|From left: Peter Johnson; William R. Reidel of Scripps Institution of Oceanography; Capt. Harold E. Saunders, USN (ret.)|
Fifty years ago the National Academy of Sciences nurtured a grand initiative in earth sciences and fostered the birth of deep-ocean drilling by sponsoring the AMSOC Committee, organizing its technical staff, and assuming management of a unique at-sea experiment to prove feasible the concept of drilling in the deep ocean. The first steps of collecting samples beneath the sea bottom and testing the technology to make it possible took place in early 1961. I came on the scene in the fall of 1960 as the naval architect on committee staff and remained until this work concluded. The Academy was an enthusiastic supporter of this project and its promise of scientific discoveries as well as a reluctant partner in a high-risk, full-scale experiment at sea with little prior precedence. But this first step did prove successful and showed the value of diligent planning and engineering combined with prudent risk-taking. In some ways the technology of the 1960s seems primitive compared to today but in other ways, many of the innovations and technical concepts of that time continue to be used today.
Both these views have merit when trying to understand the value of historical lessons while keeping progress in perspective. It is necessary to take first steps to prepare the way for further advancements in a field. Sometimes these first steps appear too aggressive and impossible to achieve -- some critics of the initial Mohole experimental drilling plans had this view. In hindsight, however, these same critics viewed the results of the experimental drilling in 1961 as obviously easy.
History also tends to repeat itself. The Academy was established during the Civil War by President Lincoln and its earliest work was related to marine technology, ships, and the sea.
For example, the second NAS committee ever appointed was charged with the consideration of means for protecting the bottoms of the Union Navy's iron ships from salt water damage. It was appointed May 9, 1863, at the request of the Navy Department. This short-lived committee made a brief report and was discharged without a recommended solution to the problem.
NAS Committee No. 3, "the Compass Committee," was appointed on May 20, 1863, also at the Navy's request. It investigated the functioning of compasses on ships, which were beginning to be built with numerous iron components. In its January 1864 report it recommended the use of appropriately placed bar magnets to counteract local attractions acting on ship compasses. The committee itself oversaw the correction of compasses on 27 Union ships.
So, 100 years after this early work, NAS again found itself at sea fitting out ships.
Project Mohole & Dynamic Positioning
|Willard Bascom's original sketch illustrating the dynamic positioning system|
Bill Bascom was the technical director of the Mohole experimental drilling project operating under the AMSOC committee and he coined the terms that became the identifying symbols of the twin science / technology initiatives during the days of designing and carrying out the work. He recalls that one day the Mohole title came to him and he shouted it down the old Academy hallways to whoever would listen. Bascom was indeed the driving force leading the project team of scientists and engineers working on Project Mohole at the time and especially the efforts to design, build, and carry out the experimental drilling at sea. He provided the energy and perseverance to assure that the venture achieved the success it did.
When Bascom hired me as part of the AMSOC staff, a substantial part of the concept design for the CUSS I conversion -- the dynamic positioning system, drilling system modifications, and other features -- was already done. The NAS Report "Experimental Drilling in Deep Water," which described these plans, was published in February 1960. Most of the design plans were followed but some were changed and improved as we approached the operating phase in 1961. A large part of that report discusses the dynamic positioning system and calculated forces on the ship to be counteracted by large thrusters installed on each corner of the CUSS and a pilot control system designed to function under expected wind and current drag on the ship. Bascom and his staff engineer Bob Taggart developed the complete system of multiple thrusters and controls as well as location targets of underwater buoys to be installed at the drilling sites.
The other key aspect of engineering design work that the Mohole project staff needed to contend with was that of upgrading then state-of-the-art drilling systems to meet the challenges of deep water, open ocean operations. These included: how to accommodate ship motions and their effect on drill pipe stresses, what was the effect of ocean currents on the drill pipe, how to drill without casing from the ship to the sea floor in deep water, etc. A number of unique designs and new subsystems were invented by staff engineers Ed Horton and Francois Lampietti, my colleagues at the time.
