Page:Popular Science Monthly Volume 90.djvu/564

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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

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