Dynamic Positioning of the Mohole Experimental Drilling Ship

Abstract

The drilling of the Mohole, a hole through the crust of the earth, will be undertaken from a drilling ship operating in true oceanic depths. Because anchoring at these depths is infeasible, the position of the drilling ship above the hole in the ocean floor must be controlled by surface propulsion units. This concept is called "dynamic positioning." An experimental drilling program was undertaken in 1961 to determine, among other engineering factors, whether dynamic positioning was feasible. A special integrated control system was developed for four steering propellers which permitted a single operator to control the position of the experimental drilling ship, CUSS I. The system operated successfully for a month at sea and proved that dynamic positioning was not only feasible but entirely practical. This system is expected to form the basis for the control of future waterborne vehicles for geophysical and oceanographic research.