• Arduino Mega 1250 or better
  • GPS board. (or use USB GPS)
  • Raspberry Pi model B. 256Mb RAM or better.
  • Wifi adaptor supported by hostapd, to enable Freeboards built-in wireless access point. (Optionally connect to a real WIFI Access Point by ethernet)
  • Powered USB Hub with enough ports! Lots of USB cables :-)

Optional Hardware

Power usage

  • Measured power usage of hub, powering Raspberry Pi, IMU, anemometer, USB WIFI, and Mega via USB power adaptor
      • 0.37-0.4A @ 12V = 4.8W

Software (on Github)

By default the RaspberryPi's hostname should be set to your boat name ("motu" for me) and the wifi server is also set to use the same name. Hence on our vessel you simply connect to wifi access point 'motu', and navigate your web browser to 'http://motu'. If you prefer OpenCPN, then set OpenCPN's TCP NMEA port to 'motu:5555'

The web browser communicates with the FreeBoard-server using HTML5 websockets, and the instruments are drawn in an HTML5 canvas. Using websockets and HTML5 canvas means that the browser reacts just like a normal PC program. There is no html page refresh/blink/flash as data updates, and changes are immediate, with smooth graphics etc.

The chartplotter is similar to google maps. It loads and zooms much like you expect, and waypoints, tracks etc are drawn just like a PC based chartplotter.


  • Web browser with support for HTML5 canvas, and websockets
  • eg any modern browser except IE. Internet Explorer still doesnt have proper support of websockets, and before IE9 does not support the canvas tag either. It wont work. I suggest getting Firefox or Chrome, or any other decent browser.


  • Currently reads NZ charts in KAP format, and eg US RNC charts
  • See OpenSeaMaps.org for more charts.Bahamas, Brazil, Argentina, Germany and Netherlands seem to be available.
  • Converters for other common formats will be added as required. Most common GIS formats are feasible.