Regrettably, I have not been on a cruise, but I was always under the impression that at evening Dinner one had to dress up with a black tie and DJ (Tuxedo). If that is the case then, I'd have thought, a tweed jacket would not be appropriate.

I agree, a nice Crail jacket, but in black barathea, would be best. It can be worn formally with a black bow tie, or less formally with a neck tie.