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Mark 14 torpedo
Mark XIV torpedo.JPG
A Mark 14 torpedo on display at Fisherman's Wharf in San Francisco
Place of origin United States
Service history
In service 1931-1980
Wars World War II
Production history
Manufacturer Bureau of Ordnance
Weight 3,280 lb (1,490 kg)
Length 20 ft 6 in (6.25 m)
Diameter 21 in (530 mm)

Effective range 4,500 yards at 46 knots (4.12 km at 85.19 km/h)
9,000 yards at 31 knots (8.23 km at 57.41 km/h)
Warhead Torpex
Warhead weight 643 lb (292 kg)
Contact or Magnetic pistol

Engine Wet-heater combustion / steam turbine with compressed air tank
Propellant Methanol
Speed 46 knots (85 km/h)

The Mark 14 torpedo was the United States Navy's standard submarine-launched anti-ship torpedo of World War II.

This weapon was plagued with many problems which crippled its performance early in the war, and was supplemented by the Mark 18 electric torpedo in the war's final months. Nonetheless, the Mark 14 played a major role in the devastating blow US Navy submarines dealt to the Japanese naval and merchant marine forces during the Pacific War.

By the end of World War II, the Mark 14 torpedo was a reliable weapon which remained in service for almost 40 years in the US Navy, and even longer with other navies.



The Mark 14 was designed in 1930 to serve in the new "fleet" submarines, replacing the Mark 10 which had been in service since World War I and was standard in the older S-boats. Although the same diameter, the Mark 14 was longer, at 20 ft 6 in (6.25 m), and therefore incompatible with older submarines' 15 ft 3 in (4.65 m) torpedo tubes.

The Mark 14's design was done at the Newport Torpedo Station (NTS), Newport, beginning in 1922 under the direction of Lieutenant Ralph Waldo Christie.[1] To go with its fairly small warhead,[2] it introduced a sophisticated new magnetic influence exploder (similar to the British Duplex[3] and German[4] models), the Mark VI, inspired by German magnetic mines of WW1,[5] designed to "break ships' backs" (fracture their keels) by causing explosions beneath them, where warships had no armor.[5]. The dynamics of this process is that the magnetic trigger allows the weapon to explode some distance below the ship. When the weapon explodes, a huge gas-bubble is produced, and when it reaches the hull, the keel suffers catastrophic failure.

Designated as Project G53,[6] "behind the tightest veil of secrecy the Navy had ever created",[6] the Mark VI exploder was produced in small quantities at high cost (US$10,000 a copy)[7] and in extreme secrecy by General Electric in Schenectady. It was tested at the Newport lab and in a small field test aboard USS Raleigh, and later, at Christie's urging, an equatorial test with Indianapolis, which fired one hundred trial shots between 10oN and 10oS,[8] collecting 7000 readings in all.[9] Yet, inexplicably, no live fire trial was ever done; Chief of Naval Operations William V. Pratt offered the hulk of Cassin-class[10] destroyer Ericsson[9] - but prohibited the use of a live warhead, and insisted BuOrd pay the cost of refloating her if she was hit in error.[9] How this made sense, when she was shortly due for the scrapyard,[11] is unclear. BuOrd declined.[9] To preserve the security of the highly sophisticated Mark VI, a service manual "was written - but, for security reasons, not printed - and locked in a safe."[9]

In 1923, Congress made NTS Newport the sole designer, developer, builder and tester of torpedoes in the United States. No independent or competing group was assigned to verify the results of Mark 14 tests. As torpedo shortages cropped up (despite three shifts of three thousand workers, production at NTS was only 1½ a day in 1937,[12] and only two thousand submarine torpedoes were built by all three[13] Navy factories in 1942),[14] NTS was unable to increase production, for there was no room, and they were already working around the clock.[14]

The Naval Torpedo Station in Alexandria, Virginia was one of three Navy factories to manufacture the Mark 14 torpedo.


The Mark 14 was central to the torpedo scandal of the US Pacific Fleet Submarine Force during World War II. Due to inadequate depression-era peacetime testing of this torpedo and its Mark VI exploder, it had defects that tended to mask each other. Indeed, much of the blame commonly attached to the Mark 14 correctly belongs to the Mark VI exploder. These defects, in the course of fully twenty months of war, were exposed, as torpedo after torpedo either missed, prematurely exploded, or struck targets (sometimes with an audible clang) and failed to explode.

