SECTION X U.S.S. TANG (SS306) Loss in Action F Or Mosa Strait 24

TANG (SS306) CONFIDENTIAL

SECTION X

U.S.S. TANG (SS306)

Loss in Ac tion

F or mosa Strait 24 October 1944

Class ...... SS285

Builder ...... U.S. Navy Ya rd, Mar e Is la:-id

Commissioned ...... November 1943

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

Beam (Extr eme) ...... 27 ft. 3-1/4 in.

Submer gence Depth (Designed Maximum) (Axis) ...... 400 ft .

Displacements

Standard ...... 1525 tons

Emer gency Diving Tr im...... 1956 tons

Submer ged ...... 2408 tons

Dr aft (Mean, Emergency Diving T r im)...... 16 ft. 2 in.

Type of Propulsion...... Diesel Electric Reduction Dr ive

Main Engines (4) ...... Fair banks- Mor se 38-D -8- 1/8

Main Motors (4) and Generator s (4) ...... Elliott Co.

References:

(a) C.O. TANG conf. ltr. SS306/ A- 16- 3 of 10 September 1945 (Report of War Patrol Number Five and Loss of Vessel). (b) BuMed conf. ltr. BLK:II, Ser ial No . 0356 of 29 July 1946 (Submar ine Escape in World War II). (c) Interviews with Various TANG Survivor s by Cdr. r. F . Duff, (MC), USNR.

Photograph No. 10- 1 (Torpedoing of U-977 - Associated P r ess) anl 10 - 2.

PLATE X

CON~IDENTIAL - 109- TANG {SS306) CONFIDENTIAL

10-1. On 24 October 1944, during her filth war patr ol, TANG was sunk in Formosa Strait as a result of the malfunctioning of one of her own torpedoes which made a circular run and returned to strike the hull abreast the after torpedo room.1 The resulting detonation caused the ship to plunge by the stern within a few seconds.

10-2. This report is based on the information contained in the references. The first portion of reference (a) is a narrative of TANG's fifth war patrol up to the time of her loss and was written from memory by the Commanding Officer upon his release from a Japanese prisoner of war camp at the end of the war, approxmate- ly one year after the action took place. The second portion of reference (a) is a reconstruction of the events which occurred in TANG after the torpedo struck. Since the Commanding Officer was washed off the bridge when the ship sank, this portion is based on the stories of the eight other survivors as related to him at the first opportunity after their capture by the Japanese; five of the eight having gone down with the boat and later making individual underwater escapes from the forward torpedo room. This reference, although understandably not as complete as formal war damage reports covering actions in which a subm'lrine returns to base and damage can be thoroughly investigated, is an excellent presentation of the available data and is the only account in U.S. Naval history of the events inside a war-damaged U.S. submarine during and after its sinking. References (b) and (c) cover the escape problerr" facing the men trapped within the boat and the procedure used by those few who made successful escapes. These latter two references are based upon personal written and oral accounts of the survivors as related to representatives of the Bureau of Medicine and Surgery. The photograph of the torpedoing of U-977 is included to illustrate the magni tude vf TANG's disaster. The PLATE was prepared by the Bureau.

10-3. The fifth war patrol of TANG was conducted in the Formosa Strait. This area was assigned in order that TANG would be in a position to intercept any Japanese shipping which might retire from Formosa as a result of the carrier strikes against that Island by the Third Fleet on 12 through 14 October 1944, and also to intercept any enemy reinforcements which might pass through Formosa Strait in support of tne Philippine campaign which commenced with the Leyte Island landing on 20 October 1944.

10-4. After normal refit at the Submarine Base, Pearl Harbor, TANG departed for Fvrmosa Strait via Midway on 24 September 1944 and reached her patrol area on 10 October. On 11 October TANG sank one large and one medium-sized cargo ship off the west coast of Formosa, the first by a da·Nn torpedo attack while submerged and the second by a night torpedo attack while surfaced. On 12 through 14 October, the period of the Third Fleet air strikes against Formosa, numerous searches were conducted along likely. enemy shipping retirement lanes ------1 ------There is evidence to indicate that the loss of TULLIBEE (SS284) on 26 March 1944 was similarly caused by a circular run of her own torpedo. See Appendix II.

-110- CONFIDE-_~TIAL TANG (SS306) CONf DENT AL to the China coast but no contacts wer e established. From 14 to 22 October, although sever al enemy ships wer e sighted, r ange to the targets could not be sufficiently closed and consequently no attacks were made. Shor tly after midnight on 22 October, r adar contact was established with a heavily escorted enemy convoy composed of thr ee large tankers, a large cargo ship, and a medium- sized tr ansport. All ships were heavily loaded and were apparently bound for support of the Philippine campaign. TANG executed a spectacular close range night surface attack, sinking all five ships of the convoy within ten minutes of firing her first tor pedo and then cleared the area at full speed, leav ing the escorts apparently engaged in a gun duel with one another.

:0- 5. Fvllo·.vinr; the action of 23 October, TAIJG proceeded north of Formosa Strait for ueer er water and then headed toward the :o;hallow protected water s along the Chin:i. coast on the theory that, due to her recent successes, all subsequent Japanese shipping passing througn the Strait would be rvuted clo~E:: inshore. This belief pruved correct, for in the early ev.qni..ng of 24 October radar contact was established with a larg9 Japanese convoy hugging the China coast and located ab::mt midway between Foochow 'tnd Amoy. The convoy was proceeding south at a speeu of abou+ twelve knots, apparently also headed for the Philippines, and consisted of at least fourteen large, heavily-loaded ships ir. column esc.:>rteu by at ... east on~ destroyer and t.velve destr0yer-escorts. Svme of thE. e..;co:::"ts were to ..;eawaru of tne c0nv0y while other.3 were on the landward side. lu-G. TANG closed for a night surface attack using radar ra1wes and TB:' bear ings, but her pre.sence W'd.:3 apparently suspected for t·.vo of the seaward enemy esc0rt~ comr.ienced to run on opposite course to the cor.voy :olumn, firing sporadic and wild bursts of ~ma~l and medium caliber projectile.:;;. As TANG C'Jntinueu to appr oach, one of th8 enemy escorts illwninated the convoy column with a large search light w!1i..le signailing and this had the favorable effect of increasing targ:et ship visibility. Three of the leaning ships, a large transport, a mediwn- sized tr ansport and a :arge tarv.er, were selected as the initial targets and, at ranges varying from ~00 to 1400 yards, TA.NG firt;;d thr e slow deliberate salvos of two torpedoes each per ship. In spite of the enemy having had apparent early knowledge of TANG's presence, no evasive tactics were employed by anf of the ships up to this time. All t0rpedoe3 ran true to their targets, .;inking the three ships alrr.ost immediately. Meanwhile, TA.NG paralleled U).e convoy to search out the next two targets. A tanker and a transport were selected for ster n torpedo attack and three torpedoes wer e fir ed at ranges between GOO and 700 yards. The escorts had now stopped their warning tactics and \'!ere directing close salvos at TANG. Just after firing at the transport, a destroyer crossed closP. to the stern of that snip and headed directly for TANG. The first tor pedo hit the tanker , which was apparently loaded with gasoline, and a tremendous explosion re.. mlted . The second torpedo was observed to hit the tr ansport and an instant later th..! destroyer blew up, either intercepting the third t;)rpedo or cross fir<; from two enemy escorts which wer e bearing down on TA:JG's beam. OnlJ the transport remained afloat anc.i she was apparently slopped deaa in the water.

CONFIDENTIAL - 111 - TANG (SS306) CONFID:N~IA.

10-7. TANG cleared the immediate area at flank speed, still on the surface and untouched by the'enemy gunfire. When 10,000 yards distant from tne enemy escorts, a halt was made to survey the situation and to recheck the last two torpedoes remaining on board. About one hour was spent on this work, the torpedoes being partially withdrawn from their tubes, batteries ventilated, gyros inspected and the steering mechanism observed to be operating freely. The two torpedoes were tnen reloaded in forward tubes Nos. 3 and 4 and TANG commenced a cautious approach to again attack the crippled transport, which was now observed to be lower in the water but definitely not sinking. Since two enemy escorts were patrolling to seaward of the transport, TANG made a wide sweep and came in very slowly to escape detection by sonic listening gear. Upon reaching a favorable position, the twenty-tt.ird torpedo was fired at the transport from a range of about \:JOO yards. Ship speed at this time was about six knots a:id the heading was conned for zero gyro angle setting on the torpedoes.

:0-8. When the phosphorescent wake of the twenty-third torpedo was .)bserved heading true for its intended point of aim on the target trans port, the twenty-fourth and last torpedo was fired. This torpedo assumed an erratic course immediately upon leaving its tube and curved sharply to the left in a tight turning circle, broaching during the first part of its turn and porpoising during the remainder.1 Due to the phosphoresence of its wake, the torpedo was observed through :so degrees of its turn. As soon as the erratic behavior was noted, which was almost imme diately after the torpeao was fired, TANG went to emergency speed and partially ext.:cuted a fishtail maneuver in a futile effort to clear the turning circle. This resulted only in the torpedo striking the boat farther aft than would have been the case had no evasive action been taken. The twt;; nty-fourth torpedo, as were all those carrieo by TA.i.'l\J'G on this patrol, was an electric-driven Mk. 18, Mod. 1, fitted with a Mk. 18, Mod .l warhead containing 570 pounds of TPX (equivalent in damaging effect to approximately 850 pounds of TNT).

10-9. ':'hP. torpedo struck TANG on her port side aft in the vicinity of eith.Jr the after torpedo room or the maneuvering room, a bout twenty seconds after being fired. The exploder mechanism (Mk. 8) used in the Mk. 18, Mod. 1 torpedo warhead is an inertia type which fires by impact from any angle and the time delay between receiving an impact blow and detonation of th.a warhead is so slight that the fuzing may be considered as instantaneous. It is therefore r.-robable that the torpedo detonated on contact with the outGr hull if it struck in way of the maneuvering room or with the single hull (pressure hull) if it struck in way of the after torpedo room. The Mk. 8 exploder mechanism arms itself by an impeller driven gear train, the impeller being caused to revolve by the ahead motion of the torpedo through the water. Arming of a Mk. 18 torpedo at its rated speed of about 29 knots should norn_ally occur in approximately 200 yards or about 12 seconds running tim•-· Based on studies of torpedo war damage experience with surface vessels .. it is estimated that the torpedo detonation probably caused complete destruction of a section of TANG's pressure hull extending

1 A torpedo anti-circular-run device is currently being developed by the Bureau of Ordnance to prevent recurrence of such malfunctioning.

-112- CON F :JENTIAL TANG (SS306) CO~F DEf"< TIAL over a longitudinal distance of at least 25 feet on the port side and extending in depth almost through to the opposite side of the hull, if in fact the hull itself was not compll'.'Jtely severed (Photo 10- 1).

10- 10. Sufficient information is available to permit a fairly complete description of the events which occurred in TANG following the detonation. The boat as a whole was violently whipped. One survivor (conning tower) stated: " With the explosion of the torpedo, the boat seemed to bounce up and down". Personnel as far forward as the control room sustained broKen limbs and Jther injuries. Pipe lines fractured, deck plates lifted up and lightly attached fittings and loose gear were flung about. The propulsion plant was destroyed instantly and men watching the pitometer log in the forward torpedo room noted that the boat lost all forwarJ motion within a fe..v seconds. The after torpedo room, mant>uvering room, after engine room, and probably all adjacent tam:s floodt..>d rapidly. The watertight door in the after oulKhead of the forward engine room was closed with difficulty agaL'lSt the inrushing water from the after engine room, but n::>t until the forward engine roo:n had been half flooded. There were no survivors from the three after compartments. The ::;hip apparently settled sloJJly for a few seconds and then plunged rapidly by the stern. Reference (a) states that " TANG sank by the stern much as you would drop a pendulum suspended in a horizontal position". Three of the nine officers and men on the bridge were thrown clear or were washed. over the side as the ooat sank and managed to stay afloat until rescued. by the Japanese about eight hours later. Nothinp; is k.rDwr. 0f the fate of the other six men on the bridge. No lookouts survived and it is possible that they may have been unable to extricate themselves from or were injured by the periscope shear guar d. rails and were carried down ·;;ith the ship. Communications were maintained betwet:n th.:: conning: to111er and bridge until the ship plunged but there wac- ins urn., i~n· time to carry out an order to close the upper conning tower hatch. Water poured through this open hatch and completely flooded the c :mmng tower within a matter of secJnds after it went below tne surface of the water. O!le officer subsequently mada a successful underwater "free" escape from within the flooded conning tower and it is known that one man was thrown through the lower conning tower hatch into the control room by the shock of the detonation, breaking his arm in doing so. Personnel in the co!ltrol room succeeded in closing the lower conning tower hatch to prevent the inrush of water into the lower compartmEmt. The hatch had been damaged, however, and leaked badly, causing the control room an.d pump room to flood. slowly.

