CDG airport to LeHavre

If you're light, take the RER B into Nord, hike to Magenta, take the RER E over to Haussman St Lazare and hike to the SNCF station. Sounds rough, but there's only about ten minutes of walking to make the connections. That'll take a bit over an hour and cost you about twelve bucks each. Alternatively, if you're heavy, take a cab into St Lazare. It will probably be a little shorter and cost less than seventy-five bucks. A non-stop train runs up to Le Havre in a couple of hours from St Lazare. The port has buses that run from the Le Havre station to the cruise terminal.

Just to be precise, while trains go directly from Gare Saint-Lazare to Le Havre, they are not non-stop. See the detailed timetables on the German Rail site.

Tim's correct, I meant no changes.