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Mark 14 torpedo
Mark 14 torpedo side view and interior mechanisms, Torpedoes Mark 14 and 23 Types, OP 635, March 24 1945.jpg
Mark 14 torpedo side view and interior mechanisms, as published in a service manual
Type Anti-surface ship torpedo[1]
Place of origin United States
Service history
In service 1931–1980
Used by  United States Navy
Wars World War II
Production history
Designer Naval Torpedo Station[1]
Designed 1931[1]
Manufacturer Naval Torpedo Station[1]
Naval Ordnance Plant
Produced 1942-1945[2]
Number built 13,000[2]
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 (4,100 m) at 46 knots (85 km/h)
9,000 yards (8,200 m) at 31 knots (57 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 last two years of the war. 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.


Captain Theodore Westfall, NTS CO and Captain Carl Bushnell of the Bureau of Ordnance, inspect a Mark 14 torpedo at the Naval Torpedo Station, Keyport, Washington, 1943[3]

A Mark 14 torpedo on display at Fisherman's Wharf in San Francisco

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 was designed at the Naval Torpedo Station (NTS), Newport, beginning in 1922 under the direction of Lieutenant Ralph Waldo Christie.[4] It had a fairly small warhead[5] and was intended to explode beneath the keel where there was no armor.[6] This required the sophisticated new Mark VI magnetic influence exploder, which was similar to the British Duplex[7] and German[8] models, all inspired by German magnetic mines of World War I.[6] The Mark VI was intended to fire the warhead some distance below the ship, creating a huge gas bubble which would cause the keel to fail catastrophically.

The Mark VI exploder, designated Project G53,[9] was developed "behind the tightest veil of secrecy the Navy had ever created."[9] Small quantities were produced in extreme secrecy, and at a cost of US$1,000 per unit,[10] by General Electric in Schenectady. The exploder was tested at the Newport lab and in a small field test aboard USS Raleigh. Only one live warhead test of the Mark 6 exploder was done. Prototype exploders were attached to Mark 10 torpedoes and fired at a stationary submarine; the first shot failed to explode, but the second sank the target.[11] At Christie's urging, equatorial tests were later conducted with Indianapolis, which fired one hundred trial shots between 10°N and 10°S[12] and collected 7000 readings.[13] Tests were done using torpedoes with instrumented exercise heads: an electric eye would take an upward-looking picture from the torpedo; the magnetic influence feature would set off some gun cotton.[14] Inexplicably, no live fire trial was ever done with production units. Chief of Naval Operations William V. Pratt offered the hulk of Cassin-class[15] destroyer Ericsson,[13] but prohibited the use of a live warhead, and insisted the Bureau of Ordnance (commonly called BuOrd) pay the cost of refloating her if she was hit in error.[13] These were strange restrictions, as Ericsson was due to be scrapped.[16] BuOrd declined.[13] A service manual for the exploder "was written—but, for security reasons, not printed—and locked in a safe."[13]

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. NTS produced only 1½ torpedoes a day in 1937, despite having three shifts of three thousand workers[17] working around the clock.[18] Production facilities were at capacity and there was no room for expansion.[17] Only two thousand submarine torpedoes were built by all three[19] Navy factories in 1942.[18] This exacerbated torpedo shortages; the Pacific Fleet Submarine Force had fired 1,442 torpedoes since war began.[20]


Mark 6 Mod 1 exploder used early in the war.[21] Later on it was replaced with the Mark 6 Mod 5.

The Mark 14 was central to the torpedo scandal of the U.S. Pacific Fleet Submarine Force during World War II. Due to inadequate Depression-era peacetime testing of both the torpedo and its exploder, the defects 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 BuOrd, 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.[22] BuOrd failed to assign a second naval facility for testing, and failed to give Newport adequate direction.

