do I need a visa for a cruise?

I am taking a cruise out of Hong Kong in January, 2012. We stop one day in Sanya. I carry a Thai passport. My adopted father, with whom I am traveling, has a US passport. The cruise line tells us that if he buys an excursion on board, they will provide a visa. Should they do me the same courtesy or do I need a visa from the embassy? If so, how far in advance of the trip should I apply for the visa?