Editing Balao-class submarine (section)

== Design ==
[[File:USS Pampanito (SS-383), ship scheme.jpg|thumb|left|Scheme of USS ''Pampanito'' (SS-383)]]

The ''Balao''s were similar to the ''Gato''s, except they were modified to increase test depth from {{convert|300|ft|m|-1|abbr=on}} to {{convert|400|ft|m|-1|abbr=on}}. 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 [[Yield (engineering)|High-Tensile]] Steel (HTS) alloy, combined with an increase in hull thickness from {{convert|9/16|in|1}} to {{convert|7/8|in|1}}, would result in a test depth of {{convert|450|ft|m|-1|abbr=on}} and a collapse depth of {{convert|900|ft|m|-1|abbr=on}}. 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 {{convert|400|ft|m|-1|abbr=on}}. Fortunately, in 1944 a redesigned Gould centrifugal pump replaced the noisy early-war pump, and effective diving depth was increased.<ref>Friedman through 1945, pp. 208-209</ref>

The ''Balao''s incorporated the [[Fairwater (submarine)|fairwater]], [[conning tower]] and periscope shears reduction efforts that were being retrofitted to the ''Gato''s and the 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.<ref name="Diagram">[https://pigboats.com/images/2/2d/A_VISUAL_GUIDE_TO_THE_FLEET_SUBMARINES_PART_5_Balao_class.pdf ''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</ref>

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. There were minor differences 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''s 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 ''Balao''s looked exactly alike.<ref>Johnston, pp. 3-10</ref>

=== 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 engine]]s powered [[electrical generator]]s, and [[electric motor]]s drove the shafts. There was no direct connection between the main engines and the shafts.

[[File:General Motors Model 16-248 V16 diesel engine.jpg|thumb|left|[[Electro-Motive Diesel|General Motors]] [[Cleveland Diesel Engine Division|Cleveland]] Model 16-248 diesel engine]]
[[File:Opposed piston engine 1.jpg|thumb|left|[[Fairbanks-Morse]] Model 38D{{frac|8|1|8}} diesel engine]]

''Balao''-class submarines received main engines from one of two manufacturers.
[[Electro-Motive Diesel|General Motors]] [[Cleveland Diesel Engine Division|Cleveland Model]] 16-278A V-type diesels or [[Fairbanks-Morse]] [[Fairbanks Morse 38 8-1/8 diesel engine|38D 8-1/8]] nine-cylinder [[opposed-piston engine]]. The [[Electro-Motive Diesel|General Motors]] [[Cleveland Diesel Engine Division|Cleveland Model]] 16-248 V-type as original installations, while boats from {{USS|Sand Lance|SS-381|2}} onward received 10-cylinder engines. Earlier General Motors boats received Model 16-248 engines, but beginning with {{USS|Perch|SS-313|2}} Model 16-278A engines were used. In each case, the newer engines had greater [[Engine displacement|displacement]] than the old, but were rated at the same power; they operated at lower [[mean effective pressure]] for greater reliability. 
<ref>{{cite book |last=Alden |first=John D. |title=The Fleet Submarine in the U.S. Navy: A Design and Construction History |date=1979 |publisher=Naval Institute Press |isbn=0-85368-203-8 |pages=90, 210–212}}</ref> Both the Fairbanks-Morse and General Motors engines were [[two-stroke cycle]] types.<ref>{{cite press release|last=Stern|first= Robert C. |date=2006|title=Gato-Class Submarines in action|url=https://quietwarriors.files.wordpress.com/2014/02/squadron-signal-4028-gato-class-submarines1.pdf|publisher= Squadron Signal Publications|access-date=2023-09-17}}</ref>

Two submarines, {{USS|Unicorn|SS-429|2}} and {{USS|Vendace|SS-430|2}}, were to receive [[Hooven-Owens-Rentschler]] (H.O.R.) 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.<ref> {{Cite web|url=https://maritime.org/doc/fleetsub/elect/chap2.php/|title=Submarine Electrical Systems|website= www.maritime.org/}}</ref>

Earlier submarines carried four high-speed [[electric motor]]s (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 [[hydrophone]]s. Eighteen late ''Balao''-class submarines received low-speed double [[Armature (electrical engineering)|armature]] motors which drove the shafts directly and were much quieter, but this improvement was not universally fitted until the succeeding {{sclass|Tench|submarine|4}}.<ref>Bauer and Roberts, p. 275</ref> 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 {{USS|Sea Owl|SS-405|2}}.<ref>Friedman through 1945, pp. 209-210</ref> 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.

===Deck guns===
[[File:USS Bullhead July 1945.png|thumb|left|USS ''Bullhead'' in July 1945 showing off the heaviest ''Balao'' class deck gun configuration of two 40 mm Bofors autocannons on the bridge and two 5 inch guns on the deck]]
[[File:5 inch 25 caliber gun USS Bowfin.jpg|thumb|upright|5"/25 caliber gun on {{USS|Bowfin|SS-287|6}}]]
[[File:HMCS Haida Hamilton Ontario 13.jpg|thumb|upright|20 mm Oerlikon twin mount displayed near [[HMCS Haida|HMCS ''Haida'']]]]
Many targets in the [[Pacific War]] were [[sampan]]s or otherwise not worth a torpedo, so the [[deck gun]] was an important weapon. Early ''Balao''s began their service with a [[4"/50 caliber gun|{{convert|4|in|mm|adj=on|0}}/50 caliber Mk. 9 gun]]. Due to war experience, most were re-armed with a [[5"/25 caliber gun|{{convert|5|in|mm|adj=on|0}}/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. {{USS|Spadefish|SS-411|2}}, commissioned in March 1944, was the first newly built submarine with the purpose-built {{convert|5|in|adj=on}}/25 submarine mount. Additional [[anti-aircraft]] guns included single [[Bofors 40 mm Automatic Gun L/60|40 mm Bofors]] and twin [[20 mm Oerlikon]] mounts, usually one of each.<ref>Johnston, pp. 3-6</ref><ref>Friedman 1995, pp. 218-219</ref>

====Mine armament====
Like the previous ''Tambor''/''Gar'' and ''Gato'' classes, the ''Balao'' class could substitute mines in place of torpedoes. For the Mk&nbsp;10 and Mk&nbsp;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. However, doctrine 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 8 torpedoes, and the largest minefields laid were 32 mines. Post-war, the Mk&nbsp;49 mine replaced the Mk&nbsp;12, while the larger Mk&nbsp;27 mine was also carried which only allowed one mine replacing one torpedo.<ref>[https://maritime.org/doc/mines-usn/index.php ORD696 Operational Characteristics of U.S. Naval Mines]</ref>