Over the past few years I have played on the Princess Line. They offer the standard AC game of 6-8 decks, DAS, 3/2 BJ, Dealer stands on soft 17.
I have never seen any heat at all, but I don't know if that is a good or bad reflection on my counting skills.
I have, however, always been suspicious of cheating. I know the Public Relations effect of getting caught at this would be quite a black eye for the cruise line, but rarely do you see all the cards displayed face up prior to sitting at an empty table. It would not take much effort to lose a 10, or two 10's out of an 8 deck shoe.
The atmosphere on a cruise ship is totally vacation like, with novice players all over the place. There are usually 2-3 $5-$100 tables. One $10-$200 table, and maybe, if it is busy, one $25-$500 table. So your spreads might well be limited.