CONFIDENTIAL

DECLASSIFIED

SUBMARINE REPORT

DEPTH CHARGE. BOMB, MINE. TORPEDO AND GUNFIRE DAMAGE INCLUDING LOSSES IN ACTION

7 DECEMBER 1941 TO 15 AUGUST, 1945

VOLUME I

The Chief of Naval Operations d rects that this report be shown only to those persons to whom the report would be of value 1n the performance of their duties. Steps shall be taken accordingly to insure that this report w.il be seen by those persons responsible for design, con· struction and repair of naval vessels, es well as for their operation, but by no others.

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Preliminary Design Branch Bureau of Ships 1 J anuary 1949 Navy Department

WAR DAMAGE REPORT No. 58

Printed By U . S. Hydrographlc OH1ce

CONFIDENTIAL

SUBMARINE REPORT

Depth Charge, Bomb, Mine, Torpedo and Gunfire Damage

Including Losses in Action

7 December, 1941to15 August, 1945

1 January 1949

APPROVED

C. L. BRAND Rear Admiral, USN Ass' t. Chief of Bureau for Ships

CONFIDENTIAL 7.1 J04S1 (I D 1 3 5 8' :> ~ '1q v I CONTENTS

~CTION Page

FOREWORD 1

II GENERAL 2

III JAPANESE ANTI-SUBMARINE WARFARE AND WEAPONS 8

Name No. Damaged by Locale Date

IV PERCH 1'76 Depth Charge Java Sea 3/3/42 17

v KING FISH 234 Depth Charge Formosa 3/23/43 26

VI TUNNY 282 Depth Charge Palau Is. 8/26/43 47

VII SALMON 182 Depth Charge S. E. of Kyushu 10/30/44 61

VIII GRENADIER 210 Bomb Malaya 4/22/43 82

IX SCAMP 277 Bomb Mindanao, P.I. 4/ 7/44 89

x TANG 306 Torpedo Formosa 10/24/44 109

XI BERGALL 320 Mine Gulf of Siam 6/13/45 125

XII GRAMPUS 207 Gunfire Truk 5/17/42 131

XIII GROWLER 215 Collision New Britain 2/'7/43 137

XIV DRAGON ET 293 Grounding Kurile Is 12/15/ 44 148

xv BEHAVIOR OF UNDERWATER NON- CONTACT EXPLOSIONS 161 XVI HULL DAMAGE AND STRENGTH 177 XVII STABILITY, BUOYANCY AND FLOODING 193 XVIII SHOCK PROTECTION 203 XIX ENGINEERING NOTES 213 xx PIPING 223 XXI HABITABILITY 233 XXII SUBMARINE ESCAPE NOTES 239 XX III CONCLUSION 248

APPENDIX I BRIEFS OF DAMAGE INCURRED BY U.S. 250 SUBMARINES DURING WORLD WAR II.

APPENDIX II TABULAR SUMMARY OF U.S. SUBMARINE 296 LOSSES DURING WORLD WAR II.

APPENDIX l1I MAP COVERING AREA OF PRINCIPAL U.S. SUBMARINE OPERATIONS.

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SECTION I

FOREWORD

1-1. This report is one of a series of sixty-two war damage re­ ports prepared by the Bureau covering damage received in action by vessels of the U.S . Navy during World War II. It is the only report of the entire series which deals with war damage sustained by sub­ marines. The remaining sixty-one reports cover cases of significant damage incurred by surface vessels, and include r::lany instances of torpedo damage which may be of interest to submarine personnel who desire information on the destructive effect of their principal World War II weapon, the torpedo.

1- 2. As a group, U.S. submarines have established an enviable record in combat, not only in destruction inflicted upon the enemy but also in their ability to sustain severe attacks without themselves receiving serious damage. Although the basic operational character­ istics of our submarines remained substantially unchanged throughout the war years, with the notable exceptio:i of considerably increased m:?.Ximum allowable submergence depth for the SS285 anj subsequent Classes, marked advances were achieved in practically every 0th :· aspect of submarine and submarine equipment design. Improvements in shock protection have resulted in subm:irines which are highly re­ sistant to damage short of actual destruction of their pressure hulls.

1-3. It is the purpose of this report, by presenting case histories selected from the great volume of war experience, to illustrate the behavior of U.S. fleet type submarines in service during World War II when subjected to enemy attack, and in particular, to attack by non­ contact underwater explosive charges since the Japanese anti-submarine forces employed the depth charge and bomb as their principal weapons. Cases of damage by mine, torpedo, gwlfire and collision are also in­ cluded. An effort has been made to present a comprehensive sum- m"l.tion of the effectiveness with which our submarin8s withstood attack, the materiel and design weaknesses revealed by war damage, the dam­ age control problems attendant upon flooding of intact spaces or de­ rangement of vital systems and equipment, and the corrective measures taken to reduce the vulnerability of our submarines to damage. It is hoped that the information presented here will be of value to submarine operating personnel and submarine design, repair and outfitting activities.

1-4. No attempt has been made in this report to evaluate the opera- tional arid military characteristics of our submarines in the light of war experience other than by statements of fact when such character­ istics were impaired through war damage, nor have casualties incident to normal service operations been discussed. Lessons learned through the recent CROSSROADS OPERATION, and their possible effect on sub­ marine design, have not been included.

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2-4. Commencing with the BARRACUDA Class of 1924 and con- tinuing through the end of World War II, all submarines built by the U.S. Navy, with the exception of the 800 ton-type submarines MACKEREL (SS204) and MARLIN (SS205) completed in 1941, were of the fleet type, designed for high surface speeds and capable of operating for extended periods at sea and covering great distances. The submarine war effort of the United States was dependent almost entirely upon these fleet ty1 e submarines and for this reason only the damage ex­ periences of fleet type submarines have been included in this report.

2- 5. It is pertinent to mention that only negligible war experience was gained by our submarine service during World War r.1 The evolution of the fleet type submarine during the years of peace pre­ ceding Worla War II was the result of hypothesis and experience obtained through simulated exercises rather than actual war service conditions. The operating characteristics of the fleet type submarine proved adequate to carry the war to the enemy throughout the entire Pacific area, although great distances were involved.

2- 6. U.S. submar:ne operations in the Atlantic during World War II were on a minor scale. Throughout the entire war only four enemy vessels were sunk by our submarines in the Atlantic, two of the four being Gerran submarines, and but five other enemy vessels were damaged. ~Y one U.S. submarine was damaged in the Atlantic through enemy action. In the Pacific, however, where the major portion of our submarine effort was exerted, the U.S. submarine service established an impressive record almost from the first day of our entry into the war. Unrestricted submarine warfare against Japan was ordered by the Chief of Naval Operations on 7 December 1941. With the exception of a few special missions and support operations during the Battle of Midway and the initial phases of the Solomons Campaign, submarines were employed during the first two years of the war as free agents in a campaign of attrition against enemy combatant vessels and merchiint shipping. With the inauguration of the Gilbert Islands campaign in November 1943, a gradually increasing percentage of the submarine effort was diverted to the support of fleet operations although normal offensive patrolling con­ tinued to the end of the war. The statistics of the Joint Army- Navy Assessment Committee credit U.S. submarines with the sinking of 54.6 percent of all Japanese naval and merchant vessel tonnage sunk during World War II by U.S. forces of all categories. The total of sinkings

1so far as can be determined, the first vessel credited as destroyed by submarine action in the history of the U.S. Navy was the Japanese cargo ship ATSUTASAN MARU (8 ,662 gr oss tons), sunk in World War II by SWORDFISH (SS193) on 16 December 1941, lat. 18° - 06'N., long. 109° - 44'E. (credited by the Joint Army- Navy Assessment Committee, NavExos Publication P - 468). 2submarine Oper ational History, World War II, prepared by Commander Submar ine Force, U.S. Pacific Fleet (Preliminary Issue). 3BLACKFISH (SS221), damaged by Ger man depth charge attack in the Bay of Biscay on 19 Febr uary 1943. See brief of damage in Appendix I.

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credited to U.S. submarines includes 201 Japanese naval vessels with a combined tonnage (standard displacement) of 540,192 tons, 28.6 percent of all Japanese naval tonnage sunk by U.S. forces, and 1113 merchant vessels above 500 gross tons with a combined tonnage (gross) of 4, 779,902 tons, 60.4 percent of all Japanese merchant ton­ nage sunk by U.S. forces.1,2 The following numbers and types of combatant Japanese naval vessels were sunk by U.S. submarines: 1 battleship, 4 lar ge aircr aft carriers, 4 escort aircraft carriers, 3 heavy cruisers, 8 light cr uisers, 38 destroyers, 23 submarines and 100 escort, patrol or mine vessels. In addition to the 1314 naval and merchant vessels credited as sunk, appr oximately 1000 Japanese ves­ sels in all categories, with an estimated combined tonnage of over It been i.> 1 000,000 tons, were damaged by U.S. submarines. 3 has estimated that approximately 275,000 Japanese were killed as a direct result of Allied submarine operations.4

2- 7. On r December 1941 there were 46 fleet type, 2 - 800 ton- type, 37 S-type, 18 R- type and 7 0-type submarines in commis-sion in the U.S. Navy. Of these, 39 fleet type and 12 S-type were in the Pacific.

On 1;:) August 19451 the day the war ended, there were 200 fleet type, ~.., S- ly";e, 10 R- type ::i.nd 5 0 - ty_ie submarines in commission. Of these, lE' J fle t type and 13 S- type submarines were in the Pacific. A total of 202 fleet type submarines were completed and commissioned during the war.5

2-8. In all theatres during World War II, 269 U.S. submarines conducted a g r and total of 1682 war patrols against the enemy. 251 submarines made patrols in the Pacific, of which 229 were fleet type boats and 22 were S-type boats. Of the total of 1682 war patrols, 948

lJapanese :--Javal and Merchant Losses During World War II by All Causes, NavExos Publication P - 468 of 3 February 1941 , prepared by the Joint Army- Navy Assessment Committee. The figures of this committee are very conservative as compared with the official statistics of the various force commands. 2oNI Statistical Section (Or- 32F- 44) data credits German submarines with the destruction of 2,321 naval and merchant vessels of the United 1'rntions, for a grand total of 12,866, 711 tons, during the period from September Hl38 to the German surrender in May 194t>. 3Submarine 0.i,)erational History, World War II, pr epared by Commander Submarine Force, U.S. Pacific Fleet (Preliminary Issue). 4Figure given by Japanese to the Administrator, U.S. Naval Shipping Control Authority for Japanese Merchant Marine. (Submarine Force Pacific Fleet Bulletin, Volume III, Number I of February 1946.) 5nuring the period from September 1339 to their surrender in May 1945, the Germans built a total of 1100 submarines, divided into the following categories: 912 attack type submarines which became operational; 119 Ty1 e XXI attack submarines which were delivered by the final assembly yards but none of which became oper ational due to hydraulic system defects; 10 experimental submarines; and 59 submarines designed for special service such as minelayers, cargo carriers and submarine tenders. --NavTechMisEu Technical Report No. 312-45 of August 1945 entitled "German Submarine Design, 1935- 1945."

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Medium caliber gunfir e damage 4 Leakage render ing depth control difficult 3 Reduction gear damage 3 Conning tower door damage 1 Bow damage (collision) 1 Strafing attack 1 Der angement of stern planes 1 Conning tower lating failure 1 Control cubicle derangement 1 Oil leakage fr om exter nal tanks 1 Contamination of hydraulic system with salt water 1 Damage to torpedo tube fittings 1 Damage to tor pedoes 1 Small caliber gunfir e (40mm) _1_ Total 49

2- 11. Fifty- two U.S. submarines were lost from all causes during the per'.od 7 December 1941 to 15 August 1945.1 A summary of these losses, with pertinent information where available, is presented in Appendix II. Of the total of fifty- two losses, at least nine were due to causes other than direct enemy action: four stranded on reefs during war patrols and wer e abandoned; two were lost due to operational or materiel casualties while on training exerc.ses; one was lost by collision with a U.S. surface vessel while proceeding to her patrol ar ea; and two were sunk by the malfunct'oning of their own torpedoes. In addition, one was destroyed by Japanese bomb attack while under over haul at NavyYard, Cavite, P.I. The remaining for ty- two submarines were lost at sea e,ther through enemy action or for reasons unknown. The circumstances regar ding the loss of six of these forty- two submarines are known from survivors' repor ts: two were scuttled after damage received by depth charge attack; one was scuttled after damage received by bomb attack; two were destroyed by mine explosions while running surfaced; and one was sunk by direct hits from medium caliber gunfire. The fate of the other thirty- six submarines is not definitely known. Assessment of the various sources of information enumerated in Appendix II of this report results in the following estimate: twenty- one submarines, probably or possibly sunk by depth charge and/or bomb attack; five probably or possibly sunk by mines; two possibly sunk by gunfire; one probably sunk by gunfire after being forced to the surface by depth charge attack; one probably destroyed, while surfaced, by Japanese torpedo attack; and six submarines whose loss remains in the unknown category. lEnemy submarines destroyed from all causes in World War II totaled 996, including 781 Ger man, 85 Italian and 130 Japanese. (Statistics com­ piled by the British Admiralty and United States Navy Department Assess­ ment Committees. Intelligence received from enemy sour ces after the termination of the war was consider ed in this evaluation.)

