Not entirely solved... I don't actually have the chartplotter yet, because I won't buy it if I can't get the maps I need to work on it. I am looking at the GPSmap 421. The North Norway Bluechart Map doesn't include detailed info. for the lake I live on, so I was hoping I could use the TOPO map with the chartplotter. Garmin lists only the TOPO Alaska Enhanced as compatible. I would ideally like to display 'Garmin TOPO Sweden Friluftskartan Pro v2 - Norra Norrland' on the plotter. I succeeded in getting the split to display in homeport by following the above tutorial, but not to do so via SD card- so I don't think the chartplotter will be able to display it. The original, unlocked .img won't pull up from SD in homeport, the split images on SD cause crash to desktop in homeport. Any ideas?