Flags – Signal Code Message Definitions
Signal flags are used at sea for communication between ships. Individual flags and combinations of flags can spell short messages, and some of them have special meanings as well.
Signal Code Flag Definitions – PDF
| Letter/Number | Signal Flags | Signal Flag Meanings | Yacht / Dinghy Racing Signal Meanings |
|---|---|---|---|
| A |  | Diver below (when stationary); I am undergoing a speed trial | |
| B |  | I am taking on or discharging explosives | Protest |
| C |  | Yes (affirmative) | Position of next mark has been changed |
| D |  | Keep clear of me, I am manoeuvring with difficulty | Don’t launch/follow this rib |
| E |  | I am altering my course to starboard | |
| F |  | I am disabled, communicate with me | |
| G |  | I require a pilot | |
| H |  | I have a pilot on board | |
| I |  | I am altering my course to port | Round the ends |
| J |  | I am going to send a message by semaphore | |
| K |  | You should stop your vessel instantly | |
| L |  | You should stop, I have something important to communicate | Change to SIs or other amendment |
| M |  | I have a doctor on board | There is a mark missing |
| N |  | No (negative) | Abandon |
| O |  | Man overboard | Rule 42 is waived |
| P |  | The Blue Peter – all aboard, vessel is about to proceed sea. (At sea) your lights are out or burning badly | Preparatory |
| Q |  | My vessel is healthy and I request free practique | |
| R |  | The way is off my ship. You may feel you way past me | Rule 42 is restored |
| S |  | My engines are going full speed astern | shortened course |
| T |  | Do not pass ahead of me | |
| U |  | You are standing into danger | One step less stringent than a black flag, allows boats back in after a general recall or abandonment |
| V |  | I require assistance (not distress) | |
| W |  | I require medical assistance | |
| X |  | Stop carrying out your intentions and watch for my signals | Individual recall |
| Y |  | I am carrying mail | Lifejackets must be worn |
| Z |  | To be used to address or call shore stations | 20% scoring penalty |
 | 1st Subsititute | ||
 | 2nd Subsititute | ||
 | 3rd Subsititute | ||
 | Answer | Postponement | |
| 0 |  | ||
| 1 |  | ||
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| 9 |  |
