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Encyclopedia of Marine and Energy Technology



Mobile Offshore Units – Self-elevating or column-stabilized units, not fitted with drilling equipment, production facilities, hydrocarbon storage, or any other system onboard handling hydrocarbons. Examples of Mobile Offshore Units are:

– Accommodation Units

– Crane Units

– Construction and Maintenance Units

– Drilling Tenders

– Pipe and Cable Laying Units

– Wind Turbine Installation, Maintenance and Repair Units and similar units used by the offshore industry.

Accommodation Unit – A mobile offshore unit primarily intended for the accommodation of more than 36 persons who are industrial personnel, engaged in some aspect of offshore or related employment, excluding members of the crew. It is intended that during jacking or towing operations, a self-elevating unit will have on board only those crew members necessary for these operations.

Construction and Maintenance Unit – A mobile offshore unit primarily intended for construction and maintenance activities in support of offshore mineral exploration and production operations.

Crane Unit – A mobile offshore unit primarily intended for the lifting of heavy loads in oil drilling and production operations, offshore construction and/or salvage operations. See also Crane vessel OLEG STRASHNOV.

Drilling Tender – A mobile offshore unit primarily intended as support to an offshore drilling platform. It may contain the power supply, circulating pumps (connected to the platform by hoses) and storage tanks, drill pipe racks, casing, cement, storage space, living quarters and generally, helicopter landing platform.

Wind Turbine IMR Unit – A mobile offshore unit primarily intended for the installation, maintenance, and repair of wind turbines, including pile driving, tower installation, nacelle and blade installation. See also Wind Turbine Installation Vessels.

Further reading: ABS “Guide for Building and Classing Mobile Offshore Units” (2008), can be downloaded from