AIS transponder, Class A, Class B:
what's the difference?

AIS transponder: Installed on board ships, the AIS transponder transmits and receives crucial information via the Automatic Identification System (AIS). It provides real-time data such as a vessel's identity, position, speed and heading, thus enhancing maritime safety.

Class A: According to international SOLAS (Safety of Life at Sea) regulations, Class A AIS transponders are required for :

• All merchant ships over 300 tons making international voyages.
• Cargo ships over 500 tons not engaged in international voyages.
• All passenger vessels, whatever their size.

Transmission: Sends data every 2 to 10 seconds.
Data: Detailed information, including IMO and MMSI numbers.
Range: Effective over several tens of nautical miles.

Classe B : Less expensive and simpler, Class B transponders are designed for small vessels not subject to SOLAS regulations. This includes :

• Pleasure boats.
• Fishing vessels under 15 meters.
• Other small non-commercial vessels.

Installation of these devices is voluntary, but they enable these vessels to participate in the exchange of AIS information to increase their visibility and safety.

Transmission: Data sent every 30 seconds to 3 minutes.
Data: Less detailed information, often without IMO number.
Range: Similar to A-Class, but adapted to less dense environments.