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2- 12. Eleven cases of submarine loss or damage have been taken up in detail in this report and are grouped as follows: four cases of depth charge damage, including one loss; two cases of bomb damage, including one loss; one loss by torpedo damage; one case of damage by mine; one case of damage by medium caliber gunfire; one case of damage by collision and small caliber gunfire; and one case of damage by grounding while submerged. The cases have been selected to in­ clude not only the most serious instances of damage sustained by our submarines during World War II but also to illustrate the effect of underwater detonations at various points along the length of a submarine. The text of each case includes a narrative describing the action, the damage and its effect on the submarine, the damage control measures taken, the habitability aboard the submarine after damage, a discussion of the ordnance material which inflicted the damage, and such conclusions as may be drawn regarding materiel behavior.

2- 13. Most of the information on the individual ship actions has been obtained from the respective Commanding Officers' patrol reports, the reports of war damage submitted by the Commanding Officers following fae form of the Bureau's letter C- FS/Lll- 1(374); C- EN28/A2- ll of 17 April 1942 which was distributed to all vessels in the U.S. Navy, the supplementary war damage reports submitted by the various repair activities or Naval Shipyards, and survivors' reports in those cases where loss of the vessel occurred.

2- 14. It is realized that the preparation of detailed reµorts during wartime often may be onerous to the individual concerned, esi:iecially when the press of other duties is extreme. However, it is through such rer orts that the forces afloat and field activities can keep the Depart­ ment fully aware of significant developments and the need for design changes or materiel imprmrements. It is emt-ihasized that reports of damage and loss have served as a basis for improvements in both de­ sign and equipment.

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SECTION III

JAPANESE ANTI- SUBMARIN'E WARFARE AND WEAPONS

3-1. Much interesting and hitherto unknown information on the Japanese anti- submarine warfare effort was gathered at the end of World War II by representatives of the U.S. Naval Technical Mission to Japan. l The most striking feature commented upon was the enormous gulf between the Japanese conceptions of such warfare and their actual accomplishments. The Japanese high command had given consideration to almost every phase of advanced anti-submarine warfare. Much thought and research effort was directed towards the developmP-nt of echo- ranging equipment, influence and acoustic proximity-fuzed depth charges, deep-setting depth charge pistols, chemical recorders, ultra high frequency voice radio, surface search radar for escort ships and aircraft, magnetic detection equipment for aircraft, ahead- thrown rockets and standardized and improved doctrine for surface and joint air-surface offensive action. Satisfactory solutions to many of these problems were obtained and limited production of equipment and operational training were un:iertaken.

3- 2. Nevertheless, at the end of the war Japanese anti-submarine warfare was still being waged without appreciable benefit from the results of their research effort. Lack of production facilities, inability to maintain adequate supply lines, and the necessarily large allocation of production to aircraft for the final defense of the Empire home islands greatly affected the anti-submarine forces, but there also existed a failure on the part of operating personnel to use what they did have to best advantage.

3-3. Although the importance of use of radar to detect submarines was recognized, many escorts were never fitted with surface search radar due to lack of equipment.2 Even those escorts which had been equipped with search radar and improved echo-ranging devices were in most cases unable to obtain satisfactory results, due to defective equipment and poor training of maintenance and operating personnel. However, both combatant ships and escorts were generally provided quite early in the war with effective directional equipment to detect radar being used by U.S. submarines.2

3-4. The value of aircraft radar in anti-submarine work, both for search and blind attack, was also well recognized. Here again, their equipment was decidedly inferior and pilots generally were either poorly trained or lacked confidence in its use and are reported to have

1 NavTechJap Target Report, Index No. S-24, of 8 February 1946 (Japa­ nese Anti-Submarine Warfare). 2 Japanese anti- submarine escorts did not begin receiving radar surface search equipment in quantity until about September 1944. Previous to that date, very few escorts were equipped with search radar since most of the available production was allocated to combatant ships. Radar detection receivers were installed on most escorts by April 1944. - U.S. Strategic Bombing Survey, Naval Analysis Division, Interrogation No. 61.

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had but little success in radar bombing attacks. Airborne radar was first used in medium bombers as early as September 1943 but there was no large-scale employment of radar- equipped planes for anti­ submarine work until the fall of 1944. Their equipment was reported to have been capable of detecting a surfaced submarine at a range of twelve miles. However, Japanese doctrine called for use of airborne radar only during night or low visibility conditions because visual search was still considered more reliable. Towards the end of the war, Japanese radar- equipped planes were making numerous contacts with cur submarines but few attacks resulted. In 1945 a few anti­ submarine aircraft were also provided with radar detection receivers but the Japanese professed to have never reached the stage of homing on U.S. submarine radar. However, war patrol reports indicate that at least some enemy pilots achieved moderate success in using such equipment for initially detecting the presence of our submarines. Precise locating was probably then accomplished with aircraft search radar rather than radar detection equipment.

3-5. By late in 1943, the Japanese had successfully developed a magnetic airborne detector (MAD) and, commencing in March 1944 this equipment was put into operational use by both the Army and Navy for anti-submarine patrol.1 Range of dete::ction was reported to have been about 120 meters under average conditions and about 250 meters was claimed under ideal conditions. Since expert pilots flew magnetic search planes only thirty to forty feet above the surface, the apparatus was therefort. presumq_bly capable of detecting a submarine at well over 300 feet submergence. Aircraft equipped with MAD were employed principally to search ahead of convoys or to exploit a sub­ marine contact made by other means. Although it was planned to use such aircrd.ft to sweep all heavily travelled convoy routes, lack of both aircraft and 111~ equipment prevented this. The instrument was con­ sidered sufficiently reliable to war .rant calling in surface craft whenever an initial contact had been established. The types of planes normally used for anti-submarine work, and equipped with MAD and/or radar when possible, were NELL, JAKE, KATE, JILL, DAVE, BETTY, ZEKE and EMILY.2 By the end of the war only about one- third of the shore based anti-submarine planes had MAD, about one- third had radar, and only a very feJJ were equipped with both. Anti- submarine planes were very seldom fitted with guns which accounts for the low incidence of strafing attacks against U.S. submarines.

3-6. Only one small land- based " hunter- killer" air-surface group existed and even thb was not organized until early 1J45. 3 The group covered the East China Sea betwee'1. Formosa and Shanghai and was comprisoo of five surface ships (DE types) known as the 102nd Surface Gquadron and abo..it 20 Navy fighters (ZEKES) of the 934th Squadron,

1 NavTechJap Target Rep.Jrt, Index No. E-14 (Japanese Magnetic Air­ borne Detector). 2 U.S. Strategic Bombing Survey, Naval Analysis Division, Interrogations l'~O::>. 200 and 371. 3 NavTechJap Target Report, Index No. S-24 (Japanese Anti-Submarine Warfan:).

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Shanghai Air Force. These planes were equipped with both radar and magnetic airborne detectors. For routine patrol, the planes usually carried two 60 Kg. depth bombs and when sent out to attack a p re ­ viously detected submarine carried one 250 Kg. depth bomb, although the 250 Kg. size depth bombs wer e also sometimes carried on patrol. Both the planes and surface escorts were provided with voice radio but could communicate only for short distances and frequently were unable to communicate at all due to technical difficulties.

3-7. The Japanese repeatedly demonstrated facility in detecting and localing submerged submarines by using sonar. Their underwater listening gear was fairly good and could frequently pick up our sub­ marines at ranges of 2000 meters or more when the listening ship was stopped or proceeding at very slow speed. A damaged submarine with a high machinery noise level, such as a reduction gear click, could of co:.irse be heard at a far greater distance than an undamaged submarine running silent or creeping. Their echo-ranging equipment was of medi­ ocre design, roughly corresponding to the early U.S. QC sonar of about 1937. The emphasis which the Japanese placed on sonar devices is clearly shown by the unnecessarily large amount of space allocated to such equipment in the already cramped quarters of their ships. At sea it was customary to man the hydrophone set continuously and to operate the echo-ranging gear at least fifteen minutes in every hour. Small escorts were generally provided only with listening gear, in some instances just a crude hydrophone lowered over the side. Japanese sc:ientists were cognizant of density layers and temperature gradients in sea water and their effect on sound transmissions in echo-ranging detection work. However, anti-submarine vessels were not equipped with bathythermographs and no tactical use was apparently made of the small amount of information of operational value issued by the Japanese Hydrographic Office.

3-8. The depth charge was the primary Japanese surface ship anti- submarine weapon. Depth charges were placed aboard practically every type of ship capable of carrying them and even the smallest of patrol craft could generally be expected to have a few. Very slow craft used parachutes to reduce the sinking rate of their charges so as to reach a safe distance from the detonations. The Japanese used depth charge throwers extE:nsively and even merchant ships were occasionally equipped with these. Fleet destroyers generally carried about 30 depth charges. Frigates (KAIBOKAN) could carry as many as 300 and were usually fitted with twelve single depth charge throwers, six to a side, an:i one stern rack. The Japanese PC-13 Class, by far the most numerous of their PC types, carried about 36 charges with two side throwers and one stern rack. Gun armament for the PC- 13 Class con­ sisted of one 8 cm. dual purpose and one twin 13mm machine gun.

3-9. There were only two types of depth charges in general use by the Japanese for surface ship launchings and both were almost exact copies of early British models of obsolete design. These were the Type 95, the Type 2, and the various modifications of each.1

1 Handbook of Japanese Explosive Ordnance, OpNav 30- 3M of 15 August 1945 and Bureau of Ordnance Pamphlet 1507 of 20 Ppril 1945.

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The Type 95 was the regular issue depth charge until the development of the Type 2. Although the Type 2 charge was adopted in 1942, Type 95 charges are known to have still been manufactured up to 1943. Both charges were probably in use during 1943 until available supplies of the Type 95 were finally exhausted. The Type 95 depth charge was cylindrical in shape, 17.75 inches in diameter and 30.5 fnches long. The Type 95, Mod. 0 was filled with 220 pounds of Type 88 ex.12losive and a Shimose2 booster; the Mod . 1 with 325 pounds of Type 973 or Type 884 explosive; and the Mod. 2 with 242 pounds of Type i 5 explosive. The Type 2 depth charge was also cylindrical in shape, 17.56 inches in diameter and 30. 5 inches long. The Type 2, Mod . 1, was filled with 35'7 pounds of Type 97 or Type 98 explosive and the Mod. 2 with 242 pounds of Type 1 explosive.

3- 10. The pistols for both the Type 95 and Type 2 depth charges were also almost exact copies of early British models and both operated on the same depth setting and firing principle, although they were not interchangeable between the two types of charges.6 The firing mechanism of both pistols was actuated by the hydrostatic pressure of sea water flowing through a small orifice and slowly filling up an inner cylinder. Depth setting was accomplished by varying the size of the water inlet, thus determining the amount of time required to fill the inner cylinder. The smaller the inlet, the deeper the setting. The Type 95 depth charge pistol used early in the war could be set for operation only at depths of 98 feet, 98 feet with parachute, 197 feet, and "Safe". Later modifica- tion of this pistol provided for an additional setting of 292 feet. The m::ucimum range of depth settings for the Type 2 depth charge pistol was much greater, a choice being available of 98 feet, 197 feet, 292 feet, 390 feet, 480 feet, and "Safe". It was apparently not possible with either type pistol to choose depth settings other than those enumerated above, even though detonation at some intermediate depth might be con­ sidered desirable.

