Depth Source
NMEA 2000
Network Checker
Know before you buy. Know before you install.
This tool calculates your NMEA 2000 network load and checks whether your existing network can support new devices — based on published LEN specifications. Results are based solely on the information you provide and assume properly installed, rated backbone cable and correct termination. Use this as a planning guide, not a substitute for professional verification.
1
Adding
2
Existing
3
Backbone
4
Power
5
Terminators
Step 1 of 5
What are you looking to add?
Select all devices you want to connect to your NMEA 2000 network. LEN values shown are per NMEA 2000 specification.
📺
Chartplotter / MFD
LEN: 2 — Garmin ECHOMAP, GPSMAP; Humminbird HELIX, APEX; Lowrance HDS; Simrad NSS/NSO
📻
VHF Radio
LEN: 2 — fixed-mount with DSC/AIS integration
🛰️
Radar
LEN: 4 — Garmin Fantom, Simrad Halo, Lowrance Halo dome/open array
🧭
Autopilot Control Head
LEN: 2 — Garmin Reactor, Simrad AP44/AP48
⚙️
Autopilot Course Computer
LEN: 2 — separate from control head on most systems
🔌
Engine Gateway
LEN: 1 — translates engine data (RPM, temp, fuel) onto N2K network
🚢
AIS Transponder
LEN: 2 — Class B AIS, standalone or combined with VHF
💨
Wind / Weather Sensor
LEN: 2 — wind speed/direction, barometric, temperature sensors
🔊
Standalone Depth Sounder
LEN: 1 — dedicated sonar module outputting depth to network
📡
External GPS Antenna
LEN: 2 — dedicated GPS/heading sensor for network positioning
Step 2 of 5
What's already on your network?
Select every device currently connected to your NMEA 2000 backbone. If you're not sure, select your best estimate — the checker will flag if you're close to the limit.
📺
Chartplotter / MFD
LEN: 2 per unit — count each display separately
📻
VHF Radio
LEN: 2
🛰️
Radar
LEN: 4
🧭
Autopilot System
LEN: 4 (head + computer combined)
🔌
Engine Gateway
LEN: 1
🚢
AIS Transponder
LEN: 2
💨
Wind / Weather Sensor
LEN: 2
📡
External GPS Antenna
LEN: 2
🔊
Depth Sounder
LEN: 1
Step 3 of 5
How long is your backbone cable?
The NMEA 2000 specification has a maximum backbone length of 100 feet. Longer backbones cause signal degradation and erratic device behavior.
Step 4 of 5
How is your NMEA 2000 network powered?
The network backbone needs its own dedicated power tap with a 3A fuse. An underpowered or improperly fused network will drop devices intermittently.
Step 5 of 5
Do you have terminators at both ends of the backbone?
NMEA 2000 requires a terminator at each end of the backbone cable. Missing terminators cause erratic behavior across all devices — this is one of the most common install mistakes.
