U. S. S. WAHOO - REPORT OF FIFTH WAR PATROL (Period from April 25 to May 21, 1943) PROLOGUE Arrived submarine base, MIDWAY ISLANDS April 6, 1943 after FOURTH War Patrol. On April 7, 1943 commenced refit by Submarine base, relief crew, and ship's force. During April 21 to 22 conducted training exercises underway. Ship ready for sea April 25, 1943. 1. NARRATIVE April 25: 1500Y; Departed MIDWAY under air escort for patrol area via Kuril Islands. Crossed the International Date Line. April 27: Tested new flashless powder during complete darkness. Still our powder is not flashless, but it gives off a diminished flash. This powder cannot be compared with that employed by the Japs against us, on numerous occasions. It is also understood that the British and German's flashless powder is as effective as the Japanese. Furthermore, this powder produces a great amount of smoke and is considered a handicap to the gun crew when firing with an unfavorable wind. April 29: 1555N: Slowed to one engine speed (80-90) due to heavy head seas. April 30: 1000N: Seas having diminished, speeded up to two main engines. 1622L: Upon surfacing from daily submerged drills sheared the shear pins in bow plane rigging mechanism. Stopped; lying to while replacing these shear pins. At 1720L, all repairs completed continued course and speed. May 2: Encountered hail and snow on the morning watch. 1423L: Sighted snow capped mountain peaks on ONEKOTAN ISLANDS of the KURIL ISLANDS. 1639L: Slowed and commenced surface patrol along the KURIL ISLANDS. Will investigate NATSUWA tomorrow in close and submerged. May 3: 0400N; Dived six miles east of NATSUWA and proceeded to reconnoiter the island. Found a four to five thousand ton freighter broken on beach of NATSUWA opposite BANJO TO, apparently a victim of a storm. Fresh appearing paint on the protruding parts indicated that this was a recent wreck. Observed will developed air field consisting of four large hangers with dispersal stowages in back, a large landing field apparently equipped with flood lights, administration buildings, radio station barracks etc. This installation is considered comparable to the air station on Eastern Island, MIDWAY. Took several photographs, and plotted positions of outstanding features on chart included as enclosure "A" then cleared island submerged. 1105K; Due to absence of any plane activity surfaced and continued patrol of the KURIL CHAIN to the southward. The islands observed this far south are barren and completely covered with snow and ice, the installation on NATSUWA being the only indication of any activity. May 4: 0420K; Dived and proceeded to reconnoiter NOYORO MAN on the northeast tip of ETOROFU ISLAND where there are sulphur works. The harbor was jammed with float ice and no activity could be observed. As the currents were apparently causing the ice floes to surround us, changed course to southeast to get clear. ATTACK No. 1 0525K; The O.O.D. sighted, through the morning mist, what appeared to be a small ship or patrol, range about six thousand yards, angle on the bow 30d port. This put him on course parallel to the Island Chain. This observation was confirmed by the Commanding and Executive Officers. Five minutes later the ship changed course presenting a zero angle on the bow. The end on view through the mist prevented identification of the ship as other than a small freighter or patrol until the range was 3,200 yards. At this time he was coming out of the mist and the angle on the bow was sufficient to identify him as a larger target and worthy of torpedo fire. On the next observation identified target as an auxiliary seaplane tender and maneuvered for stern torpedo shots. May 4: 0558L; Fired a divergent spread of three torpedoes using stack, forward goalpost and after goalpost as points of aim, range 1,350 yards, 123d starboard track, speed 11 knots. The first torpedo with torpex head hit between stack and bridge after sixty second run. The torpedo fired at his forward goalpost evidently passed ahead and the one fired aft must have been erratic or a dud. It is inconceivable that any normal dispersion could allow this last torpedo to miss a 510 foot target at this range. The target tooted her whistle, commenced firing to port, away from the WAHOO. and then turned away dropping four depth charges. She was observed to have a slight port list, but was evidently quite under control. As this ship, a KAMIKAWA MARU Class XAV-1 is capable of 21 knots and did not increase speed, it is considered probable that the one hit limited her speed to the 11 knots determined. 0636K; Continued on easterly course to clear ice-pack. 1355K; Surfaced and continued patrol of KURIL CHAIN to southward. Ice floes prevented investigating HITUKAPPU WAN on the south coast of ETOROFU. 2047K; Sent contact report to ComSubPac concerning the XAV-1. May 5-6: Patrolling KURIL CHAIN. May 78: Entered area and closed coast at full speed. 