United States E-class submarine

The E-class submarines were a class of two United States Navy submarines, built by the Fore River Shipbuilding Company of Quincy, Massachusetts, under a subcontract from the Electric Boat Company. They were used as coastal and harbor defense submarines prior to World War I. When hostilities broke out, the E class were mostly used as training boats; however, E-1 operated on war patrols based in the Azores. During this time, the need for an improved permanent bridge structure was discovered; the temporary piping-and-canvas bridges were inadequate in the North Atlantic.

Design
The two E-class submarines were analogous to the preceding D-class submarine, with very similar size and displacement and the same armament. They were essentially diesel powered D-class boats, and were the first U.S. diesel-powered submarines. The French "Z" (Q 36) was the first in the world, in 1905. Although early diesels were unreliable and the E class engines were replaced in 1915, diesels rapidly supplanted gasoline-fueled engines aboard submarines worldwide, to eliminate the substantial risk of gasoline fumes settling into the bilges of the boat at explosive concentrations.

Submerged controllability problems associated with the ever increasing size of USN submarines lead the force to adopt bow diving planes for the first time in this class. The bow planes were for precision depth control,. while the traditional set of stern diving planes handled angle control. Grayling (D-2) of the previous class tested a prototype set of bow planes and the tests were entirely successful. A larger and retractable set was installed on the E-class, setting the standard that lasted until the Skipjack-class nuclear submarines of the late 1950's.

The small conning tower fairwater (also known as a sail) initially precluded any sort of bridge structure for surface cruising. For extended surface runs, a temporary piping-and-canvas structure was erected to give the topside watchstanders some protection from the elements. The considerable time required to dismantle that structure made "crash" diving the boat impossible, but that was not seen as an impediment as USN doctrine did not call for crash dives at that time. Experience in World War I showed that the piping-and-canvas structure was inadequate in North Atlantic weather, and USN submarines serving overseas in that war (E, K, and L-classes) had the forward structure of the fairwater modified with a metal "chariot" shield. Starting in 1918-1919 using lessons learned from overseas experience, U.S. submarines had bridges more suited to surfaced operations in rough weather. By 1920, even E-2 had been retrofitted with a permanent metal chariot bridge structure.

History
The E-class and similar early submarines were known as "pig boats" due to foul living quarters and unusual hull shape. The E class was used to test and evaluate tactics and new equipment, but was quickly overtaken by newer long-range, ocean-going submarines. E-1 was forward deployed to the Azores in World War I, the oldest and smallest US submarine to perform war patrols in that war. The class was decommissioned and scrapped in 1922 to comply with the Washington Naval Treaty.

Boats

 * USS E-1 (SS-24) was laid down on 22 December 1909, launched on 27 May 1911 as Skipjack and was commissioned on 14 February 1912 (LT Chester W. Nimitz in command). Renamed E-1 on 17 November 1911 and reclassified as SS-24 on 17 July 1920, the submarine was decommissioned on 20 October 1921 and sold afterwards.
 * USS E-2 (SS-25) was laid down on 22 December 1909, launched on 16 June 1911 as Sturgeon and was commissioned on 14 February 1912. Renamed E-2 on 17 November 1911 and reclassified as SS-24 on 17 July 1920, the submarine was decommissioned on 20 October 1921 and sold afterwards.