United States D-class submarine

The United States D-class submarines were a trio of submarines built for the United States Navy in the first decade of the 20th century. All three ships served during World War I providing training for crews and officers on the U.S. East Coast, before the class was decommissioned and sold for scrap in 1922.

Description
The D-class submarines were enlarged and iterative improvements over the preceding C class, and were the first American submarines armed with four torpedo tubes. They were built by the Fore River Shipbuilding Company of Quincy, Massachusetts, under a subcontract from the Electric Boat Company of Groton, Connecticut. They had a length of 134 ft overall, a beam of 13 ft and a mean draft of 12 ft. They displaced 288 LT on the surface and 337 LT submerged. The D-class boats had a crew of 1 officer and 14 enlisted men. They had a diving depth of 200 ft.

For surface running, they were powered by two 300 bhp NELSECO gasoline engines, each driving one propeller shaft. When submerged each shaft was driven by a 130 hp electric motor. Two 60-cell batteries provided power when submerged. They could reach 13 kn on the surface and 9.5 kn underwater. On the surface, the boats had a range of 1179 nmi at 9.6 kn and 24 nmi at 8 kn submerged.

The boats were armed with four 18-inch (45.7 cm) torpedo tubes in the bow. They did not carry reloads for them. They were the first U.S. submarines to have four forward torpedo tubes which became the norm until the Tambor class which joined the fleet in 1940.

These vessels included some features intended to increase underwater speed that were standard on U.S. submarines of this era, including a small sail and a rotating cap over the torpedo tube muzzles. For extended surface runs, the small sail was augmented with a temporary piping-and-canvas structure. This structure would be disassembled and taken below before diving. USN tactical doctrine of the time did not emphasize quick dives so this was not seen as a liability.

These were the first USN submarines internally subdivided into compartments. D-1 and D-2 had four compartments (torpedo room, forward battery/berthing & control room, after battery/messing, and engine/motor room). D-3 was fitted with only two bulkheads leaving one large compartment in the middle that consisted of both battery wells and the control room. On D-1 and D-2 the helm wheel was actually in the after battery compartment, as the placement of the aft control room bulkhead dictated this arrangement.

Distinguished Commanding Officers
Many future Admirals commanded a D-class submarine early in their careers including Chester William Nimitz

Ships

 * USS D-1 (SS-17) was laid down on 16 April 1908, launched on 8 April 1909 and was commissioned on 23 November 1909 as Narwhal. Renamed D-1 on 17 November 1911, the submarine was decommissioned on 8 February 1922 and sold afterwards.
 * USS D-2 (SS-18) was laid down on 16 April 1908, launched on 16 June 1909 and was commissioned on 23 November 1909 as Grayling. Renamed D-2 on 17 November 1911, the submarine was decommissioned on 18 January 1922 and sold afterwards.
 * USS D-3 (SS-19) was laid down on 16 April 1908, launched on 12 March 1910 and was commissioned on 8 September 1910 as Salmon. Renamed D-3 on 17 November 1911, the submarine was decommissioned on 20 March 1922 and sold afterwards.