IWORMALLY there are only two types of marine machines concerned with the discovery and recovery of oil from under the ocean floor. The first, mainly engaged in the discovery of oil, is a self-propelled vessel, sometimes of very considerable size. Apart from its towering drilling derrick, it is indistinguishable from any oceangoing cargo vessel; its purpose is to drill boreholes in areas where seismological and geological studies suggest oil may exist. The technical operation of this activity is highly plex, yet these vessels have achieved a remarkable level of success. However, they suffer from two major drawbacks. Alth
