Plunger-class submarine

The Plunger class was an early class of United States Navy submarines, used primarily as training vessels for the newly formed "silent service" to familiarize navy personnel with the performance and operations of such craft. Most of these "A-class" submarines ended up being stationed in the Philippines, an American possession, prior to the outbreak of World War I. In some instances, this class of submarines is referred to as the Adder-class submarine, as USS Adder was the first boat of the class to be completed.

History
The Plunger-class submarines were built at the beginning of the twentieth century largely as experimental vessels. This class of submarines was built at two different locations on both coasts of the United States. All seven boats were renamed to A-type designations (A-1 through A-7) on 17 November 1911. They were given corresponding alphanumeric hull numbers on 17 July 1920, after all but Grampus (SS-4) and Pike (SS-6) had been decommissioned. All of the Plunger-class ships were decommissioned by 1921 and used as targets.