3- 11 No data are available as to how much variation could normally be expected between the prescribed depth settings on the pistols and the depths at which charge detonation would actually occur. The amount of error would naturally be affected by variations in sinking rates due to the following factors: (a) the method of launching, i.e., whether the charges were projected from throwers or dropped from stern racks; and (b) by the condition of the sea, i.e., whether still or disturbed. The accuracy

1 Type 88 explosive - 75% ammonium perchlorate, 16% ferro-silicon. More powerful than TNT. Power compares favor­ ably with explosives containing aluminum. 2 Shimose - Almost pure picric acid. Slightly more powerful than TNT. 3 Type 97 explosive - 60% trinitrotoluene, 40% hexanitrodiphenylamine. Slightly less powerful than TNT. 4 Type 98 explosive - 60% trinitroanisole, 40% hexanitrodiphenylamine. Power is approximately that of TNT. 5 Type 1 explosive - 81 % ammonium picrate, 16% alumir:.um. Power com­ pares with that of Torpex or about one- third to one­ half greater than TNT. 6 Handbook of Japanese Explosive Ordnance, OpNav 30- 3M of 15 August 1945 and Bureau of Ordnance Pamphlet 1507 of 20 April 1945.

CONFIDENTIAL - 11- CONFIDENTIAL with which the orifices in the pistols were initially machined would also affect the detonation depth. Tests conducted by the British on their early pistols indicated that discrepancies of as much as 60 feet should be expected for charges set for detonation at 250 foot depth. It should be noted that even though a Japanese depth charge were to come to rest in water more shallow than that for which its pistol had been set, it would still fire when sufficient water had seeped through the entry orifice to provide the minimwn pressure required. This is believed to account for many of the delayed depth charge detonations whtch have been reported by U.S. submarines.

3-12. The maximwn depth setting possible with the Type 95 depth charge is believed to have been 292 feet and the maximwn setting normally used for the Type 2 charge was 390 feet. A proportionate number of charges with these maximum settings were usually included in each attack pattern. Our submarines reported only a few cases where depth charges were set for depths in excess of 400 feet.1 As the Japa­ nese were unable to estimate the depth of a submerged target, no specific technique was developed for attacking submarines that took refuge in deep submergence. The only deep setting depth charge pistol developed was the Type 3, Models 1 and 2, designed for operation at 131, 262, 393, 524 and 656 feet.2 The design of this pistol was similar to that used in both the Type 95 and Type 2 depth charges but the extra time required to reach the greater depth was provided by a delay train initiated by the firing pin. However, issue to ships had not become general by the end of the war and no specific doctrine for its use had been developed.

3-13. Although the need for proximity- fuzed depth charges seems to have been appreciated, none were developed in time for operational use during the war. The Japanese Type 4 depth charge, designed for magnetic actuation, had been developed but trials on it were still in progress when the war ended.2 An acoustic type depth charge was also scheduled for development but work on this did not proceed beyond the preliminary design stage and no prototypes were made.

3-14. At least two types of anti-submarine explosive weapons designed for underwater tow by small surface vessels are known to have been developed and used by the Japanese, particularly early in the war. The first of these was called the " Yokosuka depth charge" and was set to explode upon contact with a submerged object. The charge was cylindrical in shape, about 1 foot in diameter by 5 feet in length, and contained 55 pounds of Type 88 explosive filler. 3 The

1 While being depth charged on 4 July 1944, during her fifth patrol, SEAHORSE (SS304) reported that her DCDI indicated a few charges were definitely detonating below the ship even though her depth at that time was 470 feet. THREADFIN (SS410) reported that while being depth charged on 28 March 1945, during her second patrol, over half of the detonations occurred at depths greater than 450 feet as indicated by DCDI. 2 NavTechJap Target Report, Index No. 0-08 of 16 December 1945 (Japanese Depth Charges). 3 Handbook of Japanese Explosive Ordnance, OpNav 30- 3M of 15 August 1945.

- 12- CONFIDENTIAL CONFIDENTIAL second .veapon was designated by lhe Japanese as the Mark 2 Explosive Hook and, although devdoped primarily for minesweeping, was occasionally used for anti-submarine work. This device was a cast iron cylinder, 8 inches in diameter and ten inches long wilh four grapnel- like arms projE:cting from the main body, each 7- 1/2 inches lJng. The bO large- scale employment was made and there is no information to indicate that damage was ever inflicted. 2

3-15. Three sizes of aerial depth bombs were developed by the Japanese Navy specifically for anti- submarine work and were used for this purpose by both Army and Navy aircraft. 3 These were designated by Lhe Navy as Mark 2 bombs an.ct by the Army as Type 4 bombs. They were fitted with anti- ricochet nose rings and had considerably higher explosive-loading factors than ordinary general purpose bombs. The smallest of the three was a 60Kg. bomb, designated by the Navy as the Type 99, No. 6, Mk. 2, Mods. 0 and 1, and was loaded with 85 pounds of Type 98 explosive. These small bombs were carried primarily by plane..; on routine ar!ti-.:;ubmarine patrol and were considt:red to have a lethal range of 12 to 15 feet. The secon:i was a 180 Kg. bomb designated as the Experimental 19, No. 25, Mk. 2, loaded with 308 pounds of Type U8 e.

1 .HandbooK of Japanese Explosive Ordnance, OpNav 30-3M of lt> AugLlSt 1945. 2 On~ St..i:,tember 1943, during her first patrol, BILLFISH (SS286) sighted a .apa.n~se convoy escorted by a small converted merchantman and a ..;ampan, the latter dragging two cables over the stern. During the subse­ quent depth charge attack, a distinct scraping sound was heard down the port side of the hull while at a depth of about 300 feet. This probably wan an explosive sweep. In at least two instances, U.S. subm"l.rines were caught by grapnels but rr.anaged to escape without damage. (a) While submerged off the entrance to Kwajalein on 9 July 1942, during her fourth war patrol, THRESHER (SS200) was hooked in her after superstructure by an ur.known type of Japanese grapnel. It was reported that the pull of the grapnel line made the boat noticeably light aft. The grapnel was finally cl1;.;ared, after ten minutes, by running at high speed with full right rudder and by increasing depth to 350 feet. (b) On her sixth war patrol, CREVALLE (S.3291) was hooked inner periscop.;; ""h.:ar.s by a crude four-pronged grapne:. The grapnel line broke and the grapnel itself fell to the deck and was recovered upon surfacing. 3 Handbook of Japanese Explosive Ordnance, OpNav 30- 3M of lb August 1~45 and NavTechJap Target Report, Index No. 0- 23 of December 1945 (Japanese Bombs).

CO"IF1DENTIAL - 13- CONFIDENTIAL

Kg. bomb C.esignated as the Type 1, No. 25, Mk. 2, Model 1, Mods. 0 and 1, and was filled with 317 pounds of Type 98 explosive. This 250 Kg. bomb was considered to have a lethal range of about 33 feet and was generally only loaded on aircraft when a definite contact had been established by other planes or surface craft.

3-16. All three of the above Mark 2 depth bombs carried time rather than hydrostatic fuzes, and depth settings could only be varied by changing the fuze ga'nes prior to loading the bombs on aircraft. Four different fuze gaines with different time delays were used for anti-submarine work, each of which could be used with all standard Navy bomb fuzes, which in turn would ft any of the three Mark 2 bombs. The first gaine, the only variable setting design adopted by the Japanese, was designated as the Type 15 and could be set for delay between 0 and l. 5 seconds after striking detonation at any desired 1 the surface of the water, equivalent to between 0 and about bO foot depth. The desired setting had to be selected prior to insertion of the gaine in the bomb fuze. Although the Type 15 gaine was not developed specifically for anti- submarine bombs, it is known to have been used extensively for the purpose of attacking surfaced or submerging sub­ marines. Each of the other three fuze gaines had a pre- fixed time delay and all three were designated as the Type 1, : lark 2 design. The Model 5 was set for detonation after 3.5 seconds delay, about 80 foot depth; the Model lA after 6 seconds delay, about 150 foot depth; and the Model 1 B after 17 seconds delay, about 300 foot depth.1 The Japanese referred to bombs fitted with the Models 5 and lA gaines as " 25 meter" and "45 meter" bombs and these were the types generally carried, although the gaines were naturally varied to suit the expected conditions.

3-17. When anti-sub31.arine MarK 2 Navy bombs were not available, the Japanese substituted common types of 60 Kg. and 250 Kg. Navy GP bombs or Army 50 Kg., 100 Kg. and 250 Kg., Type 3 bombs. Army aircraft frequently carried a mixed load of their own Type 3 bombs along with Navy Mark 2 bombs, the Type 3 bombs being fuzw instantaneously, with short delays, or with a nose plug and a special 3.5 second delay tail fuze.

3-18. The Japanese directed considerable effort toward the development of gun projectiles for anti- submarine work which would continue an undisturbed trajectory after striking the water. After extensive tests in 1943, a flat-nosed projectile was adopted in which the area of the flat front was equal to half the area of the base. Pro­ jectiles of this non- ricochet type were produced for guns up to and including 8-inch.

3-19. Many U.S. submarines rep:Jrted hearing small " sono-bomb" or "light" explosions while submerged and in contact with Japanest... surface units. SALMON (SS182) likened the noise of such successiv8 explosions to a "string of fire-crackers". These " sono-bombs" are believed to have been the Japanese Mark 3 and Mark 4 " Emit Sound Mis:;iles" (HATSUONTO). This device consisted of a can 8 inches long and 5 inches in diameter, filled with Type 88 explosive. When dropped I ------The time delays given here a:re based on U.f. tests and do not agree witn th~ figure...; contai.I1Ad in Japanese documentc. The depths corresponding to these time delays have been computed for bombs dropped from an aircrafl traveling at 100 knots at an ele·Jation of 100 feel. - 14- CONFIDENTIAL CONFIDENTIAL ir.to water, a .:>mal1 qu!lntity of sodium under the top cap explode.:;, blow­ bg th ... cap off and operating a pull igniter. Then after a short delay, tr.: explosive charge detonates. These missile.s Aere employed by the Japane0e for the lr aining of their own submar ine crews, to simulate depth charges in an attempt to frighten Allied submar ines aw;iy, 1 and later were employed very successfully in sweeping U.S.- laid acoustic mine fields. Many of thes, " light" explosioru:; heard just prior to depth charge detonations may als.J have been cauzeci oy the sound of depth charge throwers or po!3sibly even gunfire in some cases.

3-2!J. Although min2s were used by the Japn.nese as an anti-submarine m_asurt.! and certainly constituted an appreciable hazard, .:>uch mining never becarr.e really exlt.nsive during any phase of the war, prob:ibly due lo lack of mine- laying vessels.2 Both contact and controlled mine fielJs were laid in Empire coa;:.;tal waters and harbors, the accesses to tht: Sea of Japan, the southern approaches to the Empire, Formosa and. tht! Philippines. The most commonly u.s~d contact mine Wd.S the Type 93, CJntaining 220 pounds of Type 88 or ':'ype 1 cxplosive.3 This was a m0.Jri;;a mine and was designed to arm only with tension on the mooring spindlf', a drifting Type .l3 mine therefore being disarmed except for those cases wlierc the arming mechanism was locked closed by corrosion. :rne most commonly u..;ed c:::>ntrolled mine was the Type 92, containing 1100 p0unJs of Type 8~ t:xpl0sive. 3 This was also a moored mine and could oe either acoustic:il1y or magnetically monitored fr0m shore or small vesc.els. The Japanese copied the design of two German magnetic ::i.nd ac Justic.: proxirr.ity-fuzed ground mines which were br.Jughl to Japan oy a German vessel in September 1942 and r>roduced their own ac.hptations by March ltl44, both designed for planting by subm.irine. There i.., evidence that sucn mines were laid off T ruk4 and in one ., ru. )ff the east coast of Au.stralia,2 but aside frorr. these two localions tr.ere is no indication that proximity-fuzed mines were used 1.ny .vh~re else. Tr,<.! develo1 rr ·nt late in the war of the QU\. sonar mine: detector made µ'.>:Sible the penetration of enerr,y min:=fields by our submarines and permitted spectacular operations in areas long considereci invlllner­ abls by the Japanese, such as the Sea of Japan.

