Contact Us   |    Join   |    Donate

Editor’s Note: Commander Alden is a retired submarine officer with WWII war patrol experience. He has done extensive work 011 the details of the U.S. Submarines on attacks 011 Japanese shipping and is responsible for clearing up many differences in the various post-war measurements of success and failure.

The unhappy story of defective torpedoes which afflicted our submarines during World War IJ has been recounted in practically every history or memoir of that great conflict, along with the story of how submariners overcame the defects one by one and ultimately succeeded in throttling Japan’s maritime lifelines. What is not well known is that even dud torpedoes managed to send a few enemy ships to the bottom. While these results were insignificant in contributing to the overall destruction, they provide an unusual sidelight of the submarine war. The cases that follow were extracted from the historical record and are offered for their witness that unexpected success can be found no matter how uneven the odds.


17 February 1942. USS TRITON (SS 201) under the command of Lt. Cdr. Willis A. Pilly Lent was on her second patrol at 32-12N 127-42E in the East China Sea when the officer on watch at the periscope sighted a steamer heading toward Japan. Lent immediately came to the normal approach course, made ready torpedo tubes # 1 and #2 forward, and gave the order to fire at 1431 (time zone not given), only to see both fish miss astern. Quickly reversing course, four minutes later he fired two more from stern tubes #9 and # 10 at a track angle of about 140 degrees. This time he got one hit under the after well deck of the target, which he described as a conventional single-stack cargo carrier of about 5,000 tons with two stick masts, a straight bow and counter stern, apparently a coal burner. The ship stopped, but after about two minutes started ahead again. When last observed, it appeared to have settled considerably by the stern but was steering on a northerly course.

About four hours later another ship was encountered. Although it was too dark to see details, the ship appeared to be a single-stack cargo type of between 5,000 and 7,000 tons, painted dark gray, with the appearance of a naval auxiliary. Lent let fly forward tubes #3 and #4 and again saw one hit under the after well deck. The target stopped and settled aft, then there were two strong explosions, upon which Lent took his boat deep in case there was an escort present. In his patrol report be claimed- and was credited with-damaging the first and sinking the second of these ships at 6,000 tons each.

Now switch to the Japanese side. The #5 SHINYO MARU, a former cargo ship serving as a converted gunboat, was patrolling southwest of Goto Island on 16 February when at about 1800 (Tokyo time) it was struck by a dud torpedo which pierced and flooded the engine room. The ship stopped, powerless, and drifted. Early on the 17th a submarine approached the helpless ship. To fend it off the Japanese captain dropped depth charges, whereupon the flooding slowly increased until the hapless gunboat finally went down on 18 February at 32-14N 127-14E with the loss of 15 crewmen.

Readers will probably be quick to point out discrepancies and conflicts between the U.S. and Japanese accounts. Unfortunately, things don’t look the same from above and below the surface, so it is seldom that reports of such actions will agree in all particulars, but in this case the differences are greater than usual. Early patrol reports such as Lent’s were written before a standard format was prescribed by higher authorities and were often sketchy and missing important information. Lent was overcautious and went deep without confirming the result of his attack, and offered no real evidence of having damaged either target. Neither he nor any higher authority seemed to consider the possibility that the two attacks were on the same ship, even though the descriptions were so closely alike. There are also internal contradictions between different sections of the patrol report. A few months later submarine skippers would swear that their torpedoes were misfiring, but Lent didn’t claim that his hits were duds. It is known that TRITON carried Mk 14-1 torpedoes, but even this key piece of information was omitted from many patrol reports written in the early months of the war.

Japanese sources also often disagree about details of engagements, to the point that it is sometimes impossible to match their accounts to any reported submarine attacks. In this case the reports agree in the most important particulars, and there was no other submarine in the area.


