Last updated: March 30, 2022
Long before radio communication, mariners used signal flags to communicate between ships. An international code still exists at sea today. Each flag stands for a letter or number. String multiple flags together and one can send a message as far as the eye can see. If flown by themselves, single signal flags can also mean special codes.
Activity 1: Decipher Signals
Below are several messages encoded using signal flags. Use the online gallery above or the printable key to solve each message. The answers are in collapsible items that follow each code!
Radio stations have call signs used to identify them. This is true for television, FM radio, and even ships like USS Cassin Young. During World War II Cassin Young operated with the call sign November Tango Tango Hotel, or, NTTH.
The Charlestown Navy Yard is home to two ships: USS Constitution and Cassin Young.
Between Boston Harbor and Cape Cod, the Stellwagen Bank National Marine Sanctuary is home to a wide variety of wildlife, including whales.
Activity 2: Print, Cut, and Create Messages
Using the files below, print out the signal flag sheets. Cut out each flag and arrange any number of them to form a message you want to send. You can glue your message to paper or even hang them on a string.