10- 11. Although TANG's stern plunged to the bottom, the bu:>yant force of the intact amidships and forward compar tments and tanks \Na~ such that the bow remained on the sur face, the boat assuming a " spar ouoy" position with an up angle of approximately 40 degrees. Th.... offi cer who escaped from within the conning tower stated that upon reach ing the surface he observed about 25 feet of the bow projecting above water. Within the ship, all loose gear fell to the after ends of ~ach compartment and all hands held onto anything they could grasp. SornE.. lost their footing and were thrown aft.

10- 12. The men in the forward torpedo room, about ten in number, had secur ed their compartment shortly after the detonation occurred

CONFIDE: (\JTIAL TANG (SS306) CONFIDENTIAL

ana after vainly attempting to contact other compartments by phone came to the conclusion that the after part of the ship was destroyed. They discussed the possibility of escaping at once through the empty forward torpedo tubes but decided against that course because they could depth charges hear and feared the bow would be shelled. l 10-13. Personnel in the control room had also secured their n.ent immediately compart- after the detonation but possessed somewhat complete information more as to the extent of damage. Their prompt execu tion of damage control measures had established boundaries sufficient to prevent further rapid intake of water and they realized that some of the men trapped within the boat might be able to escape through the one remaining intact escape trunk in the forward torpedo room. To prevent the possibility of damage to the exposed bow by enemy action, and to facilitate escape operations by removing the excessive up angle, it was decided to sink the I bow and level off. Therefore, about fifteen minutes after the initial damage occurred, TANG was deliberately bottomed by flooding the No. 2 group of main ballast tanks. Hydraulic power not l being available, flooding of these tanks was accomplished by manual operation of the vent valves in the overhead of the control room. 10-:4. Meanwhile, classified publications were being destroyed by burning, at first in the control room and later in the forward battery compartment when the water level in the control room made it necessary to evacuate and seal that space. The survivors from the control roorr. and fon;arJ battery compartment, about fifteen men in all, then proceeded to the forward torpedo room, carrying their injured in blankets. When the door to the forward torpedo room was opened, the difference in air pressure between the two compartments due to leaking air systems amidships was such that those men near the door were literally blown into the torpedo room. 10-:5. Ab'Jut )IH:.•-half hour later, the survivors from the forward engine roorr. and after battery compartment decided to attempt to reach the forward torpedo room. This group consisted of ab.:mt twenty men, two 'Jf whom were injured. They discovered by peering through the 1 Based on the rep":>rts th:i.t TANG assumed a 40 degree up angle about 25 with feet of the bow exposed, the outer doors of the would torpedo tubes have been slightly below the surface of the water ana escape at this time throu~h the tubes would therefore have been not impossible. difficult, if There are two instances, however, where such have been accomplished escapes from U.S. submarines. (1) S-5 sank in 194 feet of water off the Delaware Capes on 1 September 1920, due to interna~ flooding through maloperation of the induction valve. The crew managed to blow the stern to the surface and with great effort cut a small hole in the shell above the waterline. All hands were released about 51 hours later when an escape access was cut exposed stern in the by the crew of the steamship GENERAL GOETHALS. (2) On 7 December 1921, S-48 sank in 67 feet of water ·1:hile on trials off Bridgeport, Connecticut. The engine room, motor room and steer ing room were flooded due to neglecting to replace a manhole cove1· on No. 5 port ballast tank. The bow was blown to the surface and all 41 meu aboard escaped through a torpedo tube.

-114- CONFIDENTIAL TANG (SS306) CONFIDENTIAL eyeport in the watertight door to the contr ol r oom that water in that space had already flooded above the door level. On testing the bulk head flappers in the ventilation piping they found the water not yet at this height. They therefore opened the bulkhead door, letting the water race through, and then proceeded to the forward torpedo r oom. When these men first attempted to open the door to the torpedo room, two men in the torpedo room tried to get them to crack the door slowly so as to gradually equalize the large difference in air pressure between the two compartments. The men in the forward battery compartment, however, did not understand the signals and thought they were being deliberately kept out. They forced the doo:r open and, being accelerated by the air pressure, it struck and severely injured one of the men in the forward torpedo room who had been trying to signal to them.

10- 16. All of those men who had survived the initial damage, a total of about forty- five, were now in the forward torpedo room. When the last group arrived, about one hour after TANG first plunged, it was learned that the boat was flooded to the forward engine room. The general feeling of the men at this time seems to have been one of mixed optimism and confidence in their ability to eventually escape combined with excitement and lack of direction. From the last radar bearin~, they knew they were only a few miles offshore and it was therefore felt that the chances of reaching land after ascending to the surface were quite favorable. They alsoJ had a fairly accurate estimate of the depth of the water from the angle the boat assumed when the stern sank and also from previous chart and fathometer soundings. Submarine escape devices, or "lungs" were passed to all hands and instructions on how to use them were reviewed. Over half the men seemed to possess but little familiarity with the operation of the " lung" equipment. The limited number of available life jackets were distributed and those without were instructed to use their " lungs" as such when they reached :he surface. The atmosphere within the forward torpedo room at this time was fairly good, although some smoke and fumes had been introduced from the burning of the classified material. Heat and humidity were increasing and the higher than normal air pressure due to accumulated air leakage caused some discomfort, but adverse physiological effects were not yet pronounced. Although the ship's service lighting system had failed a few minutes after the detonation, the emergency lighting system was functioning properly.

10-17. Preparations for escape were halted when, at about this time, several depth charges were dropped close enough to sha~e the boat considerably although no further damage was sustained. The enemy remained in close proximity for the next several hours and during this period all activity in TANG came to a standstill. Meanwhile, a fire, reported by referen~e (a) to have been of electrical origin, started in the forward battery compartment and became quite intense.

10-18. When the enemy vessels apparently had finally departed, it was decided to first altempt to blow tanks and fluoded compartments to see if the boat could be surfaced, and thereby render it much easier and quicker for all han1s to escape. A small party of men was

CONFIDE['.iTIAL - 115- TANG (SS306) CONFIDENTIAL

assembled to proceed to the control room on this mission but when they started to open the watertight door to the forward batter y compart ment, large quantities of acrid black smoke from the fire in that space blew into the torpedo room. Although the door had been cracked for only a second or two and then closed at once, fumes and smoke com pletely filled the compartment. Visibility was reduced to the extent that the lights could be but dimly discerned. Some of the men began to gag and suffered considerable distress almost immediately. The smoke was reported as having an odor similar to that of burning rubber. It is quite likely that the batteries themselves may have been on fire since it was stated that the disconnect switch for the forward battery had not been opened and numerous short circuits are known to have existed. When irritation from the smoke became severe, many men used their " lungs" as respirators, apparently with considerable success. The men were now trapped by the forward battery compartment fire and since self salvage efforts, at least to the extent of once again raising the bow to the surface, could not be made, there remained no alternative but to attempt individual escapes.

10-19. The first escape attempt was made shortly after daylight. A party of one officer and three men equipped with " lungs" entered the escape trunk, flooded it and opened the side door. It had been arranged that the last man to escape was to notify the men below by tapping just before he left the trunk so that the door could then be closed and the trunk drained down to make ready for the next party. However, due to difference of opinion as to how the trunk operated and difficulty in rigging the ascending line and escape buoy, an inordinately long period of time was consumed. The officer left the trunk before the ascending line and buoy had been streamed and was never seen again. The remaining three men finally completed rigging the escape line but by this time approximately forty minutes had elapsed and the personnel below in the torpedo room, having received no signals from the escape party, closed the trunk door by the remote operating gear and drained the trunk down, thus preventing the escape of the men within.

10-20. A second party of three men and two officers then entered the trunk and rigged for escape. Three of this group left the trunk, one of whom reached the surface alive and survived. The other two who left the trunk were not seen again. After another forty minutes or so, again having received no signals from the escape party but hearing moans from within the trunk, personnel below in the torpedo room closed the escape door, drained the trunk and found the remaining two members of the party, both officers, still in the trunk. One was in a semi-conscious condition, presumably due to inability to withstand the high partial pressures and increased carbon dioxide content of the atmosphere within the trunk. The other officer had become fouled in the unused portion of the ascending line which, after having been cut inboard of the point of attachment of the buoy line outside the trunk, was withdrawn into the trunk and apparently loosely piled underfoot. However, it was the belief of the men below that the line which fouled the officer was the buoy ascending line itself and that the buoy had been cut free outside the door.

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10- 21. The difficulties encountered in these first two escape attempts combined with the presence of the smoke and progressive deteriora tion of the atmosphere within the torpedo room had by this time noti ceably lowered the morale and physical condition of all hands. All former enthusiasm now died down and many of the men did not care whether they escaped or nol One of the survivors stated: "The constantlr increasing pressure, smoke, and heat seemed to affect everyone s thinking". Another survivor stated: "Difference of opinion among the first men attempting escapes wasted valuable minutes. The men weren' t sure of escape procedure and were afraid they would make a mistake that would be fatal to the men below. Escape proce dure is very simple on paper but somewhat different where everyone's life depends on it. One of the major difficulties encountered was the lack of proper means of communication between the men in the trunk and the men below. We didn't know what was going on or what troubles they had". One of the officers who was in the second party to enter the trunk but was unable to escape and returned below, was apparently one of the few men aboard who had made a one hundred foot training escape. He is reported to have stated that although he personally did not care to attempt to escape again, there was no reason why all of the others should not be able to escape.

10- 22. A third party, consisting of four men, then entered the es- capP trunk. They carried with them a lifering and line with the idea of streaming it for use as a new ascending line since, as previously stated, it was the.r belief that the original escape buoy had been cut adrift by the second escape party. After flooding the trunk and opening the door, it was found that there was no oxy~en available at the trunk manifold with which to initially charge their 'lungs". Although aware that the "lungs" could be blown up with their own breath sufficiently to permit safe ascent, only one of the four elected to do so. It took about fifteen minutes to rig the trunk, including preparing the lifering as a buoy, and by this time the one man intending to escape, although having no difficulty with breathing through his "lung", had become very exhausted and dizzy. He had planned to let the lifering go up to the surface and then to ascend the line attached to the lifering as in the standard escape buoy rig but, being on the verge of passing out, he simply stepped out of the trunk, holding the lifering in his arms, and started rapidly toward the surface. One of the men who remained in the trunk tried to slow down this fast ascent by jerking on the line as it payed out but this caused the escaping man to lose use of his "1unv;'' after going up about twenty feet. From that point up he made a ' free" escape by allowing the constantly expanding air in his lungs to vent through his open mouth, reaching the surface alive and in suffic.ently good condition to remain afloat until res cued. The men remaining in the trunk then drained the space and obtained more oxygen for the "lung manifold from the torpedo room. Two of these men were so completely discour aged that they refused to

CON Fl DENTIAL - 117- TANG (SS306) CONFIDENTIAL

obtained more oxygen for the "lung'manifold from the torpedo room. Two of these men were so completely discouraged that they refused to try again. The one and only man who escaped on this third attempt was familiar with the escape procedure through adequate previous training. He stated, "I felt at ease using the "lung" and knew it would work after I tested it under the water before leaving the trunk. I had made a one hundred-foot escape before".

10-23. After another forty-five minutes or so, three men from a fourth escape party reached the surface alive using "lungs" and, although exhausted, managed to stay afloat. Approximately one hour later, three others from the fifth and last known escape attempt reached the surface but were in weakened condition, apparently unable to breathe, and died shortly afterwards. At least one of the men is believed to have died as a result of air embolism.

10-24. Of the thirteen men who are known to have left the submarine via the escape trunk, only eight are known to have reached the surface and of these eight only five were in sufficiently good condition to cling to the buoy until rescued. Some of the men who were not seen again after leaving the trunk may have reached the surface alive but perhaps did not use the ascending line and were carried by currents to points out of sight of the group at the escape buoy and subsequently drowned. Conditions inside the trunk when being flooded by the various escape parties were no doubt partially responsible for the low percentage of successful escapes. One survivor reported "The compression of the air as the water flooded the trunk caused a great amount of heat. When the water was above the door, it left a very small air space and everyone had diificulty in getting their breath. The pressure made the voices very high and almost inaudible. All these combined to create a certain amount of panic in everyone".

10-25. The exact fate of the thirty odd men who remained in the forward torpedo room is not known although it is quite apparent that the viability of the atmosphere in the forward torpedo room was probably soon reduced below the point at which life could be sustained. The deleterious effects on all hands of the smoke introduced from the forward battery compartment was considered by the survivors to have been one of the greatest factors in delaying and hindering the escape attempts. One survivor stated "This smoke did more to kill the men who didn't get out than any other thing". Another stated "The smoke undoubt dly killed every man in the compartment not long after the Japs picked us up. Some men were nearly unconscious when I left. The smoke made you cough and the coughing caused more irritation in your lungs and throat". Heat and humidity reached high levels and air pressure kept increasing due to leakage through forward battery compartment drains into the No. 1 sanitary tank and thence into the forward torpedo room .through the lavatory drain. The leakage occurred in spite of check valves in the lavatory line and use of wooden plugs provided. in the depth charge kit. In addition to causing considerable discomfort in itself, the increase in air pressure in the forwar d torpedo room also accelerated the physiological effects of the smoke and whatever other noxious or toxic gases that may have been present, such as carbon monoxide.

