What Does A Blue Flag With A White And Red Squares In The Center Mean In Boating?

If you’re out on the water and you see a boat hoisting a blue flag with a white border and a red square in the center, don’t ignore it: That vessel has someone on board who needs medical assistance. Known as the W (or Whiskey) flag, this international maritime signal is the standardized way for boaters to communicate a medical need to nearby vessels. Being an international standard, it’s meant to be understood in any language, not unlike the globally recognized SOS code.

The Whiskey flag is one of twenty-six different flags, each representing a letter of the alphabet as well as a very specific alert to other boaters. For example, the Alpha flag represents the letter A and also serves as a notice that a diver is down below. (This can also be marked by a red and white flag.) A Foxtrot (or F) flag flying means that the vessel is disabled and is requesting contact. Some flags also take on a third meaning when combined with other flags. For instance, the Hotel (H) flag next to a Whiskey flag means your boat has crashed into another surface craft.

These signals have been around in some form or another since the mid-1850s. One of the earliest versions of this International Code of Signals used eighteen different flags to communicate about 70,000 different things. A revised code was put in place in 1932, then updated again and adopted in 1965.

It might seem frivolous or unnecessary with the advent of radio, phones, and now the internet, but remember: Out on the water, far from cell towers and Wi-Fi signals, even the coolest boating gadgets might not work that far from shore. In many ways, it might as well still be the 1850s out there. Hence, the continued need for the International Code of Signals.

Beyond the Whiskey flag and the other twenty-five corresponding letters, there are other flags that stand in for numbers zero through nine. When combined with other flags, boaters can quickly and clearly communicate everything from navigation plans to problems onboard to calls for help.