3- ?.l. The greatest disparity between the weapons employed in the Jaoar.~0e anti-submarirn.: pr0gram and ours was their failure to at vs! >J... · n ;.t.e1.d - thrown contact weapon similar to our Mark 10 I-: >jt:ct )r " ~~edgehog " ). 3ome development work was dune on ::i.t.eaa- thr ; .. r. r)ckE.t.:;; fireu in sa1v0s of five from " rocket guns" but r• .. nut.., were nvl satisfactory and n.e project Has ao"-ndon~d . Tnis was U1• mly type of n.heau - thrown anti-submarine v1eapon under considera­ tion uy the ]apan~se . file; U.S. Mark 10 " Hedgehog" projectile is fuz.C::J la a" t )nate on contact and th~ charge .>ize (33 pounds Torpex) is ------1 JICIJOA c·.. ptun... d :::Jocumenl No. hrt4f:l rt.!cords their use in this maru1er uy ~ao~nt.~e roi:- rcr,R.nt ..;hip anj Ci1.C, ,1c - Cinr;POA captured Item No. ~ - 1.0%v!:B i.1..;o rec.; ;r-.ts ..;ucn ll2c i.>y ]apan2s. d.t;stroyt;r..; during the cnnlr-tl 'ictiun 0f tne Ball:e for Leyte Gulf, 24 -20 October 1~44 . ', !: w'" criJ:i_r, Tar..,.cl K. port, Index IJo. 0- 05 (Ja,)anese .tJaval Mining <;rg'tr1izalion ar;,1 01 r'tlional Tt:!chniques). 0 H wloo:::>K of Jap lndsc Explosive Ordnance, OpNav 30- 3M of 15 Au ru,·t :v•4:'> '1 r idu .~urvey vi Japam.se Defen..>es at Truk, Part I, Cir.CPa<.; - \~i11CPOA B..1lteti11 3 - 46 Jf ::=i w.·uch 194ci.

CONF :)EWIAL - 1 ~) - CONFIDENTIAL such th1.t rupture of Lhe pressure hull i:::; to be expected even when detonation occurs at Lhe superstructure. The tactical problem is 3implified, for usually contact is not lost prior to launching of a "Ifodgd101 " barrage and no interference with sound apparalU!: will oecur until a hit is obtained. Probability studies based upon the various factors entering into an atta~k on a submerged submarine and statisti­ cal analysis of action reports indicate that a submarine's chance of surviving a depth charge barravt. are at least four times as great as the probability of surviving a " Hedgehog" attack. l

3-22. The Japanese failed lo achieve optimum use of their principal anti-submarine weapon, the depth charge, simply by repeatedly setting tn2ir pist0ls too shalloN. There are many instances reportt.'Ci by our submarines, especi1lly during the fir.st two years of the war, in which depth charge patterns deton:i.ted directly overhead without causing a;)prt;;chble damage but where an increa.3e in depth setting would probably have resulted in fatal or serious damage. Above all, the Jar an ;e generally lacked persisl1.;nce in both their search efforts and exploitation of a positive contact, once made. They were prone to accept the slightest evidenc-3 that a submarine had been destroyed and then dE..part. Many a U.S. submarine owes its escape to the Japanese predispo:..;ilion to take the most optimistic view.

1 From Operations Evaluation Group Report No . 51. This applies only Lo depth charges having pistols wiU1 preset depth settings, such as those used by the Japanese, and not to proximity- fuzed depth charges. An attack made with the latter is theoretically only slightly less effective than a " Hedgehog" attack.

- 16- CONFIDENTIAL PERCH (SS176) CONFIDENTIAL SECTION IV

U.S.S. PERCH (SSl i6)

Loss in Action

Java Sea 3 March :942

Class ...... SSl 73

Builder ...... Electric Boat Co., Groton, Conn.

Commissioned ...... 19 November 1936

Length (Overall) ...... 300 ft. 6-3/4 in.

Beam (Exlreme) ...... 25 ft. 1-1/2 in.

Suomergence Depth (Designed Maximum) (Ax.s) ...... 250 ft.

D:splacements

Standard ...... 1330 tons

Emergency Diving Trim ...... 1725 tons

Submerged ...... 2005 tons

Draft (Mean, Emergency Diving Trim)...... 10 ft. 11 in.

Type of Pnpulsion ...... Diesel Electric Reduction Dr.ve

Main Engines (4) ...... Winton 16-201A

Main Motors (8) and Generators (4) ...... General Electric Co.

Ref Pre;lces:

(a) En:losurP (B) to ComSubsPacAdmrn secret ltr. FF12-10(A)/ A4-l(l)/Al0-2, Serial 0034\:J of 21 September 1945 (Command­ ing Officer PERCH Statement Concerning Loss of Vessel). (o) ComSubsPacAdmin Hr. FF12-10(A)/ Al6-2, Serial 3599 of 12 October .1.'d45 (Statements of Two PERCH Crew Members Concerning Loss of Vessel). (c) ComSuosr'ac keport Enlltl1 ·d "Enemy A.1ti-Submarine Mea­

sures" no date or file numb .r 0 ivE.n (Account of Loss of PERCH). (d) Account of Loss of PERCH as Relaled to Cdr. I. F. Duff,(MC), USNR, by Lt.Cdr. J.J. Vandergrift, Jr., USN, on 5 April 1946.

Photograph No. 4- _

CONFIDENTIAL - 11- PERCH (SSl 76) CONFIDENTIAL

4-1. On 2 March 1942, while operating in the Java Sea on her second war patrol, PERCH suslamed severe depth charge damage which pre­ vented further submerged operations and reduced her maximum sur­ face speed lo about 5 knots. Shortly after dawn on 3 March, PERCH was deliberately scuttled by her own crew to prevent imminent capture by Japanese surface forces. This report is based on the information contained in references (a) through (d). These references are accounts furnished from memory by various survivors of PERCH upon th.qir release from Japanese prisoner of war camps at the end of the war, almost four years after the action took place. It mtur:->lly follows that the source data are not as complete and cannot be considered to have the same degree of accuracy as formal war damage and action reports written shortly after an action.

4-2. After normal refit, PERCH departed Port Darwin, Australia, for her second war patrol on 3 February 1942. At this lime the Japanese campaign to secure the Netherlands East Indies was in full 3Wing. PERCH was directed to patrol and perform reconnaissance in various positions in the Java and Flores Seas as part of the force then attempting to defend Java.

4-3. On the night of 25 February 1942, while patrolling the southern approaches to Kendaris, Celebes, PERCH sighted a Japa­ ne...;e supply ;,hip and commenced approach for a surface attack. How­ ever the enemy ship opened fire and scored one three-inch shell hit on PERCH which struck the light fairwater plating just forward of the C")•rning towPr proper and detonated inside the "doghouse". The pr~ssure-prnof radio antenna trunk and 200-pound air line to the whistle were ruptured, several electrical caoles were cut by shrapnel, and the pressur""-proof magnetic compass trunk system wn.s f10 >ie

'i-4. 1he fol10.~1ng night, P£RCH was ordered wes~ward into the ]av::-~ Sr>R after a largi:> jaj)anese convoy of troopships had been sighted near Bawe::rn Island with apparent intentions of landing

0 forc .; on j,1va. On 21 February, the Battle ')f the Java Sea occurred, Pnding all org i.nizni Allied surface resistance in the East Indies area. 1 hE.: Jn.panes"" landPrl on Lh"" northern coast of Java on 28 February. That nighL PERCH received notification of the exact landing point of the <'f)nvoy and was ordered Lo disregard previously '3.S.3ign°d arE•as and to altack.

4-5. On thP nP.xt night, 1 March, PERCH was still proceeding west t ll.Vad the designato::d landing area. and had reacn<>d a position about LwE'lVE miJPs northwest 0f Soerabaja, when two Japanese destroyers v.;e.rl' sir;hled. PERCH was at this time running on the surface so she mad•-' o. quick dive lo avoid detPction. There was a full moon and vi::;1uiLty conditions were excellent. The destroyers passed well c iP9.r '1..>lt>rr: ~nd out of torpedo ryPrs then came in closP

- 18- CONFIDENTIAL PERCH (SS1'76) CONFIDENTIAL on a course favorable for stern torpedo shots and PERCH made ready for altack, taking frequent periscope observations. However, on the last periscope check before firing, it was noted that the target des­ troyer, which was distant about 800 to 1000 yards at this time, had obviously detected PERCH and was charging in at high speed for an attack.

4-6. The Commanding Officer, believing he was in 200 feet of water, immediately ordered depth increased to 180 feet. When PERCH had reached a depth of about 90 to 100 feet, however, the destroyer passed directly overhead and dropped several depth charges. This first pattern was not close and caused no appreciable damage. Shortly afterwards, PERCH struck bottom 3.t about 147 feet depth with her propellers still turning over and while in this position received a second pattern of four depth charges, this time very close. This group of charges was apparently dropped by the second destroyer. Considerable damage was sustained aft and all main motor field relays tripped, causing temporary loss of propulsion. While still on the bottom, a third and final depth charge pattern was received very close aboard amidships. The enemy destroyers then ceased further attacks, apparently convinced that PERCH had been destroyed, although they remained in the immediate area. l

4-'7. Extensive damage Nas caused by the second and third depth charge patterns. As mentioned previously, all main motor field relays tripped, causing temporary loss of propulsion until they were reset. The pressure hull was dished inward by as much as 2-1/2 inches in the after battery compartment on the starboard side forward and the port side aft. The conning tower plating was depressed to a depth of about 2 inches over an area about three feet by one foot. The engine room hatch, conning tower hatch and conning tower door gaskets were crimped and leaked steadily. The inboard hull flapper valves for the ship's supply ventilation system and the engine air induction system were jammed closed. MBT No. 5 master vent valve also jammed in the closed position. The battery exhaust system outboard valve apparently opened momentarily upon one or more close detonations and sea water flooded the exhaust duct section in the control room, some of it splash­ ing onto the fire control panel. The high pressure air bank in the after battery well commenced to leak heavily. Both main batteries showed full ground. No. 2 periscope could not be moved. No. 1 periscope could be raised and lowered but required the combined effort of four men to train il. Ninety per cent of the gauges and instruments in the engine room were broken or deranged and several depth gauges were also put out of commission. Considerable inboard leakage occurred through a cracked weld al the hull flange of the air conditioning cir­ culating water supply system. ------.. 1 A list of anti-submarine attacks, received from the Japanese at the end of the war, which were assessed as resulting in "positive" sinkings, mentions several attacks in this area on 1-2 March 1942 b11t no amplifying data was submitted and none can be definitely identified as having been made on PERCH.

CONFIDENTIAL -19- PERCH (SSl 76) CONFIDENTIAL

4-8. It is interesting to note that although this first series of attacks was sufficiently severe to cause considerable permanent hull deforma­ tion, the watertight integrity of the hull proper remained substantially intact and no serious damage was sustained at this time by either the submerged propulsion plant or vital auxiliary systems and equipment. It is probable that all of the depth charges were set for detonation at 98 feet since the next deeper setting available on Japanese charges was 19'7 feet and the depth of the water in which the attack occurred was reported to have been only about 150 feet, a fact certainly known to the enemy.

4-9. Shortly after receiving the third depth charge pattern, PERCH got underway again and by using evasive tactics managed to lose both destroyers in about two hours. At about 0300, 2 March, PERCH sur­ faced and an inspection topside was made. All the radio antennae insulators were found to have been broken. An armful of fragments from the depth charge cases was picked up on deck. Both periscope head windows were shattered and both periscope tubes had completely flooded. The bridge blinker light was found compressed flat.

4-10. No. 1 main Diesel engine ran away on starting and the camshaft of No. 4 main engine was found broken, leaving only two main engines in operating condition. No. 2 main engine was put on battery charge and No. 3 main engine was put on propulsion. PERCH once again proceeded in the direction of the Japanese landing on Java, still with intentions of attacking the enemy. Repairs to damage were started where possible and the high pressure air banks were replenished.

