A typical drillship will have, in addition to all of the equipment normally found on a large ocean ship, a drilling platform and derrick located on the middle of its deck. In addition, drillships contain a hole (or ‘moonpool’), extending right through the ship down through the hull, which allows for the drill string to extend through the boat down into the water.
Drillships are often used to drill in very deep water, which can often be turbulent. Drillships use what is known as dynamic positioning systems. Drillships are equipped with electric motors on the underside of the ship’s hull, capable of propelling the ship in any direction. These motors are integrated into the ship’s computer system, which uses satellite positioning technology, in conjunction with sensors located on the drilling template, to ensure that the ship is directly above the drill site at all times.
The use of drillships will be especially preferred on Semisubmersible drilling rigs in Arctic conditions where the vessels may have to leave the drilling position in emergency because of the icebergs. They are also used when the drilling position may change often as the vessel is self sufficient for transportation, it does not need any towing support.