A heavy lift ship is a vessel designed to move very large loads that cannot be handled by normally equipped ships. They are of two types: semi-submerging vessels capable of lifting another ship out of the water and transporting it; and vessels that augment unloading facilities at inadequately equipped ports.
Submerging types – FLO / FLO
Semi-submerging are more commonly known as a “flo/flo” for float-on/float-off.
These vessels have a long and low well deck between a forward pilot house and an aft machinery space. In superficial appearance, it is somewhat similar to a dry bulk carrier or some forms of oil tanker. Its ballast tanks can be flooded to lower the well deck below the water’s surface, allowing oil platforms, other vessels, or other floating cargo to be moved into position for loading. The tanks are then pumped out, and the well deck rises to shoulder the load. To balance the cargo, the various tanks can be pumped unevenly.
The flo/flo industry’s largest customer base is the oil industry. They have transported many oil drilling rigs (flo/flo ships can carry the rigs from their construction site to a drilling site at roughly three to four times the speed of a self-deploying rig). Rapid deployment of the rig to the drilling site can translate into major savings to the oil industry. They also transport other outsized cargo and yachts.
Fonte: http://en.wikipedia.org/wiki/Heavy_lift_ship
