Unlocking Your Vessel Data
If your boat has an NMEA 2000 network, it's already broadcasting a constant stream of information: engine readings, tank levels, battery status, depth, water temperature and more. Most boaters only ever see a small part of it, on whichever display happens to support each message.
d3kOS reads the whole network, organizes the data through Signal K, and uses it for monitoring, alerts and AI analysis.
NMEA 2000 in Plain Terms
NMEA 2000 is the standard marine network used by many modern boats. Devices share one backbone cable and broadcast messages called PGNs (Parameter Group Numbers). Each PGN carries a specific kind of data.
Here are some common PGNs:
PGNContents*127488Engine parameters, rapid update (such as RPM)127489Engine parameters, dynamic (such as temperatures, pressures, alternator voltage)127505Fluid level (tanks)127508Battery status128267*Water depth
PGN names from Garmin's published NMEA 2000 PGN information tables.
d3kOS connects to the backbone through a PiCAN-M HAT or a USB-CAN-A adapter. It detects which one is present at boot and brings up the CAN interface at 250 kbps automatically. Signal K then decodes the PGNs into its data model.
Engine Data
The Engine Dashboard shows:
RPM
Coolant temperature
Oil pressure
Battery voltage
Fuel level
Alerts fire when values leave normal ranges. The Boat Log captures engine starts and stops in the background, even when the Boat Log page isn't open, so you build a running history of engine use.
Engine data depends on your engine. Many modern engines put data on NMEA 2000 directly. Older engines with analog senders need a gateway that converts sender signals to NMEA 2000. Support for more of these options is on the d3kOS roadmap.
Tank Monitoring
Fluid-level messages (PGN 127505) report tank levels as a percentage, along with the fluid type, such as fuel, fresh water or waste. With this data in Signal K, d3kOS shows fuel level on the Engine Dashboard and can use tank data for range and consumption analysis.
Electrical Systems
Battery status messages (PGN 127508) and engine alternator readings give a view of the boat's electrical health. Low voltage at the helm is often the first sign of a charging problem, a failing battery or a high load. That kind of slow-developing issue is easy to miss on a single gauge.
Environmental Sensors
The network also carries data about the world around the boat:
Depth (PGN 128267) from a fishfinder or depth sounder
Water temperature from transducers that report it
Position, course and speed from GNSS devices
When the same value arrives from more than one device, d3kOS uses Signal K source priorities so one source is authoritative and the others are fallbacks. Readings stay steady instead of jumping between sources.
AI Analysis
This is where data becomes vessel intelligence:
Context-aware answers. Ask Helm about a reading, and it can draw on your uploaded engine manual for the answer.
Pattern awareness. Logged engine runs give the history needed to spot trends.
Combined alerts. Engine, electrical, navigation and AIS data live in one place, so warnings can be put in context rather than shown on separate screens.
Remote visibility. The AtMyBoat.com companion app lets you see engine alerts and boat status from your phone.
A Note on Safety
d3kOS reads NMEA 2000 data to inform the skipper. It treats safety-related outputs with care: for example, the system design keeps synthetic or camera-derived targets from being re-broadcast onto the NMEA 2000 network as if they were real AIS.
Frequently Asked Questions
Do I need to rewire my boat to use d3kOS with NMEA 2000? No. You add one adapter (PiCAN-M or USB-CAN-A) to your existing backbone, following standard NMEA 2000 installation practice.
What if my engine doesn't put data on NMEA 2000? d3kOS still provides navigation, AIS, cameras and voice features. Engine data needs an NMEA 2000 source.
Can d3kOS read NMEA 0183 devices too? Yes. Signal K can take NMEA 0183 input, and d3kOS uses a USB GPS through gpsd.
