So young and already indispensable!
AIS, what for?
The AIS system, transmits to other vessels, equipped with compatible receivers, information concerning the vessel on which it is installed. Thus is transmitted, the vessel’s identification (MMSI number and name,) its position, course, speed, characteristics (length, width, water displacement,) and possibly information concerning its cargo and destination…All this information is emitted continuously, whether in coastal waters or on the high seas. A vessel which receives an AIS signal can thus visualise the course and speed of the sender and assess the chances of a collision long before it occurs. It is therefore, an invaluable tool for avoiding collisions at sea. This system operates on VHF frequencies (161.95MHz and 162.025MHz.) It is mandatory on all vessels over 300 tons and passenger ships. But many fishing vessels and
even recreational boaters also utilise it. For leisure craft, one may choose to be limited to a single receiver. Thus, "we see, but without being seen." These receivers are less expensive and use little energy. This is a safety device that can interface with a card reader or a computer to reveal the "targets" on the screen. One may the follow on cartography, the route of the boat transmitting. The range is a VHF range (visual range,) of about 20 MN.
The pleasure sailor may also decide to equip themselves with a transmitter/receiver. Not only does this receive information from other vessels it also transmits its own. A real addition in terms of safety, ensuring the vessel appears on the screens of large merchant ships.
even recreational boaters also utilise it. For leisure craft, one may choose to be limited to a single receiver. Thus, "we see, but without being seen." These receivers are less expensive and use little energy. This is a safety device that can interface with a card reader or a computer to reveal the "targets" on the screen. One may the follow on cartography, the route of the boat transmitting. The range is a VHF range (visual range,) of about 20 MN.
The pleasure sailor may also decide to equip themselves with a transmitter/receiver. Not only does this receive information from other vessels it also transmits its own. A real addition in terms of safety, ensuring the vessel appears on the screens of large merchant ships.
Framework
GPS required! An AIS message can not be issued if it is connected to a GPS locked onto a specific position. Indeed, the AIS system even uses the same clock as the GPS. Certain top of the range AIS even have their own dedicated AIS.
GPS required! An AIS message can not be issued if it is connected to a GPS locked onto a specific position. Indeed, the AIS system even uses the same clock as the GPS. Certain top of the range AIS even have their own dedicated AIS.
Receiver only or transmitter/receiver?
The receiver listens to other ships only. It does provide you with information on other ships around you and their intentions (course and speed notably.) You, however, do not appear on their screens. These systems may utilise the VHF antenna (simple installation) and demand little energy. A transceiver by contrast, also sends your details. It provides extra security. Disadvantages: These devices are more expensive, they require their own VHF antenna and use more electricity.
Black box, apparatus with screen or combined with the VHF?
AIS come in three forms:
-AIS “Black box”
In choosing a black box, we opt for the best price. It is an inexpensive apparatus but must be connected with a computer or compatible card reader. Alone, they have no use. These devices have an NMEA output which transmits a signal for display on the cartography. It is thus, the card reader which emits an alarm to warn of the presence of another vessel. To work it must have a computer, card reader or the two combined.
-AIS with dedicated screen.
These AIS have their own screen. One may regulate their alarms and follow, ‘targets.’ While the screen is not very big and readability sometimes difficult, this type of device can remain on standby and still provide alarms. One can then turn on the card reader to follow the target. It is a good solution for sailing vessels which must watch their electricity consumption.
-AIS combined with VHF
Newly arrived, there is now VHF DSC with integrated AIS function. No need for, “black box,” or additional connections, the AIS uses the sameantenna as the VHF and the information is returned to the (small,) VHF screen. Simple mounting and connections (it suffices to connect the VHF to a GPS,) one can also recover NMEA information and display it on a card reader. A good solution; significantly less expensive than VHF and AIS.
-AIS “Black box”
In choosing a black box, we opt for the best price. It is an inexpensive apparatus but must be connected with a computer or compatible card reader. Alone, they have no use. These devices have an NMEA output which transmits a signal for display on the cartography. It is thus, the card reader which emits an alarm to warn of the presence of another vessel. To work it must have a computer, card reader or the two combined.
-AIS with dedicated screen.
These AIS have their own screen. One may regulate their alarms and follow, ‘targets.’ While the screen is not very big and readability sometimes difficult, this type of device can remain on standby and still provide alarms. One can then turn on the card reader to follow the target. It is a good solution for sailing vessels which must watch their electricity consumption.
-AIS combined with VHF
Newly arrived, there is now VHF DSC with integrated AIS function. No need for, “black box,” or additional connections, the AIS uses the sameantenna as the VHF and the information is returned to the (small,) VHF screen. Simple mounting and connections (it suffices to connect the VHF to a GPS,) one can also recover NMEA information and display it on a card reader. A good solution; significantly less expensive than VHF and AIS.
GPS required! An AIS message can not be issued if it is connected to a GPS locked onto a specific position. Indeed, the AIS system even uses the same clock as the GPS. Certain top of the range AIS even have their own dedicated AIS.
Use the same antenna as the VHF or add a second?
AIS works on the VHF frequency. We can use the same antenna via a splitter. Be careful, this arrangement only works for a single receiver. Indeed, the VHF has priority over the AIS. So when you use the VHF, the AIS does not receive its information. Whilst not too problematic for AIS receivers, it would be a great deal more for transmitters. The transceivers must have their own antenna.
Professional advice
“AIS does not replace radar or the watch! Seeing the targets displayed on the water gives the impression of seeing every vessel. Don’t forget, not all are equipped with AIS…”
“AIS does not replace radar or the watch! Seeing the targets displayed on the water gives the impression of seeing every vessel. Don’t forget, not all are equipped with AIS…”