signalk-ais-navionics-converter

v1.0.9

Published

22 days ago

Signal K plugin that converts AIS data into NMEA 0183 (TCP) and can also generate NMEA 2000 AIS PGNs, with optional AIS position reporting to vesselfinder.com

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d.behrendt

signalk-node-server-plugin signalk-category-utility signalk-category-ais signalk-category-nmea-2000 signalk-category-nmea-0183 signalk-plugin-configurator

SignalK AIS to NMEA0183 / NMEA2000 Converter

A SignalK plugin that converts AIS vessel data to NMEA 0183 sentences and broadcasts them via TCP to clients like 'Navionics Boating App' or 'OpenCpn'. Optionally

creates AIS NMEA2000 records for a selectable can bus interface
includes AIS data for vessels from aisfleet.com
forwards AIS data to VesselFinder.com

It is intended for vessels that do not have their own AIS receiver.

By using additional AIS plugins for SignalK (like AISHub) more AIS vessels are recognized and transferred.

IMPORTANT: The following are required for the plugin to function:

a valid GPS position (visible in the SignalK Data Browser) in navigation.position
MMSI of your own vessel maintained in SignalK server settings (Server → Settings)

Content

Features

TCP Server: Broadcasts NMEA 0183 AIS messages (Type 1 - Position report AIS class A, Type 19 - Extended position report AIS class B, Type 5 - static and voyage related data class A and Type 24 - static data report class B) to connected clients
Websocket Server: Same data broadcasted by the TCP server is send via a separate Websocket Server to connected clients. In addition the vessel data is broadcasted as JSON object ({"mmsi": 123456, ....})
NMEA200 PGN creation: Optionally the plugin generates NMEA2000 'Position Report' PGN 129038 (Class A) / PGN 129039 (Class B), PGN 129794 (Class A Static and Voyage Related Data), PGN 129809+129810 (Class B static data Part A+B) and sends them to the selected CAN bus interface.
Smart Update Logic:
- Sends updates immediately when vessel data changes
- Resends unchanged vessels periodically to prevent timeout in navigation apps
- Sends complete dataset to newly connected clients
Cloud Integration: Fetches nearby vessels from AISFleet.com API and merges with local AIS data
Data Quality:
- Filters stale data based on configurable age threshold
- Corrects invalid COG/Heading values (360° → 0°)
- Optionally sets SOG to 0 for vessels with outdated position data
- Adds timestamp suffix to vessel names with old position data
VesselFinder.com Support: Optional UDP forwarding of AIS Type 1 messages
Flexible Filtering: Skip vessels without callsign or valid identification
Debug Options: Detailed logging for specific MMSI or all vessels

Warning: AIS data provided by this plugin can assist navigation. However, it never replaces the skipper's responsibility. I exclude any liability for damages resulting from the use of this plugin.

Installation

Install via SignalK App Store
Restart SignalK server
Configure the plugin in SignalK admin interface → Server → Plugin Config → AIS to NMEA0183 / NMEA2000 converter for TPC clients (e.g. Navionics)

Configuration Parameters

Basic Settings

TCP Port

Default: 10113
Description: Port for the NMEA 0183 TCP server. Configure your navigation app (e.g., Navionics, OpenCpn) to connect to this port.

Websocket Port

Default: 10114
Description: All AIS (NMEA 0183) messages are send by an own websocket server on this port to connected clients. In addition the data of the vessels is send as JSON. Data can then be used by other plugins / apps (as clients). For the communication with the Navionics app, this port is not needed. If port is set to 0 no Websocket server is started.

Update Interval for Changed Vessels

Default: 15 (seconds)
Description: How often to check for and send updates when vessel data changes. Lower values = more real-time updates but higher CPU usage.

Update Interval for Unchanged Vessels

Default: 60 (seconds)
Description: How often to resend data for vessels that haven't changed. Important for apps like Navionics to prevent vessels from disappearing. Set to 0 to disable (not recommended).

Data Filtering

Skip Vessels Without Callsign

Default: false
Description: When enabled, vessels without a callsign will not be transmitted.

Skip Vessels With Stale Data

Default: true
Description: When enabled, vessels with outdated position data will not be transmitted.