4 March 1943. The venerable USS PERMIT (SS 178) under Cdr. Wreford G. Moon Chapple was on its seventh patrol
(Chapple’s fifth in that boat) in Empire waters at 39-30N 142-0SE and running submerged when a convoy was sighted at 0637K time (one hour behind Tokyo time). There appeared to be five ships in box formation escorted by a small inter-island freighter armed with guns fore and aft and depth charge racks at the stem. At 0729 Chapple fired Mk I 4-1 A torpedoes from tubes #3 and #4 at the leading ship in the inboard column and heard a magnetic explosion. Two minutes later he fired tube #2 at the original target and tubes #5 and #6 at the lead ship in the outboard column. These torpedoes all missed. The escort promptly came after the sub and dropped 15 depth charges as Chapple evaded. He claimed that the first ship, a 5,600 ton freighter, was either sunk or damaged but was not credited with either result. In his patrol report Chapple wrote: “Hit was magnetic which indicates that torpedo had not
reached its set depth.” He was obviously referring to the secret Mark VI exploder. He had set his torpedoes to run at 12 feet, but apparently believed that they had passed well under the target and been triggered by the magnetic influence of the ship’s hull. According to the Japanese, convoy 23038 consisting of the HOKUTO MARU, BANSE! MARU, KOTAI MARU, SUMIDA MARU, and TAISEI MARU, and escorted by the converted gunboat #2 HIYOSHI MARU, had left MURORAN on 3 March for Shimizu. The HOKUTO MARU, a commercial cargo ship of 2,262 gross registered tons, was loaded with 2,080 tons of coal. At about 0630 on 4 March its lookouts spotted the tracks of three torpedoes, one of which, a dud, hit the ship in the forward end of #1 hold. Sighting a periscope 250 meters off the port bow, the Japanese captain attempted to ram the sub but aborted the effort to avoid striking the SUMIDA MARU and returned to his assigned place in the convoy. After another ten minutes the crew realized that the ship was taking on a great deal of water, so the captain turned to head for the coast while efforts were made to reduce the flow. However, the ship continued to go down by the bow and at 0643 the engine stopped. The crew was transferred to the #2 HIYOSHJ MARV as their former ship slowly sank until at 0712 its stern rose vertically and the HOKUTO MARU went to the bottom. Chapple never received official credit for this ship. The Joint Army-Navy Assessment Committee (JANAC) concluded that the HOKUTO MARU had probably been sunk by a mine at 42-00N 141-00E. The basis for this decision is no doubt buried somewhere in the archives. If any readers are veterans of PERMIT’s eighth patrol, here’s some long-delayed recognition of their unacknowledged success.


The new USS SCAMP (SS 277) under Commander Walter G. Ebert was on its first patrol east of Honshu at l 725K in the afternoon of 20 March 1943 when it encountered a small convoy at position 41-06N l 41-26E, starting what Ebert whimsically named the “Battle of Monomi Saki.” Ebert maneuvered to fire three stern tubes at what he took to be a 2,600 ton cargo ship resembling SElKYO MARU. The first torpedo prematured after 15 seconds, but Ebert saw a splash at the target’s waterline at the time the others should have hit. No one in the conning tower heard an explosion, but men in the after torpedo room reported two hits and some in the engine room heard three. Ebert then started an approach on the second ship of the convoy, which he identified as the loaded freighter TA TUMA MARU. At that point the sonar operator reported high-speed screws, which proved to belong to a single-stack destroyer “crossing astern with a bone in his teeth, no doubt after us. Range close.” Ebert fired three bow torpedoes at the warship, but they missed. SCAMP was then subjected to a drubbing from 17 depth charges before escaping. Based on the evidence noted above, Ebert claimed three hits resulting in damage to the first target. He also complained that many other torpedo failures, including four additional prematures, were experienced during the patrol. (Presumably they were all Mk 14s; the records are not specific but Ebert mentioned trying to recalibrate the magnetic exploders.) On his return to port he was credited with a disappointing three ships damaged.

The Japanese records are rather terse and do not identify the convoy, noting only that the small commercial freighter SEINAN MARU of 1,338 tons was hit under the forward mast at about 1630 by a dud torpedo and had to be run aground at 4 l -06N l 4 I – 27E because of flooding. It was still there, presumably under salvage, until on 11 June 1943 it was hit by two more torpedoes and so heavily damaged that the wreck was abandoned. JANAC credits the SEINAN MARU as probably sunk by USS RUNNER (SS 275) at 41-00N l 4 l-30E. That boat was on its third patrol under the command of Lieutenant Commander John H. Bourland. After leaving Midway on 28 May for the so-called polar circuit it was never heard from again; JANAC’s assessment was probably based on the knowledge that no other sub was in the area. (RUNNER may have been lost in a newly-laid minefield along the route to its assigned area.) In any case, SCAMP seems to deserve at least half credit for destroying the SEINAN MARU.