4-11. At about 0400, approximately two hours before sunrise, the same two Japanese destroyers were again sighted. PERCH imme­ diately submerged and lay on the bottom in about 200 feet of water with all machinery secured. This course was chosen rather than evasive running for the machinery had developed a high noise level as a result of the previous attack and it would have been necessary to use the very noisy trim pump almost constantly in order to main­ tain depth control.

4-12. Unfortunately, the enemy destroyershad either sighted PERCH before she submerged or had established definite sound contact, for several depth charge attacks were immediately delivered, resulting in serious damage. An attempt was then made to get under way and take evasive action but the propulsion plant was found to be inopera­ tive, due to short circuits in the electrical control gear or damage to the main motors, and PERCH was forced to remain on the bottom. Following this series of attacks, the enemy destroyers apparently decided to postpone further efforts until daylight but in the meantime made frequent checks on PERCH's position by echo-ranging.

4-13. Shortly after sunrise, three more attacks were delivered, the final pattern of three charges at about 0830 being the most severe of all. The enemy destroyers then left the area, probably again certain that they had destroyed their target.

- 20- CONFIDENTIAL PERCH (SSl 76) CONFIDENTIAL

4- 14. Reference (b) reports that "there was hardly any part of the boat that had not in some way been damaged." Only one of the four main Diesel engines was not damaged beyond immediate repair. However, the two auxiliary engines (Winton 6- 241) were still operable. The port reduction gear casing was cracked and lost lubricating oil constantly. As mentioned above, the submerged propulsion plant was put out of commission due to deranged control equipment and motor damage. Numerous holding down bolts on the main motors, main generators and main engines were reported to have broken.

4-15. The pressure hull overhead in the forward battery compart­ ment was dished inward to a depth of about 1-1/2 inches over an area of about 6 feet by 2-1/2 feet and many other new indentations occurred at various points along the length of the ship in addition to those received from the first series of attacks. 1n no place, however, was the pressure hull torn or ruptured.

4- 16. All lighting was cut off by a close detonation but was partially restored after a short while. Many auxiliary motors were short-circuited or deranged. There were at least nineteen cracked jar& in the forward battery and one in the after battery, causing loss of electrolyte and full grounds. All of the electric alarm and telephone circuits were out of commission.

4-17. One particularly close detonation forward caused the bow planes, then on 20 degrees rise angle, to partially rig in, damaging the bow plane rigging system. The holding down studs for the bow plane tilt- ing motor backed off or elongated and the shims dropped out. The planes were thereafter tilted by hand. The radio antenna trunk flooded. The JK sound head was put out of commission. Torpedoes loaded in forward tubes Nos. 1 and 2 and one torpedo loaded in an after tube were reported to have made " hot" runs. Many torpedo tube doors were jammed. All water closet bowls (porcelain) were shattered. The engine room deck support stanchions were torn away at their overhead connection to the pressure hull.

4- 18. Both Nos. 1 and 4 high pressure air banks bled completely down through numerous leaks and various other air system leaks developed throughout the boat. The increase in pressure of the atmos­ phere within the boat from these air leaks was consider able although it could not be measured since the barometer was broken. The excessive air pressure, extreme heat, and high humidity caused much discomfort and had a deleterious effect on all hands.

4-19. Sea water leakage into the pressure hull also incr eased markedly. Strips a quarter of an inch square in cross section had been cut from the conning tower and forward escape trunk door gaskets. Leakage around these doors and the conning tower and engine room access hatches became serious. The air conditioning circulating water supply hull flange crack, caused by the first series of attacks, became enlarged and the flange studs elongated or the nuts backed off, further augmenting the leaka~~ 'lt Ll1is point. Many

CONFIDENTIAL - 21 - PERCH (SSl 76) CONflDENTIAL other salt water systems throughout the ship also developed leaks. Fuel tanks are reported to have leaked externally.

4-20. PERCH remained on the bottom until after sunset on the evening of 2 March. Order was restored and repairs to equipment were attempted where possible during this period. Damage to one of the main motors was isolated and battery propulsion was regained on both shafts. Bilges were kept pumped down to avoid grounding electrical machinery. The forward and after trim tanks and No. 2 auxiliary tank were pumped dry.

4-21. At about 2000 on 2 March, after approximately sixteen hours submerged, the first attempt was made to surface. The boat did not move, however, for the downward thrust of the depth charge attacks had partially embedded the hull in the soft ocean floor and many master vent valves leaked or could not be seated, rendering it impos­ sible to blow the ballast tanks since air introduced into the tanks escaped through the risers. As an indication that the boat had been forced deep into the soft bottom, it was noted during the final severe depth charge pattern that PERCH's remaining depth gauge suddenly changed reading from 200 feet to 228 feet and then to 230 feet, although this might have been due to derangement of the gauge itself.

4-22. By closing the emergency vent valves and going alternately ahead and astern at maximum revolutions on both shafts, PERCH finally broke loose from the bottom on her third attempt. These efforts consumed a period of about one hour and all high pressure air was expended except for one partially filled bank. The enemy was not in sight upon surfacing.

4-23. After successively attempting to start all four main engines, only No. 3 engine was found operable and PERCH got under way at a speed of about 5 knots. About half of the holding down bolts for the No. 3 engine had broken and the engine vibrated so badly that the head covers raised one inch. The batteries were put on charge with the undamaged auxiliary Diesel generators. The steering gear was behaving erratically at this time, for the rudder could be moved from the full left position only with difficulty and upon reaching amid­ ships would suddenly snap over hard against the starboard stops. MBT No. 2 was leaking heavily from sea. Even on the surface, sea water leakage into the hull was sufficient to keep both the trim and drain pumps operating at full capacity. All gyro-repeaters had been deranged and steering was accomplished by r elaying word to the bridge from a man stationed at the master gyrocompass in the control room. Many depth charge case fragments were again found on the deck topside.

4-24. After quickly surveying the condition of the boat, the Com­ manding Officer at this time set up procedure for scuttling the ship if it became necessary. Repairs were attempted where feasible. Men working in the engine room were unable to tolerate the extreme heat and had to be relieved frequently so they could go topside to recover.

-22- CONFIDENTIAL PERCH (SSl 76) CONFIDEN.1 IAL

4- 25 . PERCH continued to run on the surface throughout the night. In order to determine whether or not the boat could submerge, it was decided to try a running dive while still dark. This was attempted about an hour and a half before sunrise on 3 March. However, in spite of hav­ ing deliberately tried to make the ship light so that trim could be established by flooding in on the dive, PERCH was found very heavy aft. The boat assumed a large up angle and water entered in large volume around the conning tower and engine room hatches which failed to seat properly. When a depth of 75 feet had been r eached and the two hatches still showed no sign of seating themselves by hydrostatic pressure, the boat was surfaced. Reference (a) reports that at this time there was still only one full air bank. By the time PERCH reached the surface, the water level in the engine room bilges was almost to the main generators.

4- 26. It was found that the conning tower hatch lacked complete seating by a gap of about 3/8 inch. The hatch dogs were removed and adjusted but with no improvement. This work was handicapped by the necessity of having to keep the ship darkened to avoid detection. Once again the dogs were removed, but while attempting further adjustments, three Japanese destroyers came upon the scene and opened fire on PERCH. Five or six shells landed in the water nearby.

4-27 . PERCH attempted to engage the enemy with her thr ee- inch deca: gun but it could neither be trained nor elevated and the sights were shattered. Torpedoes could not be fired. In this helpless condi­ tion, with no fire power, obviously unable to submerge and capable of making only 5 lrnots on the surface, the Commanding Officer decided to abandon and scuttle the boat at once. All hands were ordered topside. The diving alarm was sounded and the vents were opened by one officer who had remained below for this purpose. The men on deck literally felt the ship, which was still going ahead at one-third speed on her batteries, go out from under them. All the men leaving the ship were equipped with life jackets and some in addition carried escape " lungs" and flashlights. The officer who manned the vents had to fight his way out through the open conning tower hatch against the incominE water. PERCH went down about 100 yar ds from the survivors shortly before dawn on 3 March 1942, with her colors flying.

4- 28. As far as is known, the entire crew was taken aboard by the Japanese destroyers during the morning. Most of the survivors were imprisoned until the end of the war at Makassar, Cele bes, although a few were later transferred to various camps in Japan. Fifty-three officers and men are known to have survived to the end of the war.

4- 29. In analyzing the many factors involved in the loss of PERCH, it appears that the conning tower and engine room hatch damage was the only reason the boat was unable to submerge upon sighting the enemy destroyers on the morning of 3 March. This case is an excellent illustration of the unhappy fact that but one casualty to a vital part of a submarine can cause its loss.

CONFIDENTIAL - 23 - PERCH (SS176) CONFIDENTIAL

4-30. However, even had PERCH been able to submerge, it is problemat­ ical whether she could have escaped eventually. For example, the extent of external leakage from the oil tanks is not known. This alone might have been sufficient to disclose her exact locatio:-i to the enemy and in such shallow waters it is likely that she would not again have survived a series of well executed depth charge attacks. Even had the destr oyers not discovered PERCH on the morning of 3 March, in the event that repairs could not be made to the damaged hatches it is doubtful that she could have made a surface escape with only one engine, for the Java Sea was at this time completely controlled by the Japanese.

- 24 - CONFIDENTIAL CONFIDENTIAL

I I l ci ~ CP .--i .....c c Q) ~ ....,ro ....,0 ..c0 P...... t:- '°.--i CJ'.) •· s P:: 0 ~ u::i P. .. .--i I ~ ....,0 ..c0 P.

CONFIDENTIAL - 25-

KINGFISH (SS234) CONFIDENTIAL

SECTION V

U.S.S. KINGFISH (SS234)

Depth Charge Damage

Off Formosa 23 March 1943

Class ...... SS212

Builder ...... U.S. Navy Yard, Portsmouth, N. H.

Commissioned ...... 20 May 1942

Length (Overall) ...... 311 ft. 8 in.

Beam (Extreme) ...... 27 ft. 3 in.

Submergence Depth (Designed Maximum)(Axis) ...... 300 ft.

Displacements

Standard ...... 1525 tons

Emergency Diving Trim ...... 2050 tons

Submerged ...... 2415 tons

Draft (Mean, Emergency Diving Trim) ...... 16 ft. 10 in.

Type of Propulsion ...... Diesel Electric Reduction Drive

Main Engines (4) ...... Fairbanks-Morse 38-D-8-1/8

Main Motors (4) and Generators (4) ...... Elliott Co.

References:

(a) C.O. KINGFISH conf. ltr. SS234/A12-l/ A-16-3/ A9 of 8 April 1943 (Report of War Patrol Number Three). (b) Comdt. Navy Yard Mare Island conf. ltr. SS234/Lll-1 (33- 558674) of 17 May 1943 with enclosures thereto (Sup­ plementary Report on KINGFISH War Damage). (c) BuOrd (Re6) Memorandum dated 4 May 1943 (Report on Inspection of KINGFISH Damage and Interview of Ship' s Officers by Dr. A. B. Focke).

Photographs Nos. 5-1 through 5-16 (furnished by Navy Yard, Mare Island).

PLATE V

CONFIDENTIAL - 26-

KINGFISH (SS234) CONFIDENTIAL

5-1. On 23 March 1943, while on her third war patrol, KINGFISH underwent a severe depth charge attack north of Formosa. A total of over forty depth charges were dropped in the vicinity of KINGFISH during the 7 - 1/2 hour period she was under attack. Serious damage was caused by the final pattern of six charges, two of which detonated clos~ over the after portion of the ship while the boat was running at 300 foot depth, forcing her to the bottom in 350 feet of water. In spite of sustaining considerable permanent pressure hull deformation in various areas and widespread interior damage, no vital systems or machinery were put out of commission and watertight integrity remained substantially intact. Six hours after the termination of the attack, and without undue difficulty, KINGFISH was able to surface and clear the area at full power on all main engines. This report is based on the L'1formation contained in the references and on an informal interview with the then Commanding Officer. The Photographs were furnished by the U.S. Navy Yard, Mare Island. The PLATE was pre­ pared by the Bureau from data contained in the enclosures to reference (b).

