A Guide to Nautical Flags & Code Signals

They are a colorful feature on countless docks, seaside architecture and coastal decor, but what is the meaning and significance behind Nautical flags, aka Burgees. Their role throughout the history of maritime warfare make their origination a seaworthy tale. Here is a quick Guide to Nautical Flags & Code Signals for the recreational boater.

Nautical flags were originally used in ancient military encounters where flags signaled other fleet members to take specific actions.  Early flag communications were limited; centuries before radios and sonar, they were the only a way to communicate, instigate or investigate passing or oncoming vessels.

Code signal flags are used in an internationally-understood system that include 26 square flags which depict the letters of the alphabet, ten numeral pendants, one answering pendant, and three substituters or repeaters.  As one would expect, only a few colors can be readily distinguished at sea. Their visibility is crucial and the primary colors of red, blue, yellow, black, and white are the most discernable from afar. The combination of these colors are carefully thought out. You will notice, for clarity, the flags shown are either red and white, yellow and blue, blue and white, or black and white. Keeping the contrast was key to being effective when hundreds, if not thousands of miles off shore.

As with any language barrier, there was a need to develop a code that would work within International waters, between foreign governments and vessels. Hence, the International Code Signals (ICS) were introduced.

International Code Signals

  • A: Alpha – diver down; keep clear
  • B: Bravo – carrying dangerous cargo
  • C: Charlie – yes
  • D: Delta – keep clear
  • E: Echo – altering course to starboard
  • F: Foxtrot – I am disabled
  • G: Golf – I want a pilot
  • H: Hotel – a pilot on board
  • I: India – I am altering course to port
  • J: Juliet – vessel on fire keep clear
  • K: Kilo – I want to communicate with you
  • L: Lima – stop your vessel instantly
  • M: Mike -my vessel is stopped
  • N: November – no
  • O: Oscar – Man overboard
  • P: Papa – vessel is about to sail
  • Q: Quebec – I request free pratique
  • R: Romeo – reverse course
  • S: Sierra – engines are going astern
  • T: Tango – keep clear
  • U: Uniform – you are heading into danger
  • V: Victor – require assistance
  • W: Whiskey – require medical assistance
  • X: X-ray – stop your intention
  • Y: Yankee – am dragging anchor
  • Z: Zulu – I require a tug


  • Two-flag signals are used mostly for distress and maneuvering.
  • Three-flag signals are for points of the compass, relative bearings, standard times, verbs, punctuation and also general code and decode signals.
  • Four-flags are used for geographical signals, names of ships, bearings, etc.
  • Five-flag signals are used to relate time and position.
  • Six-flag signals are used to indicate north or south or east or west in latitude and longitude signals.
  • Seven-flags are for longitude signals containing more than one hundred degrees.

For recreational boating, Nautical Boating Flags are also used to identify a vessel. The three flags traditionally used are:

The national ensign. The U.S. national ensign, sometimes called “50-star” or “Old Glory,” is the proper and preferred flag for all U.S. vessels. Your boat should wear it from 0800 until sunset, and when you enter or leave port during daylight or at night, weather and rig permitting.

The yacht club burgee. Generally triangular in shape, although sometimes swallow-tailed, the yacht club burgee contains a unique design symbolic of the organization represented.

A private signal. This is a personal flag, often called a house flag. It is usually swallow-tailed, designed by the individual owner to depict a personal interest, hobby, family tradition, initials, or the like.

Some boaters are criticized for using flags too recreationally and decoratively as flags should only be used to send a message about the boat such as: Nationality, Maneuvering situation, Club affiliation, Office held.

Lastly, we have the very important Warning Flags that are used on recreation vessels to serve as warning to other vessels: The most recognizable of these are the Hurricane Warning Flag, which announces that sustained winds of 74 mph or higher are expected within the coastal area.  

Another well known warning flat would be the Skin Diver Down River Flag that is legally required to be used by divers to indicate their activities and diving area.You will see them wherever there are scuba schools, as well as popular wreck diving sites


As modern technology has decreased their necessity in sending messages, it is still prudent for boaters and operators to have a basic understanding of codes and signals in the event of an emergency.  And it doesn’t hurt if you can spell use your code skills to help decorate your beach house!

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