Does anyone have the file structure of a GPSMAP 620? I cannot get BOTH an automotive, i.e. CN North America NT, and a marine, i.e. Garmin Bluchart g2 Vision charts loaded on to a single SD card where the unit will load the proper maps when switching back and forth between the two modes. Works fine with 2 separate SD cards. They are unlocked, I have tried EVERY variation of naming the two files, i.e. gmapsupp.img, gmapsup2.img gmapprom.img, etc., etc. but the 620 seems to only want to load the gmapsupp.img. It would be nice to be able to switch back and forth without changing the chip as it is behind the battery. I even merged the two .img files together and still no luck. I have fought with this for two days now and still no luck. Any help/suggestions would be very appreciated.