I just finished creating a set of charts for OpenCPN using Linux. I used the instructions here:http://www.svsarana.com/make_charts_fro ... _earth.php
The only place where I had trouble was in the very small scale zooms. Around a resort area, Google tries to make the buildings 3D, which messes up the registration of the charts. As long as you stay zoomed out enough that Google Maps doesn't go 3D, you will be able to create very nice KAP files using the instructions above.