I don't think you'll need to worry we were on the same size RC ship class with a room slightly forward twice, once on deck 7 and the other on deck 8. The stablizers on this ship is really great. Not sure of the room numbers we had but we didn't have much movement at all. If you run into a storm the ship can creak some. The Navigator is an awesome ship! You're going to have the cruise of a life time!
Hey Sonny, looks like you're booked on the Mariner for a back to back? You lucky duck! The Mariner is the same size as the Navigator, right? We did a back to back on the Mariner last Jan and it was just awesome. Here's a link to the page I made from that back to back with some pics ---> Mariner Back to Back