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.

Porpoise and Pike (Full double hull, riveted)

USN photo

Portside view of Porpoise, location not known for sure, but it could be the Piscataqua River near Kittery, ME. The date is probably the fall of 1935. The P1 painted on her bow and fairwater was a visual identification expedient. It was NOT her name or her designation. The use of these identifiers was common on the fleet boats, but faded out in favor of hull numbers in 1938.

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Shark and Tarpon (Partial double hull, welded)

NHHC photo NH 41921 courtesy of the Naval History & Heritage Command.

Tarpon shown underway circa 1937. Location is most likely San Diego with the Point Loma headlands in the background. On the forward deck is the round ball of the JK sonar. Immediately aft of that is the mount for a M2 .50 caliber water-cooled machine gun. The gun has been dismounted and taken below, a common procedure. On the aft deck is the 3"/50 caliber Mk 6 deck gun. The topside is festooned with lifelines, radio aerial wires, and masts. This was a typical appearance for a fleet boat of this era.

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Perch group (Partial double hull, EB welded, Portsmouth/Mare Island riveted)

Photo courtesy of Vallejo Naval & Historical Museum via Darryl L. Baker and Navsource.org

Left to right: Perch (P5), Pollack (P9), and Plunger (P8) moored together in San Francisco, circa 1938. Of interesting note in this picture is the raised radio mast with the masthead light atop, the searchlights mounted on top of the conning tower fairwater, and the ship's bell mounted to the front of the fairwater. The bell and the searchlights would be taken below before diving.

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