numbers:
0
Yellow/black horizontal
1
White/red pennant
2
Blue/white pennant
3
Red/white/blue vertical
4
Red/white cross
5
Yellow/blue square
6
Black/white diagonal
7
Red/yellow horizontal
8
White/red cross
9
White/red/blue/yellow
Puzzle Ideas
- Photo flags: Photograph real flags on boats or marinas
- Draw flags: Include flag illustrations in your listing
- Describe patterns: "A flag with blue and white squares"
- Field placement: Print laminated flags to hide at waypoints
Step-by-Step Creation
1. Choose Your Flag System
Match the system to your cache theme. Coastal? Use maritime flags. Scout area? Try semaphore.
2. Decide on Presentation
Will you use images in the listing, physical flags in the field, or text descriptions?
3. Encode Your Message
Convert coordinates to flag signals. Test decode to verify accuracy.
4. Add Context
Create a backstory. "An old sailor left these signals before his last voyage..."
5. Test Your Puzzle
Have someone unfamiliar with flag signals attempt your puzzle with reference material.
Complete Example Puzzle
Cache Title: "Signal Station"
Cache description:
"The old signal station on the headland has been silent for decades. But if you know the maritime code, these flags still have a message to share."
[Image showing a sequence of 8 maritime signal flags]
"The flags spell out the final coordinates. The first four give latitude degrees and decimal minutes, the next four give longitude."
Solution:
Flags: 5-1-2-3 and 0-0-4-5
Decoded: N 51° 23.xxx, W 00° 45.xxx
(Minutes would need additional encoding)
Difficulty Variations
Easy (D1.5-D2)
- Name the flag system explicitly
- Use clear, labelled images
- Provide a reference chart
Medium (D2.5-D3)
- Don't identify the specific system
- Use photographs of real flags
- Mix letters and numbers
Hard (D3.5+)
- Use partial or obscured flags
- Require research to identify the system
- Combine with other encoding methods
Pro Tips
- Check flag visibility. If using physical flags, ensure colours won't fade quickly in weather.
- Consider colourblind solvers. Don't rely solely on red/green distinctions. Add patterns or shapes.
- Use standard systems. Don't create custom flag meanings unless you provide a clear key.
- Test in the field. If placing physical elements, verify they're visible and durable.