0420K; dived 12 miles from coast off BENTEN ZAKI. Observed two freighters with a destroyer or patrol, and a third lonely freighter pass ahead of us well inshore out of range. ATTACK No. 2 A and B 1039K; Sighted two ships on northerly course, hugging the shoreline. Commenced approach. Leading ship identified as similar to YUKI MARU (5,704 tons) and the second like the YOMSEI MARU (2,861 tons). The second ship however, was dark grey, fitted with gun mounts and was apparently escorting. 1115K; Fired spread to two torpedoes at leading ship, range 900 yards, 107d starboard track, speed 9 knots, followed immediately by a spread of four torpedoes at the escort. The first torpedo hit the YUKI MARU under the stack and broke her back. The second torpedo missed ahead. The patrol turned towards and successfully avoided the four torpedoes fired at her, though how she got between those four torpedo tracks will always remain a mystery. As the YUKI MARU had sunk, went deep and avoided the patrol at full speed then silent running. None of his depth charges were too close. Observed him from periscope depth and cleared vicinity. Heard considerable distant depth charging or bombing and observed planes searching remainder of the day. May 8: Proceeded down coast, skirted fishing fleet, and dived a mile and a half off KONE ZAKI. 0512K; Sighted small ship and made approach. He was running within fifteen hundred yards of the beach, turning into every cove. Broke off attack when he was observed to be too small for torpedo fire. ATTACK NO. 3 1413K; Sighted three ships coming down the coast, commenced approach. The convoy was zig-zagging, and when the range had closed was identified as two escort vessels, similar to the one encountered yesterday, escorting a naval auxiliary similar to the KIHRYU MARU (9,310 tons). 1503K; Fired spread of three torpedoes, range 2,500, 90d port track, speed 10 knots, depth setting fifteen feet. The first torpedo (torpex) aimed at MOT, prematured after 50 second run half way to the target. The second torpedo aimed at mainmast, and down practically the same track as the first, was evidently deflected by the premature or failed to explode. The third torpedo fired at the foremast hit the point of aim but failed to explode. Both sound operators reported the thud of the dud at the same time that a column of water about ten feet was observed at the targets side abreast of her foremast as the air- flask exploded. 1510K; Received first of the series of depth charges expected under these circumstances. May 9: Proceeded up coast with the intention of closing KONE SAKI prior to diving. ATTACK No. 4 A and B 0245K; When 17,000 yards from KONE SAKI by SJ range, the radar operator observed two pips, 15,000 and 15,300 yards on the same bearing with the land. Changed course and tracked target group and in the position they would occupy at dawn, dived to 40 feet. Continued tracking by radar and periscope bearings until range was 7,000 yards, then went to sixty feet. The targets were seen identified as a large tanker and freighter in column, evidently making the night run between ports without escort. 0440K; Fired a spread of three torpedoes at tanker identified as similar to HUZISAN MARU (9,527 tons), range 1,200 yards, 100d port track, speed 10 knots, and immediately thereafter a spread of three more torpedoes at the freighter identified as similar to the HAWAII MARU (9,467 tons), range 1,130 yards 90d port track, speed 10 knots. All torpedoes were set to run at eighteen feet. Just after the fifth torpedo was fired the first hit the tanker amidships breaking her back. She sank by the bow and caught fire aft. The fourth torpedo (a torpex) hit the freighter under the bridge breaking its back, and the fifth torpedo (TNT) hit her aft. She sank by the stern. Attempted taking some periscope pictures in the meager light; then when both ships had sunk cleared the area to the east. Heard distant depth charges or bombs throughout the day, and one echo ranging A/S vessel which passed close on one occasion. Our bathythermograph, which showed a two degree temperature inversion at 170 feet gave us extra confidence in our 300 foot depth. 2020K; Distant explosions and echo-ranging still heard so on surfacing cleared area to northeast to patrol TOKYO-PARAMUSHIRU route. May 10: Commenced submerged patrol on above route. 1010K; Surfaced due to poor visibility and conducted radar search. May 10- Patrolling TOKYO-PARAMUSHIRU route. Nothing sighted except one 11 trawler or patrol which we avoided. May 12: Closed coast and dived two miles off KONE SAKI. Numerous sampans and a glassy sea made periscope observation difficult. 0646K; Sighted light bomber searching vicinity. Heard several fairly loud explosions. 0730K; Sighted another light bomber headed for periscope. Cleared area to the east. Heard numerous distant bombs or depth charges throughout the morning. ATTACKS No. 5 A, B, C, D. 1725K; Sighted distant smoke in the northeast which drew to the south. Commenced approach at standard speed to close the range prior to sunset. Identified target group as two freighters in column, the leading one similar to NYOKEN MARU (4,021 tons) and the second a huge freighter similar to the ANYO MARU (9,257 tons). They were tracked at 9 knots, zig-zagging on base course south, will beyond possible position for submerged attack. 