A second means of obtaining a bathymetric profile is to plot 

 a great-circle path on a bathymetric contour chart, or series of 

 charts, and digitize the range and depth at the intersection of 

 the path with each bathymetric contour. When a large number of 

 great-circle profiles, each several thousand miles long, involving 

 dozens of bathymetric charts, are constructed, the labor costs are 

 considerable. Profiles produced manually from charts tend to be 

 schematic, blocky, and subject to human error. Most importantly, 

 both of these methods are slow and cannot be achieved in real time. 



Although various phases of both methods have been automated, 

 within the Navy and elsewhere, no totally satisfactory solution 

 has been achieved to the present time. The system proposed in 

 this report is one approach to solving the above problems. 



The Synthetic Bathymetric Profiling System (SYNBAPS) is a 

 combination of digital computer software (programs) and a random- 

 access storage file (presently a CDC 813 permanent disk) of gridded 

 bathymetric data, employed to generate random, great-circle, 

 bathymetric profiles suitable for acoustic propagation modeling. 

 SYNBAPS is completely automatic, requiring only the input, via a 

 control card, of the latitude and longitude of the beginning and 

 end points to extract the desired profile. The profile also can 

 be generated given the latitude and longitude of the beginning 

 point, the bearing, and the maximum range. The generated profile 

 is available in two forms. The first is a computer -drawn profile 

 where range in whole nautical miles is plotted against depth, in 

 either meters or fathoms; the second is a punched card deck of 

 the same data. The profile outputs in card image are available on 

 magnetic tape where large quantities of data are involved. 



A bathymetric profile along a great-circle path of about 

 8,000 nm can be generated in approximately 3 minutes of computer 

 time on a second generation computer and can be plotted in about 

 3 minutes on an incremental plotter. A cost comparison shows that, 

 by present semiautomatic methods, a set of 19 short profiles 

 totaling 9,000 nm required 144 man-hours at a cost of $900. The 

 same profiles could be produced by SYNBAPS in 1.4 man-hours at a 

 cost of $50, for a savings of 18:1 in dollars and 100:1 in time. 



OUTLINE OF SYSTEM OPERATION 



The SYNBAPS software can be broken down into three distinct 

 program functions associated with structuring, accessing, and 

 status (fig. 1) . 



The structuring programs create a gridded bathymetric data 

 base and structure it on a random-access device in a precise 

 form. The smallest cell of the data base is a 5-minute-square 

 grid where the north-south side is in meridional minutes or parts 



