The following is a description of the fitting of an Automatic Identification System (AIS) Transponder to SV Crystal Blues by Neil and Ley Langford. It originally appeared on their web site.
AIS Part 1 – A Primer
My father taught me to sail when I was about 8 years old – he’s the worried one in the old photo at right (probably because my brother Peter is on mainsheet). With great and delightful understatement, he always said that “a collision at sea can ruin your whole day”. He’s absolutely right of course, though nowadays we can use AIS technology to help avoid those “ruined days”. This is the first of three posts regarding the system, and basically describes the technology. Future posts will cover our installation experiences and the system in operation.
Some years ago the International Maritime Organisation (IMO) ratified a standard requiring all ships over 300 tons to carry an Automatic Identification System (AIS) transponder. This was a major step forward in collision avoidance for ships at sea. The system really works – AIS equipped ships constantly transmit information including name, MMSI number, position, speed, course, rate of turn, cargo carried etc etc. Commercial vessels within range receive that data, which is then displayed on dedicated screens or (in most cases) overlaid onto radar or chart plotting screens. The result is that AIS equipped vessels are readily identified, tracked and avoided.
This is a significant primary safety system, and many in the yachting community have taken advantage by purchasing low cost AIS receivers – these display ship locations on navigation chart plotters, or on suitably equiped navigation computers. Whilst an AIS receiver system is a good thing to have, I always believed that the best safety system required the big ships to see me as well – I wanted a transponder that would transmit and receive.