You don't need GPSBabel or anything else. What you need is Garmin's MapSource product:
MapSource will work with the 5212 - at least they say it does and I think there are others I know doing it. It will read and write GPX files. GPX files should be compatible between products but there are many type of data that can be in a GPX file and sometimes there is confusion about tracks vs routes vs waypoints.
The reason you'd use ActiveCaptain is that it gives you a route
archive and the ability to grab routes from many thousands of other boaters. There are other features coming with routes on ActiveCaptain too - ways of combining routes with all of the points-of-interest data we have. It will provide a really nice tools for bridge and hazard planning, finding fuel
, being alerted about specials enroute, or finding friends who will be along the same ways.
ActiveCaptain's sharing of routes isn't just between captains. It's also between devices. So having the route on the AC server will provide a gateway to the Garmin device as well as the other partner navigation
products and other products. That way you'll have the exact same route running on all devices when you're underway. You might not have an iPhone/Android/tablet now, but chances are you will in the future. It's quite nice to have the same route on your iPhone
as your Garmin while traveling along it.
This is all very new and is something that doesn't exist anywhere else. It will be a little confusing until all the pieces are unrolled and it all becomes clearer.