History
Dynamic positioning started in the 1960s for offshore drilling. With drilling moving into ever deeper waters, Jack-up barges could not be used any more and anchoring became less economical.
In 1961 the drillship Cuss 1 was fitted with four steerable propellers, in an attempt to drill the first Moho well. It was possible to keep the ship in position above the well off La Jolla, California, at a depth of 948 meters.
After this, off the coast of Guadalupe, Mexico, five holes were drilled, the deepest at 183 m (601 ft) below the sea floor in 3,500 m (11,700 ft) of water, while maintaining a position within a radius of 180 meters. The ship's position was determined by radar ranging to buoys and sonar ranging from subsea beacons.
Whereas the Cuss 1 was kept in position manually, later in the same year Shell launched the drilling ship Eureka that had an analogue control system interfaced with a taut wire, making it the first true DP ship.
While the first DP ships had analogue controllers and lacked redundancy, since then vast improvements have been made. Besides that, DP nowadays is not only used in the oil industry, but also on various other types of ships. In addition, DP is not limited to maintaining a fixed position any more. One of the possibilities is sailing an exact track, useful for cablelay, pipelay, survey and other tasks.
Read more about this topic: Dynamic Positioning
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