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10-26. Increase in CO' content was reported as not being too notice able because of the amount of smoke in the air although this corr ponent must have been present early in dangerous quantity. Though use of C02 absorbent was considered, it had not been employed up to the time the last survivor escaped since the lar ge nwnber of men in the compartment left but little area to spread the chemical. Lack of use of C02 absorbent was a serious error for calculations indicate that, Vv ith 45 men in the forward torpedo room, a 3 per cent co2 concentra tion would have been reached in only four hours. The effect on personnel of excessive co2 was also enhanced b{ the rise in air pressure known to have occurred in the compartment. C02 poisoning is believed to havt been the most important single factor causing the early debilita tion of the crew and alone could have been responsible. Oxygen was bled into the compartment several times to revitalize the air and seemed to relieve the general feeling of suffocation.

10- 27. When the fourth and last successful escape party entered the escape trunk, the fire in the forward battery compartment was reported to have reached such intensity that paint on the forward side of the torpedo room bulkhead had melted and was running down. Considerable pressure had built up in the forward battery compartment and apparently the bulkhead door was not sufficiently tight to prevent acrid smoke from seeping by the gasket. Reference (a) advances the theory that this door gasirnt may have blown out, either due to pressure 'Jr an ensuing battery explosion and that the remaining personnel were thereby asphyxiated. A.3ide from from this conjecture, however, the members of the fourth escape party believed that at the time they entered the escape trunk the breathing conditions in the torpedo room had deteriorated to such an extent, due to increased air pressure, lack of oxygen, high carbon dioxide content and the presence of fwnes and smoke, that all remaining per J:>nnel would probably have been rendered unconscious or dead within a very few hours.

10-28. All of the total of nine men who survived, five from the escapA trw.k, three from the bridge and one from the conning tower, were picl{ed up auring tne day by one of the Japanese escorts. One consolation to tht> .5urvivors was the sight of the DON of their last transport target project ing out of the water a thousand or so yards away.

10-29. The unaided "free" escape of the only survivor from within the conning tower is interesting. As the stern plunged toward the bJttom and the conning tower flooded rapidly through the open upper hatch, this officer held onto the No. 2 periscope tube for support. He at first obtained air by pressing his mouth up into the periscope stuffing box structural housing recess at the top of the conning tower, where a small bubble of air had been entrapped, and then swam under water to the forward end of the conning tower where, due to the extreme up angle of the boat, a fairly large bubble had pocketed between the forward bulkLead and the conning tower hatch. Figuring that he might be able to reach another air bubble topside, he then swam up through the ~C:fil2D:g_ t~v:e: ~a~c~ ~i:_d _f~u:_id_ a_:i ~i_: p~c~e~ ~r~ppe:_d _W:d~i:_ t~e:_ 1:il~~<:_~e l See paragraph 22- 15.

- 119- TANG (SS306) CO"JF-: NTJA, front and the officer-of-the- deck's bridge platfor m. After pausing momentarily in this bubble, and knowing that it was perfectly feasible to make an ascent without the aid of a " lung" , the officer began to swim up as rapidly as he could, expelling air all at one time when part way up, and burst out on the surface just as he thought he would have to inh.5.le some salt water. The bridge deck at this time was about fifty feet below the surface. Of the other eight men in the conning tower, one fell into the control room through the open lower hatch, at stated previously, and a second man is known to have also reached the air bubble trapped under the pilothouse but did not reach the sur face. The remaining six men were either rendered unconscious by the initial detonation or were drowned when the conning tower flooded. lC-30. It is of course obvious that had the tactical situation per mitlt.!d TANG to remain in the position she assumed immediately aftt'r being torpedoed, the escape problem would have been enor mJusly simplified. With the stern on the bottom in 180 feet of water and with the bow about 25 feet out of water, the forward escape trunk du ..>r was only 24 feet below the surface. At this shallow depth it is entirely feasible to make a "free" escape without the aid of a " lung" and without having to vent excess air through the open mouth as is mandatory when escaping from greater depths. All that is required is that the escaping man exhale slightly just prior to leaving the trunk and he can then hold his breath the rest of the way if he so prefers. However, even relatively simple escape problems become difficult when personnel have been rendered physically and mentally debilitated by long exposure to poor atmosphere. The case of HMS THETIS is an outstanding example. THETIS sank in a depth of 120 feet while on trials off Liverpool in June 1939 as a result of opening a torpedo tube breech door with the muzzle door also open. After seventeen hours the crew lightened the submarine aft sufficiently to get the stern out of water. In this position the after escape chamber was only about ten feet below the surface. By that time most of the crew had headaches and breathing was becoming increasingly difficult due to the high co2 content of the atmosphere. The extreme angle of the boat plus the deteriorated physical condition of the crew made movements to the after escape station very trying. Two officers successfully escaped at this time but when the chamber was drained down, water reached the main motor control equipment and started an electrical fire which further depreciated breathing conditions by adding large quantities of smoke to the atmosphere. Only two more men made an escape. The remainder were apparently physically and mentally incapable of making the escape effort even though at this time the escape chamber was still but slightly belo·.v the surface.

10-31. TANG's loss illustrates the following points:

(a) A surfaced submarine in maximum diving trim which sus- tains pressure hull damage of sufficient magnitude to cause immediate flooding of two or more adjacent end compartments will probably up- end

-120- CONFIDENTIAL TANG (88306) CONFIDENTIAL

so rapidly that the crew will in all lidelihood not be able to abandon ship prior to sinking.l ,2

(b) In the event of (a), if damage control measures are promptly executed it is probable that watertight integrity can be established at one of the escape stations plus several intermediate compartments as the boat sinks.2

(c) Assuming the boat then hits bottom in a depth suitable for escape operations, some or all of those men who manage to make their way to an escape position should, by properly carrying out the escape procedure, be able to reach the surface either with the aid of "lungs" and an ascendlng line or by "free" escapes. 2 TANG represents the only known case n the history of the U.S. Navy of individual underwater escapes from a disabled submarine in either war or peace.

(d) Wartime training methods were apparently not sufficiently rigorous to install adequate confidence in, and knowledge of, the escape procedure.

1 On her fourth war patrol, BESUGO (88321) secured one torpedo hit on a surfaced German submarine, U- 183 (740 tons). The U-boat sank in 2 to 4 seconds. There was only one survivor and he was carried far underwater. 2 While operating under Com SubsSoWesPac on her fourth war patrol, the Dutch submarine HNMS ZWAARDVISCH secured one torpedo hit in the forward torpedo room of a surfaced German supply submarine (1600 tons). The German boat is reported to have sunk in about 30 seconds. Twenty-one men escaped after the submarine reached bottom in 120 feet of water. The major~ty of these men made "free" escapes from the control room while only a few used breathing equipment.

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CONFIDENT'AL - 123- CONFIDENTIAL

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- 124- COl\JFIDEl\Jf:AL CO NF ID ENTIAL PLATEX

TORPEDO DAMAGE PLATE Y CON F I D EN TI A L

SK E TCH NO. 2 SKETCH NO. I SURFACE TORPEDO STRUCK IN WAY Of AFTER TORPEDO SURVIVORS LEVELED 80'AT OFF ON BOTTOM ROOM OR MANEUVERING ROOM WH I LE BOAT BY FLOODING NB T. NOS. 2A,2B,2C AND 20. WAS SURFACEO.BOAT PLUNGED BY STERN ASCENDING LINE AND BUOY WERE THEN R I GGED IMMEDIATELY AFTER BEING H I T BUT BOW FROM FORWARD ESCAPE TRUNK . SEE PARAGRAPHS REMAINED UP DUE TO BUOYANCY OF INTACT 10·19 THROUGH 10- 29 FOR ACCOUNT OF ESCAPE FORWARD CONPARTMENTS. BOAT ASSUMED ------ATTEMPTS 40 DEGREE UP ANGLE WITH STERN ON BOTTOM IN ABOUT 180FEETOFWATER ANO ABOUT 2!! FEET OF BOW PROJECT! NG ABOVE SURFACE . I M MED I A T E F LOODING DUE TO TORPEDO DAMAGE AFT 180'

180 ' FLOOD I NG WHICH OCCURRED THRO UGH OPEN CO NN I NG T OWER UPP'ER HATCH

NOR MA L F UE L OIL AND F UE L BALLAST TANKS ( F ULL I OF OI L ANO / OR SEA WATER AT ALL TI MES )

NORMA L FUE L OI L TANKS BREA CHED TO SEA

FLOODE O DELI BERATELY BY SHIPS FORC E OCEAN FLOOR OCEAN FLOOR INDETERM I NATE A MOU NT OFWATER NORMAL L Y PR E SEN T FOR TRIM OF BOAT ABOUT FORTY·FIVE MEN REACHED ESCAPE POSITION IN FORWARD TORPEDO ROOM. THIRTEEN MEN LEFT NIN!OFFICERS a MEN WERE ON BRIDGE THE BOAT VIA THE ESCAPE TRUNK . OFTHESE,EIGHT WHE THE TORPEDO STRUCK FIR E ARE KNOWN TO HAVE REACHED THE SURFACE BUT ONL'THR EE SUR VI VE D, ONLY FIVE OF THE EIGHT SURVIVED UNTIL RESCUED CONNING TOWER FLOODED RAPIDLY THROUGH OPEN BY THE JAPANESE . ------..., UPPER HATCH AS BOAT PLUNGED BY STERN . FUMES FROM F I RE ONE OFFICER MADE "FREE ESCAPE' FROM FLOODED CONNING TOWER AT ABOUT 50 FOOT DEPTH .ONE MAN WAS THROWN THROUGH LOWER C.T. HATCH TO CONTROL ROOM REMAINING SEVEN MEN DROWNED ear SANK so RAPIDLY THERE WAS IN9fflCIENT TIME TO CARRY OUT SMOKE AND FUMES FROM FIRE IN FORWARD ORER TO CLOSE CONNING TOWER BATTERY COMPARTMENT ENTERED FORWARD UPERHATCH . ---.__ TORPEDO ROOM ANO HAD SERIOUS PHYSIOLOGICAL THIS BULKHEAD WT DOOR WAS OPEN WHEN TORPEDO EFFECTS ON SURVIVORS (SEE PARAGRAPHS 10"18 STRUCK. FORWARD ENGi NE ROOM FLOODED ABOUT ANO 10·2!!).~ HALF FULL FROM AFTER ENGINE ROOM BEFORE DOOR WAS SECURED . NOTE THAT DOOR WAS CLOSED AGAINST INCOMING WATER - --- DOOR OPEl'l1BULKHEAO PROBABLY DAMAGED AS RESULT OF TORPEDO HIT.

BOW BUOY ANC Y TANK

O F ~ ER S CVARTERS F WD ENG IN E ROO M A F TER ENG i NE R OO M

N O S . I 8 2 MAIN ENG I NES 8 GENERATORS

.1 2 II 13 1 5 IT '9 2 1 53 55 57 5t 61 •3 sa 11 11 107 109 Ill 11 3 II & 117 I t IU I 3 I 5 l l7 Ill ISi I S 130

INBOARD PROFILE WATER WAS DRAINED FROM ESCAPE TRUNK CONTROL ROOM AND PUMP ROOM FLOODED AFTER TORPEDO ROOM,MANEUVER ING ROOM AFTER EACH ESCAPE ATTEMPT AND SLOWLY THROUGH DAMAGED LOWER C.T. AND AFTER ENGINE ROOM FLOODED IMMEDIATELY AFTER BATTERY COMPARTMENT PART IALLY AFTER FUEL TANKS WERE NO DOUBT BREACHED ACCUMULATED IN FORWARD TORPEDO FIRE STARTED IN)RWARO BATTERY HATCH . SURVIVORS IN THIS COMPARTMENT FLOODED OVER LIGHT BATTERY WELL DECK AS DIRECT RESULT OF TORPEDO DAMAGE . THERE ROOM BILGES . COMPARTMENT A'ER ALL SURVIVORS EVACUATED TO FORWARD TORPEDO ROOM TO SEA BUT THIS HAD LITTLE EFFECT ON TRIM WHEN THE TWENTY SURVIVORS FROM FORWARD OF VESSEL S INCE THEY WERE COMPLETELY FI LLED WERE NO SURVIVORS IN THESE SPACES . HAO REACHED FIWARO TORPEDO ROOM. WHEN WATER LEVEL ROSE TO BULKHEAD \ ENGINE ROOM AND AFTER BATTERY COMPARTMENT WITH O IL OR WATER PRIOR TO DAMAGE. BATTERY JARS NY HAVE BEEN ON FIRE. OOOR LEVEL . CONTROL ROOM WAS THEN OPENED BULKHEAD DOOR TO CONTROL ROOM SEALED. THERE WERE ABOUT FIFTEEN WHILE ENROUTE TO ESCAPE POSITION IN SURVIVORS IN CONTROL ROOM ANO FORWARD TORPEDO ROOM(SEE PARAGRAPH IO·llS). CLAS~IED PUBLICATIONS WERE DESTROYED FORWARD BATTERY COMPARTMENT,ALL TOP PLATING OF AFTER BALLAST TANKS BY BUllNG IN CONTROL ROOM ANO FORWARD OF WHOlll REACHED FORWARD TORPEDO REPORTED BLOWN OFF. THE N0.6 GROUP BATT!Y COMPARTMENT. ROOM. OF MAIN BALLAST TANKS PROBABLY FLOODED AS DIRECT RESULT OF TORPEDO DAMAGE,

NO 2 GROUP OF MAIN BALLAST TANKS WERE DELIBERATELY FLOOOED BY MANUAL OPERATION OF VENT VALVES U.S.S TANG SS-306 IN ORDER TO Lt:VEL BOAT OFF ON BOTTOM. FOR MOSA STRAI T 240CT.'44 TORPE DO DAMAGE NAV'f. DEPT. '

BERGALL (SS320) CONFIDENTIAL

SECTION XI

U.S.S. BERGALL (SS320)

Mine Damage

Gulf of Siam 13 June 1945

Class ...... 88285

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

Commissioned ...... 12 June 1944

Length (overall) ...... 311 ft. 9 in.

