1919 to 1940 Most of the Electric Boat design group spent the 1920s in the
Pacific, operating out of
San Diego and
Hawaii. In 1921, one member of this group, , was stranded at sea in the Pacific, off Hawaii, when it ran out of fuel during a
search and rescue operation. The boat rigged makeshift sails and sailed to
Hilo, Hawaii. The Hawaii-based boats returned to the mainland, on 18 January 1931, and were decommissioned to reserve status, at the
Philadelphia Navy Yard, in 1931. In the aftermath of s disaster in 1927, all of the EB design boats were modified for greater safety. A motor room escape hatch was added, the motor room being the after most compartment. The tapered after casing became a step as a result of this modification. The boats also received salvage air connections and mating surfaces around topside hatches to allow the
McCann Rescue Chamber to rescue trapped crewmen.
World War II As the war emergency in Europe became more urgent, most of the boats were recommissioned in 1940, conducting patrols in the Caribbean, or being used as sonar targets at
Key West, Florida. They also patrolled between
Submarine Base New London, in Connecticut, and
Bermuda. At least two R-boats unsuccessfully fired torpedoes at
German U-boats on the Bermuda patrols. During the war, several R class boats operated out of Key West, being assigned to support the
Fleet Sonar School. They served primarily as sonar targets for training crews of
destroyers and
destroyer escorts in
anti-submarine warfare. They also conducted patrols in the
Florida Strait, and the
Yucatán Channel. Three boats, , , and , were transferred to the
United Kingdom's
Royal Navy, as HMS
P.511, HMS
P.512, and HMS
P.514 in 1941-1942.
P.514 was lost on 21 June 1942, in a collision with the
Canadian minesweeper due to being mistaken for a U-boat. was lost on 12 June 1943, while underway off Key West. While the cause of her loss has never been definitively determined, when her wreck was found by the in 2010, by the
Lost 52 Project, it was suspected that the old boat suffered from a hull failure in the forward battery compartment. Between May and September 1945, the 15 remaining R boats in the US Navy were decommissioned and subsequently scrapped. ==Peruvian R boats==