peter l - If you are leaving from Pt. Liberty in Feb 2010 on the RCCL Explorer of the Seas you need have no fears. She is a true megaship and she rides the seas smoothly and well! She is well engineered and handles well even under the roughest conditions.
If you have fears of seasickness I suggest using seabands, eating the green apples from the buffet and taking Ginger Pills to ease any quesiness!!