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I start with a sketch of the instruments and the data you want to share. Then, the backbone, connections, and power supply are planned so that the network can function as a whole.
What do you need the network to help you with?
A good starting point is a concrete task: for example, you want to see wind data or AIS targets on the plotter. Write down both the sender and the receiver of each piece of information on your list. This makes it easier to verify whether the individual devices support the necessary data.
The most important parts
| Part | Function in the network |
|---|---|
| Backbone | The continuous main cable. |
| T-connector | Connection point on the backbone. |
| Drop cable | The connection from a T-connector to a device. |
| Terminator | Network termination; usually one at each end. |
| Power connection | Supplying power to the network according to the manufacturer's instructions. |
Garmin's basic principle is a linear backbone with termination at both ends. Devices and power are connected via the designated connectors. The number of devices, cable distances, and power consumption must be within the system's limits.
A plotter may have more than one power task
Do not assume that a plotter's own power supply also provides power to the NMEA 2000 network. Conversely, do not add a new power connection without knowing how the existing network is powered. Check the diagrams and manuals for both the network and the devices.
Garmin uses the devices' LEN values and cable distances to assess power distribution and voltage drop. The position of the power cable can therefore be significant, especially when the network is expanded.
Example: new AIS for an existing plotter
I would first find the exact model of the plotter and check its AIS support. Then, map out the existing backbone, available connection point, cable length, and power supply.
Only then does it make sense to order an AIS device and the necessary cables. A connector that looks correct does not document the entire connection.
The same network does not mean all features
Manufacturers specify supported data messages as PGNs. Check both the sending and receiving of the desired information. Chart data, radar, and other large amounts of data may require connections other than NMEA 2000.
Make a shopping list that fits the first time
- Exact model names of all devices.
- Which data should be displayed where.
- Existing cable system and connector types.
- Distance from each device to the planned backbone.
- Placement of terminators and the network's power supply.
Feel free to send a simple sketch and photos. I will help clarify which parts you can already use and what is missing.
Sources and manufacturer documentation
This guide was written by SejlStrøm. Technical information was verified on September 22, 2026. Always use the documentation for your specific model and version.