 |
You can use a magnifying glass to choose ships on the monitor. You will find out real-time details of the chosen vessels: name, nationality, speed and size. |
The information is based on the AIS or Automatic Identification System. All vessels of the defined size must regularly send their navigation details by radio to the coastal AIS receivers. Information obtained from the receivers is collected into a database maintained by the Finnish Maritime Administration. Most of the information is updated every few seconds.
With the help of AIS radios, the ships can also monitor nearby marine traffic. This is useful in avoiding dangerous situations and collisions for example in foggy conditions.
Co-operation partners:
The Finnish Maritime
Administration
Navielektro
Automatic Identification System (AIS)
The Automatic Identification
System, AIS, is a system that gives real-time, accurate information
of vessels and their movements. The system covers a large area.
According to the International Maritime
Organisation (IMO), the system is compulsory to all vessels of at
least 300 registered gross tons.
The AIS is based on a VHF-frequency radio that sends and receives information about the vessel and its movements automatically and constantly. There are two VHF-frequencies globally reserved for this action, the AIS1 and AIS2.
AIS-frequencies
|
Name of the channel |
Frequency |
|
AIS 1 |
161,975 MHz |
|
AIS 2 |
162,025 MHz |
STDMA technology can scale the sending times of automatic information messages of several different vessels. The system has divided each minute into 2250 short basic periods. Radio equipment can reserve these periods for their use using a standard mechanism. It takes only about 26,7 ms to send the vessel’s location and status information. In theory it’s possible to send altogether 4500 messages within the radio’s range, since there are two frequencies in use, each one with 2250 time periods.
The vessel’s reports
|
Status of the vessel |
Location information reported |
|
At anchor or on quay, speed less than 3 knots |
every 3 min |
|
At anchor or on quay, speed more than 3 knots |
every 10 s |
|
In motion, speed 0-14 knots |
every 10 s |
|
In motion, speed 0-14 knots, changing course |
every 3 1/3 s |
|
In motion, speed 14-23 knots |
every 6 s |
|
In motion, speed 14-23 knots, changing course |
every 2 s |
|
In motion, speed over 23 knots |
every s |
|
In motion, speed over 23 knots, changing course |
every 2 s |
In the AIS system, the exchange of information takes place mainly between vessels. In this way the AIS acts as a collision prevention system as well. It’s possible, however, to obtain the same information from support bases on mainland. Thus, the authorities have a possibility to recognise vessels and monitor their accurate status information. The authorities can also send short ”e-mail messages” to the ships. The messages usually concern safety.
Information sent by a vessel
|
Information sent by a vessel |
|
Radio signal (MMSI) |
|
Status (in motion, at anchor etc.) |
|
Rotation speed (ROT) |
|
Speed (SOG) |
|
Accuracy of localisation |
|
Location |
|
Course (COG) |
|
Heading |
|
International identification number of vessel (IMO) |
|
Radio call |
|
Name of vessel |
|
Type of vessel and cargo |
|
Measurements of vessel |
|
Source of location information |
|
Estimated time of arrival at destination |
|
Draught |
|
Destination |
The strength of AIS
AIS makes it possible to be aware of the location and course of vessels even in faint visibility and in situations where a radar cannot offer the same information. Especially in the archipelago or in very narrow and winding navigation routes this is an important service. It is an excellent tool to monitor several different vessels at the same time and to foresee safe encounters. The AIS helps to prevent collisions. In dangerous situations the captains of ships can communicate with each other through radio with the help of AIS-information: name of vessel and radio signal.The AIS is helpful in emergency situations. Through the system, ships can ask for help and direct help to the correct place.
This technology enables mainland bases to send messages to vessels, for example authority directions and safety measures as well as weather and wind information.
Even individual yacht owners can benefit from AIS, since the equipment needed to receive and interpret AIS information is not very expensive. A lap-top screen is good enough, provided it has been equipped with special programmes and devices.
Updated
8.1.2007/KT
