If you are motorized the best thing to do besides the small ferries that cruise the harbour, is to drive to Dania Beach from Ft. Lauderdale. This will take you approx. 20 minutes depending on traffic. Find your way to the beach by either Dania Beach Blvd. or Sheridan, these two streets lead to bridges that cross the Intracoastal waterway. Once on the A1A road (Ocean Drive) head north until you reach the JOHN U.LLOYD BEACH STATE PARK. There is a 5$ park entrance fee as I recall for cars. Once there, drive to the very last parking, you may stop at a couple spots along the way and peek through the mangroves to see ships that are docked on the Intracoastal part of the port. Once at the parking you can walk to the breakwater and go quite far out to sea. This spot is good from morning to about 1600. The further out you go the more unobstructed view you will have, I was there both pre and post 9/11 and was never bothered despite spending hours standing waiting for ship movements. There is a beach right next to the breakwater where non-spotters can take in the sun. Fishermen are usually not taking all the space because pelicans do the most fishing around the breakwater.
Finally, cap or hat is a must as well as good sunscreen as there is absolutely , positively, no shade unless you withdraw from the breakwater.