Heavy Lift Ship

A heavy lift ship is a cargo ship built with specialized equipment, either powerful onboard cranes or a hull that can be partially submerged, to carry exceptionally large or heavy individual cargo items that cannot be broken down into standard container or bulk-cargo units, such as oil rig modules, large industrial equipment, other ships and sections of bridges or offshore platforms. Semi-submersible heavy lift ships load their cargo by flooding ballast tanks to lower the ship's deck below the waterline, floating the cargo into position above the deck, and then pumping out the ballast to lift the cargo clear of the water for transport, a method used for moving damaged or newly built vessels too large to carry by any other means. The heavy lift shipping sector grew substantially alongside the expansion of offshore oil and gas infrastructure and large-scale industrial construction projects in the later twentieth century.