548 



Popular Science Monthly 



Every member of the crew knows exactly what he must do; not only that, but 

 he knows, as a rule, the duties of every other man. This means team work 



As this vivid description indicates, a sub- 

 marine is submerged by letting sea water 

 flow into tanks. 



A submarine has two kinds of tanks — one 

 for ballast, the other for trimming. The 

 trimming tanks, used to trim the boat fore 

 and aft, are in the bow and the stern; the 

 ballast tjanks at the bottom and sides. The 

 torpedo tubes are usually in the bow of the 

 boat, although there may also be tubes in the 

 stern and even in the side as in some for- 

 eign boats. Let Lieutenant C. N. Hinkamp 

 of our Navy tell us how the boat is handled : 



"The actual submerging of the boat can be done in 

 two ways, one called the 'static' dive; the other the 

 'running dive.' In the static dive, also known as 

 'balancing,' the boat is submerged, but does not 

 move except in the vertical plane. This dive can be 

 accomplished in two ways; by trimming the boat 

 and maintaining her trim by adjusting the ballast, or 

 by dropping the anchor, trimming the boat to 

 within a few hundred pounds positive buoyancy, and 

 then heaving in or veering on the anchor cable. 



"The mass of a submarine itself amounts to 

 several hundred tons, but the actual forces used to 

 sink it from a neutral state are very small. The 

 addition of 50 pounds of water will cause the boat 

 slowly to descend. ... 



"The static dive by adjustment of ballast is made 

 as follows: After getting the fore and aft trim. . . . 

 the main ballast tanks are flooded through large 



valves, the Qperation requiring from one to two 

 minutes. . . . The boat being trimmed down as 

 far as the main deck, still has too much buoyancy to 

 run submerged. The tank next flooded is the 

 auxiliary ballast tank. This holds enough water to 

 destroy the remaining buoyancy. . . . The final 

 trimming is done by slowly filling the adjusting tank. 

 When the vessel is trimmed until there is about two 

 or three hundred pounds of positive buoyancy, it can 

 be readily handled submerged. This is considered 

 the best trim for all around work and completes the 

 static dive. From this condition any operation sub- 

 merged can be commenced. To be able to determine 

 when to stop is almost the entire secret of the art of 

 balancing. 



"The running dive is made from the awash con- 

 dition. In the awash condition the trimming tanks 

 and auxiliary ballast tanks are flooded to the amount 

 necessary for the proper trim when submerged; the 

 main ballast tanks are empty. The vessel being 

 underway 'awash,' the order is given to submerge. 

 All hands get into the boat, the engines are stopped 

 and the electric motors are started. As soon as the 

 engines are stopped the conning tower is closed, all 

 ventilators are housed, and the main ballast tank is 

 flooded. . . . The boat is inclined slightly, about 

 one half a degree down by the head, and the inrush of 

 the water controlled by manipulation of the valves. 

 All this is done in the short period of from one to 

 two minutes." 



A submarine may run submerged with 

 only her periscope sticking out above the 

 water. Then she can see all about her 



