Originally Posted by You
hang it on a hanger, cover it with a plastic dry cleaners or a clear vinyl garment bag, place it on top of all the luggage in the car. I am not sure that you can carry it on to the ship as it won't fit thru the scanner, but then again if security can plainly see that its a dress you just might be able to carry it on. I would check with your ta or the cruise line to find out definately, otherwise you will have to hand it over to a porter with all your other checked baggage
A standard garment bag should go through the hand luggage scanner lengthwise. The hand luggage scanner takes my two suiter (26" roller back) with no problem, in spite of a baggage handlers in San Diego and a transfer operator in San Juan who have tried to tell me that it would not.