SNAME L.A. Section Hears Paper On Air Cushion Drilling Systems
A former chairman appeared before the Los Angeles Metropolitan Section of The Society of Naval Architects and Marine Engineers and presented a paper on " A i r Cushion Drilling Systems." Harold D. Ramsden, manager b u s i n e s s d e v e l o p m e n t , Global Marine Development, Inc., was the guest speaker. He was accompanied by G. Dayton Knorr, Global's Air Cushion Project manager. The two prepared the paper f o r presentation to the Section. According to the guest speakers, it all started in 1968, when Global Marine acquired the first lease for offshore exploration in the Canadian Arctic. This began a program to develop an Air Cushion Drilling System (ACDS). The task eventually involved a long series of tests simulating 50- below-zero working conditions. All operational functions of the system had to be designed with these criteria in mind.
The air cushion system, as explained by Messrs. Ramsden and Knorr, consists of a basic rectangular steel platform surrounded on its periphery by a flexible air skirt. The flexible skirt segments contain an air bubble as the structure rises above the surface. The air cushion is generated by four d-c motor-driven centrifugal fans, rrlaintaining an overall average pressure of iy2 pounds per square inch. This is sufficient to raise a typical drilling platform of several thousand tons to a normal operating height of 8 feet for moving.
The environmental considerations involved working over landfast ice in the Arctic regions, offshore in water depths of 1,800 feet, and over land, permafrost, or marsh areas, without upsetting the ecological balance on these remote sites. It was to be a yearround activity with drilling capability down to 16,000 feet over ice or 25,000 feet over marshlands. The system concept was successfully extended to pipelaying, transporters for both cargo and personnel, and living accommodations. All were designed to be moved from site-to-site through wilderness and undeveloped areas. An unexpected and highly successful application of the concept was realized with the design and utilization of an icebreaker employing the same principles. It was tested on Thunder Bay, Ontario, Canada. The performance evaluations resulted in assigning effiiciency ratings far in excess of expectations. The craft built was named Iceater-1.