On 6 September 1943, USS HALIBUT (SS 232), newly under Lieutenant Commander Ignatius J. Pete Galantin, was on its 6lh patrol off the south coast of Hokkaido when a target was sighted through the periscope: a 6,000 ton freighter similar to the ITALY MARU, heavily loaded and with a deck cargo. There were no escorts in sight, and at 0552K Galantin fired bow tubes #5 and 6 at a range of 3,300 yards on a 115 degree starboard track with a depth setting of 10 feet. Two minutes later he noted a very small splash of water under the target’s stack, and the sonar operator
reported two weak explosions. These were not heard through the hull, and the freighter appeared to swing toward the submarine. At 0601 Galantin fired his last two bow torpedoes (all were Mk 14-3As set for contact rather than magnetic detonation), saw the ship tum away, and was sure no hits had been made.

Then, after another seven minutes, the skipper was surprised to see that the target was slowing down and settling by the stem; his first torpedoes must have been effective. At about 0640 sound reported breaking-up noises, and when the periscope was raised “it was all over. The only thing in sight was the bottom of his keel and it soon disappeared.” Two boats full of survivors were left at the scene. This is apparently the only occasion where a ship hit by duds was actually seen to go down. Galantin and his boat properly received credit for its sinking. In his analysis of the attack Galantin noted that the very small splash observed and the low intensity of the explosions indicated that the torpedoes had run deeper than set. These symptoms would suggest that the exploder had been triggered magnetically, even though it had been set otherwise. The Japanese account is very sketchy, merely reporting that the SHOGEN MARV, a commercial cargo ship of 3,362 tons, was torpedoed and sunk about 0500 at HALIBUT’s position. No crewmen were killed by the attack.

An interesting sequel occurred at 2125K that day when Galantin fired four stem torpedoes at what he thought was a destroyer, at an ideal range of 2,000 yards and a 95 degree starboard track. Again he was disappointed that no explosion resulted, although men below reported hearing a dull thud. Sonar then detected a whistling sound like a circling torpedo, so Galantin immediately went deep and six minutes later heard two end-of-run explosions. What actually happened was that two dud torpedoes had hit the heavy cruiser NACHI, causing slight damage. Intelligence later learned that the cruiser reached port with one of HALIBUT’s fish embedded in its side. Galantin fired 23 torpedoes during the patrol and claimed only four hits, three of which were clearly duds. Many of the 19 misses were undoubtedly also attributable to faulty torpedoes or exploders.


The redoubtable Lieutenant Commander Samuel D. Sam Dealey, commanding USS HARDER (SS 257) on its second patrol, was patrolling along the 50-fathom curve off the coast of Honshu on the night of 9 September 1943. Not having obtained a navigational fix in 24 hours, he was somewhat unsure of his position – about 35-30N l40-40E – when the SJ radar picked up a contact hugging the coast. Dealey eased his way inshore where the depth was 23 fathoms and waited on the surface until the target came into sight. At 0438K with the range down to 1, 700 yards he fired bow tubes #1, 2, and 3 at a 4,000 ton cargo ship. The torpedoes (Mk 14-3As with Mk 6-1 A exploders set for contact) left a phosphorescent track, the target zigged, and the fish apparently missed ahead. The freighter then sent a blinker message to an escort and radioed a warning on the 450-kilocycle channel. With the escort dead ahead, Dealey cleared the bridge and passed 1,200 yards abeam the warship with “one thumb on the diving alarm,” making 20 knots. The escort never saw the sub as Dealey cleared the area and headed back to deep water.

According to the Japanese records, the 3,021 ton commercial cargo ship KOYO MARV left Yokohama on 8 September bound
for Hakodate, together with the KOAN MARU and the escorting minesweeper W 3. She was loaded with 300 tons of flour, 150 tons of steel products, and 850 tons of general cargo. At about 0340 the next morning, in the Katsuura Sea, she was hit in a coal bunker by a dud torpedo. The leak caused the boiler to flood, and the crew abandoned ship, transferring to the other two vessels which continued to watch the slowly sinking maru. At 1500 the old
destroyer SA WAKAZE arrived and took the cripple in tow, but it soon nosed down and after another hour went down at 35-23N 140-38E. Dealey was not credited with this sinking during the war, and a Japanese escort caught up with him on the HARDER’s sixth patrol. However, the postwar JANAC assessment concluded that the KOYO MARU (which it rated at 3,010 tons) was probably sunk by HARDER.


