What Do the Flags Mean
Signal flags are used to identify ships and were also to communicate between ships in the era before radio. The first International Code was drafted in 1855. It contained 70,000 signals using 18 flags! The International Code of Signals, as it is known today, has gone through several revisions since then.
Even today, because these flags have a specific, internationally agreed upon meaning, some signal flags are used by ships to communicate. For example, the "B" flag, or "Bravo" flag, is understood to mean that the ship flying that flag is carrying dangerous cargo. Additionally, flags can be combined in groups of two, three, four, five, and even six and seven flag groups.
There are 26 square flags for the letters of the English alphabet, ten numerical pendants, one answering pendant, and three "substitute" or "repeater" flags.
Only certain colors are used in signal flags, because these colors can be readily discerned over long distances at sea.
The 26 letter flags and their meanings are:
|A||Alpha||I have a Diver down. Keep well clear at slow speed|
|B||Bravo||I am taking on, carrying, or discharging dangerous cargo|
|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.
When made by fishing vessels on fishing grounds it means "I am hauling nets".
|H||Hotel||I have a pilot on board.|
|I||India||I am altering my course to port.|
|J||Juliette|| 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 immediately.|
|M||Mike||My vessel is stopped and making no way through the water.|
|P||Papa|| At Sea - My nets have come fast upon an obstruction.
In Port - All persons should report on board as the vessels is about to proceed to sea.
|Q||Quebec||My vessel is healthy and I request free pratique|
|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.|
|W||Whiskey||I require medical assistance.|
|X||X-Ray||Stop carrying out your intentions and watch for my signals.|
|Y||Yankee||I am dragging my anchor.|
|Z||Zulu|| I require a tug.
When made by fishing vessels on fishing grounds it means "I am shooting nets".
Source: HO 102 - International Code of Signals, National Imagery and Mapping Agency, 1969 edition (Revised 2003)