Stale Data Threshold

Default: 60 (minutes)
Description: Position data older than this threshold will be considered stale and filtered out (if "Skip Vessels With Stale Data" is enabled).

Timestamp Added to Ship Name

Default: 5 (minutes, 0=disabled)
Description: Adds a timestamp suffix to the vessel name if position data is older than specified minutes. Format: SHIPNAME MIN15, SHIPNAME HOUR2, or SHIPNAME DAY3. Vessel names are truncated to 20 characters.

Speed Over Ground (SOG) Correction

Minimum SOG for Alarm

Default: 0.2 (m/s)
Description: SOG values below this threshold will be set to 0. Used by the AIS encoder.

Maximum Minutes Before SOG Set to Zero

Default: 0 (minutes, 0=disabled)
Description: Automatically sets SOG to 0 for vessels whose position timestamp is older than specified minutes. Prevents false collision warnings in navigation apps for vessels with outdated data. Set to 0 to disable this feature.

NMEA2000 PGN Creation

Default: false
Description: When enabled, the plugin generates NMEA2000 'Position Report' PGN 129038 (Class A) / PGN 129039 (Class B), PGN 129794 (Class A Static and Voyage Related Data), PGN 129809+129810 (Class B static data Part A+B) and sends them to the selected CAN bus interface. This option is only visible, if miminum 1 CAN interface (including virtual CAN interfaces) is available! Since Socket CAN is only available for Linux, the option will not be visible in Windows or MAC environments. If there is more than one existing interface, the corresponding interface can be selected.

VesselFinder Integration

Enable VesselFinder Forwarding

Default: false
Description: When enabled, AIS Type 1 and Type 19 messages (position reports for AIS class A and B) are forwarded to VesselFinder.com via UDP.

VesselFinder Host

Default: ais.vesselfinder.com
Description: Hostname for VesselFinder UDP server.

VesselFinder UDP Port

Default: 5500
Description: UDP port for VesselFinder server.

VesselFinder Update Rate

Default: 60 (seconds)
Description: How often to send position updates to VesselFinder.

AISFleet Cloud Integration

Include Vessels from AISFleet.com

Default: true
Description: Fetches nearby vessels from AISFleet.com cloud API and merges them with local SignalK vessel data. Requires internet connection and own position (in SignalK key "navigation.position" must exist). If the plugin "AIS Fleet" is already installed and enabled in SignalK, this option is not shown.

Radius for Cloud Vessels

Default: 10 (nm / nautical miles)
Description: Radius around own vessel position to fetch cloud vessels from AISFleet.com (1-100 nm).

Debug Options

Debug All Vessel Details

Default: false
Description: Enables detailed debug logging for all vessels in the server log. Option only visible if plugin is in debug mode. Useful for troubleshooting or understanding of send data.

Debug MMSI

Default: empty
Description: Debug output will be filtered for only this MMSI. Option only visible if plugin is in debug mode. Leave empty to disable.

Debug Stale

Default: false
Description: Stale vessels will be shown in debug log - option only visible if plugin is in debug mode and debug all vessel details is enabled

Debug JSON

Default: false
Description: JSON data of vessels will be shown in debug log - option only visible if plugin is in debug mode and debug all vessel details is enabled

Debug AIS data

Default: false
Description: AIS NMEA0183 data output will be shown in debug log - option only visible if plugin is in debug mode and debug all vessel details is enabled

Debug corrected SOG

Default: false
Description: Vessels with corrected SOG will be shown in the debug log - option only visible if plugin is in debug mode and debug all vessel details is enabled

How It Works

Data Flow

Data Collection:
- Fetches vessel data from SignalK API (http://<IP_OF_SIGNALK_SERVER>:<PORT_SIGNALK_SERVER>/signalk/v1/api/vessels)
  - use other SignalK plugins (like AisHub WS) to receive more vessels for SignalK with AIS information
- Optionally fetches nearby vessels from AISFleet.com API (if plugin "AIS Fleet" is not installed or not enabled)
- Merges both sources, preferring newer timestamps
Data Processing:
- Filters out stale data based on age threshold
- Corrects invalid navigation values (COG 360° → 0°)
- Applies SOG correction for outdated positions
- Filters vessels without valid name AND callsign
NMEA Generation:
- Creates AIS Type 1 (class A) or Type 19 (class B) messages (position reports)
- Creates AIS Type 5 (class A) or Type 25 (class B) messages (static vessel data)
- Encodes as NMEA 0183 sentences
Broadcasting:
- Sends to all connected TCP clients
- Sends to all connected Websocket clients
- Optionally forwards to VesselFinder.com via UDP
- Resends periodically to prevent client timeouts

