Heavy-lift ship is an ocean-going vessel designed to transport extremely heavy, large, or awkward cargoes. Such cargoes may be impossible to transport over land or using other ships . Sometimes larger cargoes can be taken apart, transported, and then reassembled elsewhere. But for other sorts of structures, it is more economical and practical to ship them in one piece aboard immense ships heavy-lift ships.
Some heavy-lift ships function like submersible dry docks . A dry dock is a facility in which a vessel can lie out of the water. Known as semi-submersible ships, float on-float off ships, or flo-flos, such ships have decks that can be partly submerged. The flo-flo ship is lowered by letting seawater into long buoyancy chambers in its hull (outer shell) until the deck is underwater. Another ship or other load can then be floated onto the deck. Next, water is pumped out of the buoyancy chambers, and the flo-flo ship’s deck rises above the water level, carrying its cargo with it. Once the flo-flo ship reaches its destination, its deck is sunk again, and the smaller ship is floated off. Flo-flos often transport vessels to shipyards for repair or improvements. They are also used to transport offshore oil rigs.
The other kind of heavy-lift ship is the crane-lift variety. These colossal vessels have their own cranes . They can lift entire locomotives, wind turbines, and huge structures used in power plants onto their decks. Sometimes, shoreside cranes also are used to help lift heavy loads. Then the cargo is transported to its destination, where it is lifted off the ship.
Heavy-lift ships are unusual and extremely rare. Only a few companies in the world own and operate them.
