With a top speed of 21 knots, a range of 11,000 nautical miles (20,000 km) (allowing patrols in Japanese home waters), and a reliable propulsion plant, along with the Salmons they were an important step in the development of a true fleet submarine.

[7] The Bureau of Steam Engineering (BuEng) and the General Board desired a full diesel-electric plant, but there were some dissenting opinions, notably Admiral Thomas C. Hart, the only experienced submariner on the General Board, who pointed out that a full diesel-electric system could be disabled by flooding.

Four of the class (Sargo, Saury, Spearfish, and Seadragon) were equipped with the troublesome Hooven-Owens-Rentschler (HOR) double-acting diesels.

An attempt to produce more power from a smaller engine than other contemporary designs, the double-acting system proved unreliable in service.

It was replaced by the Mark 9 4-inch (102 mm)/50 caliber gun in 1943-44, in most cases removed from an S-boat being transferred to training duty.

In October 1941, the remaining Sargos and most other newer available submarines were transferred to the Asiatic Fleet in the Philippines as part of a belated effort to reinforce U.S. and Allied forces in Southeast Asia.

The Japanese occupation of southern Indo-China and the August 1941 American-British-Dutch retaliatory oil embargo had raised international tensions.

Sailfish of this class sank the Japanese aircraft carrier Chūyō, which was carrying 21 survivors from the submarine Sculpin; only one of these prisoners survived the sinking.

In early 1945 the surviving boats of this class were transferred to training roles for the remainder of the war, eventually being scrapped in 1947-48.