Signal K to Boating

Signal K Node Server plugin that bridges the boat's GPS, depth, and Signal K AIS target data to standards-based NMEA 0183 over UDP for Garmin/Navionics Boating and compatible marine applications.

Version 1.0.1 is the current stable release. It preserves a one-way data flow: the plugin reads current Signal K values and never writes navigation, depth, or AIS data back into the Signal K model.

Output

• Own-vessel GPS: GPRMC, GPGGA, GPVTG
• Depth: SDDBT, SDDPT
• AIS targets: !AIVDM
  • Class A: AIS message 1 plus periodic message 5
  • Class B: AIS message 18 plus periodic message 24A/24B

The default UDP port is 2000. UDP broadcast and unicast to a specific IP can be enabled independently or at the same time.

Install

Install the stable package from npm on the Signal K host with:

cd ~/.signalk
npm install signalk-to-boating

For development or pre-release testing, install a local checkout or packed .tgz instead.

To require this stable major version explicitly, use npm install signalk-to-boating@1.

Restart Signal K Server, then open Server -> Plugin Config -> Signal K to Boating, enable the plugin, and configure its UDP output.

Recommended UDP configuration

For a normal onboard LAN, start with broadcast enabled:

• Send UDP broadcast: enabled
• Broadcast address: 255.255.255.255
• Send to a specific IP: disabled
• UDP port: 2000

If Wi-Fi client isolation or broadcast filtering prevents reception, enable unicast and set Specific destination IP to the phone/tablet running Boating. Broadcast and unicast can remain enabled simultaneously for maximum practical compatibility.

Boating setup

1. Put the phone/tablet running Boating on the same Wi-Fi/LAN as Signal K Server.
2. Enable this plugin.
3. In Boating, open the supported paired-device / NMEA Wi-Fi connection workflow.
4. If broadcast is not received, enable unicast to the device's Wi-Fi IP.
5. Verify that Boating receives GPS and depth. AIS targets should appear when AIS display is enabled and the application/account supports that feature.

Signal K data paths used

Own vessel:

• navigation.position
• navigation.speedOverGround
• navigation.courseOverGroundTrue or navigation.courseOverGround
• navigation.gnss.altitude
• navigation.gnss.satellites
• navigation.gnss.horizontalDilution
• navigation.gnss.methodQuality
• environment.depth.belowTransducer by default
• environment.depth.transducerToKeel by default

AIS targets are read from vessels.*, using MMSI, position, SOG/COG/heading, sensors.ais.class, name, callsign, AIS ship type, dimensions, and draft when available.

Depth is emitted only from the configured depth reference, which defaults to below-transducer depth. The default positive Signal K transducer-to-keel distance is emitted as a negative NMEA DPT keel offset. AIS sentences are sent one per UDP datagram to avoid oversized batches.

Compatibility scope

The plugin emits genuine NMEA 0183 GPS/depth sentences and AIS !AIVDM messages. Garmin documents NMEA 0183 over Wi-Fi support for compatible Boating integrations, but a complete proprietary interoperability specification for arbitrary third-party UDP bridges is not public. For that reason this project targets standards-based interoperability and does not claim undocumented vendor guarantees.

Documentation

• Getting started
• Architecture
• Contributor and coding-agent instructions
• Changelog

Development

Requires Node.js 20 or newer.

npm test
npm run lint
npm run coverage
npm pack --dry-run
npm audit --omit=dev

The repository calls Signal K's canonical reusable plugin CI workflow on every push and pull request. It runs the unit and coverage suites on Linux x64/arm64, macOS, and Windows with Node.js 22 and 24, checks armv7/Node.js 20 for Cerbo GX compatibility, and performs a Signal K integration install. The CI badge above links to the authoritative run history.

App Store indicators

Signal K's App Store indicators are heuristic signals assembled by the Signal K Plugin Registry. This repository supplies machine-detectable tests, current release notes, substantial documentation, and packaged visual assets. GitHub stars, open-issue activity, contributor count, and npm download totals are external activity metrics; they can remain unavailable or at zero for a correct, newly published plugin and must not be manufactured.

After a CI run or npm release, allow the registry cache to refresh before expecting the App Store detail page to change. A local test run proves the package itself, while the App Store indicator reflects the latest data the remote registry has collected.

npm publication

The package is intended to be published on npm as the unscoped package signalk-to-boating by the npm account uniparthenope.

Before a release, the publisher should verify:

npm whoami
# expected: uniparthenope

npm test
npm run coverage
npm audit --omit=dev
npm pack --dry-run
npm publish

No runtime npm dependencies or install-time lifecycle scripts are required.

License

Apache-2.0.