You should carry a copy of your passport off the ship with you for this reason. I always take a Xerox copy in my pocket. This could also benefit you if you were to get injured while in port and taken to the hospital.
well i'm not sure about losing it off the ship but i lost mine 4 times in a drunkin mess on my last cruise and a 3 am trip to the pursers desk solves the problem. by the second time they knew me by name and would just laugh. i would always leave it in some chicks room and then forget which room she was in. spring break cruises rule!
good question, itcould be a hassle trying to get back on board, some ports you can't even get onto the dock without your ships card.
Ask your travel agent. My guess would be that you would have to show security your passport or a picture id, then they would pull you up on the computer.
My sail and sign card got eaten by the water filtration pump in the swimming pool last year. I now have swimming trunks with valcro on the pocket. No problem replacing the card on the ship, just go to the purser's desk. They electronically punch out another card which also contains your photo. Some folks punched a hole in the corner of the card and put it on a chain around their neck. Whatever works.
Jan/00 RCCL Viking Serenade
May/01 CCL Elation
Apr/02 CCL Sensation
May/03 CCL Fantasy
Jan/04 CCL Ecstasy
Dec/04 NCL Norwegian Star
Dec/05 CCL Legend
May/06 CCL Paradise
Jan/07 CCL Liberty
Just a footnote for the ladies....if you have a purse that has a magnetic clasp (my small black purse I used for formal nights had one) and put your Sail & Sign card in it, the magnet will deactivate your card and render it useless, you will have to go to the Purser's desk so they can issue you a new card.