Boston Harbor will be filled with dozens of vessels from around the world on July 11 as the city celebrates the Parade of Sail, Sail Boston's biggest day. More than 60 ships will sail through the harbor before docking at their assigned berths, and WCVB has identified five of the must-see ships visitors can look for during the parade.We consulted with Sail Boston to identify the largest ship, the smallest, the oldest and the ship traveling the farthest distance to Boston.