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Dedicated in Memory of Ralph A. Alpher, Ph.D. (1921-2007), Naval Ordinance Laborato1y (1940-1944), Johns Hopkins APL (1944-1955).

Dr. Alpher is an independent research consultant based in Austi11, Texas. He is an elected member of the Society of Sigma Xi (Scientific Research Society}. He has a long and distinguished career as a researcher and practitioner in psychological assessment and neuropsychology. He has published widely, including a number of recent works in Military History and the History of Science.

“The BARB spent a day outside the Golden Gate for test-depth dives and 5-inch gun training. Another day at a degaussing pier in San Francisco made her less sensitive to magnetic mines or torpedoes-a real joy to contemplate. Having shaken off her magnetism overnight, she would return to Mare Island the next morning.” (A rare mention of degaussing in a wartime memoir; Thunder Below by Admiral E.B. Fluckey, University of Illinois Press, 1992, p. 299.)


Part I of this series of two articles examined the reasons for generation of Degaussing Policy (DP) by the Chief of Naval Operations and its effects throughout the Fleet, Merchant Marine, and the Anny’ s surface vessels. In late 1942 through 1943 proposals were made for modification of DP in ways that would substantially affect its success. Proposals and analyses are discussed. Ultimately, the Chief of Naval Operations rejected all such major proposals at the end of 1943. Advancements in degaussing today assure its importance to future naval operations.

Degaussing Policy and the Submarine Service

In a memorandum dated 19 September 1940 from the U.S.S. AUGUST A, Flagship of the United States Asiatic Fleet, at Tsingtao, China, Commander-in-Chief Admiral Thomas Hart discussed the installation of degaussing equipment on vessels of the Asiatic Fleet. In order of priority, he placed submarines first, followed by cruisers and then destroyers. He stated at the time, that “the following general order of priority best meets the needs of the Fleet and should be followed in so far as circumstances permit.” Moored enemy magnetic mines could threaten submarines at depths of 300 fathoms (1800 feet).

As Degaussing Policy (DP) was developed, submarines did not routinely receive degaussing coils, but were regularly subjected to flashing to counter acquired magnetization (described in detail in the first paper of this series). However, by late 1941 and early 1942, the Chief of the Bureau of Ordnance, W.H.P. Blandy, and the Chief of Naval Operations, F.J. Home-Acting, were still recommending that degaussing coils be installed on submarines as long as this did not result in a delay in the completion of the vessel.

Degaussing Policy Under Scrutiny

By 1943, however, the extent of DP was being questioned-not by the operations in the Fleet, but by the central agencies guiding its implementation.6 It was already known that the degaussing program of the U.S. and its Allies was vastly superior to the Axis.

Why tamper with success? Cost-containment seems to be the motivating force-almost routine in some organizations. For example, to save costs, there were only two experimental live tests of the Mark 14 torpedo in 1926-a clearly bad decision. 7 Yet, in other areas of new development, cost-containment was explicitly eschewed during the early war period in favor of speedy development and implementation. One of the clearest examples is the development of the Proximity Fuze under Dr. Merle Tuve. This was a Navy “Section T” contract to the Department of Terrestrial Magnetism of the Carnegie Foundation, as were many ordnance development contracts. They would later be adapted as needed for Army and Army Air Force use during the war.

In a lengthy study entitled “Value of Deperming” Dr. H.M. Mott-Smith of BuOrd concluded that the most cost-effective deperming stations were those close to the continental U.S. and not forward stations. He believed that Degaussing Officers were most effectively assigned to these facilities. Aside from materials, each Deperming Station required the following personnel per shift covering a 24 hour schedule:

1. One Officer (usually a Lieutenant [j.g.])
2. Two Physicists
3. Three Petty Officers
4. Twenty Seamen
5. Five cooks, Mess Attendants, Firemen, Guards, etc.
6. Thirty One Total Personnel

Mott-Smith proposed that a reduction in the building and maintenance of forward stations would be more cost-effective because little change appeared necessary once the many vessels were in operational status. However, the existing policy of six-month intervals for deperming necessitated forward deployment of deperming installations and deperming barges. Return to the continental U.S. was costly, impractical, and inefficient. It was proposed that minesweepers be outfitted to perform flashing in forward areas.

Buord and BuShips Challenge the DP Directive

A joint letter, marked CONFIDENTIAL, from BuShips and Buord to the Vice Chief of Naval Operations, is dated 16 August 1943-Subject: General Degaussing Policy. JO This significant document, six pages long, is over the signatures of H.G. Rickover, C.L. Tyler, A.H. Van Keuren, and W.H.P. Blandy, and may represent the single most important coordinated work of these bureaus during the War-both of which had heavy responsibility for executing Degaussing Policy. Together the Bureaus recommended significant change in DP.

