Welcome to the Raymarine Technical Forum Ray,
Raymarine's Voyage Planner PC software supports importing data from archive.fsh and exporting data to .gpx files and vice versa.
Voyage planner is the worst software I have ever had the misfortune to need. I am still looking for a way to convert GPX to FSH files that would preclude me from having to use Voyage planner. GPSutility is good but they want $60 to get the full version and the site is gone so you can't get it anyway. GPSBabel will convert to .rwf but not .fsh, I'm still looking.