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

Submergence Depth (Designed Maximum)(Axis) ...... 400 ft.

Displacements

Standard ...... M...... 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) ...... General Motors 16M278A

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

Reference:

(a) C.O. BERGALL conf. ltr. SS320/Al6-3/A9, Serial No. 0267 of 17 June 1945 (Report of War Patrol Number Five).

CONFIDENTIAL - 125- BERGALL (SS320) CONFIDENTIAL

11-1. While conducting a surface search for a Japanese convoy in the Gulf of Siam on the night of 13 June 1945, during her fifth war patrol, BERGALL sustained d8.mage to propulsion machiner1 as the result of a'1 underwater deto:iatio:i. which occurred close aboard on her port quarter. The detonation is believed to have been caused by actuation of a proximily fuzed mine. Propulsion power was temporarily lost and both reduction gears were damaged, although not seriously enough to render the machinery plant inoperative. As a result of the ensuing high noise level in both reduc tion gears, BERGALL was forced to terminate her patrol. This case is primarily of interest in that it is one of the few war damc.ge experiences which illustrates the effect of a close underwater detonatio:i. on the Diesel propulsion plan~ of a U.S. submarine while running surfaced.! In addition, it is one of the many cases which demonstrates the susceptibility of reduction gears to damage. This report is based on the information con tained in the reference.

11-2. After a two-week refit by the U.S. Navy Submarine Repair Unit No. 137, BERGALL departed Freemantle, West Australia, on 12 May 1945 for her fiith war patrol. On 21 May she arrived on station in her assigned area in the waters of the Gulf of Siam. Altho.igh BERGALL covered her area thoroughly, only two contacts worthy of attack were made. The first was on 30 May when two Japanese tugs and five barges were sunk by the combined use of 20mm, 40mm and 5-inch/25 cal. gun fire at a range of about 600 yards.

11-3. The second contact was made during daylight on 12 June when a slow convoy of two small tankers and one small cargo ship, escorted by one surface vessel and one aircraft, was sighted close inshore and pro ceeding north. BERGALL commenced a submerged approach but range could not be closed to less than 5000 yards due to the shallow waters in which the enemy ships were operating. It was therefore decided to refrain from attacking at that time but to attempt to regain contact with the convoy after dark for a possible night surface attack.

11-4. BERGALL surfaced at 2010 that night and headed north, searching for the enemy convoy along the coast and in likely anchorage areas. Contact had not yet been regained, ho;vever, when at 0110 on 13 June, while investigating the bight in the Gulf of Siam near Kaw Luem, lat. 11° 45'N., long. 90° 50'E., a heavy detonation occurred close aboard BERGALL's port side abreast the maneuvering room. At this moment, BERGALL had just completed her search of the bay and was reversing course with left full rudder. The ship was making about 13 or 14 knots with two engines on propulsion, the shore line was less than two miles distant and the water depth was but 42 feet.

11-5. It is quite likely that the detonation was caused by a proximity fuzed mine, inadvertently actuated by BERGALL, for this particular area had been previously mined by U.S. and British aircraft operating from bases in Asia. A subsequent check of BERGALL' s track disclosed that she had run three miles inside the limits of the minefield. Seventh Fleet Submarines had not at this time been notified of the presence of Allied mines in this area. The field contained both acoustic and magnetic- lone other such case is that of FLYING FISH (SS229) on 24 May 1944 as the result of a premature detonation of one of her own torpedoes. See brief in Appendix I.

- 126- CONFIDENTIAL BERGALL (SS320) CONFIDENTIAL induction gr ound mines of v ar ious types, with explosive char ges r anging from 490 pounds to 700 pounds T PX.l

11 - 6. The impact of the detonation jarred the entir e ship. Personnel were knocked off their feet, tossed out of bunks, and in the maneuver ing r oom wer e thrown up against the over head. Lighting failed in the maneuver ing and after t or pedo r ooms. The overspeed trips operated on Nos. 2 and 3 main Diesel engines, which wer e on pr opulsion, and No . 1 main Diesel engine, which was char ging the batter ies, causing all thr ee engines to stop and ther eby cutting off power to the main pr opulsion motor s . The loss of load on Nos. 1, 2 and 3 gener ator s and the jarring of the contactor s for these gener ators in the main contr ol cubicle caused sever e a rcing acr oss the contactor tips and ignition of the leads. Sever e ar cing also occurr ed acr oss the closed motor bus tie contactor tips in the control cubicle. Inspection disclosed that these contactor surfaces were extensively burned. The No. 4 gener ator r everse current r elay was found to have been r ender ed inoper ative.

11 -7. P r opulsion was quickly shifted to the for war d and after batter ies, enabling the ship to get under way again within a few minutes after the detonation. Loud knocking was hear d in the port reduction gear and to a lesser extent in the star board gear. The port shaft was secur ed imme diately to pr event possible additional damage to the por t reduction gear and BERGALL pr oceeded to clear the area on the star board shaft only. No enemy inter fer ence was encountered.

11-8. AJ5 stated above, when the detonation occurr ed, BERGALL was r eversing course with full left rudder. The steering system was in power operation. Electrical power to the steer ing motor was lost at once due to fuzes in the motor contr ol panel jarring out of their holders. This occurred in spite of the fact that these holder s wer e of the improved high impact design. The casing on the lower after bearing of the port tiller ram was torn loose although the bear ing itself appeared undamaged. The rudder jam.med hard against its stops but after shifting to hand operation at the change valve in the contr ol room, steering control was regained in time to steady on the desired escape course. No difficulty was experienced with the rudder in hand operation. The rudder angle indicator transmitter worm wheel was jarred out of mesh with its rack on the tiller ram and remained out of commission until repaired several hours later. In the intervening period, rudder angles were determined by the after torpedo room rudder angle indicator and relayed to the control room and bridge by sound powered telephone.

1 The records of this minefield indicate that it contained a total of 6 acoustic and 28 magnetic-induction type mines. All were aircraft laid ground mines. Types and numbers of these mines were as follows: 6 - U.S. Mk. 13, Mod. 5 (Acoustic, 490 pounds TPX) 6 - U.S. Mk. 26, Mod. 1 (Magnetic, 525 pounds TPX) 3 - U.S. Mk. 36, Mod. 1 (Magnetic, 635 pounds TPX) 2 - U.S. Mk. 13, Mod. 0 (Magnetic, 700 pounds TPX) 2 - British A-Mk. V (Magnetic, 675 pounds Minol) 15 - British A- Mk. VII (Magnetic, 620 pounds Minol)

- 127- BERGALL (SS320) CONFIDENTIAL

11 - 9. Chlorine gas was r eported in the for ward battery compar tment immediately after the detonation and this space was pr omptly sealed. It was found, however, that a vinegar jug in the galley had br oken and the erroneous chlorine gas repor t o r iginated when the vinegar fumes were carried through the supply ventilation system to the for ward batter y room. The compartment was ther efore opened up again.

11- 10. By 0130, twenty minutes after the damage occurred, two main Diesels had been started again and put on pr opulsion. Both batter ies were secured. Normal power operation of the steer ing system had been regained. BERGALL headed for the mouth of the Gulf of Siam, still using the starboard shaft only. At 0445 power was put on both shafts and speed was increased to 14 knots. The port reduction gear was very noisy at this speed but the vibration was not considered dangerous.

11- 11. At 0705 BERGALL submer ged, stopped the por t shaft and opened the port reduction gear inspection plate. No tooth damage was apparent but the after end of the port gear casing was found to have shifted 3/16 of an inch outboard on the bedplates, the studs apparently having either been bent or sheared.

11 - 12. Since the noise level of the r eduction gear s was too high to permit submerged approach on escorted ships, and the lack of contacts to date in that area indicated little likelihood that an opportunity might present itself for a night surface attack during the few days remaining of her scheduled on- station period, BERGALL terminated the patrol and proceeded to Subic Bay, P . I., for further inspection and repairs.

11-13. With the exception of one sheared holding-down bolt outboard and aft on No. 4 main engine, and the operation under impact of the overspeed trips for Nos. 1, 2 and 3 main engines, no damage occurred to the Diesel engines proper and they performed satisfactorily until the next Navy Yard routine overhaul. The bushing on the engine air starting lever twisted loose, however, resulting in considerable loss of air (500-pound) from the air starting flasks. There was no other reported damage to equipment or systems in either of the two engine rooms. No damage occurred forward of the engine rooms with the one exception of bent slip rings on the SJ radar antenna.

11-14. In the maneuvering room, no damage occurred to 'he main control cubicle other than that mentioned in paragraph 11-6 above. Various minor derangements were found in this space, however, such as sheared studs, fractured welds on brackets, displacement of sheet metal bulkheads, etc.

11-15. In the motor room, a considerable leak developed around. the port stern tube packing. Adapters on the lubricating oil lines were cracked at the forward bearings for main motors Nos. 1, 2 and 3 and at the after bearing of main motor No. 4. The bearing caps on Nos. 3 and 4 main motor bearings were found to have been loosened.

-128- CONFIDE!\JT,AL BERGALL (SS320) CO NF l DENTIAL

11-16. The dog operating mechanism of the upper hatch for the after torpedo room access trunk spun open and it is interesting to note that the holding turnbuckles, which had been installed during the previous refit, were all that prevented this hatch from opening.

11-17. Considerable damage occurred to the operating gear of the after torpedo tubes. The emergency poppet valve for tube No. 9 jammed in the open position. The torpedo tube blow and vent manifold was jarred loose and the studs holding the vent-closing valves of the poppet system for tubes Nos. 7, 8 and 9 to the underside of the blow and vent manifold were sheared. The stop bolt rods on the four after torpedo tubes were distorted, resulting in minor leakage into the boat through the packing glands at the after trim tank bulkhead. Later inspection dis closed that three of the four after torpedo tubes were distorted to the extent that the torpedoes within had to be removed by chainfall and re loads could not be made. Both the hydrogen burning panel and the Mk. 18 torpedo charging panels were torn loose from their mountings. The track locking mechanism on one torpedo handling skid was broken. One Mk. 27 torpedo was thrown up from its stowage rack and struck the bunk above, causing a slight dent in the case of the TPX-loaded warhead.

11-18. BERGALL arrived at Subic Bay on 17 June 1945. Since investi- gation- of the damages indicated that complete repairs were beyond the capacity of local forces, the ship was ordered to the Navy Yard, Ports mouth, N. H., where she arrived on 5 August. There complete war damage repairs together with routine over haul and outstanding alterations were accomplished, the major item of work being repairs to the main reduction gears. Both of these gears were removed from the ship for complete inspection. On the port reduction gear, the noisiest one, it was found that the outboard pinion had been driven into the bull gear by the shock of the mine detonation. The gear assembly was considered mechanically satisfactory for it had been used during the entire 10,000-mile run to the U.S. east coast from the Philippines. However, although all points of observable impact were stoned, the high noise level in this gear could not be reduced to meet satisfactory operational requirements. It was then sent to the manufacturer for reconditioning and a new port reduction gear assembly was installed in the ship. The starboard reduction gear was found to be only slightly damaged and was returned to the ship after repairs by the Navy Yard. All work was completed and BERGALL was returned to service on 19 November 1945, about five months after the initial damage was incurred.

11 - 19. That BERGALL did not sustain more severe damage from the detonation was due to the fact that the mine was actuated while still at an estimated distance of between 90 and 120 feet from the hull, well outside the sertous damaging- range of the mines known to have been in this field. Since both acoustic and magnetic proximity-fuzed mines are known to have been present in BERGALL 's vicinity, it is not possible to determine which type of mine caused the damage.