Well-documented failures

On 24 December 1941, Commander Tyrell D. 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[23] and making certain TDC bearings matched perfectly before firing two torpedoes at each ship, at an average of 1,000 yd (910 m), very close range. All missed.[24]

A few days after he discovered the torpedoes were running too deep, and corrected the problem,[25] Jacobs detected a big, slow tanker. Again, his approach was meticulous, firing one torpedo at a close 1,200 yd (1,100 m). It missed. Exasperated, Jacobs broke radio silence, openly questioning the Mark 14's reliability.[26]

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.[27]

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 yd (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;[22] the torpedoes had run true but the magnetic feature had fired them too early.[28]

Dan Daspit (in Tinosa) carefully documented his efforts to sink 19,000-ton whale factory ship Tonan Maru III on 24 July 1943. He fired four torpedoes from 4,000 yd (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 yd (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.[29] 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.[22]

At Pearl Harbor, despite nearly all his skippers' suspicions about the torpedoes,[30] Admiral Thomas Withers refused to deactivate the torpedo's Mark VI exploder, arguing torpedo shortages stemming from inadequate production at NTS made it impossible.[31] 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.[32] Only in May 1943, after the most famous skipper in the Sub Force, Dudley W. "Mush" Morton, turned in a dry patrol, did Admiral Charles A. Lockwood, Commander Submarine Force Pacific (COMSUBPAC), accept the Mark VI should be deactivated, but waited to see if Bureau of Ordnance commander Admiral William "Spike" Blandy might yet find a fix for the problem.[33] The Bureau of Ordnance sent an expert to Surabaja to investigate, who set the gyro backwards on one of Sargo's trial torpedoes; the potentially deadly setting, guaranteed to cause erratic running, was corrected by torpedo officer Doug Rhymes. Though he found nothing wrong with maintenance or procedures, the expert submitted a report laying all the blame on the crew.[34]


The Mark 14 torpedo had four major flaws.

  • It tended to run about 10 feet (3.0 m) 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 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 only tested with an exercise warhead filled with water to set the depth. However, the live warhead contained more mass than that, and it reached buoyancy equilibrium at a lower depth.[35] Also, the depth mechanism was designed prior to the warhead's charge being increased, making the torpedo even heavier overall. Furthermore, 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,[36] 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.[37]

Premature explosions

The later Mark 6 Mod 5 exploder with electric exploder and ball switch. The original Mark 6 was 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)[38] 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. Ironically, a direct hit on the target at a 90 degree angle, as recommended in training, would result in a failure to detonate; the exploder only functioned when the torpedo impacted the target at an oblique angle.

Circular runs

There were numerous reports of the Mark 14 running erratically and circling back on the firing boat. This is known to have sunk at least one submarine, Tullibee.[39] Likewise Sargo was almost sunk by a circular. The Mark 15 torpedo had collars to prevent circular runs, 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 influence feature of the Mark VI exploder, suspecting it was faulty. An increase in hits was reported. Shortly after replacing Wilkes in Fremantle,[40] newly minted Rear Admiral[40] Lockwood ordered a historic net test at Frenchman Bay on 20 June 1942.[41] Eight hundred torpedoes had already been fired in combat,[41] 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 ft (3.0 m), from 850 yards (780 m). It hit the net at a depth of 25 ft (7.6 m).[42] Not satisfied, James Fife, Jr. (formerly Chief of Staff to COMSUBAS John E. Wilkes, who Lockwood was replacing in Perth-Fremantle)[43] followed up the next day with two more test shots; Fife concluded they ran an average 11 ft (3.4 m) deeper than the depth at which they were set. BuOrd was not amused.[42] Neither was the CNO, Admiral Ernest J. King, who "lit a blowtorch under the Bureau of Ordnance".[44] The fact that destroyers' 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'".[5] This satisfied Lockwood and Robert H. English (then COMSUBPAC),[45] who refused to believe the exploder could also be defective.[5]

Finally, in July 1943, Admiral Lockwood ordered his boats to deactivate the Mark VI's influence feature and use only its contact pistol.[36]

Tests were carried out by COMSUBPAC's gunnery and torpedo officer, Art Taylor. Taylor, "Swede" Momsen, and others fired warshots into the cliffs of Kahoolawe, beginning 31 August. Additional trials, supervised by Taylor, dropped dummy warheads filled with sand from a cherry picker raised to a height of 90 feet (27 m), producing a 70% failure rate. A quick fix was to encourage "glancing" shots[46] (which cut the number of duds in half),[47] until a permanent solution could be found.

