Plunger-class submarine

	USS Plunger (SS-2)
Class overview
Builders	Electric Boat (design); Crescent Shipyard (SS-2, -3, -5, -7, -8); Union Iron Works (SS-4, SS-6);
Operators	United States Navy
Preceded by	USS Holland
Succeeded by	B class
Built	1900–1903
In commission	1903–1921
Completed	7
Retired	7
General characteristics
Type	midget submarine
Displacement	107 long tons (109 t) surfaced; 123 long tons (125 t) submerged;
Length	63 ft 10 in (19.46 m)
Beam	11 ft 11 in (3.63 m)
Draft	10 ft 7 in (3.23 m)
Installed power	160 bhp (120 kW) surfaced ; 150 bhp (110 kW) submerged;
Propulsion	1 × Otto Gas Engine Works gas engine; 1 × Electro Dynamic electric motor; 60-cell battery; 1 × shaft;
Speed	8 kn (15 km/h; 9.2 mph) surfaced; 7 kn (13 km/h; 8.1 mph) submerged;
Test depth	150 ft (46 m)
Complement	1 officer; 6 enlisted;
Armament	1 × 18-inch (450 mm) torpedo tube (3 long or 5 short torpedoes)

The Plunger class was an early class of United States Navy submarines. In the first years of their service, they were used primarily as training and experimental vessels for the newly formed "silent service" to familiarize naval personnel with the performance and operations of such craft. They were known as the "A class" after being renamed to A-type designations (A-1 through A-7) on 17 November 1911. All except Plunger ended up being stationed in the Philippines, an American possession, prior to the outbreak of World War I. They were shipped there on colliers (coal-carrying ships) and formed an integral part of the harbor defense system for Manila. In some instances, this class of submarines is referred to as the Adder class, as USS Adder was the first boat of the class to be completed.