Maritime signal flags

Marinade uses the maritime signal flags (from the International Code of Signals, which may be obtained through the International Maritime Organisation) as part of its logo and, as you can see, for navigational purposes on the web. We thought it would be only fair to provide an explanation of the flags and how they are used, not least since this will explain to you why the sixth flag in MARINADE is not the same as the second.

From this page, you can access various demos showing more advanced aspects of signal flags. On this page, the basics:

To the right, you can see the set of 40 signal flags used for international signalling. The alphabetic flags and the numeral pennants are used to represent their respective characters. The answer pennant and the substitute pennants have special functions which are described on other pages.

Usually, the signal flags are not used to spell out complete words. Instead, each flag has a special meaning when hoisted on its own - these meanings are listed here. (Note that some organisations, notably navies, attach their own meanings to the signals, while using the same flags. When a naval ship signals a merchant ship, it will sometimes fly the answer pennant at the top of the hoist, to indicate that it is applying the International Code of Signals. But merchant ships normally use the ICS only.)

There are also two-letter codes, sometimes supplemented with a numeral, for a range of possible messages between ships. For example, RU means "Keep clear of me; I am manouvering with difficulty". ZD1 means "Please report me to Coastguard, New York", while ZD2 means "Please report me to Lloyd's of London". And sometimes a two-letter code is followed by a numeric indication, for instance MG120 means "You should steer course 120".

Three-letter codes are often known by their first letter (you may have heard of Q codes for radio amateurs). For maritime use, there are M codes which indicate various questions and possible answers about medical symptoms or problems. We do not list these, nor the full set of two-letter codes, because it's a very long list and also the IMO holds the copyright.