in the PACIFIC  1941 - 1945




U.S. Submarine Fleet - Pacific Theater 1941 - 1945

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  Torpedo problems plagued the fleet submarine  throughout much of the war, but the early years proved to be the most trying time for sub skippers regarding the ordnance they carried. Malfunctioning torpedoes were reported by boat captains from the onset of hostilities and the response from BuOrd was always the same: The weapons were fine, it was the crew's inabilities that were to blame. History has proven otherwise. 

  US fleet submarines went into battle armed with the MK XIV steam torpedoes which were equipped with the MK VI influence exploder. The design behind the exploder was to allow the torpedo to detonate within the magnetic field under the keel of the target boat, effectively breaking the ship's back.  This "top secret" device was highly regarded by the Navy which believed they possessed a device that would revolutionize submarine warfare. In fact, they so tightly guarded the information about the MK VI that they conducted few actual tests. I addition, training in its' use was restricted for fear that the secret about this lethal miracle might leak out. During the same time the US was tenaciously safeguarding the MK VI, both Britain and Germany abandoned their use of a similar devices they had developed due to the equipment's unreliability. Skippers complained that, after developing an ideal attack setup, their torpedoes would detonate prematurely, miss completely or not explode at all. In December of 1941, after having fired in excess of 70 torpedoes at 28 targets only one hit was recorded. Theories as to the cause were widespread. The most popular being that the weapons were running deeper then they were set. Report after report of potentially faulty torpedoes came down the pike, only to be officially attributed as "crew error". Resolution to the problem took its first step forward when in June of 1942 RADM Charles Lockwood (photo below right), a submarine veteran, was assigned the command of the Asiatic Fleet. His first order of business was to test the MK XIV for running depth. His findings were consistent with the reports from the submarine commanders: the MK XIV ran deeper then their settings. The skippers were advised to adjust the running depth accordingly in the hopes of correcting the defect. Unfortunately, the number of sinkings and total tonnage scores remained disturbingly lower then expected. Continuing on the belief that the poor showing was due to ineffective skippers, many were relieved of their commands, replaced by younger, more aggressive officers.

  If the possibility of conducting a war patrol armed with faulty torpedoes was not a huge enough problem, the shortage of their supply, defective or otherwise, was. Political arms limitation agreements prior to the war restricted the ability of countries to produce certain weapons. Even with the advent of antisubmarine technology, submarines themselves were considered to be an extremely deadly weapon of war, and there was a worldwide effort to restrict their production. Rules of engagement even set boundaries as to how a submarine could be employed. The United States entered WW II with an inadequate supply of torpedoes and too few facilities to produce the numbers required. The resulting shortage severely handcuffed skippers during a patrol. By November of 1942, Pearl Harbor's supply had dwindled down to zero. The Navy issued guidelines detailing the number or torpedoes that could be expended on any one target.  As a result, many potential targets escaped. 

  By 1943, with the submarine fleet still unable to prove their overall effectiveness, boat captains were once again casting the blame for their troubles on faulty ordnance. Patrols returned to base with tales of torpedoes which would explode about half of the time. Finally convinced that the MK VI influence exploder was the culprit, Lockwood ordered them to be disconnected. But the saga of defective weapons continued. As numerous patrol reports continued to describe perfect set ups followed by torpedoes striking the targets but failing to explode, (one account detailed an attack where 13 out of 15 hits did not detonate) Lockwood ordered new tests to be conducted. Firing torpedoes at a vertical cliff face, the duds were closely examined. It was determined the when a torpedo struck at a 90 degree angle (which was considered ideal) the firing pin would often become distorted before it could contact the explosive cap. The results confirmed what many had feared, that submarines went into battle armed with defective weapons. Installing a stronger firing pin resolved the issue of malfunctioning torpedoes virtually overnight. The resulting dramatic increase in tonnage scores removed any doubt as to the cause of the problem that bedeviled the submarine fleet during the first few years of WW II.  


U.S. Submarine Fleet - Pacific Theater - World War II


  • Gyro Angle - The angle between the fore-and-aft axis of your own sub and final track of the torpedo, measured clockwise from the bow of your boat.

  • Own Course - The angle between the North-South line and the fore-and-aft axis of your own boat, measured clockwise from North to your own boat's bow.

  • Target Course - The angle between the North-South line and the fore-and-aft axis of the target, measured clockwise from North to the target's bow.

  • Angle on the Bow - The angle between the fore-and-aft axis of the target and the Line of Sight (LOS), measured clockwise from the target's bow to starboard (right) or port (left).

  • Relative Target Bearing - The angle between the fore-and-aft axis of your own sub and and the LOS, measured clockwise from the bow of your boat.

  • True Target Bearing - The angle between the North-South line and the LOS, measured clockwise from the North.

  • Track Angle - The angle between the fore-and-aft axis of the target and the torpedo track, measured from the target bow to starboard or port.

  • Range - The distance in yards from your periscope to the target.

  • Torpedo Run - The distance in yards which the torpedo travels from the tube to the target.

  • Distance to Track - The distance in yards from the submarine to the target track, measured along a line perpendicular to the target track.

For more naval terminology click here


Torpterm2.jpg (87722 bytes)
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AB - Angle on the Bow C - Target Course
B - True Target Bearing Co - Own Course
Br - Relative Target Bearing G - Gyro Angle






Product photo
United States Submarine Operations in World War II
By Theodore Roscoe
United States Naval Institute
George Banta Company Inc Copyright 1949
Product photo Silent Victory: The U.S. Submarine War Against Japan
By Clay Blair
J.B. Lippincott Company
Copyright 1975
Product photo Subs Against the Rising Sun:
U.S. Submarines in the Pacific

By Keith H. Milton
Yucca Free Press
Copyright 2000
  U. S. Submarines in World War II:
An Illustrated History of the Pacific

By Larry Kimmett & Margaret Regis
Navigator Publishing
Copyright 191996


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