Signal flags, sometimes called Code of Signals or International Code of Signals, are the colorful flags attached ribbon-like to the masts of boats. Today they are mainly decorative, serving to dress up ships, but they have a real, vital function. And that function is understood by sailors throughout the world.
Signal flags are used at sea and in harbors for communication between ships. They spell out short messages, and individual flags and various combinations of flags also have special meanings. Experienced sailors have learned the international signal flag language and communicate with each other whether they are in their home country or thousands of miles away in foreign waters.
Peter Thompson, an American sailing off the coast of Costa Rica, can attest to their value. "Because I was a relatively inexperienced sailor and unfamiliar with this particular Costa Rica harbor, I used the yellow and blue Keep Clear signal flag to warn other boaters," he remembers humorously of his 2008 Central American adventure. "The other boats gave me a wide berth and made docking a breeze. I didn't damage any other vessel and avoided an international incident."
Devised over a hundred and fifty years ago, signal flags include 26 square flags which depict the letters of the alphabet. Depending on the boat, flags are available in a variety of sizes. Only bold, easily seen colors are used on the flags including red, blue, yellow, black and white. For clarity at a distance, flags are either red and white, yellow and blue, blue and white or black and white. There are also solid yellow and red signal flags.
Here are the 26 alphabet signal flags and their meanings.
Alfa for A flag means diver down, keep clear.
Bravo for B means dangerous cargo.
Charlie for C designates yes.
Delta means keep clear.
Echo means altering course to starboard.
Foxtrot for F means disabled.
Gold for G means want a pilot.
Hotel for H means pilot on board.
India means altering course to port.
Juliet means on fire, keep clear.
Kilo designates desire to communicate.
Lima means stop instantly.
Mike = I am stopped.
November is no.
Oscar = man overboard.
Papa is about to sail.
Quebec means request pratigue or license to enter port.
Romeo means the way is off my ship.
Sierra = engines going astern.
Tango = keep clear.
Uniform = standing into danger.
Victor = require assistance.
Whiskey = requires medical assistance.
Xray means stop your intention.
Yankee = am dragging anchor.
Zulu = require a tug.