Responsibility lies with the Bureau of Ordnance, which specified an unrealistically rigid magnetic exploder sensitivity setting and oversaw the feeble testing program. Additional responsibility must be assigned to the United States Congress, which cut critical funding to the Navy during the interwar years, and to NTS, which inadequately performed the very few tests made.[15] BuOrd failed to assign a second naval facility for testing, and failed to give Newport adequate direction.

Early suspicions

On 24 December 1941, Commander Tyrell Dwight Jacobs in Sargo fired a total of eight torpedoes at two different ships, with no results, and had become very frustrated; when two additional merchantmen came in view, he took extra pains to get it right, pursuing for fifty-seven minutes[16] and making certain TDC bearings matched perfectly before firing two torpedoes at each ship, at an average of 1,000 yards (910 m), a very close range. All missed.[17]

A few days after he discovered the torpedoes were running too deep, and corrected the problem,[18] Jacobs detected a big, slow tanker. Again, his approach was meticulous, firing one torpedo at a close 1,200 yards (1,100 m). It missed. In exasperation, Jacobs signalled headquarters, questioning the Mark 14's reliability[17] on an open radio circuit.[19] In six attacks, he had fired thirteen torpedoes; all had failed to function correctly.[16]

A similar experience was had by Pete Ferrall in Seadragon, who fired eight fish for only one hit, and began to suspect the Mark 14 was faulty.[20]

Uniquely, Lieutenant Commander John A. Scott in Tunny on 9 April 1943 found himself in an ideal position to attack aircraft carriers Hiyo, Junyo, and Taiyo. From only 880 yards (800 m), he fired all ten tubes, hearing all four stern shots and three of the bow's six explode. No enemy carrier was seen to diminish its speed, though Taiyo was slightly damaged in the attack. Much later, intelligence reported each of the seven explosions had been premature;[15] the torpedoes had run true but the magnetic feature had fired them too early.[21]

Dan Daspit (in Tinosa) carefully documented his efforts to sink 19,000 ton whaling factory ship Tonan Maru III on 24 July 1943. He fired four torpedoes from 4,000 yards (3,700 m); two hit, stopping the target dead in the water. Daspit immediately fired another two; these hit as well. With no enemy anti-submarine combatants in sight, Daspit then took time to carefully maneuver into a textbook firing position, 875 yards (800 m) square off the target's beam, where he fired nine more Mark 14s and observed all with his periscope (despite the Japanese firing at it). All were duds.[22] Daspit, suspicious by now he was working with a faulty production run of Mark 14s, saved his last remaining torpedo to be analyzed by experts back at base. Nothing out of the ordinary was found.[15]

At Pearl Harbor, despite nearly all his skippers' suspicions about the torpedoes,[23] Admiral Thomas Withers refused to deactivate the Mark VI, arguing torpedo shortages stemming from inadequate production at NTS made it impossible.[24] As a result, his men did it on their own, doctoring their patrol reports and overstating the size of ships to justify using more torpedoes.[25] Only in May 1943, after the most famous skipper in the Sub Force, Mush Morton, turned in a dry patrol, did Admiral Lockwood (now COMSUBPAC) order the Mark VI deactivated.[26]


The Mark 14 had four major flaws.

  • It tended to run about 10 feet deeper than set.
  • The magnetic exploder often caused premature firing.
  • The contact exploder often failed to fire the warhead.
  • It tended to run "circular", failing to straighten its run once set on its prescribed gyro-angle setting, and instead, to run in a large circle, thus returning back to strike the firing ship.

Running too deep

The torpedo tended to run some ten feet (3 meters) too deep for two reasons. The first was that it was never tested with the correct mass density in its warhead. A concrete dummy warhead was used to set the depth during development of the weapon. The dummy warhead was lighter than the wartime load. Additionally, the depth mechanism was designed prior to the warhead's charge being increased, making the torpedo heavier overall. Also, two depth testing devices used by NTS to verify results were both off by the same amount in the same direction, which compounded the problem. After hearing of the problem, most submarine skippers simply set their torpedoes running depth to zero,[27] risking a broach. By August 1942, the faulty running depth situation was in hand and submarines were getting more hits with the Mark 14. Ironically, curing the deep-running problem caused more prematures and duds, now that hits were being achieved. The number of sinkings did not rise.[28]

Premature explosions

Mark VI magnetic exploder assembly: off-limits to service personnel until July, 1943

Many submarine commanders in the first two years of the war reported explosions of the warhead with little to no damage of the enemy. The magnetic exploders were triggering prematurely, before getting close enough to the vessel to destroy it. Earth's magnetic field near NTS, where the trials (limited as they were)[29] were conducted, differed from the areas where the fighting was taking place.


