NMEA 2000 uses the CAN (control area network) designed originally for the automotive market, but adapted for the marine industry.

The older version, NMEA 0183, allowed a GPS or chartplotter to send steering commands to the autopilot, for example, but this was a one-way street; one device talking and the other listening. Now, with NMEA 2000, digital signals can go in two directions simultaneously, with the result that each onboard device can talk to as many as 50 other devices. 

The way this works is through a backbone cable running the length of the boat, with individual devices connected via spur cables. The backbone carries both data and power to attached devices. This reduces the complexity of the installation and means far fewer cables. 

NMEA standard

Under the NMEA standard, manufacturers can use the cable and connector design of their choice as long as it meets certain criteria. So, for example, you could opt for Raymarine’s SeaTalk 2, ST^ng, Simrad Simnet and Furuno CAN – all rebranded versions of NMEA 2000. 

A typical STng set-up that might be installed in a vessel like the PBO Project Boat Maximus

Raymarine’s ST^ng is what we’ll be using on our PBO Project Boat Maximus, a Maxi 84. This means data from our AIS (originating from the VHF), wind direction and speed data (from the i70s and i60), and depth, speed and temperature (from the Analogue Tri Transducer) can be shared and shown on the Element 7 MFD along with its chartplotter functions – as well as link with instruments we might add in future.

Converting analogue to digital

As we’re starting from scratch we’ll be using Raymarine’s iTC-5 instrument to convert the analogue transducer signals from the wind, depth, rudder angle, etc. into digital ST^ng data. 

However, if you already had NMEA 2000 instruments on board from other brands, or Raymarine’s older version, SeaTalk 2, you can still connect them to each other using Raymarine’s DeviceNet cabling and connectors.