Automatic Identification System - What is it?

Most agree a Chartplotter and VHF radio are essential, but many are confused about whether they really need extra tools such as Radar or AIS. This week we will look at what AIS does and the things to consider when deciding to fit it (or not).

What is AIS?

AIS is a system that uses VHF radio to broadcast a vessel's position, speed, course, and other information to other vessels and coastal authorities. This information can be displayed on a chartplotter, radar display, or other device, allowing boaters to see the location and movement of other vessels in the area. AIS can also help identify the type of vessel, its MMSI number (Maritime Mobile Service Identity), and its name, according to Icom UK.

Benefits of AIS:

• Improved situational awareness: AIS helps boaters see the traffic around them and make better decisions about their course.
• Collision avoidance: AIS can help prevent collisions by allowing boaters to see the location and speed of other vessels.
• Enhanced search and rescue: AIS can help authorities locate and track a vessel in distress.
• Improved communication: AIS allows vessels to communicate with each other using their MMSI numbers, says Icom UK.
• Automation: The system is fully automated with absolutely no human intervention.
• No weather limitations: Unlike Radar, it is not affected by rain or sea conditions.
• Good propagation: Its propagation is better than that of radar, due to the longer wavelength.
• Sees around bends: It's possible to "see" around bends and behind islands if the land masses are not too high.
• Nighttime vision: Additional safety at night time.

Limitations of AIS

• The system coverage range is similar to other VHF digital applications which depends upon the height of the antenna. Typical range is 20 NM.
• With the help of repeater stations, the range can be increased.
• Some vessels like fishing vessels, leisure craft, and vessels below 500 GRT may not be fitted with AIS.
• Accuracy of the information received is only as accurate as what is entered in the static/voyage or safety messages data.
• The operator should always be aware that AIS fitted on other ships, under certain circumstances, can be switched off on the master's professional judgement.

Do you need it?

Whether you need AIS (Automatic Identification System) depends on the size and type of your vessel, and whether you are sailing on an international voyage. AIS is a system that allows ships to transmit their location and other information to other vessels, and to coast guard services, to help improve navigation and prevent collisions.

• Commercial vessels: Large commercial vessels (over 300 gross tonnes on international voyages, or 500 gross tonnes on non-international voyages) are required to have AIS, according to the International Maritime Organization (IMO).
• Passenger ships: All passenger ships, regardless of size, must have AIS.
• Recreational boats: There is no requirement for recreational boats to have AIS, but many boaters choose to install it for safety reasons.
• Other vessels: Vessels not required to carry AIS by regulation may still choose to do so.