This document is also quite significant in that it also reveals standards for the criteria used for determining what ships received 110 coils, M-coils, or MFQ coils, at a minimum. No coils were installed in “[v]essels which normally operated in unswept, mineable waters,” Wooden vessels with beams less than 20′ received no coils, and wood-hulled vessels with beams greater than 20′ received M-coils. Steel-hulled ships with less than 15′ beams received no coils, those with beams of 15′ to 30′ received M coils, and those with beams greater than 30′ received MFQ coil setups. For “Major Combatant Vessels, and Special Auxiliaries” (all of which were steel-hulled), vessels with beams equal to or less than 62′ received M-Coils, and those with beams greater than 62′ were fitted with MFQ Coil arrangements.

They also recommended that degaussing by flashing be used “in lieu of coils” on vessels that policy then required M-coils only, as well as vessels employing no coils. This would be promulgated for vessels operating in areas where the vertical component of the earth’s magnetic field varied by 110 more than gauss, and these vessels would be prohibited from operating outside the specified area unless facilities for reflashing the vessel for the new latitude were available. Elimination of the M-coils would result in cost and material savings.

However, these changes would require magnetic ranging facilities such that vessels would be checked at a minimum of every two months instead of the current six. There would be a need for more forward Degaussing Stations, not less. Also, such vessels would not be permitted to operate outside of areas where course accuracy greater than plus or minus 3 degrees was necessary (i.e., following marked channels), and therefore, a gyro compass rather than a magnetic one would be sufficient. However, elimination of coils on a class of ships that had previously had them would have predictable negative effects on morale and efficiency.

Table 1 (January 15, 1942) shows a cost analysis for each type of degaussing i11stallation. It examines data on Weight, Cost and Time of Installation.11 The four basic types of coiling setups were designated Mark I (M-coil), Mark II (M & A [athwartship] coils), Mark III (M, F, & Q coils), Mark III Mod 1 (M,F, & Q coils, distributed) and Mark IV {M,F,Q, & A coils). This analysis was made just at the time of the introduction of the German 4 milligauss mine. Revision of DP was not seriously considered again until early 1943.

The Chiefs of BuShips and BuOrd wrote to the Vice Chief of Naval Operations, suggesting changes in Degaussing Policy for Naval Auxiliaries, U.S. Anny Vessels, Coast Guard Vessels, and Panama Canal Vessels, in a CONFIDENTIAL JOINT LETTER dated 17 March 1943.12 They stated that DP over-protected smaller vessels and should be reduced.

Degaussing Versus Minesweeping

Another important analysis appears in late 1942 archives of the BuShips and BuOrd correspondence in the National Archives. “REPORT NO. 9-Mine Countenneasures – Proper Relationship of Degaussing to Magnetic Minesweeping” is marked SECRET and is also numbered, both of which are designations signifying its intelligence importance and potential controversiality.13 This report is a thorough analysis of the results of minesweeping by both the British and U.S. forces, seen in the context of the massive degaussing effort. The most revealing part of this report is the cost analysis, which was summarized:

“These curves [graphs included] show that without degaussing a mine of about 50 mg. [milligauss] sensitiv-ity would be most effective. With any reasonable amount of degaussing, the most effective mine is a sensitive mine of about 5 mg. sensitivity. This is just half of the value for the E.R. [Effectiveness Ratio; E.R. = Target Width/Sweep Width] for 50 mg. mines and no de-gaussing. In other words, degaussing has reduced the effectiveness of enemy magnetic mines by a factor of ‘h. This is what we have bought for $128,000,000.”

It is concluded that by doubling the minesweeping program, the same effect could be attained. Unfortunately, the conclusion is based only on merchant ships lost, including Liberty ships- at the time of the analysis, a total of 2550 ships having an average beam of 52.5 feet. With new ships being degaussed during construction, the degaussing program overall “contemplates the coiling of about 2400 of these vessels.” This would mean M-coils only, except for ships with beams greater than 62 feet, which would receive additionally F and Q coils. The final conclusions of this report are summarized thus:

(a) Degaussing has resulted in a twofold increase in the safety of our merchant marine against magnetic mines.
(b) Effective results could be obtained by increasing minesweeping at two-thirds the cost of degaussing. This favorable situation of minesweeping cost to de-gaussing cost is only valid, however, if we do not over-protect [sic] ourselves against magnetic mines.
(c) Our sweeper needs are calculated on the hypothesis that we should carry our countermeasures only to the point where the mine is as effective as a torpedo (emphasis added by author; there is no mention of the origin of this criterion).

