United States Porpoise-class submarine


The Porpoise class were submarines built for the United States Navy in the late 1930s, and incorporated a number of modern features that would make them the basis for subsequent,,,,, and classes. Based on the s, enlarged to incorporate additional main diesels and generators, the Portsmouth boats were all riveted while the other boats were welded. In some references, the Porpoises are called the "P" class.

Design

In general, they were around long and diesel-electric powered. Displacement was 1,934 tons submerged for the first four boats, 1,998 tons for the later ones.
The goal of a 21-knot fleet submarine that could keep up with the standard-type battleships was still elusive. The relatively high surfaced speed of was primarily to improve reliability at lower cruising speeds. A major improvement essential in a Pacific war was an increase in range from Perch onwards, nearly doubling from to at. This allowed extended patrols in Japanese home waters, and would remain standard through the Tench class of 1944.
Although it proved successful with improved equipment beginning with the Tambor class of 1940, the diesel-electric drive was troublesome at first. In this arrangement, the boat's four main diesel engines drove only electric generators, which supplied power to high-speed electric motors geared to the propeller shafts. The engines themselves were not connected to the propeller shafts. For submerged propulsion, massive storage batteries supplied electricity to the motors. Problems arose with flashover and arcing in the main electric motors. There was also a loss of in transmission through the electrical system. The Winton Model 16-201A 16-cylinder diesels also proved problematic, and were eventually replaced with 12-278As.
Five of the class received an additional pair of external bow torpedo tubes, probably early in World War II: Porpoise, Pike, Tarpon, Pickerel, and Permit. The original Mark 21 3 inch /50 caliber deck gun proved to be too light in service. It lacked sufficient punch to finish off crippled or small targets quickly enough to suit the crews. It was replaced by the Mark 9 4 inch /50 caliber gun in 1943-44, in most cases removed from an S-boat being transferred to training duty.

Ships in class

The Porpoise class consisted of the following three subclasses:
P-1 Type
NameHull no.BuilderLaid downLaunchedCommissionedDecommissionedFate
SS-172Portsmouth Naval Shipyard27 October 193320 June 193515 August 193515 November 1945Reserve training ship; scrapped 1957
SS-173Portsmouth Naval Shipyard20 December 193312 September 19352 December 193515 November 1945Reserve training ship; scrapped 1957

P-3 Type
NameHull no.BuilderLaid downLaunchedCommissionedDecommissionedFate
SS-174Electric Boat24 October 193321 May 193525 January 193611 February 1942Lost 11 February 1942, probably to gunfire from destroyer
SS-175Electric Boat22 December 19334 September 193512 March 193615 November 1945Reserve training ship; expended as target 1957

P-5 Type
NameHull no.BuilderLaid downLaunchedCommissionedDecommissionedFate
SS-176Electric Boat25 February 19359 May 193619 November 19363 March 1942Lost 3 March 1942
SS-177Electric Boat25 March 19357 July 193626 January 1937April 1943Lost to enemy action April 1943
SS-178Electric Boat6 June 19355 October 193617 March 193715 November 1945Scrapped 1958
SS-179Portsmouth Navy Yard17 July 19358 July 193619 November 193615 November 1945Reserve training ship; scrapped 1957
SS-180Portsmouth Navy Yard1 October 193515 September 193615 January 193721 September 1945Scrapped 1947
SS-181Mare Island Navy Yard14 January 193611 March 193712 June 1937August or September 1943Lost August or September 1943, possibly to enemy action on 17 September 1943

Service

Following participation in exercises from 1937, all but three of the ten Porpoise class were forward deployed to the Philippines in late 1939. In October 1941 most of the front-line submarine force, including all sixteen Salmon and Sargo class boats, joined them. The Japanese occupation of southern Indo-China and the August 1941 American-British-Dutch retaliatory oil embargo had raised international tensions, and an increased military presence in the Philippines was felt necessary. The Japanese did not bomb the Philippines until 10 December 1941, so almost all of the submarines were able to get underway prior to an attack. Two of the class were lost in Southeast Asian waters in early 1942, and another two were lost near Japan in 1943. By early 1945, all six surviving boats had been transferred to New London, Connecticut for training duties. Of these, four were used postwar as decommissioned reserve training submarines until they were scrapped in 1957.