This was funded by donations from St Mawes Sailing Club and from a private individual – thank you both!
How the AIS transponder works
Many vessels now have a MMSI number. (MMSI stands for Maritime Mobile Service Identity.) This identification number can be transmitted automatically by electronics such as a VHF radio, and by a transponder.
AIS stands for Automatic Identification System. It is a system used by larger vessels to help identify a ship and to let others know the ship’s position.
An AIS transponder sends out a signal which contains the sender’s MMSI number and the ship’s position. It gets the ship’s position from a GPS antennae. (GPS stands for Global Positioning System.) Another ship receiving this signal will be able to see an icon on their navigation screens showing a vessel named “Hardiesse”, its position, and a brief description.
This is a great step forward in safety. Even in fog, a large ship travelling fast towards Hardiesse will see us on their AIS display, and if the two ships are converging courses, this system enables the two ships to communicate by radio and to alert each other to say that an alteration in course would be sensible.
The AIS transponder will be switched off if Hardiesse is at mooring in Falmouth and no-one is on board. The electrics will be switched off to conserve battery power. When the ship is under way however, the instruments will be switched on and the transponder will be broadcasting the position constantly, and so when Hardiesse is sailing, you can see where she is by looking on one of the AIS websites: