The Balao class is a design of United States Navy submarines that was used during World War II, and with 120 boats completed, the largest class of submarines in the Navy. An improvement on the earlier , the boats had slight internal differences. The most significant improvement was the use of thicker, higher yield-strength steel in the pressure hull skins and frames, which increased their test depth to . A Balao-class submarine, the USS Tang, actually exceeded her depth gauge's maximum reading of in 1944, when taking on water in the forward torpedo room while evading a destroyer.
Design
The Balao boats were similar to the Gato class, except they were modified to increase test depth from to . In late 1941, two of the Navy's leading submarine designers, Captain Andrew McKee and Commander Armand Morgan, met to explore increasing diving depth in a redesigned Gato. A switch to a new high-tensile steel alloy, combined with an increase in hull thickness from to , would result in a test depth of and a collapse depth of . However, the limited capacity of the trim pump at deep depths, and lack of time to design a new pump, caused Rear Admiral E. L. Cochrane, chief of the Bureau of Ships, to limit test depth to . Fortunately in 1944, a redesigned Gould centrifugal pump replaced the noisy early-war pump, and effective diving depth was increased.Friedman through 1945, pp. 208-209
The Balao boats incorporated the fairwater, conning tower, and periscope shears reduction efforts that were being retrofitted to the Gato and preceding classes in the original design, refining the reductions and reducing the sail to the smallest practical size. By the time the boats began to be launched, lessons learned from patrol reports had been worked into the design, and the bridge and sail proved to be efficiently laid out, well equipped, and well-liked by the crews.A Visual Guide to the U.S. Fleet Submarines Part Three: Balao and Tench Classes 1942–1950 pp. 2-3, Johnston, David (2012) PigBoats.COM
For the masts and periscope shears, the original arrangement for both the Government and Electric Boat designs had (forward to aft) the two tapered, cone-shaped periscope support shears, followed by a thin mast for the SJ surface search radar, and then by a thin mast for the SD air search radar. Minor differences existed in how the periscopes were braced against vibration, but both designs were nearly identical. About halfway through their production run, Electric Boat altered their design, moving the SJ radar mast forward of the periscopes, then altered it again a few boats later by enlarging the SD radar mast. Late in the war, many Balao boats built with the original design had the SD air search radar moved slightly aft onto a thickened and taller mast. These mast arrangements, along with the tremendous variation in the gun layout as the war progressed, account for the numerous exterior detail differences among the boats, to the point that at any given time, no two of the class looked exactly alike.Johnston, pp. 3-10
Engines
The propulsion of the Balao-class submarines was generally similar to that of the preceding Gato class. Like their predecessors, they were true diesel-electric submarines; their four diesel engines powered electrical generators, and electric motors drove the shafts. No direct connection was made between the main engines and the shafts.
Balao-class submarines received main engines from one of two manufacturers. General Motors Cleveland Model 16-278A V-type diesels or Fairbanks-Morse 38D 8-1/8 nine-cylinder opposed-piston engine. The General Motors Cleveland Model 16-248 V-type as original installations, while boats from onward received 10-cylinder engines. Earlier General Motors boats received Model 16-248 engines, but beginning with Model 16-278A engines were used. In each case, the newer engines had greater displacement than the old, but were rated at the same power; they operated at lower mean effective pressure for greater reliability. Both the Fairbanks-Morse and General Motors engines were two-stroke cycle types.
and were to receive Hooven-Owens-Rentschler diesels, which proved unreliable on previous classes, but both boats were cancelled.
Two manufacturers supplied electric motors for the Balao class. Elliott Company motors were fitted primarily to boats with Fairbanks-Morse engines. General Electric motors were fitted primarily to boats with General Motors engines, but some Fairbanks-Morse boats received General Electric motors. Allis-Chalmers motors were to be used in SS-530 through SS-536, but those seven boats were cancelled before even receiving names.
Most Balao class submarines carried four high-speed electric motors (two per shaft), which had to be fitted with reduction gears to slow their outputs down to an appropriate speed for the shafts. This reduction gearing was very noisy, and made the submarine easier to detect with hydrophones. NineteenAlden, pp 212 - 213Bauer and Roberts, p. 275 late Balao-class submarines were constructed with low-speed double armature motors, which drove the shafts directly and were much quieter, and this improvement was universally fitted on the succeeding . The new direct-drive electric motors were designed by the Bureau of Ships' electrical division under Captain Hyman G. Rickover, and were first equipped on .Friedman through 1945, pp. 209-210 Many of the earlier Balao class submarines would be re-fit with the new gearless motor scheme during the GUPPY programs after the war. On all US World War II-built boats, as the diesel engines were not directly connected to the shafts, the electric motors drove the shafts all the time.
