I have not been on this particular itinerary; however have sailed the Constellation in March of this year. There is no requirement for gentlemen to wear a jacket/tie at dinner; although looks nice, dinners with exception to formal nights is smart casual. Polo, button shirt and nice pants (dockers/chinos etc) with closed shoes is suitable attire. On formal nights some gentlemen go all out with tuxedos etc; however if your guy does not have one, a dark jacket/pants will do just fine. I always find ships a little cool - so a light wrap/shawl/sweater is always on my packing list. Hope this helps and enjoy the ship - it's truly wonderful.