CHAPTER VII 

 SUBMARINE SEARCH PROCEDURE 



The problem of determining the proper methods of search 

 for submarines entered into mere than half of the anti-submarine 

 tactics and into a great deal of naval tactics in other fields,, 

 This problem, therefore, occupied much of the attention and 

 required the expenditure of considerable energy on the part of 

 Group Mo 



The ocean is wide and it is impossible to watch all parts 

 of it all of the time„ The alternative is to watch some parts 

 of it some of the time, not casually, but in conformity with 

 a carefully devised procedure built upon an analysis of all 

 the essential factors. 



Basis of Search Plans . 



In considering search plans, one cf the first factors 

 which must be taken into account is the range of detection, 

 whether it be by eye, by radar, or by sonar gear. At first 

 the simplest possible assumption was made, that is that noth- 

 ing was detected outside the range of detection, while every- 

 thing was detected which came within the range It was soon 

 recognized that this simple assumption of a sharply limited 

 search range was a very crude approximation, Actually, 

 some surfaced submarines are seen at great distances by air- 

 craft, and others under the same conditions, are not seen 

 until close in. 



It was necessary, therefore, in studying the search prob- 

 lems, to calculate the probability that a submarine might be 

 seen at a given ranga. From this probability one can then 

 compute the average range under which the submarine will be 

 detected under certain conditions „ 



More important than the range of detection is the search 

 rate, that is the rate at which a craft with its detection 

 gear can search over the ocean for the enemy submarine or 

 surface vessel. In order to compute the number of square 



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