Jeff,
Just the DAT and EXT files directly in the data folder. If your old computer can still be used, it may be easier and more reliable for you to open the Offshore Navigator program on your old computer, go to File > Export Data to File > Marks (you would have to do Routes and Track separately) This will allow you to export all data out of the program files onto your hard drive and in a format that can be imported into Offshore Navigator on your new computer. You can copy these files to a disk and copy to the hard drive on your new computer, where you can then use the File > Import data from File option to import your waypoints into Offshore Navigator.
-Justine Baldwin
Technical Support Specialist