Heavy-Transport Ship (Float-On/Float-Off)

A semi-submersible heavy-transport vessel that ballasts down to submerge its open deck, lets a floating cargo (an oil rig, a damaged ship, port cranes, or a yacht) move into position over the deck, then deballasts to lift the cargo clear of the water. This float-on/float-off (FLO/FLO) method needs no shore crane and suits indivisible loads of tens of thousands of tonnes. Operators include Boskalis (former Dockwise) and COSCO Shipping Heavy Transport. The deck cargo is then sea-fastened for the voyage.