Dear developers, there was a discussion about changing the header of the img files in a way they will load on a newer Garmin marine device (e.g. GPSMap 4xx, 5xx): http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2010q1/006427.html As a workaround, a tool called Marinator can patch the img files for making them usable on newer marine devices: http://www.mediafire.com/file/muizdgzyewz/BlueChartG2_Marinator.rar Having to use this tool, there is no way to produce a gmapsupp that works on marine devices directly with mkgmap. You will always have to create a MapSource version, patch the imgs and then create a gmapsupp. This makes it impossible to produce marine maps automatically under linux. Is there a chance to modify mkgmap in a way the maps do not have to be patched anymore?