Wrapping up the USN G Class subs.
USA, G-3 USS Turbot (SS-31)(1915)
Another Lake designed boat the Turbot G-3 had six 18 inch (457 mm) 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.
USA, SSK G-4 USS Thrasher (SS-26)(1914)
G-4 had two bow and two stern 18 inch (457 mm) 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 submarines experienced.
None of the Simon Lake designed boats of this period were well received and all had design and operational problems. As a result they were all scrapped shortly after WW1.
CraigH