em-trak B921 Class B AIS Transceiver – 2W CSTDMA

Description

Share your boat’s AIS position while keeping power draw low with the em-trak B921 Class B AIS Transceiver. Its 2W CSTDMA transmitter, 72-channel GNSS receiver, and compact IP-rated housing make it a practical choice for sailboats, center consoles, and cruisers that need AIS target data at a compatible chartplotter. Need a straightforward Class B AIS unit without a built-in display? The B921 connects through NMEA 2000, NMEA 0183, and USB while using multi-color LEDs to show operating status.

Key Specifications

• em-trak B921 Class B AIS transceiver.
• 2W Class B CSTDMA AIS transmission protocol.
• Operates across 156.025–162.025 MHz AIS/VHF frequencies.
• Typical Class B reporting interval ranges from approximately 30 seconds to 3 minutes, depending on vessel speed and AIS rules.
• Integrated 72-channel high-sensitivity GNSS receiver.
• NMEA 2000, NMEA 0183, and USB connectivity.
• Multi-color LED status indication.
• 12V/24V DC input with less than approximately 170 mA average draw at 12V.
• IP66/IP67 environmental protection and operating range of -13°F to 131°F (-25°C to 55°C).
• Approximate dimensions: 5.9 × 4.3 inches; approximate weight: 0.77 lb (0.35 kg).
• Includes power/data cable and mounting bracket.

Integration

The B921 transmits and receives AIS data but requires a properly installed VHF AIS antenna or approved antenna splitter, a correctly located GNSS antenna or GPS source as specified by the manufacturer, and programmed MMSI/static vessel details. It is not a radar, chartplotter, VHF voice radio, emergency beacon, or collision-avoidance guarantee.

AIS target information depends on VHF coverage and other vessels transmitting accurate AIS data. Not every boat, buoy, object, or navigational hazard transmits AIS. In the U.S., confirm MMSI registration, radio licensing requirements, and applicable FCC or Coast Guard rules before activating the transmitter. [926][928]

Installation Notes

Install the transceiver in a dry, accessible location with proper ventilation and cable strain relief. Mount the GNSS antenna where it has a clear sky view, route VHF/AIS coax away from high-current wiring, and use an AIS-rated VHF antenna or manufacturer-approved splitter. Connect NMEA 2000, NMEA 0183, or USB to the intended navigation display or computer.

Program accurate vessel data, including MMSI, vessel name, call sign, dimensions, and GNSS antenna offset. Use correctly sized 12V/24V wiring and suitable circuit protection. Have a qualified marine-electronics installer verify transmission, reception, and network data before regular use.

Before Ordering

Confirm Class B AIS suitability, MMSI registration, antenna or splitter requirements, GNSS antenna placement, NMEA 2000/NMEA 0183/USB compatibility, 12V/24V power, and required programming support before ordering.