On my Oregon 400c, the BlueChart G2 file /Garmin/gmapprom.img is around 400MB. Whilst it is possible to copy this file to a USB drive, it is also possible to copy the file to an OS X disk image for the fastest HomePort performance. Disk images are easily created using OS X Disk Utility as follows:
1. Open Disk Utility (under Applications/Utilities)
2. Click New Image
3. Enter file name (eg Garmin-BlueChartG2) in Save As field (optionally navigate to alternate directory etc)
4. Enter volume name (eg Garmin-BlueChartG2) in Name field
5. Change the size to be a bit larger than the gmapprom.img file (set Custom size using pull down menu)
6. Change format to Mac OS Extended
7. Click Create
8. Quit Disk Utility
9. Open Finder
10. On the newly mounted volume, create a directory 'Garmin'
11. Now copy your gmapprom.img file (or whichever Garmin .img file) to this directory... this may take a while
Before starting Homeport, simply make sure the new BlueChart volume is mounted. The chart will show up after a few seconds under My Garmin Devices (top left). Finally select the BlueChart under the Charts menu.
Enjoy!
