Just now heard of this site on crusing the cut. Really cool. Saw the announcement on the Google map issue
Have you looked at open street maps as an option?
Www.openstreetmap.org (http://www.openstreetmap.org)
We are using our own map tile server - using data from Open Street Map but with canalplan specific tile overlays on top of it.
Progress on the move over to the new maps is detailed here:
https://canalplan.org.uk/wiki/mapping_update