CONF IDE NTIAL - 129- BERGALL (SS320) CONFIDENTIAL

11-20. The sensitivities of such proximity-fuzed mines are normally set for the average acoustic or magnetic characteristics of the vessels they are intended to act against so that detonation will occur when within a range calculated to cause severe or lethal damage. It is entirely possible for such mines to be swept at relatively harmless distances when the actuating influence is considerably greater than expected. For example, in the case of acoustic mines of the sonic frequency type, such as those in this field, the frequency and intensity of sound generated by submarine Diesel propulsion plants is understood to be capable of causing detonation at a considerably greater range than surface ship steam propulsion plants.

11-21. The magnetic- induction type influence mine is fuzed to detonate when the rate of change in the surrounding magnetic field exceeds a pre determined amount. This rate of change is proportional to the ve1ocity of the ship with respect to the mine and, for a given relative velocity, will be greatest when the ship is turning through a north or south magnetic heading. Since BERGALL was reversing course at about 14 knots when the mine detonated, it is probable that her magnetic "influence" was at or near the maximum possible for that speed. It is understood that many U.S. magnetic ground mines are fuzed so sensitively that steel hulled minesweepers are not considered safe when passing overhead in less than 120 feet of water. It is not unusual for magnetic mines to detonate at distances of over 100 feet. BERGALL was ranged at Freemantle, Australia, in November 1944, at which time it was found that her signature was similar to that of an untreated and undegaussed submarine. The ship was again ranged at Pearl Harbor in July 1945, while en r oute to the United States shortly after the damage occurred, and her signature at this time was reported as being satisfactory for the Pearl Harbor area. Due to variation in the earth's magnetic field with latitude, however, this signature would have been 4 or 5 times greater than that of a degaussed submarine for the magnetic conditions existing in the Gulf of Siam where the mine was detonated. This would of course have greatly increased the likelihood of remote operation of a magnetic-induction type mine.

- 130- CONFIDENTIAL GRAMPUS (SS207) CONFIDENTIAL

SECTION XII

U.S.S. GRAMPUS (SS207)

Gunfire Damage

Off Tru.k 17 May 1942

Class ...... SS198

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

Commissioned ...... 23 May 1941

Length (Overall) ...... 307 ft. 2 in.

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

Submergence Depth (Designed Maximum)(Axis) ...... 250 ft.

Displacements

Standard , ...... 14. . 7 5 tons

Emergency Diving Trim ...... 1990 tons

Submerged ...... 2359 tons

Draft (Mean, Emergency Diving Trim)...... 16 ft. 9 in.

Type of Propulsion ...... D.iesel Electric Reduction Drive

Main Engines (4) ...... General Motors 16-248

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

References:

(a) C.O. GRAMPUS conf. ltr. A16- 3/SS207, Serial No. 04 of 17 June 1942 (Report of War Patrol Number Two). (b) C.O. GRAMPUS conf. ltr. Lll-1/SS207, Serial No. 05 of 30 June 1942 (Report of War Damage).

Photographs Nos. 12-1 through 12- 3 (furnished by C.O. GRAMPUS).

CONFIDENTIAL - 131- GRAMPUS (SS207) CONF'DENTIAL

12-1. On the night of 17 May 1942, while conducting a surface patrol off Truk during her second war patrol, GRAMPUS was detected by a Japanese patrol vessel and forced to make a quick dive. While passing 30 foot depth, one shell, believed to have been a 3- inch or 4. 7- inch common projectile, struck the starboard bulwark of the cigarette deck and detonated approximately three feet beyond its point of impact about two feet above the cigarette deck over the main engine air induction trunk. While no damage of a serious or military nature was caused, and GRAMPUS experienced no difficulty in subsequently evading the enemy, the action has been included in this report to illustrate the shrapnel effect of medium caliber projectiles and the obvious vulner ability of submarines to such attacks. While other U. S. submarines have been more heavily damaged by gunfire attack, this experience of GRAMPUS was chosen since it is the only such action in which photo graphs of the damage were available to the Bureau.

12-2. The damage report, reference (b), submitted by the Command ing Officer while the ship was undergoing repairs by arus (Ex-AS20) at Fremantle, W.A., is clear and comprehensive, and is therefore repro duced below in lieu of the usual narrative.

Fleet Post Office San Francisco, California 30 June 1942

From: The Commanding Officer To: The Chief of the Bureau of Ships

Subject: War Damage Inflicted upon U.S.S. GRAMPUS, Report of.

Reference: (a) BuShips ltr. C-FS/Lll-1(374); C- EN28/A2-ll of April 17 1942.

Enclosure: (A) Photographs of subject damage.

1. At 1906 (ZT) on May 17, 1942, the U.S.S. GRAMPUS surfaced on course 270° T., about twenty miles North West of the North pass to Truk Island in approximate Latitude 08 ° -02' -00 11 North and Longitude 151°-301-00" East. This vessel had been conducting sub merged patrol in assigned area. There was a moderate sea from the North Ea.st with a surface wind of about eight knots, estimated visi bility 4,000 yards. At 1910 sighted a light astern that appeared to be a flash of a searchlight. At 1912 changed course to 340° T., and headed away. At 1917 echo ranging was heard on bearing 270° relative. Nothing sighted upon careful observation. At 1927 changed course to 000° T., and went to standard speed on two engines. At 1941 slowed to listen with sound gear. At 1947 simultaneously sighted and picked up with sound a vessel approximately 1500 yards on the starboard beam identified as a Japanese patrol vessel of about 500 tons. Imme diately thereafter, the patrol vessel illuminated with its searchlight. The bridge was cleared and a quick dive was made to escape. At

- 132- CONF1DENTIAL GRAMPUS (SS207) CONFIDENTIAL

1949 while at 30 foot depth, a sharp crack was felt in the vicinity of the bridge. The ship was checked quickly for leaks but no flooding was detected. The ship was ordered to run silently at deep sub mergence. At 1952 upon reaching 100 foot depth, the explosions of three depth charges were felt which were evidently close by. Between 2001 and 2005 eight depth charges were felt and screws and echo ranging heard on sound gear from three different sources. At 2044 one explosion was heard at a long range. Shortly afterwards lost contact with enemy. At 2125 surfaced on course 320° T.

2. A survey of the ship revealed that the following damage had been sustained: (1) Large shell hole approximately 4 feet in diameter in the starboard bulk.head of the cigarette deck. (2) Wooden gratings on cigarette deck splintered. (3) Cigarette deck above engine induction dished in and riddled with shrapnel holes. (4) .50 caliber machine gun mount blown off its foundation and a number of shrapnel holes in the mount. (5) Shrapnel hole about 1/2" in diameter in R.D.F. antenna loop shafting. (6) Port bulkhead and bridge structure including shelter space riddled with shrapnel leaving holes in plating varying from 3 inches in diameter to 1/411 in diameter. (7) Both after radio antennae carried away. None of the damage suffered was of a serious or mili tary nature.

3. The best estimate of the size of the projectile used was of about 4. 7 11 in diameter. It was evidently a· high explosive shell with an instantaneous fuze. The shell pierced the bulkhead and exploded approximately three feet beyond its point of impact just above the engine induction. The fragmentation was small with a wide dis persion. The heaviest plating penetrated by the projectile and the shrapnel was 5 pound galvanized iron plate.

4. The damage was repaired by the repair force of the U.S.S. OTUS at Fremantle, W.A.

E. S. HUTCHINSON

Copies to: COMINCH BUORD

12-3. The damage to GRAMPUS as the result of this attack was super- ficial (Photos 12-1, 12-2 and 12-3) and she remained on patrol in the TRUK area until 5 June, when she departed for Fremantle, W.A., arriving on 17 June. The nature of the damage indicates that a 3 or 4. 7- inch com mon projectile was employed. The larger Japanese anti-submarine ves sels, such as frigates and large gunboats, usually were provided with one or more 12 cm./45 caliber gurn(4.7-inch) with common projectiles having bursting charges ranging from 4 to 7 pounds of TNT or picric acid. Smaller anti-submarine vessels, such as the PC-13 Class, usually mounted one 8 cm./40 caliber gun (3-inch) with common pro jectiles having bursting charges ranging from 1 to 1. 5 poun$ of TNT or picric acid. Special flat-nosed anti-ricochet projectiles were fre quently used by the Japanese for anti- submarine work.

CONFIDENTIAL - 133- GRAMPUS (SS207) CONFIDENTIAL

12-4. Had the projectile struck a foot or so lower, or had GRAMPUS been a second or two slower in diving, serious damage would have re sulted.

12-5. For other cases of gwrlire damage to U.S. submarines, atten- tion of the reader is invited to the following briefs of damage in Appen dix I: SWORDFISH (SS193), 7 February 1943; SKATE (SS305), 6 October 1943; NAUTILUS (SS168), 19 November 1943: BOWFIN (SS287), 28 November 1943; ROCK (SS274). 29 February 1944; RONQUIL (SS396), 17 November 1944: BERGALL (SS320), 13 December 1944; POGY (SS266) 19 April 1945; MUSKALLUNGE (SS262), 8 August 1945.

- 134- CONFIDENTIAL CONFIDENT AL

Ph::ito 12- 1: GRAMPUS (SS207). P r ojectile entry hole in starboard bulwark of cigarette deck.

Photo 12- 2 : GRAMPUS (SS207). View showing fragmentation damage. Proi:ctile is be1ieved to have detunated approximately over the out ooard engine air rnducti0:1 valve about tw0 feet above the cigarette deck.

COt-.ffiDEf'lTIAL CONFIDENTIAL

Photo 12-3: GRAMPUS (SS207). Fragmentation damage, port bulwark, forward end of cigarette deck.

- 136- CONFIDENTIAL GROWLER (SS215) CONFIDENTIAL

SECTION XIII

U.S.S. GROWLER (SS215)

Collision and Machine Gun Strafing Damage

Off New Britain, Bismarck Archipelago 7 February 1943

Class ...... SS212

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

Commissioned ...... 20 March 1942

Length (Overall) ...... 311 ft. 9 in.

Beam (Extreme)...... 27 ft. 3-3/4 in.

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

Dis placements

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) ...... General Motors Model 16- 248

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

References:

(a) C.O. GROWLER coni. ltr. C-88215/Al6 - 3, Serial No. 0153 of 17 Februar y 1943 (Repor t of War Patrol Number Four). (b) CTF 42 coni. ltr. FF12-15(42)/Al6-3/00-jm, Serial No. 057 of 18 February 1943 (Comments on C. O. GROWLER Report of War Patrol Number Four). (c) ComSubRon Eight Coni. ltr. FC5-8/Sll/Lll, Serial No. 054 of 25 May 1943 (Repair s to GROWLER Battle Damage).

Photogr aphs Nos. 13-1 through 13-8 (furnished by Commander Submarine Squadron Eight).

CONFIDENTIAL - 137- GROWLER (SS215) CONFIDfNTIAL

13-1. On 7 February 1943, while on her fourth war patrol, GROWLER underwent the unique experience of ramming and possibly sinking a large enemy patrol frigate. Damage to GROWLER due to the collision and subsequent close quarter enemy machine gun fire was not sufficiently serious to prevent her from making a submerged escape and returning to base in a seaworthy condition. This report is based on the information contained in the references and on interviews with various officers attached to GROWLER. The Photographs were furnished by Commander Submarine Squadron Eight.

13-2. GROWLER arrived at BFisbane, Australia, on 10 December 1942 from her third war patrol. Normal refit was undertaken by FULTON (AS11) and completed on 31 December. On 1 January 1943 GROWLER departed Brisbane for her fourth war patrol and on 11 January reached her assigned patrol area in the waters adjacent to New Britain and New Ireland Islands in the Bismarck Archipelago.

13-3. Although many contacts were made with enemy shipping during her first few days on station, GROWLER was able to close to attack position only once. This occurred on 16 January when she sank a medium-sized freighter northwest of Watom Island with two torpedo hits during a daylight periscope attack. On 20 January GROWLER shifted her patrol area to cover the western approaches to Rabaul and on 30 January damaged a medium-sized freighter near Mussau Island by one torpedo hit during a night surface attack.

13-4. On 2 February GROWLER started patrolling toward Rabaul. On the night of 4- 5 February, when south of Steffen Strait, radar contact was established with an enemy convoy and GROWLER commenced a surface chase. However, with range cbsed to about 5000 yards, she was detected, subjected to medium caliber gun fire and forced to sub merge. Shortly afterwards, two fairly close depth charge attacks of four charges each were delivered by one of the convoy's escorts, the second of which partially blew out the gasket to the No. 1 MBT boiler type manhole cover in the deck of the forward torpedo room.

13-5. Water entered in considerable volume through this opening but not in sufficient quantity to seriously affect depth control and GROWLER managed to lose the enemy escorts about one-half hour later. The leak grew steadily worse, however, and by one hour after the initial attack, water was entering the forward torpedo room at an estimated rate of over 1000 gallons per hour. The drain pump was run continuously on the torpedo room bilges and this sufficed to keep the water level within the compartment under control. An effort was also made to close off the manhole by using a sheet rubber gasket backed by deck plates held in place by shores and two jacks. This measure did not stop the leak but was reported to have prevented it from becoming more serious. Surfacing during daylight hours for repairs was not considered feasible due to the close proximity of the searching enemy anti- submarine vessels and, although diving trim control was poor, GROWLER remained submerged. Upon surfacing after dark, repairs were quickly effected by placing the forward

- 138- CON Fl DENTIAL GROWLER (SS215) CONFIDENTIAL tor pedo room under 7 pounds per square inch air pr essure and renewing the manhole gasket. A trst dive was then made and the new gasket was found to be satisfactory.

