A drillship can be one of two types: 1) It can be a ship which was designed and built to be a drilling vessel; or 2) A drillship can be an older vessel which has been refitted with drilling equipment. Drillships are self-propelled, carrying a complete ship's crew while underway, as well as a crew of drilling personnel. Drillships are moored either by the standard anchoring system or by dynamic positioning of the vessel. Dynamic positioning is the use of a computer-operated inboard thruster system which keeps the vessel on location without the use of anchors. This arrangement allows vessels to drill in ultra-deep water. The record is held by Sonat Offshore's Discovery Seven Seas, which drilled in 6,448 feet of water in 1984.
Photo by Ron Edwards