Preparation for Experimental Drilling
Those of us who were charged with preparing for the test drilling operations in the spring of 1961 had a busy time designing the specific pieces of hardware, checking the designs with tests wherever possible, getting the equipment built, and preparing it for installation. My responsibility was the positioning buoys and related equipment. The buoy system was designed with a dead-weight anchor, a thin wire rope from the sea floor to a buoyant spheroid, about 200 feet below the sea surface, that exerted an upward tension on the wire, and a surface buoy attached to the subsurface buoy with a flexible line. The subsurface buoy (mounted with a sonar transponder) would maintain a fixed position wandering only slightly off station when pushed by ocean currents, which were minimal at that depth. The surface buoy had a radar reflector on it to both check the sonar location info and to provide the comfort of a visual marker.
It was a valuable experience as a young engineer to be intimately involved with each phase of this project from design to building to operation. I recall some design problems related to the high strength buoy mooring wire rope. It was manufactured at a steel plant in Pennsylvania where the wire was extruded and the strands twisted together. The design water depth was 12,000 feet and, when installed, the subsurface buoy would exert an upward force to stretch the wire. We decided to test the elongation on a section at the factory and use the test data to predetermine the length of wire needed when installing the buoys at sea. I was also on board the ship to install these buoys and cut them free to see them, hopefully, take their proper position. This was just a small example of attention to engineering details that we followed.
|CUSS I during trials off La Jolla, Calif.|
The CUSS I
John Steinbeck, who sailed with the crew aboard CUSS I to the Guadalupe Island site, noted that the ship had the "sleek race lines of an outhouse standing on a garbage scow." In fact, it was probably the most advanced floating drilling rig the oil industry had built at the time and probably the only available platform that could be readily adapted for this project. This vessel was selected for the deep drilling platform because it was one of only a few existing floating drilling vessels built by the oil industry; it had the capabilities to handle the required length of drill string and other drilling equipment; it could be modified for dynamic positioning; and the owners were willing to work with us in the planning and engineering phase. The CUSS was developed by a cooperative group of oil companies who had already used it to drill offshore California, moored by anchors in up to a few hundred feet of water. Offshore oil drilling experts assisted the staff in many aspects of engineering studies done prior to the at-sea tests. And, this experience also fostered future industry work in ocean drilling.
The AMSOC Committee selected two sites for the ocean drilling experiments -- one of which was the site for initial sea trials to make sure all of the equipment would function as designed. The site was close to home port (San Diego) so that any problems might be readily corrected before leaving for the deep ocean site about 200 miles south. A few problems did crop up, and one of them was my responsibility. I was aboard the Scripps research vessel Horizon installing the navigation buoy system in preparation for CUSS arrival at the drill site. The first day we set the first buoy and waited overnight before installing the rest. The next morning the buoy had disappeared. After searching far and wide we concluded that the surface float had broken loose, and we did not have the means for locating the subsurface buoy (the plan was to install the sonar transponder on it later). Although we never found any of these parts, a close evaluation of the design led us to identify the fault in the mooring connections between the surface and subsurface buoy. A design correction was quickly applied to the remainder of the buoys and they all performed well after that. While Bascom almost fired me on the spot for my error, the show went on and I am probably the only one who remembered the incident more than a day later.
|The crew of the Horizon lowering buoys into the water|
Drilling in Deep Water
The proof of the pudding for us engaged in the engineering preparations and the operations at the Guadalupe Island site was drilling the test holes into the sea floor in 12,000 feet of water and recovering samples of both soft sediments and hard rock of the second layer. Despite worse-than-expected weather of 20 knot winds and 12 foot waves, a long slow voyage from San Diego to the site, and the first-time tests of many unique components, the vessel remained on station and the drilling went ahead with few problems or unexpected incidents.
Even though the at-sea experiments lasted only a few weeks, the intense preparations of designing, testing, and building many components and the mobilization of ship and crew served to bring together a close-knit team with shared goals and aspirations. Steinbeck commented that the most unique equipment on board the CUSS was an elite and motley crew. On the voyage from San Diego to the drill site, Bascom gave a series of lectures on both the science and engineering features we were testing -- attended by cooks, drillers, and scientists. There is great motivation in combining doing and thinking. Perhaps this is the important history lesson.