GPS Tracker vs AIS: Which One Does a Vessel Owner Need?

GPS tracker vs AIS is a question many vessel owners ask once they realise their vessels already show up on public ship-tracking websites. If anyone can see the vessel on a map, why install a separate tracker? The short answer is that the two systems were built for different jobs, send their data to different people, and carry different information. Most operators who need to manage a fleet end up relying on both.

What AIS is for

AIS, the Automatic Identification System, was designed for safety at sea. An AIS transponder on board broadcasts the vessel's identity and movement over VHF radio so that nearby vessels and shore stations can see who is around them and avoid collisions.

A typical AIS message includes the vessel's identity (such as its name and MMSI), position, speed and course over ground, heading, navigational status, and voyage details such as destination and ETA. Some of these fields are entered by hand by the crew, so their accuracy depends on someone keeping them up to date.

There are different classes of AIS equipment, commonly Class A for larger or commercial vessels and Class B for smaller craft, with different reporting behaviour. Which vessels must carry AIS, and which class, depends on the vessel's size, type and trade under the international and national rules that apply to it.

Who can see AIS data

AIS is a broadcast. Any receiver in range can pick it up: other vessels, port authorities, coastal stations, and networks of shore and satellite receivers that feed public tracking websites. That openness is the point, because collision avoidance only works if everyone can see everyone.

For an owner, it also means:

• Your vessel's position is visible to anyone, including competitors.
• Coverage depends on receivers. VHF range is limited by line of sight, so away from coastal stations the data depends on satellite AIS, which may be delayed or less frequent on public services.
• The transponder can be switched off or can fail, and the vessel simply disappears from the map.
• AIS carries nothing about the engine, the fuel or the condition of the equipment on board.

What a GPS tracker is for

A GPS tracker, sometimes part of a wider vessel monitoring or fleet management system, is built for the owner rather than for other vessels. It sends the vessel's position over cellular, satellite or onboard internet to a private server, and only people with an account can see it.

Because it is a private system, a tracker can do things AIS was never meant to do:

• Report on a schedule you control, and keep a history you own.
• Carry sensor data alongside position, such as engine RPM, fuel flow or alarms.
• Show whether the device itself is working, not only where the vessel is.
• Control who sees what, for example giving a charterer the position of one vessel without exposing anything else.

The trade-off is that nobody outside your organisation sees it, so a tracker does nothing for collision avoidance or for authorities that rely on AIS.

GPS tracker vs AIS side by side

| | AIS | GPS tracker | |---|---|---| | Main purpose | Safety and collision avoidance | Fleet operations and control | | Who sees the data | Anyone with a receiver or public tracking site | Only authorised users | | Transmission | VHF broadcast, relayed by shore and satellite receivers | Cellular, satellite or onboard internet to a private server | | Engine and fuel data | No | Possible, depending on the system | | Whether carrying it is required | Depends on vessel size, type and trade | Owner's choice |

When you need both

For many commercial vessels AIS is not optional, so the real question is whether AIS alone is enough to run the fleet. Usually it is not, when:

• you need to know what the engines and fuel were doing at each point on the track, not just where the vessel was;
• the vessel works in areas where public AIS coverage is patchy;
• you want a history that you control, with no gaps you cannot explain;
• you want to share position with a charterer without making your whole operation public.

In those cases AIS keeps the vessel visible and safe, while a private tracker gives the office the operational picture.

How MANTRAZ handles tracking

MANTRAZ tracking comes from the vessel itself: each vessel sends its position, speed and status every 60 seconds, and each connection is marked Online, Offline, No GPS or No Sensor. Tracks can be replayed for 1 to 14 days at up to 16x, and vessels beyond cellular range can report through the app's satellite mode. Position sits next to engine and fuel data from the same vessel, and charterers can get a GPS Viewer account that shows the position and track of the vessels assigned to them, with no fuel data, bunkering or reports.

To see private vessel tracking alongside engine and fuel data on a fleet like yours, request a MANTRAZ demo.