Page:Popular Science Monthly Volume 91.djvu/411

 How the U-Boats Get Through the Nets

They are equipped with remarkable motor-driven circular knives and with steel flanges that spread out like doors

��FROM reports that reach us from Europe we learn that Germany has equipped some of her U- boats with ingenious devices to enable them to cut their way through submarine nets. One boat with a double flange of thin sheet steel pro- truding from both sides of the bow is said to have been destroyed by shell fire and .the device itself, practically intact, is said to be in the hands of the British Ad- miralty. A second boat, equipped with heavy motor- driven circular knives at- tached to steel hawsers, tor- pedoed a merchantman, and the captain, while in a small boat, made a drawing of the device for the Admiralty.

The accompanying illustration gives a clear idea of these net-cutters. The double flange of thin sheet steel which protrudes from both sides of the bow of the subma- rine is, operated by electrically-controlled gears. The flanges spread on either side of the bow to a distance of eighteen feet, or

���Perspective >S»l view of double flange

���The double flanges of steel protruding from both sides of the bow are operated by electrically-controlled gears

��The net-cutting device consists of heavy circular knives attached to steel haws:rs extending from bow to stern

��thirty-six feet in all, whenever the nose of the vessel touches an obstruction. Their action is said to be automatic, although an operator within the boat can extend or withdraw the device at any time, by moving two heavy metal arms.

The U-boat equipped with the circular knives is obviously far bet- ter able to cut its way through a net than the boat j ust described. 1 1 does not bother about a de- vice at the bow, figuring, no doubt, that the sharp nose of the vessel and its rounded hull are sufficient to get through a net or stop the boat before it becomes entangled. . However, it does not permit its con- ning tower to go unpro- tected. Several strands of stout steel hawsers contain- ing motor-driven knives, a foot in diameter and placed about a foot apart, are stretched from the bow through the conning tower to the stern. Striking a net, the knives would re- volve on a flexible shaft.

���Plan, view of bow showing flanges extended on both sides

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