Save our SOS

It's 100 years since SOS came into force across the world as the standard signal for ships in distress. But times have changed in the rescue business.

Before the advent of radio if your ship got into trouble on some far off stretch of roiling sea, that trouble was not easy to get out of.

Communication off the ship could only be achieved with other ships within distance, using either lights, flags or flares.

If you were in dense fog or in a howling gale far out at sea, and you started taking on water, the first communication most sailors would make was heaven-wards.

At the tail end of the 19th Century, radio changed that.

It's easy to forget today, but in the early days of radio there was no voice.

If you wanted to say you were in trouble, if you wanted to say anything in fact, you had to do it through morse code. The code had been born after the advent of the telegraph and when the telegraph went "wireless" it continued in the new format.

"In the early days when they were sending a radio signal there was no way of modulating. The only thing you could do was turn a transmitter on or off," says Carlos Eavis, amateur radio manager of the Radio Society of Great Britain.

Calling signals

Wireless telegraphy - or radio as we prefer to style it now - had its biggest early impact on maritime communication. Ships had been working out ways to communicate with other ships for centuries, but radio opened up the possibility of reliable communication with ships that were out of sight for the first time.

And the most important of all calls that a ship's radio operator could make was a distress signal indicating the vessel was in danger of sinking.

But if your ship got into trouble on its Atlantic crossing in the early years of the 20th Century you wouldn't necessarily have signalled SOS. Before SOS there was CQD

You can read the rest of this fascinating BBC News article at: http://news.bbc.co.uk/1/hi/magazine/7444184.stm