13- 6. During 5- 6 February GROWLER remained on submerged patrol off Watom Island. At 2200 6 February orders were r eceived to shift station and GROWLER pr oceeded to her new area on the surface at 17 knots. At 0110 7 February, while in a position about 50 miles off the northwester n end of New Britain Island, lat. 3° 34 1S., long. 151 ° 09'E., GROWLER established contact with a lar ge Japanese conver ted patrol frigate. Visibility was poor and limited to about 2000 yar ds. The enemy ship was just barely discer nible off the starboard bow and was pro ceeding on opposite course. GROWLER immediately turned away, made her tubes ready and then headed directly toward the frigate for a surface torpedo attack.

13- 7. When GROWLER was almost in firing position, with radar r ange of 2000 yards and track angle 130° star boar d to the tar get, the enemy frigate sighted her , immediately r eversed cour se and closed to make a counterattack. This maneuver was appar ently not immediately dis cerned by the br idge on GROWLER although the fir e control party in the conning tower is r eported to have given accur ate radar ranges and to have had the TDC solutio:-i. At 0134, after range to the enemy vessel as indicated by TDC track and r adar was too close to permit torpedo fire, the bridge gave the order " Left full rudder" and sounded the collision alarm. At 0135, while swinging with left rudder and at speed 17 knots, GROWLER rammed the enemy frigate head on, str iking midway between her bow and bridge.

13- 8. The impact of collision was terrific, heeling GROWLER to about 50 degrees and knocking most of the crew off their feet. Imme diately afterwards, the enemy opened fire on GROWLER' s bridge with one or more 13mm machine guns2 at point blank range and on GROWLER the order was given " Clear the br idge". Four of the seven men present on the bridge descended into the conning tower. Two of these men wer e wounded and had to be heloed through the upper hatch. After approxima tely 30 seconds had elapsed since the last man had come below and still no one else had appeared at the hatch, the diving alarm was sounded, upper conning tower hatch was secured and GROWLER submerged. The enemy continued strafing the bridge with machine gun fire until it was under water. It is believed that the three men remaining topside, the Commanding Officer, the assistant Officer of the Deck and a lookout, were killed or seriously wounded by the enemy fire before GR OWLER submerged and for that reason were unable to clear the bridge.

1 As a result of GR OWLER' s experience and reports of similar casualties from other submarines, the Bureau authorized by ShipAlt SS167 of 12 Wiarch 1943 the replacement with welded blanks of the forward and after ballast tank boiler type manhole covers as installed in the torpedo room decks on SSl 75-284. On SS285 and subsequent submarines, such ba:last tank accesses were omitted from the design. 2 Recovered projectiles were measured and found to be 13mm.

-139- GROWLER (SS215) CONFIDENTIAL

13- 9. Damage to GROWLER can be conveniently divided into two categories: (a) damage due to the collision and (b) damage due eilher directly or ·na·rectly to the enemy machine gun fire. Damage due to collision was limited to the extreme forward por tion of the ship. The entire bow structure for ward of frame 10, a length of about 25 feet, was e:ther crumpled or cons.derably distorted and brward of frame 4 was bent about 90 degrees to port (Photos 13- 1 and 13- 2) . This structure consists only of the relatively light plating and framing of the bow buoyancy tank (10- pound MS) . Deck plating back to frame 12 was wrinkled and torn. Bulkhead No. 10 was dished in only about 3/4 inch at the centerline in way of the torpedo tube nest but above the tubes was distorted somewhat more extensively (Photo 13- 3). Grease lines, bow buoyancy tank vent valves and operating gear, and the torpedo tube shutters and operating gear were completely wrecked. On subsequent docking, 1t was found that ~o. 3 torpedo tube shutter had jammed into No. 3 tube outer door gasket groove but that no damage had occurred to any of the forward tor edo tubes roper. The bow planes operated without difficulty and were undamaged with the exception of slight misalignment of tne tilting shaft. Der-th control was reported as be:ng somewhat difficult after tile colhs.on and durillg the return trip to base. This is attri butabk to tne f rotrud ng structure of the damaged bow (Photos 13- 1 and :3- 2) wnicr. dCted as both a fixed plane and "plow' ' at maximum lever- arrrl distance from the turning center of the boat and also blanked off normal flow of water to the port bow plane, thereby con siderab:y altedng !.ts planing effect.

13- 10. Direct materiel damage due to the enemy machine gun fire was in itself relatively minor but the indirect damage caused by resultant flooding became quite serious. Although the br idge and conning tower fairwater were hit in numerous placesl (Photo 13- 4), fortunately only o:ie projectile pierced the pressure hull. This penetrated the br onze upper conning tower hatch while it was in the open position pr ior to diving and tore a hole about 1/2 inch wide and 3/4 inch long (Photo 13- 5). Two other projectiles struck the No. 1 periscope shear pipe structure in the bridge " covered wagon", jamming the per iscope so that it could neither be trained, raised or lowered but caused no damage to the periscope tube itself (Photo 13- 6). Electr ical cables on the bridge for the collision alarm, lMC, sidelights, target bearing tr ansmitters and bridge steering repeater s were shot away. On submerging, water entered the conning tower in large volume through the sheathing of these punctured cables2 in addition to the hatch bullet hole. Although the leaks were observed as soon as GROWLER's conning tower went under, no attempt was made to surface due to the presence of the ene:rriy vessel above nor was the conning tower abandoned. Efforts were made to plug the leaks but wer e largely unsuccessful. Depth was maintained at 150 feet in spite of the floodin:r and the subsequent detonations of two depth charges which were not close and did no damage. ------1 The conning tower fairwater and bridge plating on GROWLER wer e but Ei-pound and 7-1/2 pounj weight MS. As a result of this and other actions, the installation of 25- pound and 30- pound STS plating for the pr otection of bridge personnel was author ized by ShipAlt SSl 77 of 16 April 1943 for all fleet type submarines subsequent to SSl 97. 2 For further discussion of cable sheathing leaks, see par agr aph Hl- 12.

- 140- CONF'DENTIAL GROWLER (SS215) CONFIDENTIAL

13-11. Water overflowed from the conning tower bilges to the control room deck, where it reached a depth of about 6 inches, and further drained to the pump room bilges where it accumulated to a depth of several feet. Both the trim and drain pumps were continuously operated in an effort to control the flooding. Most of the electrical circuits in the conning tower, control room and pump room grounded out or received minor damage from salt water spray or direct flooding. All gyro, I.C., lighting and heater circuits, and the majority of the electrical panels in these spaces were completely disabled. The ST radar range indicator unit in the conning tower was flooded out. In the pump room many auxiliaries were grounded and, as a result of these short-circuits, a small fire broke out in the No. 2 auxiliary power panel aft in the maneuvering room. This was promptly smothered by co2 fire extinguish ers and all circuits were temporarily pulled with the exception of the field circuits for the main generators. Several small hydraulic and air piping an:i fitting leaks developed in various places as a result of the collision impact, but these were not serious and were either tightened up, isolated, or left as is.

13-12. At 0145, the JK-QC sound gear, which had been temporarily deranged (reason not reported), was placed back in commission. How ever, no contact could be established with the Japanese patrol vessel. Since the light hull of the enemy ship must have been opened to the sea over a considerable area as a result of being rammed by GROWLER, it is quite possible that she might either have sunk or become completely immobilized by this time due to progressive flooding. 1

13- 13. At 0201, after approximately one-half hour of submerged rwming since the collision had occurred, and still not having obtained any sound contacts with the enemy vessel, a battle surface was made. No ships were in sight so GROWLER cleared the area by a surface run to the westward. Topside and internal damage was then surveyed and emergency repairs made where possible. The conning tower hatch leak was plugged with a bolt and lead washers. At dawn the ship sub merged once more and remained down until evening. Leaks in the conning tower were still very bad but were under control. A canvas chute was rigged from the conning tower lower hatch through the control room hatch to the pump room bilges and this proved adequate to prevent further water damage. At 1848 GROWLER again surfaced, continued with repair work, and sent a report to Commander Task Force 42 stating that a return to base was being made via the designated emergency routing. During this period the No. 2 periscope, No. 1 high pressure air com pressor, No. 1 low pressure air compressor, and refrigeration and air conditioning units were placed in operating condition and grounds cleared. All remaining leaks were effectively stopped. Diving control was reported as still being somewhat difficult.

1 Japanese records obtained upon the termination of World War II contain no mention of any anti- submarine attack or the sinking of any Japanese ship which could conceivably have corresponded to this action of GROWLER. Japanese records were nortoriously inaccurate and incom plete, however, and it is entirely possible that the enemy patrol vessel may have been sunk and yet never reported as sunk or even overdue to any central Japanese agency.

COt\JFIDENTIAL - 141- GROWLER (SS215) CONFIDENTIAL

13 - 14. GROWLER made the return trip back to base by running submerged during daylight hours while in enemy patrolled waters and running surfaced at night. She arrived alongside FULTON (ASll) at Brisbane, Australia, on 17 February 1943.

13-15. After a survey of the damage it was considered both possible and desirable to undertake complete repairs with local facilities, pro vided damage to the forward torpedo tubes was not extensive. A drydock examination disclosed that the tubes were undamaged and in correct alignment, with the exception of the previously mentioned damage to muzzle door operating gear and shutters. The Eva.:1.S Deakin Company of Brisbane undertook replacement of the damaged bow structure, prefabricating and installing the new bow in two horizontal sections (Photo 13-7). Fittings were salvaged from the damaged structure where possible. The work was accomplished in the Moreton graving dock, Brisbane. FULTON undertook all other battle damage repairs and in addition gave the ship a regular refit. All work was completed and GROWLER was returned to service on 4 May 1943.

13-16. GROWLER's experience illustrates that, should the tactical situation so require, it is possible for modern fleet type submarines to successfully ram light-hulled vessels such as destroyers or patrol craft without necessarily destroying their own watertight inlegrity, seaworthiness and ability to conduct submerged operations. This is principally attributable to the 30 odd feet of non-watertight bow structure ahead of the forwardmost pressure hull bulkheads, in this case the forward and after bulkheads of the forward trim tank. This bow structure effectively cushions collision shock by absorbing the damage in a non-vital area while depleting the relative momentum of the two ships involved, and tends to prevent serious injury to pressure hull structure farther aft.

13-17. GROWLER' s experience also demonstrates the extreme vulnerability of unarmored submarines, when surfaced, to even small caliber projectiles, as from aircraft strafing or light machine gun fire from surface vessels. It was fortunate for GROWLER that the enemy machine gun fire was directed at her bridge instead of her pressure hull or conning tower. Had the latter been the case, the resulting numerous small holes might have prevented GROWLER from 1 ~oth~r- e;~ell;nt ;x~~ple- i~ lli~ ~ol.1i.sio~ bet;e~n-ARGONAuT-(ss475) and HONOLULU (CL48) on 8 January 1946 off the U.S. east coast. The angle of collision was about 30 degrees, ARGONAUT's bow striking about 75 feet aft of the stem on HONOLULU's starboard bow. Although both ships started backing down just prior to the collision, the relative speed of the two ships at the instant of initial contact is believed to have been in excess of 20 knots. Damage to ARGONAUT was very similar to but more severe than that which occurred to GROWLER. The bow forward of frame 11 was completely crumpled and bent 90 degrees to starboard. Minor damage was sustained to plating, framing and the vertical keel between frames 11 and 16 (MBT No. 1) but no damage occurred to the forwardmost pressure bulkhead at frame 16. The outboard and intermediate sections of all forward torpedo tubes were bent to starboard. No internal flooding whatever occurred on ARGONAUT and she remained seaworthy and could have submerged had the occasion required. -142- CONFIDENTIAL GROWLER (SS215) CONFIDENTIAL making a submerged escape after the ramming and in that case the enemy frigate very probably would have completed her destruction. Even presuming GROWLER were to escape the enemy ship on the surface, multiple small holes in the pressure hull and external tanks might still have caused her loss, either by direct flooding or by pre venting submergence if again attacked while making the surface run back to base through enemy controlled waters. Ballistic data shows that U.S. 50 caliber AP (M2) and Japanese 13mm AP projectiles, when fired from within 500 yards range at 0° obliquity, will penetrate both the outer and inner hull of a submarine, assuming the plating to be 3/8-inch and 7/8- inch medium and high tensile steel, respectively. Even when fired at 30° obliquity, and assuming the projectiles tumble after penetrating the outer hull so as to strike the inner hull lengthwise, the 50 caliber and 13mm AP projectiles will pierce both hulls within a range of at least 100 yards.

