AIS

SOLAS CARRIAGE REQUIREMENT

The carriage of AIS on board ships is governed by SOLAS regulation V/19.2.4. The regulation requires AIS to be fitted aboard all ships of

• 300 gross tonnage and upwards engaged on international voyages,
•  cargo ships of 500 gross tonnage and upwards not engaged on international voyages and
• All passenger ships irrespective of size.

PURPOSE:

        The purpose of AIS is to help identify ships, assist in target tracking, assist in search and rescue operation, simplify information exchange (e.g. reduce verbal mandatory ship reporting) and provide additional information to assist situation awareness. In eneral, data received via AIS will improve the quality of the information available to the OOW, whether at a shore surveillance station or on board a ship.

WHAT IS AIS?

        Very simply, the Automatic Identification System is a broadcast transponder system, operating in the VHF maritime mobile band.

AIS operates principally on two dedicated VHF frequencies or channels:

AIS 1 - 161.975 MHz - channel 87B (Simplex, for ship to ship) and

AIS 2 - 162.025 MHz - channel 88B (Duplex for ship to shore).

        AIS uses Self-Organizing Time Division Multiple Access (SOTDMA) technology to meet this high broadcast rate of 9600 bits per second and ensure reliable ship-to-ship operation.It normally works in an autonomous and continuous mode, regardless of whether it is operating in the open seas, coastal or inland areas.

        Each station determines its own transmission schedule (slot), based upon data link traffic history and knowledge of future actions by other stations.

A position report from one AIS station fits into one of 2250 time slots established every 60 seconds.

DATA TRANSMITTED

    AIS transmit the following categories of information:

• Static information
• Dynamic information
• Voyage related information

Short safety-related messages

Static information: (Every 6 min and on request)

 MMSI

 IMO number (where available)

 Call sign & name

 Length and beam

 Type of ship and

 Location of the position-fixing antenna

Dynamic information: (Dependent on speed and on speed/course alteration)

 Ship’s position with accuracy indication and integrity status

 Position time stamp (in UTC)

 Course over ground (COG)

 Speed over ground (SOG)

 Heading

 Navigational status (e.g. at anchor, underway, aground etc. And

 Rate of turn (where available).

Voyage related information (Every 6 min, when is data amended, or on request)

 Ship’s draught

 Hazardous cargo (type)

 Destination and ETA and

 Route plan (waypoints)

Short safety-related messages: Free format text message (sent as needed) addressed to one or more specified destinations or to all stations in the area. The content should be relevant to safety messages e.g. buoy missing, ice-berg sighted etc.

REPORTING INTERVAL

At Anchor / Moored--3 minutes

At Anchor / moored and moving faster than 3 konts--10 seconds

Speed 0 – 14 Konts--10 seconds

And changing course--3 1/3 seconds

Speed 14 - 23 Knots--6 seconds

And changing course--2 seconds

Speed > 23 Knots--2 seconds

And changing course--2 seconds

AIS TYPES

Class A mandated by the IMO for vessels of 300 gross tonnage and upwards engaged on international voyages, cargo ships of 500 gross tonnage and upwards not engaged on international voyages and passenger ships irrespective of size.

Class B provides limited functionality and is intended for non-SOLAS vessels. It is not mandated by the International Maritime Organization (IMO) and has been developed for vessels such as work craft and pleasure craft