THE SUBMARINE OF TO-DAY AND TO-MORROW. 



By L. Y. Spear, Esq., Member. 



[Read at the twenty-third general meeting of the Society of Naval Architects and Marine Engineers, held in 



New York, November 18 and 19, 1915.] 



THE SUBMARINE OF TO-DAY. 



In view of the very prominent, not to say leading, part taken by the submarine 

 in the great struggle now raging in Europe, it is interesting to note that "the sub- 

 marine of to-day" is for all practical purposes a development of the twentieth cen- 

 tury only. At the opening of this century, the United States, France and Italy 

 had just acquired the nuclei of their present flotillas; submarine construction had 

 begun in Great Britain, while the other naval powers had nothing. At the present 

 time this type is found in every navy. Owing to the secrecy imposed by war con- 

 ditions, the number of boats built or building to-day is not definitely known, but 

 the best information available indicates that about 350 have already been completed 

 and that about 200 more are now under construction. 



When we turn to examine the characteristics not only of the boats built in the 

 past, but also of those now building, we are confronted with what at first appears 

 as a bewildering confusion of types and sizes. On analysis, however, logical rea- 

 sons are easily found for the existing variation in characteristics which in fact are 

 due partly to considerations almost purely mechanical and partly to considerations 

 which are purely military. 



In the early days, the problem of the submarine designer was the production 

 of a practicable boat suitable for harbor defense, a role which did not require high 

 speed, long radius, or great sea-keeping qualities, and hence did not involve large 

 displacement. The submarine, however, did not escape the general law governing 

 the displacement of all naval types, and to meet the demand for increased speed, 

 radius, seaworthiness and armament, it has been necessary to progressively 

 increase the displacement. When the capabilities of the type had sufficiently 

 increased, it ceased to be considered as suitable for harbor defense only and was 

 assigned to the larger role of coast defense, and with further development it has 

 come to be considered as an aid to the high seas fleet, as well as a useful weapon 

 for independent ofifensive action in enemy waters. 



As the submarine is dependent for propulsion both on the surface and sub- 

 merged on special types of machinery, the rate of increase in displacement and mil- 

 itary characteristics has necessarily been governed to a very large extent by the 

 development of these features. As all naval powers carry on their lists numbers of 

 vessels several years old, it follows that there are now many intermediate types in 