13-18. After completing six more patrols, GROWLER was lost in action with all hands on 8 November 1944 while attacking a Japanese convoy in the central Philippines area during her eleventh patrol. Information furnished by HAKE (SS256) and HARDHEAD (SS365), both of whom were operating with GROWLER at the time, indicates that the loss possibly occurred either as a result of enemy depth charging or the malfunctioning of one of GROWLER's own torpedoes. During her first ten patrols GROWLER sank 17 ships for a total to.:mage of 74,900, and damaged 7 ships for 34,100 tons.

CONFIDENTIAL - 143-

CONF DENTIAL

Photo 13- 1: GROWLER (SS215). General view looking forward at collision damage to bow. Section forward 01 frame 4 is bent 90 de grees to '.)Ort. This protruding structur<> ir~reased difficulty of maintaining submerged control of ship.

Pnoto 13- 2: GROWL R (SS215). General view from starboard forwud showing collision damage to bow.

CONFIDEN~IA._ - 144- COl\JFIDENTAL

reton r/d CK, N te absencP of t. e t.>rpedo tubes and tr. ir u ... t r 00;1-..;;.

- 4 - CONFIDENTIAL

Photo 13 - 5: GROWLER (3S215). View of conning tower upper hatch, showing 13mm IJr ojectile hole (1/2" x 3/4" ).

Photo 13- 6: GROWLER (SS215). View showing damage to No . 1 perisc.:>pt shcoar trunK rn bridge " covered wagon". Arrows point to the two gouges made by 13m:n projectiles. The periscope was jammed by these gouges so that it could nol be trained, raised or 10wered. However. the oeriscope tube itself was undamaged.

CO"JFIDE~TIAL - 146- CONFIDENTIAL

P!1oto :3- 7: GROWLER (SS215). Upper horizontal section of pre fabricated oow being erected. Lower section already welded in place. Ship is in Moreton DrydocK, Brisbane.

P.1uto 13 - d: GROWLER (SS215). Undocking fron: Moreton Drydoci< on 1 May 1943 with the new bow completely installed.

- 147- CONFIDENTIAL DRAGONET (SS293) CONFIDENTIAL

SECTION XIV

U.S.S. DRAGONET (SS293)

Gr ounding While Submer ged

Off Matsuwa To, Kur ile Islands 15 December 1944

Class ...... SS285

Builder...... Cr amp Shipbuilding Co., Philadelphia, Pa.

Commissioned ...... 6 March 1944

Length (Over all)...... 311 ft. 8 in.

Beam (Extreme) ...... 27 ft. 3- 1/4 in.

Submer gence Depth (Designed Maximum) (Axis) ...... 400 ft.

D isplacem.:ints

Standar d ...... 1525 tons

Emergency Diving Trim ...... 2050 tons

Submerged ...... 2414 tons

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

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

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

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

Main Generator s (4) ...... General Electr ic Co.

References:

(a) C.O. DRAGO:JST coni. ltr. SS293/A16 of 20 December 1944 (Report of War Patrol Number One). (b) C.O. DRAGONET secr et ltr. SS293/A2 - ll/Lll- 1, Ser ial No .1 of 26 December 1944 (Report of Damage Due to Gr ounding). (c) Comdt.Navy Yard Mare Islani coni. ltr. SS2'd3/Sll- 1(360- 718391) of 19 March 1945 (Supplementary Report on DRAGONET Grounding Damage).

Photographs Nos. 14 - 1 thr ough 14- 8 (furnished by Navy Yard, Mare Island.).

PLATE XIV

CON Fl DENTIAL - 148-

DRAGONET (SS293) CONFIDENTIAL

14-1. On 15 December 1944, during her first war patrol, DRAGONET holed and flooded her forward torpedo room as a result of striking an uncharted reef while running submerged off the Kurile Islands, and sank to the bottom in about 90 feet of water. DRAGONET was able to surface only after expelling the water from the torpedo room with sal vage air, and she made the run back to base, through heavy weather, by continuing to maintain an air bubble in the damaged compartment. Although this case cannot be said to have resulted directly from enemy action, it has been included in this collection of war damage experiences to illustrate the problem of a submarine having one end compartment flooded while submerged. It is considered quite possible that other and less fortunate U.S. submarines during World War II may have received damage from enemy action, mines, ramming or grounding, which resulted in the flooding of an end compartment, and that the loss of these vessels may have been caused thereby. This report is based on the information contained in the references and on an informal interview with the then Commanding Officer. The Photo graphs were furnished by Navy Yard, Mare Island. Tne PLATE was prepared by this Bureau from data contained in the enclosures to ref erence (c).

14-2. On 9 November 1944, DRAGONET departed Midway for her first war patrol and on 17 November reached her assigned patrol area in the Sea of Okhotsk and along the Kurile Islands chain. For the next 28 days, until the grounding on 15 December, DRAGONET searched her area thoroughly but no enemy ship contacts worthy of torpedo fire wer e made. Weather conditions were extremely adverse during this period and strong currents and tide rips were experienced when operating close offshore or between islands.

14-3. During the early morning hours of 15 December, DRAGONET was conducting a surface patrol in an area slightly to eastward of the Kuriles chain. It was planned to submerge at daylight at a point about five miles south of the town of Yamato Wan on the east coast of the Island of Matsuwa To and to patrol across the southern approaches to this anchorage. Study of available hydrographic information indicated that navigational hazards in this area existed only close inshore. At 0515 DRAGONi:T submerged in Rashowa Strait to a depth of 100 feet in order to trim the boat. Although the sea was flat calm there were pronounced tide rips which rendered depth control difficult.

14-4. At 0717, in a position six miles south of Matsuwa To, DRAGONET was returning to a depth of 100 feet after a periscope observation at 63 feet, and had reached a depth of 70 feet, when a slight jar forward was felt. At this time the boat was running counter to the current in Rashowa Strait on course 090°(T) and had just rung up a change from one-third speed (1 - 1/2 knots) to two- thirds speed (4 knots). When the jar occurred, the ship had probably reached a speed of only about 3 knots and since observations had indicated that the current was about 2 knots, DRAGONET was probably making only about 1 knot over the ground. A dive angle of about two degrees was being carried. Immediately after receiving the jar forward, the boat assumed a three degree up angle and started to rise.

CONFIDENTIAL -149- DRAGONET (SS293) CONFIDENTIAL

14-5. The first reaction on DRAGONET was that a plane or small patrol craft, not seen by periscope, had located the boat and was dropping depth bombs or charges. Reference (b) states that " the feeling was much the same as experienced during depth charging when explosions are not very close". Enemy aircraft bombing was entirely possible, for visibility was unlimited, flying conditions were excellent and DRAGONET was only about 12,000 yards distant from a lmown seaplane base on Matsuwa To. Available information also indicated that there might be a military air base on the southeast side of the Island.

14-6. Following this reasoning, it was decided to seek safety in depth as quickly as possible and by the time the boat had risen to 58 feet, the negative tank was flooded, a two degree dive angle was ordered and emergency speed was rung up. These actions enabled the boat to gain depth rapidly but when 90 feet was reached, only 10 or 15 seconds after rt:lceiving the first slight jar forward, a series of heavy jolts accompanied by loud noises shook the entire boat and caused it to lurch violently. DRAGONET's speed at this time is estimated to have been about 6 or 7 knots by shaft turns, or about 4 or 5 lmots relative to the bottom. This second and violent jolting was also at first interpreted as another depth charge or bombing attack an::J. orders were issued to proceed to 150 feet and rig the ship for depth charge. Almost imme diately afterwards, however, it was noticed that the boat was hanging at a depth of 92 feet with a dive angle of 20 degrees, the log recorded zero speed, and further jars occurred forward accompanied by loud grinding sounds. It was then realized that the boat had gone aground on a submerged reef or pinnacle and both shafts were stopped at once. The ship had no appreciable list at this time.

14- 7. At about 0718, directly after the second grounding had occurred, word was received in the control room that the forward torpedo room was flooding rapidly (PLATE XIV). The collision alarm was sounded and the forward torpedo room was ordered abandoned. Only four members of the crew were present in that space and they promptly retired to the forward battery compartment. A watertight boundary was immediately established at the after bulkhead of the forward torpedo room by closing the bulkhead door and the bulkhead supply and exhaust ventilation flapper valves. Salvage air (225- pound) was then bled into the torpedo room through the bulkhead connection in an effort to halt the flooding, but was secured when the pressure within the compartment had reached about 55 pounds per squar e inch. Shortly afterwards, word was received in the control room that the torpedo room was " completely flooded". Complete flooding could not have occurred, however, since the rupture in the compartment was just above the watertight deck flat, allowing air to be entrapped in the overhead, and it is presumed that this report was made after the water passed over the top of the sight glass in the bulkhead watertight door. Later inspection disclosed that the water level in the compartment reached a height of about 1 foot above the upper bunks, or about 1- 1/ 2 feet below the overhead of the torpedo room. Since a clock located just below the maximum flood line in the torpedo room stopped at 0720, it appears reasonable to assume that flooding of that space took place in appr oximately two minutes or less.

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14-8. As DRAGONET was pounding violently and lurching with the surge of the current at this time, it was feared that further serious dam age would be sustained and that the hull might possibly break up unless the ship were quickly taken off the rocks. Word was passed to all hands to obtain objects that would float in case the boat might have to be abandoned. At about 0721, 3 minutes after the grounding occurred, the first attempt was made to get off the bottom. All main ballast tanks were blown plus bow buoyancy, negative and safety tanks. Nos. 3, 4 and 5 fuel ballast tanks were empty of oil but due to unfavorable sea conditions had not yet been converted to main ballast tanks by removing the riser blanks, and therefore were not blown since subsequent rapid venting, if the boat were required to again submerge, would have been impossible. 14-9. The increase in buoyancy resulting from the blowing of the main ballast tanks caused the stern of the boat to rise to the surface but the bow remained either on or near the bottom, due to the flooded compartment for ward.1 When the stern rose, it acquired sufficient momentum to consider ably overshoot its point of static buoyancy and surged out of the water far enough to project the extended No. 2 periscope above the surface for a second or two. The Commanding Officer had time only to make a partial sweep to port, but this brief observation disclosed that all was clear in the direction of Matsuwa To. The stern then settled back in the water until it reached its equilibrium point for the static buoyancy condition, the boat assuming a down angle of about 30 degrees. Since both peri scopes went under the surface, no further observations could be taken.

14-10. As the stern was protruding out of water and therefore might be sighted by the enemy, and the bow could still not be raised due to the loss of buoyancy forward, all tanks were again flooded to submerge the ship. This action was taken at about 0730. DRAGONET once more settled to the bottom, in a depth of about 92 feet and with a 16 degree down angle. The ship's heading had non swung from 090~(T) to 110°(T) and the action of the current once again caused DRAGONET to pound heavily on the reef. It was thought at this time that perhaps the bow had been prevented from rising by being wedged in the rocks, so a brief attempt was made to back clear of the reef using emergency power. This proved unsuccessful, however, and the plan was abandoned.

14-11. At 0732 a report was received that the 55-pound per square inch air pressure which had originally been built up in the forward torpedo room had now diminished to 40 pounds and that the water in that compart ment was below the eyeport in the bulkhead door and continuing to recede. A few minutes later, air could be heard blowing outside the torpedo room hull, indicating that the water level in the compartment had been lowered to the point of rupture and the down angle on the boat began to decrease slowly. The order was then given to blow the forward main ballast tank group, bow buoyancy, safety and negative tanks. As this caused the ship to trim by the stern, the after group of main ballast tanks was then blown. The ship rose slowly and surfaced at 0738, in clear sight of the shore establishments on Matsuwa To. When 26 feet was reached, the upper conning tower hatch was opened and the tanks were then blown with the low pressure (10- po..md) air system as in any normal surfacing. 1 For further discussion see paragraph 17 -16.

CONFIDENTIAL -151- DRAGONET (SS293) CONFIDENTIAL

14-12. All four main engines were started immediately and the area was cleared as rapidly as possible by proceeding south at emergency speed. All automatic weapons wer e manned and ammunition was broken out. Fortunately, no enemy interference was experienced as DRAGONET retired. Course was then set for Midway, the nearest Allied base.

14 - 13. The boat was "Inly slightly down by the head on surfacing but was reported to have assumed about 15 degr ees port list, for ruptures in the outer plating of port MBT Nos. 6B and 6D prevented tho;se tanks from being blo..vn below a few feet from the tank tops. Steps were taken immediately to increase freeboar d, to reduce trim by the head and to correct the excessive list. Flood valves on Nos. 3, 4 and 5 fuel ballast tanks, both port and starboard, were opened and these tanks were blown in order to increase freeboard. MBT No. 6A and FBT No. 3A on the starboard side were then made free-flooding to compensate for the 15 degrea port list. All variable tanks were pumped dry with the exception of No. 3 auxiliary, which was flooded as an additional list correction, and after trim tank, which was left about 3/ 4 full in order to add weight aft. No . 6 normal fuel oil ta!l.k was put on service to add weight aft by displacing fuel oil with heavier sea water. Air pressure was maintained on the forward torpedo room through the salvage air system and this kept the water within the damaged compartment at a low level. The after bulkhead of the torpedo room hel:i tight with the exception of a few minor electrical cable stuffing gland l·::aks.