Lieutenant Commander Slade Cutter, commanding USS SEAHORSE (SS 304) on its second patrol, spotted the smoke of a convoy in the Korea Strait west of Kyushu at 01l7H on 22 November 1943 and immediately headed toward it. After about an hour he could see that it consisted of three small cargo vessels heading eastward at five and a half knots and escorted by two destroyers. Diving to periscope depth, he selected as his target a ship resembling the 3,817 ton AKITA MARU and at 0245 fired four Mk 14-3A torpedoes from the bow tubes, with Mk 6-1 exploders set for contact firing. After hearing two correctly-timed explosions, he found the target obscured by heavy smoke, and sonar reported that its screws had stopped and crackling sounds could be heard. With a destroyer coming in fast, Cutter pulled the plug and went deep. During the next hour or so the escort dropped 13 ineffective depth charges as SEAHORSE slipped away and was ultimately credited with downing a 3,800 ton cargo ship. Japanese records identify the victim as the DAISHU MARU (or TAISHU MARU in some sources) a commercial freighter of 3,323 tons. At about 0812 Tokyo time it was hit on the starboard side of the engine room by a dud torpedo. Flooding ensued through the hole and the ship sank at 1233, with the loss of three of the crew.

Some Conclusions

There are many instances of other ships that were damaged by duds, and possibly others that were sunk; the records are often too sketchy to be sure. The cases described above, all involving various models of the Mk 14 torpedo and its infamous Mk 6 exploder, are illustrative of the three major defects later identified and corrected: torpedoes running deeper than set, an unreliable magnetic exploder, and a firing pin that could jam and fail to make
contact with the detonator. Both Chapple and Galantin thought that their torpedoes might have run deeper than the depth set. This problem was exposed by tests run by Admiral Lockwood in Australia during June and July 1942. After some initial reluctance, BuOrd corrected the problem by relocating the pressure-sensing mechanism and providing a kit for modifying torpedoes already in the field. The change was indicated by suffixing the letter A to the Mk 14 model numbers, so it had already been accomplished in both cases. (The Mk 14-3 differed from the 14-1 mainly in having a heavier warhead and several internal parts made of stronger steel.) Nor does depth control appear to have been a problem in TRJTON’s case, since the torpedoes clearly hit the sides of the victim. However, the skippers in all six instances described here successively lowered their depth settings from 12 feet in the first two cases and 10 feet in the next three to 8 feet in Cutter’s attack.

In TRJTON, PERMIT, and SCAMP cases the magnetic feature was apparently armed, but the Japanese reports clearly show
that the torpedoes hit the ships’ sides, in which case neither the magnetic nor the contact detonator operated correctly. On the other hand, the fact that one of the SCAMP’s torpedoes prematured would indicate an over-sensitive magnetic exploder.

Two significant policy changes were made before the next three attacks occurred, reflecting growing official concern about submarine torpedo performance. In April 1943 submarine commanders were ordered to use a prescribed standard format for reporting attacks, including listing the model and serial number of each torpedo and exploder fired. Then on 24 June 1943 Admiral Nimitz instructed the boats in his Pacific command to deactivate the magnetic feature of the Mk 6 exploder. Thus HALIBUT, HARDER, and SEAHORSE torpedoes were all set for contact detonation but failed to explode. A possible cause was that they had hit the target too squarely; their track angles ranged from 115 to about 138 degrees. In the earlier PERMIT and SCAMP attacks the track angles were almost 90 degrees, while the TRJTON’s was 140 degrees. Apparently the firing pin could jam over a wider range of angles than a near-90 degree hit. Oddly, a fourth and potentially lethal defect does not appear to have received the attention focused on the other three: circular running torpedoes. These caused the known loss of two submarines, TULLIBEE (SS 284) and TANG (SS 306) and 157 of their crews. Unfortunately, confirmation of these tragedies was not received until the I 0 survivors were recovered from Japanese prison camps. Reports from other boats that managed to dodge their own erratic torpedoes caused most skippers to became particularly sensitive to any visual or sonar indication of a circular run and make haste to escape by speeding up and turning away or going deep. Nevertheless, submariners will always wonder whether other missing boats may have fallen victim to this most insidious torpedo defect.

Naval Submarine League

© 2022 Naval Submarine League