5-2. KINGFISH arrived at Pearl Harbor from her Se(:ond war patrol on 23 January 1943. Norr"lal refit was nndertaken by repair forces of the Submarine Base, Pearl Harbor, and completed on 7 February. Deperming, sound tests and training were completed on 15 February and, on 16 February, KINGFISH departed Pearl Harbor for Midway, arriving on 20 February. Minor voyage repairs "·ere made ther e and fuel and lubricating oil weretopped off. She departed Midway on 21 February for her third war patrol and arrived on station in the welters adjacent to the Island of Formosa on 7 March, destroying a 250-ton enemy trawler by three-inch gunfire attack on 4 March while en route. On 17 March Kili!GFISH sank a medium- sized freighter by two torpedo hits during a night submerged periscope attack and on 19 March sanK a medium- sized troop transport by two torpedo hits during a daylight submerged periscope attack. Three other attacks were made but no hits were obtained, apparently due to faulty torpedo performance.

5- 3. At 0300 on 23 March, while surfaced about 60 miles north of Formosa, lat. 26° 20' N., long. 121° 55' E., KINGFISH sighted at a range of approximately 5000 yards what appeared to be either a small Japanese destroyer or minelayer of about 1200 tons. Battle stations were manned at once and an attempt was made to gain a position ahead of the enemy ship for a dawn attack. However, at 0325, the target ship detected KINGFISH and headed toward her at a speed of about 16 knots. KlNGFISH was able to dr aw away slowly at flank speed but twenty minutes later, at 0345, the enemy illuminated her with a searchlight. At this point, KINGFISH submerged to a depth of 250 feet, rigged ship for depth charge attack and silent running, and commenced evasive action.

5-4. These maneuvers were unsuccessful, however, for at 0448 KINGFISH received the first of a long series of depth charge attacks.1 1 A list of anti- submarine attacks received from the Japanese at the encl of the war, and assessed as resulting in " positive" sinkings, contains no mention of this series of attacks on KINGFISH.

CONFIDENTIAL - 27- KINGFISH (SS234) CONF DENTIAL

Evasive tactics were continued at a depth of 300 feet but the enemy was both tenacious and experienced, and seemed to have no difficulty main­ taining contact. He appeared to use sonic listening for determination of azimuth and echo-ranging for distance. Sound conditions were excel­ lent. Three attempts were made by KINGFISH to approach the surface and fire circular run torpedo shots, but each time the enemy counter­ attacked before a depth of 100 feet was reached and this plan had to be abandoned. At 0752 the screws of a second ship were heard. This vessel took no direct action, apparently having no depth charges, and used no sound gear other than a fathometer. A total of 41 depth charges in eight separate patterns were dropped during the entire 7-1/2 hour period KINGFISH was under attack. Attacks were spaced at about one hour intervals and consisted of from 3 to 8 charges each.

5-5. No serious damage was sustained until the final attack at 1227, at which time a pattern of six depth charges was received very close aboard while the ship was running at 300 foot depth. The charges were dropped in pairs, the first two detonating over the after portion of the ship, dishing in the pressure hull and forcing KINGFISH to the bottom in about 350 feet of water. The second pair of charges detonated forward of and above the ship, causing but little damage. The third pair of charges was delayed nearly a minute and detonated forward, also caus­ ing only minor damage. Following this attack the enemy vessels stayed in the vicinity for several more hours, occasionally making transits across KINGFISH, but did not drop any additional charges.

5-6. The two close detonations aft, at 1227, caused severe vertical flexural vibrations of the hull as a whole. Reference (a) reports that the ship "humped like a measuring worm" and was forced con­ siderably off her course. Reference (c) notes that there were " three strong up and down vibrations, followed by gradually decreasing ones" . This type of vibration had not been observed during any previous depth charge attacks experienced by KINGFISH. The motions were of such magnitude as to throw two men from their bunks to the deck and other personnel lost their footing even though braced in anticipation of shock. Some 12 of the 41 charges dropped on KINGFISH were close enough to cause at least minor damage. The more distant of these 12 charges broke lights, stopped clocks, jarred cork insulation from the hull and, in general, caused lightly attached hull fittings to come loose. Closer-in charges caused numerous hull valves throughout the boat to open. Two observers claimed to have seen flame shoot past the breech door of one of the after torpedo tubes coincident with the detonations of the two very close depth charges aft. Smoke and fumes were also detected in the after torpedo room.1

5-7. All of the depth charges dropped by the enemy were probably of the Type 2, Mod. 1 design containing 357 pounds of Type 98 explosive. The two close detonations aft at 1227, which were responsible for most of the damage, are believed to have been centered as follows: One charge at the after end of the ship about ten feet above the deck level, causing the phenomena observed at the torpedo tube and forcing the

1 For further discussion, see paragraphs 15-18, 15- 19 and 15- 20 .

- 28- CONFIDE:.NTIAL KJNG FISH (SS234) CONFIDENTIAL stern down with resultant plating failure under compression at the lower outer hull between frames 103 and 108; the second charge approximately 40 feet directly above the hull at about frame 83, causing the pressure hull structural deformation which occurred in way of the forward engine room.

5- 8. Upon being forced to the bottom, the ship was silenced completely and, while awaiting darkness, the crew made temporary repairs to damage where feasible. Plans were prepared for scuttling ship in case escape proved impossible after surfacing. In partial execution of these plans, the ECM was destroyed and the torpedo data computer was rendered inoperative by disabling the forward angle solver. Only two after effects of the attack caused serious concern at this time. The first was the profuse leakage of sea water which occurred in both engine rooms through the distorted engine induction hull valves, the external induction system having completely flooded. This leakage was almost completely stopped within 15 minutes by forcing the valves hard against their seats with the aid of chain falls. The second was the high pressure air leakage into the boat through a damaged fitting in the No. 3 air bank piping and at partially opened cone joint connec­ tions at the high pressure air manifolds in the control room. The air pressure within the boat increased markedly as a result of this leakage. Since all manometers and barometers were disabled, the amount of increase in air pressure could not be determined but cal­ culations indicate that it was of the order of eight or more pounds per square inch.

5- 9. At 1500 and again at 1800 the screws of an enemy vessel were heard plainly through the hull for periods of about 15 minutes although no more depth charges were dropped. At 1848, after dark, KJNGFISH manned battle stations and surfaced. A patrol vessel of about 1000 tons was sighted lying- to approximately 2000 yards off the starboard bow. No difficulty was experienced in immediately getting underway and the area was cleared at flank speed using all four main engines. Fortunately no oppos,tion was encountered from the enemy patrol craft.

5- 10. Since the damage made further offensive action impossible, KINGFISH returned to base for repairs, arriving at Pearl Harbor on 9 April 1943. The return run was made submerged during daylight hours for the first two days. The only difficulty encountered in these submerged operations was the minor leakage into the engine air induction system and the complete flooding of the ship's supply ventilation system outboard piping which occurred on each dive.

5- 11. Damage to the ship was of varied nature and of general extent throughout (PLATE V and Photos 5- 1 through 5- 16), but was most severe in the vicinity of the forward and after engine rooms, conning tower, and after torpedo room. Structural damage in these areas consisted of minor distortion to the circularity of the pressure hull and nume- rous depressions of the hull plating between frames. Damage in way of the engine rooms extended from frames 77 to 93 , with the more

CONFIDENTIAL - 29- KlNGFISH (SS234) CONF DENTIAL severe depressions occurring in the upper pressure hull plating between tank tops from frames 80 to 87. Depressions ofl-1/4 inchmaximumdepth occurred at frame 86 on the forward engine room riveted access patch and between frames 82 and 83 (Photos 5- 1 and 5- 3). The keystone frame connections at frames 85 and 86, in way of the hard patch, pulled slightly apart due to depression of the hull in this vicinity (Photo 5- 2). Although the riveted butt and seam connections appeared to be the weakest points of this hard patch, it is significant to note that only minor leakage developed around the rivets in spite of the considerable distortion and impact to which this region of the hull was subjected. Small leaks also developed around the forward and after battery compartment bolted access patches, although these were remote from areas of hull damage. Except for the minor distortion which occurred to frame 83 (Photo 5- 3), all frames appeared to retain their proper shape. 5-12. Local depressions of the outer shell plating up to a maximum depth of ab:)ut 1 inch occurred between frames, port and starboard, in way of three after lubricating oil tanks as follows: motor and reduction gear lubricating oil sump tanks Nos. 1 and 2, "A" strake (30-pound MS) between frames 103- 105; motor and reduction gear lubricating oil stowage tank, "A" strake (30- pound MS) between frames 105- 107; engine lubricating oil stow­ age tank No.5, " B" slrake (20- pound MS) between frames 107- 108 (PLATE \,S Photo 5- 4). These areas are subject to full sea pressure and were structur­ ally somewhat weaker than corresponding outer hull structure in way of the auxiliary and safety tanks. The depressed areas of the "A" strake between frames 104-106 occurred in 30- pound. plating backed by frames spaced on 30-inch centers instead of 24 - inch centers as in the auxiliar y and safety tanks and the " B" strake depressions between frames 107-108 occurred in way of 20-pound plating on 24-inch frame s~acing instead of 30- pound plating as in the safety and auxiliary tanks. The deformations in these areas could have been caused by either direct explosive loading from a close detonation or, possibly, as a result of the strong flexural vibrations reported by the ship, the depressed area occurring at the quarter length or natural node of vibration of the ship's structure as a whole.

5- 13. Farther aft, minor depressions occurred in the shell plating just above the stern tubes, port and starboard, and the top of the after trim tank was indented to a depth of approximately 1 inch in two small areas, port and starboard, between frames 127 and 128. The trim tank depres­ s ions were located at the pomts where the port and starboard propeller guard struts had been orig'nally attached. These guards had previously been permanently removed on KING FISH when it was found that the plating in way of the strut attachments had cracked, due to vibrat~on . The cracks were welded up and covered with small doubler plates, causing local hard spots in the structural continuity, and this probably accounted for the local deformation at those points. The trim tank did not leak, however.

1 While not critical, as a result of KINGFISH's experience it was con­ sidered 1;hat the outer hull plating in these areas should be reinforced. ShipAlt SS192 of 19 May 1943 therefore authorized the installation of 20- pound MS doublers in way of these lubricating oil tanks on SS198- 284. SS285 and subsequent submarines were designed with heavier plating in these areas.

- 30- CONFIDENTIAL KING FISH (SS234) CONFIDENTIAL

5- 14. Investigation of the ship's structure in the after torpedo room disclosed minor variation from the designed offsets and the top of MBT No. 7 was dished upward between frames 110 and 118 to a maximum of Hi/32 inch. No evidence of buckling of the tank top stiffener s could be found, however. The movement of the tank top forced the torpedo stowage and loading tracks out of alignment with the torpedo tubes to such an extent that they later had to be cut adrift and reset. The MBT No. 1 tank top plating in the forward torpedo room was also pushed upward, but to a lesser extent. However, realignment of the forward torpedo tracks was also found necessary in order to secure satisfactor y tor pedo handling and loading.

5-1~ . Both the end bulkheads and shell plating of the conning tower cyEndrical structure sustained permanent deformation. The conning tower bulkheads installed on KINGFISH at this time were of the type having a 15- pound medium steel inwardly dished plate acting as the bulk­ head proper with a heavy forged ring connecting the periphery of the dished plate to the cylindrical wrapper plate (Photo 5- 5) . It was reported by the ship's officers that the forward bulkhead was initially forced in to such an extent that the steering wheel moved approximately two inches aft relative to the lockers on the port side, and that the locker drawers could not be opened due to interference with the wheel. Dur.ng the tr.p back to base, however, the ship reported that the amount of bulkhead deformation gradually reduced until, upon arrival, it was only about one- third the original amount. Offsets taken at the Navy Yard, Mare Island, one month after the damage occurred indicated a variation from the designed offsets of only 1/2 inch at the forward bulkhead and 3/4 inch at the after bulkhead. These figures mean little, however, since the dished plates are frequently shaped with at least that much deviation from the designed radius of curvature.I No means were available for determining the actual bulkhead offsets as originally fabri­ cated and installed at the building yard. It is certain, however, from the known change which occurred in the relative positions of the steering wheel and lockers, that the forward bulkhead was deformed considerably.

