Modern Italian Submarine—Fiat Construction—Laurenti Design. Vessel of the Double Hull Buoyant Superstructure. Hydroplane Controlled Type
German "U" Boat—Krupp Design VARIOUS TYPES OF MODERN FOREIGN SUBMARINES
27 and 28, vertical rudders; 29 and 30, hydroplanes for controlling depth of submergence; 9, periscopes; 21, engines; 20, motors; 22, storage batteries; 4, drop keel; 31, torpedo tubes.
The majority of the British and American boats are developments from the original Holland of Mr. Holland's design. Increasing the stability, greater subdivision of ballast compartments, refinements in steering gear, and the addition of hydroplanes forward have enabled Mr. Holland and his successors to produce submarines that operate very well. These boats, however, with only one pair of forward planes, still require constant manipulation of the horizontal rudder to control them when submerged. This rudder, controlled by power gear, is very effective and will, by expert manipulation, hold the submarine to practically even depth. The only danger the writer can see is that the diving rudder gear might fail to function after it is set in the diving position, in which case the vessel might continue diving until she struck bottom or reached a depth great enough to cause her to collapse.
The modern submarines, therefore, as built and used in all the world's navies, owe their final success to principles of construction and control devices invented and introduced into the art by two American inventors.