that the boats were not optimized for combat. Armament needed to be upgraded and new technologies needed to be implemented. The conning tower fairwater in particular was deemed a liability as it was too large and easily sighted by the Japanese while surfaced. The Navy immediately authorized modification programs to address these issues. The conning tower fairwater was reduced in size in a fashion similar to the other fleet submarines, with both the forward and after sections cut away. This gave the fairwater a smaller, stepped appearance. Reducing the size of the fairwater also provided new platforms for mounting heavier machine guns, with two Oerlikon 20 mm cannons being mounted. An SD air search radar was mounted on an extendable mast on the forward edge of the conning tower fairwater, and an SJ surface search radar was added on a short mast on the bridge itself. As noted above the torpedo armament was upgraded on five of the boats, and improved engines were installed. 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. See also Allied submarines in the Pacific War Unrestricted submarine warfare Torpedo List of submarine classes of the United States Navy List of lost United States submarines List of submarines of the Second World War Notes References Campbell, John Naval Weapons of World War Two (Naval Institute Press, 1985), Gardiner, Robert and Chesneau, Roger, Conway's All the World's Fighting Ships 1922-1946, London: Conway Maritime Press, 1980. . Johnston, David "No More Heads or Tails: The Adoption of Welding in U.S. Navy Submarines", The Submarine Review, June 2020, pp. 46-64. Johnston, David A Visual Guide to the U.S. Fleet Submarines Part Four: Porpoise Class 1934-1945 Lenton, H. T. American Submarines (Navies of the Second World War) (Doubleday, 1973), Silverstone, Paul H., U.S. Warships of World War II (Ian Allan, 1965), External links On Eternal Patrol, website dedicated to all US submarines and submariners lost to all causes All Submarines Navsource.org fleet submarines page Pigboats.com pre-1941 submarine photo site DiGiulian, Tony Navweaps.com later 3"/50 caliber gun Submarine classes Porpoise