How did ships talk to each other before the days of radio?

Semaphore A system of waving flags to create a message.

 

Flags were the main way ships sent messages.

Do you know the most famous flag message ever sent?

 

Morse Code

Do you know your dits from your dashes and your dahs from your dots.

A way of transmitting information using electrical pulses, originally along a telegraph wire.

See what Morse code looks like.
Try the Morse Code Converter

Now hear the Morse Code

Morse Code can also be sent by flashing a light. The Aldiss lamp was found on all ships.