If you are in the Mobile AL area and want to do some ship spotting, I would suggest going to the Gulf Quest Museum. The museum is an EXCELLENT museum on shipping.
http://www.gulfquest.org/Also the adjacent waterfront is on the Mobile River in the main port area with ships passing by often, and Austal Shipbuilding and BAE Shipyards are in visual range. Do be prepared to pay for parking.
Good Luck!!!