5- 16. It is interesting to note that the 20- inch by 38- inch six- dog watertight escape door fitted in the after bulkhead of the conning tower remained substantially intact and that no leakage occurred in spite of the probable large bulkhead deflection. The door frame was sufficiently distorted, however, so that the door dogs bound against the seat and prevented the door from opening more than a few inches (Photo 5- 5) . It was fortunate that the door seat was wide and flat, for had it been narrow or rounded, as was the case with earlier designs, the door gasket very probably would have been cut or blown out when the bulk.head deformed and serious leakage into the conning tower would have resulted.2

1 Allowable tolerance from designed radius of curvature for such bulkheads was plus one inch and minus nothing--BuShips dispatch 122222 of June 1943. 2 As a result of this casualty, similar war damage experiences of other sub­ marines, and tests conducted at the Navy Yard, Portsmouth, conning tower doors were removed on all submarines per BuShips ltr. SS/S16- 2(515) of 30 April 1943. This was accompltshed on ships in service by completely renewing the after bulkhead of the conning tower. Such doors were omitted from the designs for SS285 and subsequent submarines.

CONFIDENTIAL - 31 - KINGFIBH (SS234) CONFIDENTIAL

5- 17. The conning tower plating was slightly deformed at the top after portion of the cylinder. The maximum depression occurring in this region was only 3/8 inch, located between the after bulkhead forged ring and the hoop stiffener just forward. Cork insulation under the depressed areas was cracked and loosened. A check of the gener al circularity of the conning tower cylinder showed that it conformed to the designed allowable diametrical tolerance of one-half the plate thickness.

5-18. Damage to structure and fittings external to the pressure hull was negligible. Two eyeports in the pilothouse were shattered and the light access door leading from the pilothouse to the forward gun plat­ form was sprung so that it was difficult to close. The after torpedo room deck loading skid was jarred loose and lost overboard. No other damage worthy of mention was sustained by the superstructure, conning tower fairwater or bridge.

5-19. Dams.ge to external hatch covers occurred in only two places. The forward escape trunk upper hatch cover was warped do-..vnward sufficiently to partially unseat itself and the trunk completely flooded. The hatch dogging mechanism was also bent, apparently when the cover was forced up under the action of one or more depth charges. Although the trunk flooded, the lower hatch held tight and no water entered the ship. No damage was sustained by the after watertight door of this escape trunk. The upper conning tower hatch cover seat was found to be distorted slightly but no leakage occurred. An interesting minor effect of depth charge impact was that the pins securing the upper handwheels to the squared ends of the wor m shafts sheared off on both the forward and after escape trunk hatches. Aside from the conning tower bulkhead door ::ame, previously men­ tioned, no other damage occurred to external hatches, seats, gaskets or operating gear. However, the transverse struts fitted at the forward and after torpedo loading hatch bosses showed evidence of excessive compression, for their threads were jammed together to such a degree that subsequent removal was difficult. Three covers on topside pressure-pro::>£ ammunition sto·.vages were distorted sufficiently to permit the stowages to flood. These were the two 3- inch/ 50 cal. ready servi;;e ammunition stowages located in the forward end of the conning tower fairwater and one 20mm ready service stowage located on the bridge (Photo 5- 6).

5-20. There was considerable leakage of water into several interior compartments, but due to prompt damage control measures, at no time throughout the attack did flooding endanger the safety of the ship. Leak­ age occurred as follows:

(a) Into the forward torpedo room to a depth of 2 inches over the top of MBT No. 1 through a sound projector electrical cable hole.

(b) Into the pump room to a depth of 4 inches through the SJ radar mast stuffing box, the conning tower voice tube and an electric cable to the bridge, all of the water draining down from the conning tower bilge.

- 32- CONFIDENTIAL KINGFISH (88234) CONFIDENTIAL

(c) Into both engine rooms to the level of the lower floor plates through the main engine air induction hull valves.

(d) Into the motor room through the starboard stern tube stuffing gland to a level 2 inches below the lower flat. This stuffing gland had been leaking heavily due to slight bending of the propeller shaft. on a previous patrol. A close depth charge detonation aft, however, fortu­ nately caused the packing to seal tight so that no further leakage was experienced while the boat was on the bottom. Simultaneously with this close detonation, two observers claim to have seen " a ball of fire" enter through the starboard stern tube.1

(e) Into the maneuvering room through the crew's water closet when the after sanitary tank No. 3 flooded due to its sea valve opening slightly under depth charge impact.

The maneuvering room leak, item (e), would not have occurred if the head flapper valve had not been open to receive water bailed from the engine rooms. Leakage in the forward torpedo room was caused when a parted cable to the port sound head was forced up through its stuffing tube into the ship by external water pressure. This leakage was stopped by driving a wooden plug into the cable hole and securing it with clamps (Photo 5- 7). The water was removed by bucket brigade to the officers' shower and by the drain pump. A further troublesome source of leakage was caused by discharge of fuel oil into the engine room upon each close depth charge detonation. Pressure built up in the collecting tank through the compensating system stand pipe and opened the inboard relief valve, thus allowing oil to enter.

5-21. The most serious leakage was that which oc,_:u.rr.:d in both engine rooms when the outboard engine air inductiC'n piping flooded and water leaked by the inboard valve seats which had been slightly distorted due to pressure hull deformation. The forward engine room induction hull valve seat was forced out of round by 1/ 4 inch athwartships and the after engine room induction hull valve seat was forced out of round 1/4 inch fore and aft (Photo 5- 15). The exact manner in which the topside induction piping became flooded is not known since a test of this system at the Navy Yard, Mare Island, disclosed no leaks and the outboard mushroom valve closed satisfactorily even though its stem was slightly bent (Photo 5- 16). It is believed that the induction s.ystem probably flooded in either one or both of the following two ways: (a) fluttering of the outboard mushroom- type valve during successive close detonations, (b) temporary distortion of the main induction valve trunk while the valve was forced up during one of the detonations with subsequent eccentric seating of the valve when it came down again. This latter hypothesis might also account for the bent valve stem of the outboard induction valve. Personnel in the conning tower reported hearing air venting from the system. Leakage into the engine rooms was controlled after 15 minutes by taking up hard on the inboard valves with chain falls (Photo 5-8). Water in the forward engine room was discharged through a hose connection to the trim line while that in

1 For further discussion see paragraph 15-18.

CONFiJENTIAL -33- KINGFISH (SS234) C,ONF ENT AL

the after engine room was cleared by forming a bucket brigade to the maneuvering room head in addition to using the trim and drain pumps. On later dives during the trip back to base, the induction system leaked a smc.11 amount, indicating that the induction outboard valve was not at this time seating properly. The ship's supply ventilation system piping also flooded on each dive and again no reason was evident. The hull valve for this system remained tight, however, and no inboard leakage occurred.

5-22. It was probably very fortunate for KINGFISH that the bottom was close and at only 350 foot depth, for had she been in deep water and therefore r quired to continue operating, the increase in weight of approximately 9 tons of water taken into the engine induction and ship's supply ventilation piping topside would almost certainly have caused I er to lose -Je:·th control, as int.he case of SCAMP (SS2'"'") and SALMON (SS182). With enemy surface vessels overhead, an inad­ vertent rise to shallow depth or a possible broach might very well have proved fatal.

5- 23. Damage to the main propulsion plant was very minor. There was some slight misalignment of the main reduction gears, resulting in an opening of .035 inches at the top of the starboard gear coupling and .030 inches at the top of the port gear coupling. Both the main motors and main reduction gears were rechocked during the subsequent over­ haul. It was also discovered during the overhaul that the forward end-bells on all four m::tin motors had been dished out such that offset oil-seal rings had to be manufactured for the forward bearings, the offset varying from 1/8 to 3/16 inches. The starboard shaft was bent approximately .180 inches but was straightened during the same overhaul without difficulty. Practically all holding down bolts and studs on the main and auxiliary machinery were stretched, although the nuts were still tight, indicating that this stretching probably was caused by excessive tightening during the original installation. There was no shearing of holding down bolts, studs or dowels. The circulatin~ water pump attached to N::>. 1 service air compressor came 100se due to the securing bolts backing off, but no further damage resulted. Excessive pressure on the valve disc of No. 1 outboard exhaust valve distorted both the disc itself and the seat (Photo 5- 9). The disc was renewed and the seat had to be remachined. Lubricating oil piping in the maneuvering room developed serious leakage when flanges partially opened.

5-24. Damage to electrical equipme:it and systems was also quite minor. Direct damage was sustained by phenolic fixtures, terminal strips, contact makers, connection boxes and numerous light bulbs. Although the main control cubicle was not shock mounted, it withstood the attack with only a few small items of damage. A close depth charge detonation jarred one set of contactors open momentarily, causing considerable arcing and tip pitting, and one arcing shield fell off. This arcing might possibly explain the " ball of fire" which two observers claimed to have seen at the starboar d stern tube, paragraph 5- 20(d) above.

- 34- CONFIDENTIAL KINGFISH (SS234) CONFIDENTIAL

5- 25. At the time of the attack, the ship's service lighting system had been secured and the emergency system was in use. The majority of the ship's service lighting system fixtures were shock mounted by means of felt washers, but the mounting bolts were screwed down fairly tight, neutralizing the shock absorbing effect to a great extent. Bulbs screwed directly into such fixtures in general were broken throughout the ship, while those screwed into short flexible pendant cords withstood shock satisfactorily. The emergency lighting fixtures were similarly shock mounted on felt but the majority of the washers were free to absorb most of the shock and as a result, only a few of the lamps in this system were broken. A number of watertight globes in various com­ partments throughout the ship fractured. Overhead in the engine room, where shock was very severe, several phenolic light sockets were badly shattered (Photo 5- 10). Several indicator lights burned out on the TP- TR panel as a result of the shock, although the panel, mounted on rubber pads, was otherwise undamaged.

5- 26. Several micro- switches in hull opening indicators fractured (Photo 5- 11), causing the TP- TR panel to record many incorrect readings. The plastic cases of these micro-switches were also broken, either by impact or due to the lever arms over-traveling. Over- travel of the contact makers was caused by slippage of the arms on their shafts since, due to an oversight, several of the arms were not pinned through to the shafts but were secured by means of nuts only. More recent type micro- switches are of the cam type, precluding this type of failure. Terminal strips in 16 contact maker aluminum connection boxes were fractured, two across the center of the strip and the rest at the ends in the vicinity of the mount screws. Failure of the strips allowed tne terminals to contact the metal covers, causing short- cir­ cuits (Photo 5-12). The boxes themselves were undamaged, although they were secured directly to the hull. A metal plug in a broken receptable above the mctin control cubicle dropped into the bus structure but fortunately did not cause a short circuit. l There were approximately ten similar cases of receptacles breaking throughout the ship (Photo 5- 11). Recent designs for such receptacles specify molded phenolic construction with a fabric filler and have a greater impact resistance than those installed on KINGFISH. The covers of two pressure-proof connection boxes for the external bridge reproducers were dished in and as a result, water entered the boxes, passed through the connecting cable2 and entered the lMC amplifier assembly, disabling that system.

5- 27. In general, all gauges throughout the ship withstood impact without receiving serious damage but required complete recalibration. Tne mounting clips broke on practically all gauges which were mounted directly to bulkheads or hull structure, leaving such gauges without any other means of support than the gauge piping, while gauges that were mounted on gauge boards, particularly electric meters, withstood the shock with very little damage. Depth gauges appeared to be among the most susceptible of all the instruments. Depth charging caused

1 See paragraph 9-29, SCAMP (SS277) . 2 See paragraph 19-12for discussion of cable end sealing.

CONFIDENTIAL - 35- KlNGFISH (SS234) CONFIDENTIAL permanent inaccuracies of as much as 40 or 50 feet in the readings of the contr ol r oom depth gauges, although they were apparently undamaged internally. The conning tower depth gauge was deranged by shock and registered a fixed reading of 28 feet. The 450-foot control room depth gauge jumped by as much as 150 feet during depth charging, the needle coming hard up against the peg. Several liquidometer gauges in the engine room and the after trim tank liquidometer were deranged due to the indicator needles jamming against the stops. Although the tor­ pedo data computer was shock mounted on rubber, a pin in one of the shafts dropped out, rendering the after angle-solver inoperative. Both periscopes were housed during the attack. The lower prism on No. 1 periscope shattered, leaving only a small corner able to transmit an image. The upper prism on No. 2 periscope was shattered and the periscope tube flooded. No damage was sustained by the gyrocompass (Arma). The face on the pitometer log indicator in the control room shattered and the conning tower log indicator jammed when the distance counter broke free from its mounting lugs and dropped into the indicator. The rudder angle indicator system was disabled as a result of a selsyn stator winding short-circuiting (Photo 5- 13).