Merge Logic

When the same vessel exists in both SignalK and AISFleet cloud data:

Position/Navigation: Uses data with newer timestamp
Name: Prefers any non-"Unknown" value
Callsign: Prefers any non-empty value

Client Connection Handling

When a new TCP client connects:

Complete dataset of all vessels is sent immediately
Client appears in "clients" count in logs
Ensures navigation app shows all vessels right away

Usage with Navionics Boating App

Configure plugin with desired settings
In Navionics app:
- Go to Menu → Connected devices
  - Add new connection (via + sign in upper right corner)
  - Enter name for the connection (e.g. SignalkAIS)
  - Enter SignalK server IP address
  - Enter configured TCP port (default: 10113 - same setting like in SignalK plugin)
  - Select TCP (not UDP)
  - Save connection
- Go to Menu → Chart options → AIS settings
  - turn 'Display AIS targets' on
Vessels should appear on chart immediately and in 'Connected devices' you should see as status for the connection: 'connected' (in green) and 'AIS data reception'

Usage with OpenCpn

Configure plugin with desired settings
In OpenCpn:
- Go to Menu → Tools → Options → Connections
  - Add new connection as follows:
  - Save connection
- Go to Menu → AIS
  - enable AIS targets
Vessels should appear on chart immediately

Troubleshooting

No vessels appear in navigation app

Check that plugin is enabled and TCP server is running
Verify TCP port in app matches plugin configuration
Check firewall settings on SignalK server
Enable debug logging to see if vessels are being sent

Vessels disappear after a while

Increase "Update Interval for Unchanged Vessels" (recommended: 60 seconds)
Check if "Skip Vessels With Stale Data" is filtering out vessels
Increase "Stale Data Threshold" if needed

False collision warnings

Enable "Maximum Minutes Before SOG Set to Zero"
Set appropriate threshold (e.g., 5-10 minutes)
This prevents CPA calculations for vessels with outdated position

Too many/few vessels

Adjust "Stale Data Threshold" to filter outdated vessels
Enable/disable "Include Vessels from AISFleet.com" (if plugin "AIS Fleet" is not installed)
Adjust "Radius for Cloud Vessels" to control area coverage

Debug Logging

To enable debug output:

In SignalK admin interface: Server → Settings → Logging
Change setting for plugin AIS to NMEA 0183 converter for TPC clients (e.g. Navionics) to debug logging
Restart SignalK
Check logs in Server → Logs

Debug information includes:

Number of vessels sent/unchanged
Connected clients count
Vessel filtering reasons
AIS sentence output (when Debug MMSI is set)
NMEA2000 sentence output (when NMEA2000 creation is enabled and debug MMSI is set)

Requirements

SignalK server (Node.js version)
Own vessel position (for AISFleet cloud integration, if "AIS Fleet" plugin is not installed)
Own vessel MMSI
Navigation app with NMEA 0183 TCP support (e.g. Navionics boating app, OpenCpn,...)

API Description

The Plugin provides two HTTP API endpoints that allow external clients or user interfaces to query system capabilities and integration status.

http://:/plugins/signalk-ais-navionics-converter/can-interfaces — List available CAN and vCAN interfaces Returns a JSON object containing all detected CAN and vCAN interfaces on the host system, including their operational state. Only interfaces that physically exist on the system are listed.

Example response:

json { "can0": { "state": "up" }, "vcan0": { "state": "up" } } This endpoint is typically used by configuration UIs to allow users to select an active NMEA2000 interface.

http://:/plugins/signalk-ais-navionics-converter/aisfleet-status — Check AIS Fleet plugin availability Returns whether the AIS Fleet plugin is installed on the system and whether it is currently enabled.