Early reports of torpedo action included some dud hits, heard as a dull clang. In a few instances, Mark 14s would strike a Japanese ship and lodge in its hull without exploding. The contact pistol appeared to be malfunctioning, though the conclusion was anything but clear until running depth and magnetic exploder problems were solved. Daspit's experience was exactly the sort of live-fire trial BuOrd had been prevented from doing in peacetime. It was now clear to all at Pearl Harbor the contact pistol was also defective.


There were numerous reports of the Mark 14 running erratically and circling back on the firing boat. This sank at least one submarine, Tullibee, for certain.[30] Likewise the USS Sargo (SS-188) was almost sunk by a circular running torpedo. The Mark 15 torpedo had collars to prevent circulars, but the Mark 14 was never given this feature.


Two Mark 14 torpedoes stored in the after torpedo room of the museum ship USS Pampanito

Against orders, some submariners disabled the magnetic feature of the Mark VI, suspecting it was faulty. An increase in hits was reported. Shortly after replacing Wilkes in Freemantle,[31] newly minted Rear Admiral[31] Charles Lockwood ordered a historic net test at Frenchman's Bay on 20 June 1942.[32] Eight hundred torpedoes had already been fired in anger,[32] more than a year's production from NTS.

Jim Coe's Skipjack did the honors, firing a single fish with an exercise head, set at 10 feet (3m), from 850 yards (780 m). It hit the net at a depth of 25 ft (7.6 m).[33] Not satisfied, Fife followed up the next day with two more test shots; Fife concluded they ran an average 11 ft (3.4 m) deep. BuOrd was not amused.[33] Neither was Admiral King, who "lit a blowtorch under the Bureau of Ordnance".[34] The fact destroyer Mark 15 torpedoes were suffering the same failures may have had something to do with it as well. On 1 August 1942, BuOrd finally conceded the Mark 14 ran deep, and six weeks later, "that its depth-control mechanism had been 'improperly designed and tested'".[2] This satisfied Lockwood and English, who refused to believe the Mark VI could also be defective.[2]

Finally, in July 1943, Admiral Lockwood ordered his boats to deactivate the Mark VI magnetic influence exploder and use only its contact pistol.[27]

Tests were carried out by COMSUBPAC's gunnery and torpedo officer, Art Taylor (ex-Haddock). Taylor, Swede Momsen, and others fired warshots from Muskallunge[35] into the cliffs of Kahoolawe, beginning 31 August. Their third test shot was a dud.[36] This revealed the firing pin had not been able to contact the detonator hard enough to fire the warhead.[36]

To avoid "shaking hands with St. Peter" (as Lockwood put it),[36] E.A. Johnson, USNR, supervised by Taylor, dropped dummy warheads filled with sand from a cherry picker from 90 feet (27 m). In 7 out of 10 of these trials, firing mechanisms bent, jammed, and failed with the high inertia of a straight-on hit (the prewar ideal).[37] A quick fix was to encourage "glancing" shots[38] (which cut the number of duds in half),[37] until a permanent solution could be found. Lightweight aluminum alloy (from propellers[37] of downed Pearl Harbor attackers) was machined to take the place of the Mark VI's heavy pin block so inertial forces would be lower. Electrical switches, developed by Johnson,[37] were tried as well. Both fixes worked and were relatively easy to implement. In September 1943, the first torpedoes with new contact pistols were sent to war.[39] "After twenty-one months of war, the three major defects of the Mark 14 torpedo had at last been isolated....Each defect had been discovered and fixed in the field - always over the stubborn opposition of the Bureau of Ordnance."[38]

Once remedied, sinkings of enemy ships rose noticeably. By the end of World War II the Mark 14 torpedo had become a much more reliable weapon. Lessons learned allowed surface ships such as destroyers to remedy the failings of the Mark 15; the two designs shared the same strengths and faults.

After the war, the best features of the improved Mark 14 torpedo were merged with the best features of captured German torpedoes to create the hydrogen peroxide-fueled Mark 16 torpedo with a pattern-running option. The Mark 16 became the standard United States post-war anti-shipping torpedo, despite the large remaining inventory of Mark 14 torpedoes.[40]


Official US Navy naming policy had settled on using Arabic instead of Roman numerals to designate torpedo models since the 1917 development of the Bliss-Leavitt Mark 4 torpedo.[41] However, many instances exist of the Mark 14 being referred to as the "Mark XIV" (Roman style) in official documentation and reports as well as accounts by historians and observers.


