Many people choose to bring alcohol on board but to me it just does not seem worth the hassle. It's a vacation..why add all that stress to save only a few bucks?? If you are on one of the newer ships you can check your cabin bill on the TV each day to always know exactly what you owe. If your ship does not have that feature you can go to the pursers desk and have the bill printed out anytime you would like. There should be no surprises.
Relax and enjoy.
8 Norwegian: Sky, Jewel, Dawn, Epic, Pearl, Breakaway, Getaway, Escape
10 Windjammer: S/V Legacy X3, S/V Polynesia, S/V Caledonia, S/V Diamant, S/V Sagitta X2 S/V Mandalay, S/V Vela