The Heavy Ship Cannons are extremely useful and powerful ship-mounted weapons. They provide heavy firepower. They are usually placed nearby the hangar bays (Providence-class Destroyer), or are mounted on top of the ship itself (Venator-class Star Destroyer). The Imperial Star Destroyer has one usually on the port side hangar bay. side, and on the Mon Calamari cruiser there is one located on each side. In the campaign version there are four that need to be destroyed to finished your objectives.