It is possible to embed Google maps into a webpage that is accessible from the both the boat and computers that are connected to the internet. Version 3 is now out and does not require an API key to use. There are no limits to the number of maps that can be generated by this API.
There are different controls that are outlined in the link that can be used for various things including showing paths traveled and points of interest, such as way points, in the form of markers.
Looks straight forward and easy to incorporate into a webpage UI to make the GPS location of the boat more user friendly to read.