Add battery power supply, stick it into a water proof box / container, and take it on the water.
Add Wifi module and create a http server to give access to navi data over LAN / WAN.
Write a first cut of a browser app - of course in JavaScript - that pulls the data with an AJAX request, processes is and displays it text and graphics... and eventually will drive a widget or window with a google map positioned to the received geo location.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Extended the display with the display of the velocity. Velocity is shown in nautical miles. Code is updated.
Next steps are:
Time line is open....