
United States B-class submarine

The B-class submarines were three United States Navy submarines built by the Fore River Shipbuilding Company in Quincy, Massachusetts, under a subcontract from the Electric Boat Company. They were eventually stationed in the Philippines, an American possession, beginning in 1912–15. They were shipped there on colliers (coal-carrying ships). All three were stricken and expended as targets 1919–22.
Design.
These vessels introduced some features intended to increase underwater speed, including a small sail and a rotating cap over the torpedo tube muzzles. The streamlined, rotating torpedo tube muzzle cap eliminated the drag that muzzle holes would otherwise cause. In the stowed position, the submarine appears to have no torpedo tubes, as the holes in the cap are covered by the bow stem. This feature remained standard through the K class, after which it was replaced with shutters that were standard through the 1950s.
For extended surface runs, the small sail was augmented with a temporary piping-and-canvas structure (see photo). Apparently the "crash dive" concept had not yet been thought of, as this would take considerable time to deploy and dismantle. This remained standard through the N class, commissioned 1917–1918. Experience in World War I showed that this was inadequate in the North Atlantic weather, and earlier submarines serving overseas in that war (E class through L class) had their bridge structures augmented with a "chariot" shield on the front of the bridge. Starting with the N class, built with lessons learned from overseas experience, US submarines had bridges more suited to surfaced operations in rough weather.