NMEA 2000 Connections

The NMEA 2000 protocol promotes conversations between GPS and sonar, between engine and display, between autopilot and electronic compass, and between chart plotter and AIS. These conversations take place over a network that uses plug-and-play components such as T-connectors and drop cables. Proper connections ensure that network communications function as intended.

1. Network Power
NMEA 2000 networks require electrical power. Connectors with integral positive and ground wires (with in-line fuses for the positive wires) supply onboard power to the backbone — the main communication channel for the system. In order for the system to function properly, connect the power in the middle of the backbone.

2. Verify Voltage
NMEA 2000 networks use 12-volt DC power only. Avoid connecting the power wires to any other power source such as 24-volt DC.

3. T-Junction Function
There's a tendency to string together a number of T-connectors while tying into the system, but such strings are prone to damage and broken connections. Instead, use T-connector junctions. These are more robust and compact.

4. Short and Sweet
NMEA 2000 signals can be hampered by resistance, which increases with cable length, so keep the length for a single drop cable to less than 20 feet. If you require a longer cable run, use a T-junction in the middle of the run to tie in 12-volt DC power. Augmenting the power helps prevent an excessive drop in voltage.

5. Side Action
Use only the sides of the T-connectors to assemble a NMEA 2000 backbone. Also, use only the top of the T-connector to attach devices and sensors.

6. Terminator Too
Terminators are required at each end of an NMEA 2000 backbone in order for the network to function properly. Use one female terminator and one male terminator at opposite ends of your NMEA 2000 backbone.

Read Boating Magazine's orignal March 20, 2017 article