OCEANOGRAPHY IN THE UNITED STATES 227 



Certain problems submitted to the Applied Mathematics Laboratory by the 

 Bureau of Ships, the David Taylor Model Basin and some of its private con- 

 tractors are purely oceanographic, and illustrate the points just mentioned. One 

 such problem is to define the wave conditions in the vicinity of a ship that is 

 undergoing extensive structural and seaworthiness tests in order to relate ship 

 behavior to the state of the sea. Such wave data sent to the Applied Mathematics 

 Laboratory are subjected to hundreds of thousands of calculations before the 

 resultant numbers will define that particular state of sea. Since this problem 

 was submitted several years ago, a total of 902 cases have been handled. Several 

 minutes are required for the computer to perform the arithmetical operations 

 in the solution of one case. If all 902 cases were run consecutively, perhaps 5 

 weeks would be involved. The computation of one case, by hand, on a desk 

 calculator, took 2 months for one man to complete. If one man worked on all 

 902 cases, about 150 years would elapse before the work was completed. For a 

 crude comparison, then, 5 weeks of computer time is equivalent of 1.50 man- 

 years, in the solution of typical oceanographic problems. The greater speed 

 of LARC should appreciably decrease the requisite computer time, when that 

 machine becomes available in about a year. Another problem of oceanographic 

 origin involves the theory of sound propagation in surface sound channels. 

 Sound wave potentials were calculated on Univac for a wide range of acoustic 

 frequencies, depths, and horizontal distances. The purpose of this work was to 

 verify new theory on sound-'channel propagation. 



Model basin experiments in producing irregular seas in its towing tanks center 

 about the ability to reproduce in the laboratory phenomena occurring at sea. 

 It is necessary, then, to compare model tank waves with real waves. Wave 

 measurements made in the basin are analyzed by the IBM 704, and the results 

 are used to verify or to modify techniques for artificial wave generation. 



The behavior of sound at all depths in the ocean depends on the physical struc- 

 ture of the water ; in particular, its changing temperature characteristics. Sound 

 transmission through a warm water mass and a cold water mass successively 

 may be further complicated by internal waves at the boundary. In order to 

 investigate the behavior of sound under such conditions, a set of three simul- 

 taneous differential equations, of a highly complex nature, have been developed. 

 In order to solve them, the computer numerically traces an acoustic ray through 

 such an ocean system. This is accomplished for rays of many different frequen- 

 cies until a complete description of sound transmission under such conditions is 

 evolved. 



The problems discussed here relate to the oceanographic aspects of Navy work. 

 It is not necessary to stop there. The continually increasing capabilities of mod- 

 ern electronic digital computers are of such inagnitude as to permit the predic- 

 tion that collection of oceanographic data, no matter how great, will not exceed 

 the ability of such calculating machines to process it. 



The Interrelation of Oceanography and Submarine Operation 

 (By E. E. Johnson) 



As demonstrated by the sustained submergence of Seawolf, the modern sub- 

 marine is no longer tied to the surface or near surface for operations as were the 

 air-breathing submersibles of the prenuclear era. Indeed, the flexibility and 

 mobility of nuclear-powered submarines is virtually unbounded — except for the 

 lack of oceanographic information to guide their operations — and the ability 

 to provide structural integrity at greater depths. 



Because the lead time between research and reality of a machine as compli- 

 cated as a submarine is long, the Structural Mechanics Laboratory of the model 

 b.'sin -s now engaged in research to provide the basis for the structural design 

 of submarines capable of descending to depths several times deeper than current 

 submarines can. These ships will be capable of collecting oceanographic data 

 during their normal operations just as every existing naval ship now does. 

 Naval ships today collect and forward to the Hydrographic Office information 

 as to depth, temperature, currents, salinity, and general weather for each ocean 

 passage. Nautilus and Skate have expanded this function during their trans- 

 polar expeditions. The circle is endless : As more is learned, new developments 

 are required. 