14-14. Heavy seas and high winds built up on 16 December. The bow planes were still rigged out and pounded so heavily that the entire ship vibrated and it was feared that further serious hull damage forward might result. A slight air leak developed around the top of the bulkhead door to the forward torpedo room but did not become serious. One of the bulkhead cable packing gland leaks increased somewhat, allowing water to enter the pantry. The gland nut was located in such a position that it was inaccessible and could not be tightened. When the grounding occurred and the forward torpedo room flooded, the Mk. 18 electric torpedoes in tubes Nos. 1 and 4 were in a partially withdrawn position for charging. Consequently, the inner doors of these tubes were open and the outer doors were closed but not locked. As the water level in the torpedo room was noted to be rising during this perio:i of heavy weather, and salvage air had to be used in increasing quantities to maintain the air bubble in the torpedo room, it was believed that air must be leaking through one or both of the torpedo tube outer doors. Both high pressure air compressors had to be run continuously to provide sufficient salvage air. The three air banks on service were never allowed to drop below 2500 pounds pressure while the two emer gency banks were kept at full pressure.

14-15. By 1800, the storm had increased in intensity. In order to decrease the draft forward and, therefore, the water level in the torpedo room, the contents of NFO tank No. 1 were blown aft into FBT Nos. 5A an:l. 5B. During this transfer, DRAGONET developed a 20 degree port list, indicating that most of the water and oil in NFO No. 1 had ended up in FBT No. 5B, the port tan.1<.. The list shortly

-152- COl\JFIDENTIA._ DRAGONET (SS293) CONFIDENTIAL decreased to about 10 degrees but the ship commenced to roll heavily, reaching a maximum of 40 degrees to port. Compensation was accom plished by opening the floods of FBT No. 5B and blowing its contents to sea but this apparently over-corrected the list, for No. 3 auxiliary tank was then pumped dry.

14-16. By morning of 17 December the seas had abated somewhat, the oow was riding higher and the water in the forward torpedo room was d'Jwn to about 12 inches above the floor plates and appeared to be maintaining this level. However, the bow planes were still pounding heavily. It was therefore decided to attempt to enter the forward torpedo room to rig in the planes, tighten up the torpedo tube outer doors and to determine the extent of damage.

14-17. A party of three officers and two men entered and secured the forward battery compartment. Rescue breathing equipment and " lungs" were carried in case chlorine gas might be generated should sea water inadvertently enter the battery cells from the forward torpedo room. Air prE;ssure was built up in the battery compartment by the salvage air system and the control room bulkhead was then inspected and found tight. The small line to the salvage air gauge for the torpedo room was then disconnected in order to equalize the pressure between the two forward compartments. Bulkhead flapper valves in the hull v.:intilation system were not opened to accomplish this for fear they could not be securely closed again. When the pressure between the compart ments had equalized, the bulkhead door was opened and the party entered the forward torpedo room. As the water level in that compart ment was well below the bulkhead door, no water entered the battery compartment and the rescue breathers and " lungs" were discarded. By worKing in relay.s, the bow planes were rigged in by hand and the torpedo tubes were secured. The air in the torpedo room was foul with oil fumes so oxygen was bled into the compartment to improve worKing conditions.l When the bow rose in the seaway, daylight could be seen through a ruptured area in the pressure hull plating, centered at frame 23, port side, just above the top of the forward trim tank. This was the first positive information that any of ship's company had as to the nature of the damage causing the flooding. Upon completion of the work, the torpedo room was again abandoned and sealed, and the air in the forward battery compartment was bled into the control room. The success of this well-executed and potentially hazardous operation for the safety of the ship removed many of DRAGONET' s diificulties. The bow planes were subsequently further secured by running chains through the rigging gear quadrants in the superstr ucture.

14-18. Heavy seas and winds of gale force were again encountered late in the evening of 17 December and continued until the afternoon of the next day. At 0245 on 18 December, with the seas approaching from the starboard quarter, DRAGONET took a very large roll to port and " hung" ~ ------.... The introduction of pure oxygen into a compartment containing strong petroleum vapors is a potentially dangerous expedient, for it may re sult in an explosive mixture which will ignite upon the introduction of a sparic or open flame. The safest procedure in a case of this nature is to don rescue breatrers or " lungs" when oil fumes become objectionable.

CO!\JFIDEl\I flAL - 153- DRAGONET (SS293) CONFIDENTIAL

'-lt an extreme angle for an appr eciable period of time. This roll was measured on the clinometer in the control room as 63 degrees.1 Men were throwr, frorr. bunks and mercury spilled from the flotation cnamber of the master gyro::;ompass, completely disabling it. Seas fiLed the port side of the oridge, but fortunately did not reach the upper corming tower hatcn. :'he rudder was put at full left and the ship's heading was swunp; tLrougt. iOf> degrees before the ship slowly came bacK to about 20 degrees port li3t. When MBT No. 6A and FB:' Ne. 3A were vented, the ship came upright again, indicating that the flood openings of these tanks may have bt.co1r e exposed by the coincidence of a deep wave trough at the extreme rol1, allowin5 the water within to escape and causing air pockets to form. Both MBT No. 6A and FBT No. 3A had been previously flooded to com perw'1.te for the port list whicr, DRAGONB;T had assumed on surfacing.

:4-l'd. DRAGONET arrived at Midway on 20 December :944. and was docKed tne same day in ARD b for inspection and emergency repairs. Temr;0rary patches were installed over tne holes in the forward wrpedo room pressure hull and the outer plating of MBT Nos. 2B, oB and 6D. The ship departed Midway on 23 December for Navy Yard, Mare Island, and 'lrrived on 4 January 1945. Complete repairs together with many outstanding alterations were accomplished there and DRAGONET was returned to service on 26 March :945 .

• 4-20. StructuraJ. damage due to grounding was found to have occurred in five diiferent areas along the hull, these being de3ignated hereinafter a::- d amages "A" , " B " , , "c" " D " , and " E " . T h e l ocat10n . and nature vf each damage i:;; shown in PLATE XIV and Photos 14- 1 through 14 -8. PLATE XIV also indicates the extent of structural replacements in way of the damaged areas which were accorr,olished by Navy Yard, Mare Island, to effect permJ.nem repairs. It should be c1oted that all of Lhe structural damage areas, with the exception of damage "A" and "B" at the bow, occurred along the port side of tne ship at aoout maximum be1.rn of the ship at eac', point and that no damage was sustained oy tne keel or adjacent structure. This indicates that the ocean floor itself was soft and that the damage was caused by DRAGONET striking the horizontal promontories of an outcropping of rocK.

14 - 21. In connection with damage at "B" (Phows 14- 1, 14- 2, and 14 - 3). it was at iirst believed that the ~ower torpedo tubes, and possibly the entire nest of tubes, were out of line. However, when the ship was docr::ed at Mare Island, oore gaging and a careful inspection disclosed that no damage or misalignment of the tubes had occurred. The damage at "c" to the single (pressure) hull :µlating (37. 5- pound HTS) caused the flooding of the forward torpedo room (Photos 14 -1. 14-4, and 14 - 5). Since that compartment was flooded for several , days, most of the electrical equipment within had to be replaced a.nd all of the ordnance ge'ir had to be overh1.uled. :::>amage at "D" (Photo 14 - o) was extensive to outer shell r.lating but no deformation occurred in the inner hulL The outer hul.:. was breached ir: only one place in this area, a 12- inch crack at frame 49 below the bilge keel (Photo 14- 7) in way of MBT No. 2B. The damage at "E" (Photo 14 - ~) ruptured the outer shell plating of MBT Nos. 6B and UD at about the mid-height of each tank. Since these tanks could be blown down only

1 For further discussion see par agraph 17- 7.

- 154- CONFIDENT'AL DRAGONET (SS293) CONFIDENTIAL to the point of r upture, the r esulting off- center water loading caused the ship to assume a por t list upon surfacing.

14- 22. The 37. 5- pound ID'S shell plating of the forward torpedo room, which was ruptured over a wide area as a result of the grounding, (damage "C"), was cut out of the ship in one section (Photo 14- 4) and sent to the Industrial Laboratory of the Navy Yard, Mare Island, for examination and testing. The mode of fracture (Photo 14- 5) had suggested that possibly this plating on DRAGONET possessed insufficient ductility or other undesirable qualities. Physical tests and chemical analysis on seven ID'S samples from the damaged area, however, indicated that all complied with the requirements of Navy Department Specifications 48- S5- (INT). Although the granular appearance of the torn edges suggested that the crystalline structure of the ID'S plating might have been large, a comparison with another specimen of known quality demonstrated that the damaged ID'S was similar to that in general use. It appears, therefore, that the material was sound and failed as a result of heavy concentrated loading when that area of the hull struck a rocky promontory, although the low temperature of the water, 29°F., may have been a contributing factor.1

14- 23 . DRAGONET' s experience illustrates several pertinent matters. First, the great value of the internal salvage air system as fitted in U.S. submarines was once again demonstrated. Second, the damage which occurred to DRAGONET represents the best available example of what should be expected when a modern heavy-hulled sub marine grounds forward on a har d reef while running submerged at low speed. W~th the trend in submarine design now tending toward increased operating depths and higher submerged speeds, it is con sidered likely that more instances of this nature will occur in the future. Third, this case clearly demonstrates tht: fact that a sub marine on the bottom, with an end compartment flooded, can be brought to the surface in a horizontal attitude only if the longitudinal center of buoyancy resulting from tank blowing is very close to the longitudinal center of gravity. If this condition is not satisfied, only the light end will rise and the ship will assume a spar buoy position, as was the case with DRAGONET on her first attempt to surface. The most obvious method of longitudinally balancing a submarine in such cases is to eject that water which is responsible for the off balance condition by any means available, usually the salvage air systPm. This was the method used by DRAGONET which permitted her to surface on her second attempt. If dewatering is found im possible, then longitudinal moment balance may be achieved by flooding the compartment at the opposite end of the ship and/ or by flooding and blowing only such a combination of internal and external tanks as will offset the moment of the originally flooded compartment and yet provide the maximum reserve buoyancy possible. On DRAGONET,

1 For further discussion see paragraph 16- 25.

CONFIDENTIAL - 15b- DRAGONET (88293) CONFIDENTIAL

for example, if all external tanks aft of and including the No. 6 MBT groups had been left flooded and the after trim tank and after WRT were completely filled, the ship could then have been surfaced, even though the torpedo room was completely flooded, by blowing the amidships and forward MBT, FBT and variable tanks. This loading would have resulted in a reserve buoyancy after surfacing of about 300 tons, or only about 50 tons less than the emergency diving trim condition. It should be noted that normal fuel oil tanks are also available for blowing should such be considered desirable or necessary to achieve longitudinal moment balance.

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OFFICIAL PHOTOGRAPH HOT TO BE RELEASED FOR PUBLIC ATIOH 'IU.YY YNIJ HARE ISLN-Cl .Al CONFIDENTIAL

Photo 14-1: DRAGONET (SS2\:J3). General view looking aft on port side, showing damaged areas resulting from grounding.

Photo 14 - 2: DRAGONET (SS293). View from port side showing damage "B" to torpedo tube shutters and fairing structure.

CONFIDENTIAL - 157- CON Fl DENTIAL

Photo 14-3: DRAGONET (SS293). View from starboard side showing damage "B" to torpedo tube shutters and fairing structure. No mis alignment occurred to torpedo tubes.

OFFICIAL PHOTOGRAPH HOT TD BE RELEA5ED FOR PUBLICATION flj.4'/Y YARf) w,br :A CON!' IOEl\i TiAL I

Photo 14-4: DRAGONET (SS293). View showing close detail of damage " c" to port pressures hull plating (37.5 pound HTS) of forward torpedo room. Small section of plate has been removed for test.

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Photo 14- 5: DRAGONET (SS293). View taken from interior of forward torpedo room looking down and to port, sho-Ning close detail of typical fracture in pressure hull plating (37. 5 pound HTS) at damage " c".

Photo 14- 6: DRAGONET (SS293). View showing damage ''D" in way MBT Nos. 2l3 and 2D. Although considerably deformed, the outer shell plating above the bilge keel was not ruptured.

CONFIDENTIAL - 159- CONFIDENTIAL

Photo 14- 7: DRAGONET (SS293). View showing 12 inch vertical cr ack in A- strake, below bilge keel, at frame 49 in way of MBT No. 2B outer shell plating.

Photo 14- 8: DRAGONET (SS293). View of damage " E" showing r upture and deformation of outer shell plating of MBT Nos. 6B and 6D at wing bulkhead 85 dividing the two tanks. Flooding of these two tanks caused boat to assume 15 degrees por t list on surfacing. - 160- CONFIDENTIAL CONFIDENTIAL PLATEXJY

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