Lloyd Dobler was pretty close. The Magic went to Key West and left at the usual time Sunday night and then went "full steam ahead" from Key West to Cozumel so Monday was a "day at sea" but they arrived at Cozumel about 5:00 pm and spent the night leaving about 5:00pm or so today (Tuesday).
FYI, I think they normally overnight at Cozumel but don't usually get there till late so guests aren't allowed ashore till the morning.