There is no bus from the pier to the train station. Most of the cruise lines do run a shuttle bus into town, but they drop you in the center of town nowhere near the train station. Its than possible to get a local bus or taxi to the station (its usually a little less than a mile). Keep in mind that those shuttles are not free (most lines charge $5 pp one-way). Most of the taxis do not want to go to the station (too close) but there are usually a few that will do the run. Depending on the demands of the driver you might expect to pay up to 20 Euros, but split 4 ways its probably the best way. The taxi to the station takes about 10 min. When you return the taxis at the train will have no problem taking you to the ship, but there are a limited number at the station. So get back at least an hour early, and it is a good idea to be one of the first off the train, than walk quickly through the station so you beat the crowd to the taxi queue (outside the front door). If all the taxis are gone, be patient because others will show within a few minutes.