Using it
Type a message and each letter is drawn as its flag, each digit as its numeral pennant. Every word becomes its own hoist, read from the top, which here means left to right. The steps name each flag, say what it looks like, and give the meaning it has when flown alone. Punctuation is dropped, because the code has no flags for it. A full stop between digits is the exception, and becomes the answering pennant as a decimal point.
A ship carries only one set of flags. So a letter can't simply be flown twice in one hoist. Set Repeated letters to Use substitutes and the repeat is made the way the code does it, with a substitute flag. Leave it on Fly the flag again for bunting or a decoration.
The nautical flag alphabet
The nautical flag alphabetstringmash.com/nautical-flags
What each flag means on its own
| Flag | Name | Meaning |
|---|---|---|
| A | Alfa | I have a diver down; keep well clear at slow speed. |
| B | Bravo | I am taking in, or discharging, or carrying dangerous goods. |
| C | Charlie | Yes (affirmative). |
| D | Delta | Keep clear of me; I am maneuvering with difficulty. |
| E | Echo | I am altering my course to starboard. |
| F | Foxtrot | I am disabled; communicate with me. |
| G | Golf | I require a pilot. (From fishing vessels close together on the grounds: I am hauling nets.) |
| H | Hotel | I have a pilot on board. |
| I | India | I am altering my course to port. |
| J | Juliett | I am on fire and have dangerous cargo on board: keep well clear of me, or I am leaking dangerous cargo. |
| K | Kilo | I wish to communicate with you. |
| L | Lima | You should stop your vessel instantly. |
| M | Mike | My vessel is stopped and making no way through the water. |
| N | November | No (negative). |
| O | Oscar | Man overboard. |
| P | Papa | In harbour: all persons should report on board, as the vessel is about to proceed to sea. |
| Q | Quebec | My vessel is “healthy” and I request free pratique. |
| R | Romeo | No meaning on its own. |
| S | Sierra | I am operating astern propulsion. |
| T | Tango | Keep clear of me; I am engaged in pair trawling. |
| U | Uniform | You are running into danger. |
| V | Victor | I require assistance. |
| W | Whiskey | I require medical assistance. |
| X | Xray | Stop carrying out your intentions and watch for my signals. |
| Y | Yankee | I am dragging my anchor. |
| Z | Zulu | I require a tug. (From fishing vessels close together on the grounds: I am shooting nets.) |
Substitutes: repeating a flag
The three substitutes are triangular flags that copy another flag in the same hoist. The 1st substitute repeats the topmost flag of the kind just above it, letters or numerals. The 2nd repeats the second, and the 3rd the third. Each can be used once in a hoist, and the answering pennant, flown as a decimal point, doesn't count.
The code gives three examples. VV is V then the 1st substitute. 1100 is 1, the 1st substitute, 0, then the 3rd substitute, because that 0 is the third numeral from the top. In L 2330 the substitute follows a numeral, so it counts numerals only and skips the L, giving L, 2, 3, the 2nd substitute, 0. A repeat that no substitute can make needs a second set of flags. The steps say so.
Where the code came from
A committee of the British Board of Trade drafted the first international code in 1855, and it was published in 1857: 70,000 signals using eighteen flags. It was revised in the 1890s and again in 1930, and the code used today was adopted in 1965 and in force from 1969, in nine languages. Two- and three-letter groups stand for whole messages, so a ship can say a great deal without a common language: NC means I am in distress and require immediate assistance, and CB means I require immediate assistance.
Ships also fly the flags for show. Dressing ship means stringing every flag from bow to stern on a holiday, and yacht clubs and seaside towns hang them as bunting. The names on the plate, Alfa to Zulu, match the NATO phonetic alphabet, which the code uses for spelling by voice.
Questions
What does the O flag mean?
Oscar, cut corner to corner in red and yellow, means Man overboard. It's the best known single-flag signal, and the same red and yellow are used for semaphore flags at sea.
Which flag means a diver is down?
A, Alfa, white and blue with a swallowtail: I have a diver down; keep well clear at slow speed. The red flag with a white diagonal stripe seen at dive sites in the US is a separate, recreational sign, not part of the code.
Why do some flags have the same colours?
The code uses only red, blue, yellow, black and white, because they stay tellable apart at a distance and at sea. The shades aren't fixed: makers choose their own, so the colours here are ours.
How do you show numbers?
With the ten numeral pennants, the long tapering flags. Older code books and navies use their own numeral flags, so you may see other designs.
Sources
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