Initially in World War II, major defects in the Mk. 14 torpedo-the ultimate arbiter of the effectiveness or failure of any weapon -delayed the effectiveness of our submarine campaign for well over a year.1 When war broke out, the Mk. 14 torpedo was the most recent model in quantity production. Ostensibly it had been certified for combat use by both submarines and destroyers by the Naval Torpedo Station, Newport, Rhode Island, which had the responsibility for checking its running depth and the testing of the exploder and warhead. But, from the outset, major defects in its performance and that of other torpedoes became clearly evident. Those defects may be classified into three broad categories: (1) either they ran deeper than set depth, (2) had a tendency to explode prematurely, or (3) frequently failed to explode even on impact. All three defects were interrelated-directly or indirectly -with the performance of the Mk. 6 exploder.
The major features of the Mk.6 exploder were that it was designed to be triggered either by the magnetic signature of a target when the torpedo passed under its keel or by direct impact against its hull. In either case, the same firing pin mechanism was used to initiate an explosion of the main charge. Although there was no direct relationship between running depth and the Mk. 6 exploder, the failure of its magnetic feature masked both the deep running and dud defects, which in tum prolonged the search for solutions.
Previous firings of the Mk. 10 torpedo, which did not have a Mk. 6 exploder, provided ample evidence that it was running deeper than set. On S January 1942, Buord acknowledged that the Mk. 10 ran four feet deeper than set. But it was not until August of 1942 that tests conducted by Admiral C .A. Lockwood, Jr, ComSubSoPac, confirmed that the Mk 14 was running 10-11 feet deeper than set. A significant point here is that Admiral Lockwood took the unusual and career risking action of testing a piece of ordnance without specific approval from Buord. The test was simple. At Albany, Australia, a fish net was rigged in Frenchman’s Bay, and on 20 June 1942, a series of Mk. 14 torpedoes were fired into it from a range of 850 yards. Holes in the net indicated that the torpedoes had run at between 11 and 15 feet below set depths. Admiral Lockwood reported his findings to Buord. Buord disagreed on technical grounds. Admiral Lockwood repeated the tests and reported that the Mk. 14’s were running 11 feet deeper than set and requested that Buord conduct equivalent tests. Finally, on 1 August 1942, Buord confirmed that tests conducted at Newport corroborated reports that Mk 14 torpedoes were running 10 feet deeper than set. Thus, after almost eight months of war, BuOrd confirmed that the Mk. 14 torpedo had a major defect.
Determining the causes for prematures and duds were more complex because of the closer interrelationship between the two. Repeated reports of torpedoes exploding shortly after arming or before reaching the target led to a blizzard of correspondence between the submarine forces and Buord. Summarizing the results: on 27 April 1943, Buord stated that the Mk. 6 was susceptible to prematuring if set for 12 feet or less and recommended disconnecting the magnetic feature in favor of contact shots; on 3 and 7 May Buord informed Admiral King, CNO, that the effectiveness of the Mk. 6 would be increased by 10 to 30 percent if the arming distance were increased from 450 to 700 yards and fired under a list of additional limitations; Admiral King replied that the in-creased arming distance was unacceptable and concurred with Admiral Lockwood (by then ComSubPac) that the MK. 6 exploder should be replaced; on 24 June, Admiral Nimitz, CincPacFlt, ordered ComSubPac and ComDesPac to inactivate magnetic exploders on all torpedoes; next day BuOrd asked why; Admiral Nimitz diplomatically but firmly replied that his decision was made because the Mk. 6 was .. ineffective” and because of “the impracticability of selecting the proper conditions [recommended by Buord] under which to fire”. Thus, Admiral Nimitz’ order stood and Admiral Lockwood’s submarines were rid of the beast.
Not so for the boats in ComSubSoWestPac-Lockwood’s former command but not under Nimitz’s theater command-where Admiral Ralph Christie ordered that the magnetic feature be retained. Nevertheless, CDR H.P. Hottle, CO GROUPER, in his patrol report of September 1943 to Admiral Christie recommended inactivation of the Mk. 6 exploder and had the testicular fortitude [balls] to opine:
“It would appear far better to sink the enemy vessels encountered . . . than to continue spoiling good chances just to prove that a really useless mechanism [emphasis added] can be made to function a fair proportion of the time.”
Still, it was not until March 1944 that it was inactivated in SoWestPac submarines. Two down and one to go.
With che running depth and premature problems solved, The interaction of which masked the dud problem, it was now possible to solve the latter more readily. The problem manifested itself dramatically when Lieutenant Commander L.R. Dan Daspit in TINOSA fired eight Mk. 14’s at a deadin-che-water 19,262 ton whale factory, converted to an oil tanker, from a point blank range of 850 yards with a optimum 90 degree track-torpedo strikes perpendicular to the target’s hull. Admiral Lockwood, mindful of che prolonged effort with Buord to even admit to the premature problem. tackled the dud problem himself. Two Mk. 14’s with warheads attached were fired at submerged cliffs at Kahoolawe; one was a dud, recovered and disassembled. Examination of the firing pin-an integral part of the Mk. 6 exploder-revealed that it had been released but had not traveled far enough along its guide rails to strike the primer cap with sufficient force to initiate an explosion. To confirm this diagnosis, 10 dummy warheads, fitted with Mk. 6 exploders, were dropped from a height of 90 feet onto a steel plate. Seven of the IO were duds. Disassembly revealed once again that the firing pins in the duds had not traveled the entire distance required along their guide rails to set off the primer cap. Further investigation concluded that the design of the firing mechanism was not rugged enough to withstand the distorting force of deceleration equivalent to 500 times the force of gravity with a frictional component of 190 pounds on the firing pin guide rails when the torpedo struck square-on.
Armed with this information, Admiral Lockwood approved the production of modified Mk. 6 exploder firing pin mechanisms on the tender HOLLAND. On 30 September 1943, BARB departed Pearl on patrol with 20 torpedoes, all equipped with the modified firing pins. And by mid-October, HOLLAND had produced enough of the modified firing pins for all the torpedoes issued to submarines departing Pearl on patrol.
In summary, at the beginning of the war, the Mk. 14 torpedo ran 10-11 feet deeper than set, had a tendency to premature, and frequently failed to explode even after striking the target. Almost two years later, all of these defects had been detected and corrected in the fleet by modifying the procedure for calibrating the depth setting mechanism, disconnecting the magnetic feature of the Mk. 6 exploder, and modifying the design of the Mk. 6 firing pin mechanism. Thus, submarines and destroyers finally had a reliable torpedo which could have been realized from the beginning if the pre-production testing and post-production proofing by the test firing of torpedoes with warheads attached had been more comprehensive.
The effect of these defects is summarized by a consensus of those submariners who fought the war:
The war would have been foreshortened and many American lives saved had a reliable torpedo been available from the beginning …. The cost to the United States war effort in lives, dollars and time remain incalculable.