These single-hull boats were structurally similar to the preceding O class, but larger and therefore with more powerful machinery to maintain the required speed.

Electric Boat departed from their traditional rotating bow cap that acted as the muzzle doors for the torpedo tubes.

The Lake-style flat shovel stern with ventrally mounted rudder, diving planes, and propellers were retained for this class.

[12] In 1921 one member of this group, the R-14,[13] was stranded at sea in the Pacific off Hawaii when it ran out of fuel during a search and rescue operation.

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.

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.

Built after World War I using materials assembled from cancelled S-class submarines, they were refitted in 1935–1936 and 1955–1956, and renamed Islay, Casma, Pacocha, and Arica in 1957.

These were the first submarines built directly by Electric Boat at their newly established shipyard along the Thames River in Connecticut.