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January 2012 www.sname.org/sname/mt (historical note) the project team and directed the eorts to design, build, and carry out the experimen- tal drilling program. Another colleague, Bob Taggart, who later became editor of the classic SNAME textbook Ship Design and Construction , and I were responsible for the DP system design, and I supervised the con- struction and installation of the navigation buoys. Taggart designed and built the DP control system, which enabled the pilot to monitor radar and sonar displays and control the vessels thrusters with a joystick to keep it in position above the sea oor drill, within a circle of a few percent of the water depth. We began with a design for the con- version of an oil drilling barge, CUSS I , including the dynamic positioning system, drilling system modications, and other fea- tures. Early analyses showed that the type of anchoring then in use for shallow water oil drilling was not feasible in deepwater. However, dynamic positioning would be capable of holding the required position. We calculated that wind and current forces on the ship could be counteracted by large thrusters installed on each corner of CUSS I and that the control system could function under expected conditions. We installed the system of multiple thrusters and controls on the drilling vessel and used an auxiliary ship to install a ring of location targets of underwater buoys at the drilling site. The other key aspect of engineering design and conversion was that of upgrading the shallow water drilling systems to meet the challenges of deepwater, open-ocean operations. ese challenges included com- pensating for ship motions and minimizing their eect on drill pipe stresses; accommo- dating the eect of ocean currents on the drill pipe; and providing the ability to drill without casing from the ship to the sea oor in deep water. The writer John Steinbeck, who sailed with the crew aboard CUSS I to the Guadalupe Island site as project historian, noted that the vessel had the ?sleek race lines of an outhouse standing on a garbage scow.? In fact, it was probably the most advanced oating drilling rig the oil industry had built at the time and probably the only available platform that could be readily adapted for this project. is vessel was selected for the deep drilling platform because it was one of only a few existing oating drilling vessels built by the oil industry. It had the ability to handle the required length of drill string and other drilling equipment, it could be modi- ed for dynamic positioning, and the owners were willing to work with us. CUSS I was converted from a surplus navy barge by a cooperative group of oil companies who had already used it to drill for oil o the shore of California, moored by anchors in up to a few hundred feet of water. Oshore oil drilling experts from indus- try also assisted the sta in many aspects of engineering studies done before the at- sea tests and also provided the expertise to manage the daily drilling operations at sea. is cooperative experience fostered future industry innovations in oshore drilling long after this initial experiment took place, as both the oshore oil business boomed and subsequent scientic exploration of the deep seas continued. Dynamic positioning and deepwa- ter drilling are now proven technologies and in use worldwide both by industry and by continuing international scientic ocean drilling projects sponsored by sev- eral nations, including the United States. DP has evolved substantially from this rst experiment and now uses modern and pre- cise navigation techniques (to replace target buoys), automated computer control sys- tems, and improved thrusters and power supplies. ese enable the system to work reliably on the largest deepwater drill ships and semisubmersible platforms. þÿ M TMTPeter A. Johnson is a marine and ocean engineer working as a consultant to the National Academy of Sciences, international environmental groups, and private clients on renewable energy development and pollution prevention. Early analyses showed that the type of anchoring then in use for shallow water oil drilling was not feasible in deepwater. þÿ IInstalling the deep-moored buoys for navigation markers. Bill Bascom and Bob Taggart with one of four thrusters to be installed on CUSS I .Deep Sea Drilling and Dynamic Positioning continued Further Reading For a more comprehensive discussion of the þÿ MMohole Project and the rst deep ocean drilling experiment, go to www.nationalacademies.org/mohole.html þÿ TThe site also provides a link to Bill Bascom?s popular book A Hole in the Bottom of the Sea ; project historian John þÿ SSteinbeck?s þÿ AApril 1961 Life magazine article and log of the CU þÿ S SSS I voyage; Bascom?s documentary lm of the drilling operations; and the þÿ NNational þÿ AAcademy of þÿ SSciences project reports, Experimental Drilling in Deep Water , and Design of a Deep Ocean Drilling Ship .54_C3_BDept_SNAME_Jan12_P4.indd 6412/22/11 3:45 PM