5- 28. As indicated in paragraph 5- 8 above, several serious high pressure (3000- pound) air system leaks developed as a result of the attack and the lar ge increase in pressure of the atmosphere within the boat caused much concern to personnel. No. 3 high pressure air bank in the after batterx compartment lost air through a leak at one of the silver soldered 'tee" connections to an air flask. This caused the loss of all air within that bank.1 Serious air leaks also developed at the cone joints of the short riser pipes connecting the high pressure air receiving and distribution manifolds. Inadequate suppor~ of these manifolds resulted in excessive movement during the attack, causing the joints to partially open. Since no stop valves were provided in these risers, ·twas necessary to secure the entire r eceiving manifold to tighten the joints. A further difficulty was encountered when it was found that the original receiving manifold had been replaced with a manifold having the riser outlets at 18- 1/2 inch centers instead of the des'gned spac.ng of 19- 1/2 inches, making it necessary to offset each of the short pipe connections by 1/2 inch. A considerable number

1 The internal high pressure air banks located in the forward and after battery compartments of 88212 Class Electric Boat Co. designed sub­ marines are piped together in a common junction at the control room receiving manifold. With such an arrangement, a casualty similar to that which occurred on KINGFISH could cause the loss of all air in internal flasks. To prevent this, ShipAlt 88197 of 9 June 1943 autho­ rised the installation of stop valves in the lines between the forward and after groups and the control manifold. The installation of a stop valve at each flask was considered but not approved due to the labor involved in installation, the difficulty of maintenance of such valves and the added number of joints in the high pr essure air piping, each joint being another potential source of leakage.

- 36- CONFIDENTIAL K1NGFISH (SS234) CONFIDENTIAL of other flanged piping and valve connections developed minor leaks as a result of the attack, principally due to holding nuts backing off under im­ pact and allowing the joints to loosen. The most notable cases were the MBT No. 7 vent risers in the after torpedo room, various salt water lines, the hull valve on the bow buoyancy blow line, and the external flanges on the tor pedo impulse air flask piping. Since air leaking from the latter flanges outside the hull released large bubbles to the surface, the impulse bottles were immediately bled down.

5- 29. Numerous hull valves backed off their seats during close depth charging, allowing pr essure to build up in various internal piping sys­ tems.1 After each close detonation, it was necessary to close the valves and bleed off excessive pressure in the lines. It was reported that all valves that opened had stems with Acme standard screw threads, including such valves as the torpedo tube outboard vents, sanitary tank overboar d valves, inboard exhaust valves, water r-loset sea and stop valves, depth gauge valves, etc. Ballast tank flood and master and emergency vent valves wer e generally unaffected and did not leak although it was r eported that the hand operating gear for most outboard valves worked more stiffly after the attack than before, apparently due to slight hull distortion. The operation of the bow buoyancy tank vent valves was considerably more difficult immediately after the attack due to slight distortion of the bow structure causing binding of the long operat­ ing shaft.2 After getting under way, operation of these valves eased up considerably. The gasket of one of the safety tank master vent valves is reported to have blown out. The ship' s supply ventilation outboard mush­ room valve could not be operated upon surfacing due to the backing out of a connecting pin in the operating linkage.

5- 30. At the time of the attack, tor pedoes were loaded in seven tubes, three forward and four aft. Muzzle doors were closed on all tubes. These torpedoes shifted under impact, bending the gyro setting spindles and causing stop bolts and guide studs to burr and wedge firmly together. One torpedo loaded aft sustained a ruptured diaphragm. :Muzzle doors and shutters could not be opened immediately after the 'lttack due to binding of the interlock mechanism. After a short time, however, the binding was no longer evident. The muzzle door gasket on tube No. 10 was damaged, allowing that tube to flood completely. Minor leakage occurred in all tubes, indicating that the muzzle door s fluttered during successive impacts. Minor damage to sever al breech door gaskets was also reported.

5- 31. When KING FISH was forced to the bottom, both her sound projec- tors w~re in the extended position and wer e bent aft. The port head was sheared off and the starboar d head was badly damaged (Photo 5- 14). The ------1:r or further discussion see paragraph 20- 14. 2ShipAlt SS330 of 7 March 1946 authorized changing the supports for the bow buoyancy tank vent valve shafting so as to connect to the pressure hull rather than the super structur e in order to eliminate casualties of this natur e.

CONF DrNTIAL - 37- KINGFISH (SS234) CONF DEf\JTIAL

:flexible cable to the port head was parted and, as previously mentioned, this cable was forced up into the forward torpedo room, allowing water to enter. Adjacent sound equipment was thoroughly sprayed with water, grounding and disabling the entire sound system. No damage to radar or radio equipment occurred, with the exception of the parting of two topside radio antenna cables. b-32. After receiving temporary repairs at the Submarine Base, Pearl Harbor, KINGFISH proceeded to the Navy Yard, Mare Island, arriving on 20 April 1943. Complete battle damage repairs, regular overhaul and numerous outstanding alterations were accomplished t11ere and KINGFISH was returned to service on 16 June 1943.

5-33. The experience of KINGFISH indicates that at this period of the war a creditable balance between strength of hull structure and damage resistance of vital machint.ry and systems had been achieved on SS212 r.lass submarines. Although she was subjected to depth charge detonations along her entire length close enough to cause con­ siderable permanent pressure hull deformation in several areas, KINGFISH remained fully operational in both submerged and surfaced conditions and her torpedo offensive power could have been almost wholly restored by repairs within the capacity of the ship's force.

-38- CON F1 DENTIAL CONFIDENTIAL

,.._,,-?--, __ .,: ...... _...,,. . ------...... ' -...... ' ' !." ...... ---:-- .,,,,,-- ...... _ " ...... '--~ - _>I.. ,,.!:- ..... --- \ ,---;;;--) -- - -:__ _J ---- - ~ - ) ~---- ~

.l:-'.... ot..> ~ - 1 : .r:il'JGFISH (SS234). Section of damaged pressure huE r.- ... atir.~· removed oetween frames 78 - of> over the forward engine room. M0te rr,3.xirr.um indentatL:m of : -1/4 :nches ..ietween frames 02- 83. Riveled ; .ate edge shown here is forwarr! tn nsverse bu:t of forward t:ngine room hard patch.

I r.uto t.. - <: KU-!GFISH (SS~34) . View .;howing distorti0n at starboard r~vt:~ed 2vint of r:e/..5tur.e frame t.b, ir. way of ri,;e:ed ri rd pi.ten over iuri.'I 1rd en •in~ r0on •.

C'OIV Jr i flAL - 39- CONFIDENTIAL

Photo b- 3: KINGFISH (SS234). View showing distor tion of frame 83 and depre.s.:;ions in pressure hull plating between frames 82- 84, over forward engine room.

Photo G-4: KINGFISH (SS234). View showing depressions in shell plating, port side, frames 103- lJc<, in way uf lubricating oil tanks. Damag~ on ,;tarboard side was similn.r.

-40- CONFIDENT AL CONFIDENTIAL

Ph0to 5- 5: KINGFISH (S[,234). View showing cunning wwer after bulkhead, indicating points at which W. T . door dogs bound due to dis­ tortion of bulkhead and door seat.

f. l

.Photo b - ti : KLl'JGFISH ~SS234) . View showing distortion to cover of 20mm ready service ammunition stowage located on the after bridge di:::cr:. Thi..5 stowage flooded.

CONrlDENTIAL - ~ll - CONFIDENTIAL..

Phot..) t - 1: Ka·:GFL3H (SS234). View showing par ted cable to pon JK -QC ... ur.ar r ro:eeL>r and the improvised plugging arrangement for the -.:able stuffing tube.

Phuto 5- 8: KINGFISH (SS234). View showing chain fall rig used for se­ curing leaKage around air induction hul: flapper va:ve at frame 82- 1/2 in the g_fter engine room. Valve seat was slightly distorted by adjacent pressure null deformation. (See Photo 5- 15 ).

-42- CONFIDENTIAL CONFIDENTIAL

OFFICIAL PHOTOGRAPH HOT TD BE RELEASED FOR PUBLICATI ON l\A't T Ylltf' .. A '> ...... ,CAL

CC~IOENTIAL

Photo b- 8 : KINGFISH (SS234). View showing distortion which occurred to the No. 1 engine outboard exhaust valve disc.

OFFICIAL PHOTOGRAPH HOT TO BE RELEASED FDR PUBLICATION HI.VY YA.IW _..,u :....»fJ _._. CONFIDE NTIAL

Pr10to ~) - 10 : KlNGFISH (S.5234). ·view .;Lowing LypiccJ.l d..i.rnage to phenolic light socKet..5 in over head of engine r0on •..5 .

CONFIDENTIAL - 43- CONFIDENTIAL

OFFICIAL PHOTOGRAPH HOT TO BE RELEASED FOR PUBLIC ATI OM N.AVY 'UllQ lW-\0.. lSl..AHJ ~ f

Photo 5- 11 : KINGFISH (SS234). View showing typical examples of damage which occurred to micro-switches and receptacle cover s . \

)

TtRM 1NAL STRIP ( NOS &ROK(N OUT SECURING SCRE.WS Ut-JOAMAGEO, 130JC (A~UM I NUM CASTIN G) UNDAMAGED

Photo 5- 12: KINGFISH (SS234). View sh·)wing damage to ter minal strips in COrL'leclion boxes which allowed the terminals to fall against the box and cause short-circuits.

-44 - CONFIDENTIAL CONFIDENTIAL OFFICIAL PHOTOGRAPH HOT TO BE RELEASED FOR PUBLICATION NJtl"rturJ~ NCJ AUF 0:~1".,.ll;J..

Photo 5- 13 : KllJGFL..SE (SS234). Sr.orted selsyn transmitter stator which disab!ed the rudder angle indicator !"'ystem.

Photo 5- 14 : KlNGFISH (ss;::34). Grounding damage to .:>larboard QB son::i.r projc-ctor. Both the port ar.d ...>l 1ruvard prJjector.., were in ex­ ter,ded position v..r.er. the boat waf' fvrced to the bottom.

CO"lFIDE-NT AL - 't; - CONFIDENTIAL

Photo 5- 15: KINGFISH (SS234). View showing distortion of seat for after en~ ine room air induction hull valve at frame 92-1/2. Leakage around this valve flooded after engine room to level of lower floor plates. (See Photo 5- 8).

OFFICIAL PHOTOGRAPH HOT TO BE RELEASED - FOR PUBLIC ATIOH

Photo 5- H:i : KINGFISH (SS234). View showing distortion of engine air induction outboard mushroom valve due to bent valve stem. Valve is r eported to have sealed tightly when tested at Navy Yard, Mare Island.

- 46- CONFIDENTIAL CONFIDENTIAL PLATE "IL

DEPTH CHARGE DAMAGE PLATE Y CONFIDENT I AL

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t• LEGEND

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SECTION AT FRAME 117 L009CING '0111W.\ll!O SECTION iT FRAME 93 IQWIJril<:. V.t,lll.lfl i..':! lfTWfl:lill U.SS KINGFISH SS-234 PROF! LE ON 'l SH IP L009Clfll0 ,OllWA"O (U flJrilG AHO O(S18N&O HUL OFF FORMOSA 23 MARCH 1943 1 .t.HO 1111.I f NO 7 TAN• fOJt •110•1"( SECTION AT FRAME 103 '12 SECTION AT FRAME 107 12 ""(9. 1 1 L001t1NO 'OlllWAllD 'T()Jlfl;,. 104 12 a 105 12 DEPTH CHARGE DAMAGE LOOICIHO ro .. wa• o BUREAU OF SHIPS - PLATE Y CONFIOE NTI A L

MA I N DECK

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USS KING FISH SS- 234 OFF FORMOSA 2 3 MARCH 1943 DEPTH CHARGE DAMAGE BUREAU OF SHI PS