  • Function: Anti-ship
  • Powerplant: Wet-heater combustion / steam turbine with compressed air tank
  • Fuel: Methanol
  • Length: 20 ft 6 in (6.25 m)
  • Weight: 3,280 lb (1,490 kg)
  • Diameter: 21 in (530 mm)
  • Range / Speed:
    • Low speed: 9,000 yards at 31 knots (8.23 km at 57.41 km/h)
    • High speed: 4,500 yards at 46 knots (4.12 km at 85.19 km/h)
  • Guidance System: Gyroscope
  • Warhead: 643 lb (292 kg) of Torpex
  • Date Deployed: 1931
  • Date Withdrawn from service: 1975–1980


  1. ^ Blair, Clay, Jr. Silent Victory (Philadelphia: Lippincott, 1975), p.54-5.
  2. ^ a b c Blair, p.278.
  3. ^ Fitzsimons, Bernard, general editor. The Illustrated Encyclopedia of 20th Century Weapons and Warfare (London: Phoebus Publishing, 1978), Volume 8, p.807, "Duplex"
  4. ^ Dönitz, Memoir.
  5. ^ a b Blair, p.54.
  6. ^ a b Blair, p.55.
  7. ^ Blair, p.61.
  8. ^ Blair, p.61-2.
  9. ^ a b c d e Blair, p.62.
  10. ^ Fitzsimons, Volume 5, p.541, table.
  11. ^ Fitzsimons, Volume 5, p.542, "Cassin".
  12. ^ Blair, p.69.
  13. ^ NTS, Alexandria, and Keyport. Blair, p.69.
  14. ^ a b Blair, p.281.
  15. ^ a b c Roscoe, 1967
  16. ^ a b Blair, p.141.
  17. ^ a b Blair, p.140.
  18. ^ Blair, p.141. BuOrd would wait months to do the same.
  19. ^ Jacobs' courage here is exemplary, recalling Ned Beach's a generation later in relation to the Tang-class' terrible "pancake" diesels. It could have gotten him court martialled for insubordination, and he knew it, not to mention being detected by the Japanese. On his return, he was upbraided by his commanding officer, Admiral Wilkes. Blair, p.169.
  20. ^ Blair, p.171.
  21. ^ Blair, p.413.
  22. ^ When he returned, Daspit was livid. Blair, p.435-7.
  23. ^ Blair, p.216.
  24. ^ Blair, p.206.
  25. ^ Blair, p.206. This helps explain why US tonnage claims per ship were routinely about a third higher than actual sinkings.
  26. ^ Blair, p.427.
  27. ^ a b Shireman, Douglas A. U.S. Torpedo Troubles During World War II
  28. ^ Blair, p.292.
  29. ^ Milford, Frederick J. "U. S. Navy Torpedoes." The Submarine Review, April 1996.
  30. ^ The replacement Mark 18 torpedo was no better, sinking Tang. Blair, p.575-6 and 767-8.
  31. ^ a b Blair, p.274.
  32. ^ a b Blair, p.275.
  33. ^ Cite error: Invalid <ref> tag; no text was provided for refs named Blair.2C_p.276; see Help:Cite error.
  34. ^ Blair, p.277.
  35. ^ Under command of Willard Saunders. Blair, p.437.
  36. ^ a b c Blair, p.437.
  37. ^ a b c d Blair, p.438.
  38. ^ a b Blair, p.439.
  39. ^ Milford, Frederick J. "U. S. Navy Torpedoes. Part Two: The great torpedo scandal, 1941-43." The Submarine Review, October 1996.
  40. ^ Kurak, Steve (September 1966). The U. S. Navy's Torpedo Inventory. United States Naval Institute Proceedings.  
  41. ^ United States of America Information on Torpedoes. Torpedo Nomenclature


  • Blair, Clay, Jr. Silent Victory. Philadelphia: Lippincott, 1975. ISBN 0-553-01050-6.
  • Gannon, Robert. Hellions of the Deep: The Development of American Torpedoes in World War II. Pennsylvania State University Press, 1996. ISBN 027101508X
  • Roscoe, Theodore. Pig Boats: The True Story of the Fighting Submariners of World War II. Bantam, 1967.
  • United States of America Torpedoes of World War II
  • Dud torpedoes of WWII


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