United States G-class submarine

The G-class submarines were a class of four United States Navy submarines. While the four G boats were nominally all of a class, they differed enough in significant details that they are sometimes considered to be four unique boats, each in a class by herself. They were the result of agitation (presumably from industry and Congress) for competition in submarine design; all previous US submarines were designed by Electric Boat. "G-1", "G-2", and "G-3" were designed by Simon Lake of the Lake Torpedo Boat Company, while "G-4" was designed by American Laurenti. "G-1" was built by Newport News, "G-2" and "G-3" by Lake (completed at the New York Navy Yard due to Lake's temporary dissolution), and "G-4" by Cramp.
Design.
"G-1", "G-2", and "G-4" were the last gasoline-powered submarines in the US Navy. The Lake-designed "G-1" was equipped with three sets of diving planes spaced along the midships part of the hull, and no bow planes. This was to facilitate level diving, which Lake thought was safer than the angle diving of the numerous Electric Boat designs. During World War I, "G-1" and "G-2" were fitted with "chariot" bridge shields for improved surface operation in rough weather, although they were not deployed overseas.
"G-1" was essentially a private venture that the Navy did not initially request; a result was that her hull number of SS-19½ was in between and . By the time the Navy's designation system was overhauled in 1920, "F-1" had been lost, so "G-1" became SS-20 at that time. "G-1" had six 18 inch (450 mm) torpedo tubes: two in the bow, and four in two twin trainable mounts in the superstructure. These mounts could only fire abeam, not dead ahead or dead astern.
"G-2" had four 18-inch torpedo tubes: two bow internal, one bow external, and one stern external, with 8 torpedoes. She was the first US submarine with a stern tube. A preliminary drawing shows four engines installed, in tandem, probably with a clutch between them. This would likely create severe vibrations in operation, as it would be impossible to perfectly synchronize the engines, a problem the later s experienced.
"G-3" had six 18-inch torpedo tubes: two bow internal, two bow external, and two stern external, with 10 torpedoes. She was the only one of the class with diesel engines. While being completed at the Brooklyn Navy Yard she was fitted with sponsons to improve stability.
"G-4" had two bow and two stern 18-inch internal torpedo tubes, with 8 torpedoes. Four engines were installed, in tandem as in "G-2", except there was no clutch between them. This created severe vibrations in operation, as it was impossible to perfectly synchronize the engines, a problem the later "AA-1" class experienced.