In September 1943, the first torpedoes with new contact pistols were sent to war.[48] "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."[46]

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 were merged with the best features of captured German torpedoes to create the hydrogen peroxide-fueled Mark 16 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.[49]


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.[50] 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 (8,200 m) at 31 knots (57 km/h)
    • High speed: 4,500 yards (4,100 m) at 46 knots (85 km/h)
  • Guidance system: Gyroscope
  • Warhead: 643 lb (292 kg) of Torpex
  • Date deployed: 1931
  • Date withdrawn from service: 1975–1980


  1. 1.0 1.1 1.2 1.3 "Torpedo History: Torpedo Mk14". Retrieved 13 June 2013. 
  2. 2.0 2.1 Jolie, E.W. (15 September 1978). "A Brief History of U.S. Navy Torpedo Development". Retrieved 2013-06-05. 
  3. Poole, Lisa (1989). Torpedo Town U.S.A. Diamond Anniversary Publishing. ISBN 0-9621829-0-7. 
  4. Blair 1975, pp. 54–55
  5. 5.0 5.1 5.2 Blair 1975, p. 278
  6. 6.0 6.1 Blair 1975, p. 54
  7. Fitzsimons, Bernard, general editor. The Illustrated Encyclopedia of 20th Century Weapons and Warfare (London: Phoebus Publishing, 1978), Volume 8, p.807, "Duplex"
  8. Dönitz, Memoir.
  9. 9.0 9.1 Blair 1975, p. 55
  10. Blair 1975, p. 61
  11. Patrick 2012. The article has a picture of the first torpedo running underneath the submarine.
  12. Blair 1975, pp. 61–62
  13. 13.0 13.1 13.2 13.3 13.4 Blair 1975, p. 62
  14. Patrick 2012. This explanation for the picture seems a bit suspect. It would make sense to trigger the camera from the magnetic influence feature to determine where the torpedo would have exploded.
  15. Fitzsimons, Volume 5, p.541, table.
  16. Between 1934 and 1936. Fitzsimons, Volume 5, p.542, "Cassin".
  17. 17.0 17.1 Blair 1975, p. 69
  18. 18.0 18.1 Blair 1975, p. 281
  19. NTS, Alexandria, and Keyport. Blair 1975, p. 69
  20. Blair 1975, p. 553
  21. Patrick, John (Winter 2012). "The Hard Lessons of World War II Torpedo Failures". 
  22. 22.0 22.1 22.2 Roscoe 1967
  23. Blair 1975, p. 141
  24. Blair 1975, p. 140
  25. Blair 1975, p. 141. BuOrd would wait months to do the same.
  26. Blair, pp.140-141 & 169
  27. Blair 1975, p. 171
  28. Blair 1975, p. 413
  29. When he returned, Daspit was livid. Blair 1975, pp. 435–437
  30. Blair 1975, p. 216
  31. Blair 1975, p. 206
  32. Blair 1975, p. 206. This helps explain why U.S. tonnage claims per ship were routinely about a third higher than actual sinkings.
  33. Blair 1975, p. 427
  34. Blair 1975, pp. 169–170
  35. Scott, James (2013). The War Below: The Story of Three Submarines That Battled Japan. Simon and Schuster. p. 88. ISBN 143917685X. 
  36. 36.0 36.1 Shireman, Douglas A. U.S. Torpedo Troubles During World War II
  37. Blair 1975, p. 292
  38. Milford, Frederick J. "U. S. Navy Torpedoes." The Submarine Review, April 1996.
  39. The subsequent Mark 18 torpedo was no better, sinking Tang. Blair 1975, pp. 575–576 and 767–768
  40. 40.0 40.1 Blair 1975, p. 274
  41. 41.0 41.1 Blair 1975, p. 275
  42. 42.0 42.1 Blair 1975, p. 276
  43. Blair 1975, pp. 131,197,273–275
  44. Blair 1975, p. 277
  45. Blair 1975, pp. 226–227
  46. 46.0 46.1 Blair 1975, p. 439
  47. Blair 1975, p. 438
  48. Milford, Frederick J. (October 1996). "U. S. Navy Torpedoes. Part Two: The great torpedo scandal, 1941–43.". 
  49. Kurak, Steve (September 1966). "The U. S. Navy's Torpedo Inventory". United States Naval Institute Proceedings. 
  50. United States of America Information on Torpedoes. Torpedo Nomenclature


  • Blair, Clay, Jr. (1975). "Silent Victory". Philadelphia: Lippincott. ISBN 0-553-01050-6. 
  • Roscoe, Theodore (1967). "Pig Boats: The True Story of the Fighting Submariners of World War II". New York: Bantam. OCLC 22066288. . Originally published in 1949 as United States submarine operations in World War II; Bantam version may be abridged.
  • United States of America Torpedoes of World War II

Further reading

External links

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