On 14 April 1943, J.L. Doob, of the Bureau of Ships, pro-duced a Rough Draft of a position paper on Degaussing Policy. The data used for his analysis were those for Liberty Ships. He considered the potential losses of discontinuing degaussing to be quite acceptable – additional losses of I ship per month at the end of 3 months and 2 ships per month at the end of 6 months (Atlantic), and comparable losses in the Pacific at 3 and 6 months. These statistics were based on an assumption that in the Atlantic, the enemy would be laying 500 mines per month, and in the Pacific, 300. However, he nonetheless concluded that discontinua-tion of the degaussing program currently in effect was inadvisable; because of the startup cost, time lost, and casualties incurred over the year’s delay in reintroducing degaussing, should enemy mining activity increase. Also sweepers in use as patrol vessels would have to be recalled in favor of increased minesweeping. This would almost certainly be detected and investigated by the enemy. The conclusion: current DP was sound.

Mine Warfare Operational Research Report OpNav 30M-C, No. 27, Discussion of Degaussing Policy is dated 14 June 1943.15 Report No. 27, CONFIDENTIAL, appears over the signatures of F. Bitter, Commander, USNR and Officer in Charge of the Mine Warfare Operational Research Group, and of LS. Fiske, Captain, USN and Assistant Director, Base Maintenance Division. This report comes to different conclusions regarding the possible losses in the Atlantic and Pacific to the Liberty Ship fleet, again founded on base rates of 500 mines per month laid in the Atlantic and 300 per month laid in the Pacific. Losses due to curtailing the Degaussing Policy with respect to Liberty ships in the Atlantic was estimated at 0.8 ships per month in the first 3 months, and 1.5 ships per month at the end of 6 months, 2.8 ships per month at the end of a year, increasing slowing to 13. In the Pacific, additional ship losses were estimated at 0.6 per month in the first 3 months, but only I ship at the end of 6 months, 2 ships per month at the end of a year, increasing slowly to 8.

Who, however, would want assignment to Liberty Ship with no degaussing coils? Perhaps only with an increase in the existing system of hazard pay. For surviving a torpedo attack or air-to-sea bomb, for example, merchantmen received increased pay (this applied to the Murmansk run according to Lt. Col. C.J. Lyons; personal communication, January 5, 2010). The M-coils given all Liberty ships were important psychologically as well as strategically.

Arguments Against Modification of DP

Degaussing reduced the magnetic field around a ship by a factor of about three, rendering German magnetic torpedoes and mines much less effective. Curtailment of degaussing would necessitate the minesweeping of new areas. Any increase in the amount of minesweeping would surely be noticed by the enemy and analyzed-and if it Jed to an increase in mining, many vessels would be lost during the ensuing year of re-implementing degaussing, flashing, and other components of DP.

Finally, and most important, this report makes, for the first time, a more detailed examination of the effect of degaussing on morale-and I believe the weight of evidence is that this is the factor that eventually prevailed. For example, it was concluded that personnel on ships without degaussing facilities would become lax in their duties, knowing that new ships were 1101 even being degaussed! Of course, some personnel would attempt to compensate for the lack of degaussing protection-in potentially unproductive ways-such as increase in visual observation to the detriment of other assignments.

Some small landing craft would also lose degaussing protec-tion. Coastal areas were frequently mined. Such a measure would leave combat troops vulnerable when assaulting new areas, such as when Marines were transported to new islands in the Pacific, and Army Rangers attacked the Atlantic Wall in Normandy on 0-Day. It was concluded that although minesweeping was the most effective component of magnetic-mine countermeasures, “total losses in the event of a magnetic mine blitz would be several times as large if we gave up degaussing.”

The CNO Closes the Door on Changes in DP

The CNO appears to have brought any considerations of altering policy -except to increase the effectiveness of mine-sweeping and the effectiveness of degaussing of minesweepers -to an end, after receiving much information from the various sources mentioned here, and possibly others. A Confidential Memorandum dated 13 December 1943 from the Office of the CNO with extensive Atlantic and Pacific Fleet distribution reveals these final conclusions.

Figure 1 shows the Submarine Tender Orion on September, 1944, off the coast of Saipan. This photograph illustrates the effects of Degaussing Policy-from the essential degaussed tender, to the subs depermed at advanced bases. Without these interlocking units of iron, steel, sailors, and copper, submarines could not have sunk 5,320,094 million tons of enemy shipping in the Pacific. The majority of these losses were to merchant shipping, crippling the Empire of Japan.

Final Words as a New Era Dawns on Degaussing

One rarely sees extensive discussions of technology, although DP was and is an essential dimension of Naval warfare. A testament to the enduring value of degaussing is that many WWII vessels served in later conflicts in Korea as well as Vietnam.

In July, 2008, the first high-temperature ceramic superconductors were installed in the USS HIGGINS to perform degaussing. On April I, 2009, the Higgins successfully passed through the U.S. Navy Magnetic Silencing Range at San Diego. This new method is more energy-efficient than copper and lighter in weight. A bright new era in the history of degaussing technology has commenced.

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