Drilling Rigs - Semi-Submersible
A Semi-submersible platform or rig, is a mobile structure used for drilling for oil and natural gas in offshore environments. Their superstructures are supported by columns sitting on hulls or pontoons which are ballasted below the water surface. They provide excellent stability in rough, deep seas. Semi-submersible rigs can be moved from place to place; and can be ballasted up or down by altering the amount of flooding in buoyancy tanks; they are generally anchored by cable anchors during drilling operations, though they can also be kept in place by dynamic positioning. Semi-submersibles can be used in depths from 600 up to 35,000 feet (180 to more than 10,600 m).
Dwarfing the ferry on the Cromarty Firth in northern Scotland, the HENRY GOODRICH is a Sonat/Mitsui ...
A cable laying vessel, the Apache, passing a rig anchored in the Cromarty Firth.
This is the Frontier Driller, ex KNV, ex Transocean Explorer being towed out of the Cromarty Firth b...