Torpedoes At the beginning of World War II the standard torpedo for US fleet submarines was the 21-inch, Mark 14 torpedo. Due to a shortage of this torpedo, several substitutions were authorized, including using the shorter Bliss-Leavitt Mark 9 torpedo and Mark 10 torpedo, and the surface-fired Bliss–Leavitt Mark 8 torpedo, Mark 11 torpedo, Mark 12 torpedo, and Mark 15 torpedo. The surface-fired torpedoes required minor modifications. Due to their excessive length, Marks 11, 12, and 15 torpedoes were limited to the aft torpedo tubes only.https://maritime.org/doc/fleetsub/tubes/chap11.php#11A8 Ordnance Pamphlet 1085 21-inch Torpedo Tubes Marks 32 to 39 and modifications as in SS-198 and upAs torpedo production ramped up and the bugs were worked out of the Mark 14, substitutions were less common. As the war progressed, the Navy introduced the electric wakeless Mark 18 Torpedo and the Mark 23 torpedo, a simplified high-speed-only version of the Mark 14. Additionally, a small 19" swim-out acoustic homing Mark 27 torpedo supplemented the armament in fleet boats for defense against escorts. Near the end of the war, the offensive Mark 28 torpedo acoustic homing torpedo was introduced. Well after the war the Mark 37 Torpedo was introduced.http://navweaps.com/Weapons/WTUS_Main.php NavWeaps.com Weapons-Torpedoes-United States of America
Deck guns
Many targets in the Pacific War were sampans or otherwise not worth a torpedo, so the deck gun was an important weapon. Early Balaos began their service with a /50 caliber Mk. 9 gun. Due to war experience, most were rearmed with a /25 caliber Mk. 17 gun, similar to mounts on battleships and cruisers, but built as a "wet" mount with corrosion-resistant materials, and with power-operated loading and aiming features removed. This conversion started in late 1943, and some boats had two of these weapons beginning in late 1944. , commissioned in March 1944, was the first newly built submarine with the purpose-built /25 submarine mount. Additional antiaircraft guns included single 40 mm Bofors and twin 20 mm Oerlikon mounts, usually one of each.Johnston, pp. 3-6Friedman 1995, pp. 218-219
Mine armament Like the previous Tambor/Gar and Gato classes, the Balao class could substitute mines in place of torpedoes. For the Mk 10 and Mk 12 type mines used in World War II, each torpedo could be replaced by as many as two mines, giving the submarine a true maximum capacity of 48 mines. The doctrine, though, was to retain at least four torpedoes on mine-laying missions, which further limits the capacity to 40 mines, and this is often stated as the maximum in various publications. In practice during the war, submarines went out with at least eight torpedoes, and the largest minefields laid were 32 mines. After the war, the Mk 49 mine replaced the Mk 12, while the larger Mk 27 mine was also carried, which only allowed one mine replacing one torpedo. This mine could be set to travel 1000 to 5000 yards from the sub before deploying. (not to be confused with the Mk 27 homing torpedo)ORD696 Operational Characteristics of U.S. Naval Mineshttp://navweaps.com/Weapons/WAMUS_Mines.php NavWeaps.com Weapons-ASW and Mines-United States of America-Mines
Boats in class
This was the most numerous US submarine class; 120 of these boats were commissioned from February 1943 through September 1948, with 12 commissioned postwar. Nine of the 52 US submarines lost in World War II were of this class, along with five lost postwar, including one in Turkish service in 1953, one in Argentine service in the Falklands War of 1982, and one in Peruvian service in 1988.United States Submarine Losses in World War II, Naval History Division, Office of the Chief of Naval Operations, Washington: 1963 (Fifth Printing) Also, flooded and sank while fitting out at the Boston Naval Shipyard on 15 March 1945. She was raised but not repaired, and was listed with the reserve fleet postwar until struck in 1958. Some of the class served actively in the US Navy through the middle 1970s, and one (Hai Pao ex-) is still active in Taiwan's Republic of China Navy.
SS-361 through SS-364 were initially ordered as Balao-class, and were assigned hull numbers that fall in the middle of the range of numbers for the Balao class (SS-285 to SS-416 and 425–426).Fleet Submarine index at NavSource Thus in some references, they are listed with that class.Lenton, p. 94 However, they were completed by Manitowoc as Gatos, due to an unavoidable delay in Electric Boat's development of Balao-class drawings. Manitowoc was a follow yard to Electric Boat, and was dependent on them for designs and drawings.Friedman through 1945, p. 209 Also, the Balao class and are listed with the Tench class in some references, as their hull numbers fall in the range of that class.Lenton, pp. 100-102Silverstone, p. 203 These were built by Cramp Shipbuilding, a follow yard for Portsmouth Navy Yard and waited for Government plans.
Cancellations
In total, 125 U.S. submarines were cancelled during World War II, all but three between 29 July 1944 and 12 August 1945. The exceptions were three Tench-class boats, cancelled 7 January 1946. References vary considerably as to how many of these were Balao and how many were Tench boats. Some references simply assume all submarines numbered after SS-416 were Tench class; however, and were completed as Balaos.Silverstone, pp. 203-204Gardiner and Chesneau, pp. 145-147 This yields 10 cancelled Balao-class, SS-353-360 and 379–380. The Register of Ships of the U. S. Navy differs, considering every submarine not specifically ordered as a Tench to be a Balao, and further projecting SS-551-562 as a future class. This yields 62 cancelled Balao class, 51 cancelled Tench class, and 12 cancelled future class. Two of the cancelled Balao-class submarines, and , were launched incomplete and served for years as experimental hulks at Annapolis and Norfolk, Virginia. The cancelled hull numbers listed in sequential order here, including those launched incomplete, were SS 353–360, 379–380, 427–434 (all Balao class), 436–437 (Tench class), 438–474 (Balao class), 491–521, 526–529 (Tench class), 530–536 (Balao class), 537–550 (Tench class), and 551–562 (future).
Service history World War II