Porpoise Class

Design and Construction Notes

By 1933 the Navy had learned a lot from the largely experimental V-class fleet submarines. That experience led the Navy to design the Porpoise class of fleet submarines, a refinement of the earlier Dolphin and Cachalot. The National Industrial Recovery Act of 1933 provided needed money to spur shipbuilding in the U.S. and the Navy took advantage by ordering four submarines for Fiscal Year 1934. Now firmly in charge of the submarine acquisition process, the Navy ordered two of these boats to be built at the Portsmouth Navy Yard in Kittery, ME., and two from the revitalized Electric Boat Company (EB) of Groton, CT. The Navy allowed EB to build its two boats to a divergent, but similar design that used a welded partial double hull. Portsmouth, still not convinced of the efficacy of welding, built its two boats to a traditional riveted full double hull design. All four boats had the same armament, engineering plants, and performance so they were considered to be in the same class. FY-35 appropriations approved funds for six more boats, so the Navy decided to standardize on the EB style partial double hull for all six. The Perch group consisted of two boats built at Portsmouth, one at Mare Island, and three built by EB. The three Navy yard boats were the last riveted submarines for the Navy, while the EB boats were fully welded. The ten boats of the Porpoise class also set a new precedent: they were the first USN submarines to have all-electric drive. All previous submarines were equipped with direct drive diesel engines. For the Porpoise class the engines drove only generators and were not connected directly to the propeller shafts. The electricity they generated drove motors attached to the shafts.