A single submarine was built in 1929 -- 1930 .
A single submarine was was tested at sea early in 1931 , under the manufacturer 's designation of submarino E-1 , since no navy had yet commissioned the ship .
A single submarine was built in 1929 -- 1930 , and was tested at sea early in 1931 , under the manufacturer 's designation of submarino E-1 , since no navy had yet commissioned the ship .