It appears on the cruise tickers site, there is no option to adjust the time zone. So I guess in order for it to be right, you have to put in the set sail time in GMT?
Good question. I'm not sure. Mine is way off now as well. I used the Cruisetickers.com site, and was able to get mine pretty close before by adjusting the sailing time, but now it is off. I'm probably not the best person to answer this as it has confused the heck out of me previously.