 As a single-ship division, SubDiv Zero, she returned to New London in the spring to continue experimental duty.As part of a series of studies conducted by the United States Navy after World War I into the possibility of submarine-borne observation and scouting aircraft, "S-1" became the experimental platform for this project late in 1923.She was altered by having a steel capsule mounted abaft the conning tower; a cylindrical pod which could house a small collapsible seaplane, the Martin MS-1.