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classified as part of the Jack Up Lightship Weight.
“Mission Equipment” refers to the equipment and systems
aboard a Jack Up Unit, which are necessary for the Jack Up to
complete its Mission. Mission Equipment varies by the mission
and by the Jack Up. Two Jack Up Units which are involved in
Exploration Drilling may not have the same Mission Equipment.
Examples of Mission Equipment may include derricks, mud
pumps, mud piping, drilling control systems, production
equipment, cranes, combustible gas detection and alarms systems,
etc. Mission Equipment is not always classified as part of the Jack
Up Lightship Weight. Some items, such as cement units, are
typically classified as variable deck load as they may not always
be located aboard the Jack Up.
MODES OF OPERATION OF A JACK UP
Jack Up Units operate in three main modes (fig. 1.4):
transit from one location to another, elevated on its legs, and
jacking up or down between afloat and elevated modes. Each of
these modes has specific precautions and requirements to be
followed to ensure smooth operations. A brief discussion of these
modes of operations along with key issues associated with each
follows.

Figure 1.4 -- Digrametic view of the operation of
Jack up rig

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