2005K; Surfaced and went after convoy at full speed while charging batteries. 2030K; Sighted smoke of freighters in clear night. 2051K; Picked up freighters on SJ, range 9,400 yards, and commenced working around their stern so that attack could be made with them silhouetted in the setting quarter moon. 2245K; Having determined enemy zig-zag plan, and speed as 8.5 knots, dived in position for a "two ship" shot where they would come by in column. As both freighters were loaded set torpedo depth at 18 feet. 2338K; Fired spread of two torpedoes at ANYO MARU, range 1,200 yards, 95d port track, speed 8.5 knots, and immediately thereafter a spread of two torpedoes at the leading ship, range 1,480 yards, 126d port track, speed 8.5 knots. The first torpedo fired at the mainmast hit. The second torpedo, fired at his stack amidships, is believed to have been erratic or a dud. The target course and speed had been most accurately determined and it is inconceivable that a normal dispersion could cause it to miss. No hits were obtained on the leading ship. The ANYO MARU was now observed still going, so waited until the range had opened to 5,000 yards then surfaced and commenced another "end- around". The moon had nearly set, so gained position for surface attack tracking target by radar with TBT bearings as he came in. May 13: 0107K; Fired last remaining bow torpedo at ANYO MARU, range 1,800 yards, 90d port track, speed 7.5 knots, and then turned with full rudder and speed for an almost identical stern tube shot. Nothing was seen of the bow torpedo or its wake and the enemy apparently did not know he had again been fired upon. 0111K; Fired last remaining torpedo into the ANYO MARU, range 1,800 yards, 110d port track, speed 7.5 knots. Some phosphorescence was observed as this torpedo headed to intercept the target. It hit under the bridge with a dull thud, much louder then the duds we have heard only on sound, but lacking the "whacking" which accompanies a whole- hearted explosion. It is considered that this torpedo had a low order detonation. Some sparks were observed on the target above the impact, but he turned away apparently under control, belching smoke. At this time the NYOKEN MARU which was on our starboard bow opened fire and forced us to dive for six minutes. When we surfaced and closed the ANYO MARU, she was lagging a mile behind the NYOKEN, smoking furiously, and making six knots. We manned the deck gun, but withdrew, quite helpless to stop the cripple, when the NYOKEN turned and rejoined the ANYO. 0225K; Cleared area to east on three main engines. 0336K; Sent message to ComSubPac concerning expenditure of torpedoes. 2200K; Set course for PEARL. May 18: 2105Y; Sighted four ships on starboard bow, two of them appearing to be destroyers. Believe it to be the convoy for MIDWAY which STINGRAY had met earlier. Tracked them on course 290, speed 7, and sent contact report. May 19: 0130Y; Received information concerning possible meeting with convoy. May 21: 1000VK; Arrived PEARL 2. WEATHER Excellent weather was encountered throughout the patrol. 3. NAVIGATIONAL AIDS All lights were burning, but dimmed. 5. ENEMY SHIPS SIGHTED Date : Time : Position :Course : Speed : Type ---------------------------------------------------------------------------- 5/4/43 : 0525K :Lat. 45-20 N : 060d :11 knots: XAV-1 KAMIKAWA : :Long.149-00 E : : : MARU CLASS ---------------------------------------------------------------------------- 5/4/43 : 0420K :Lat. 40-04 N : 170d : 8 KNOTS: 2 FREIGHTERS : :Long.141-54 E : : : 1 DESTROYER ---------------------------------------------------------------------------- 5/7/43 : 0832K :Lat. 39-59 N : 350d : 8 knots: 1 FREIGHTER : :Long.142-04 E : : : ---------------------------------------------------------------------------- 5/7/43 : 1039K :Lat. 40-05 N : 350d : 9 knots: YUKI MARU -(YONIE MARU : :Long.141-53 E : : : GUN MOUNTS) - ESCORT ---------------------------------------------------------------------------- 5/8/43 : 0512K :Lat 39-02 N :VARIOUS: 8 knots: SMALL SHIP : :Long.141-58 E : : : (1,000 TON) ---------------------------------------------------------------------------- 5/8/43 : 1413K :Lat. 39-02 N : 210d :10 knots:2 ESCORT VES(CONVT'D AK) : :Long.142-02 E : : :1 AUX (KINRYU MARU) ----------------------------------------------------------------------------- 5/9/43 : 0245K :Lat. 38-57 N : 210d :10 knots:TANKER HUZISAN MARU : :Long.141-49 E : : :FREIGHTER HAWAII MARU ----------------------------------------------------------------------------- 5/11/43 : 1520K :Lat. 39-27 N :VARIOUS: SLOW :SMALL PATROL BOAT OR : :Long.122-16 1/2 E: : :TRAWLER ----------------------------------------------------------------------------- 5/12/43 : 1725K :Lat. 39-40 N :ZIGGING:8.5KNOTS: 2 FREIGHTERS: MYOKEN & : :Long.122-24 1/4 E: 180d :7.5KNOTS: ANYO MARU ----------------------------------------------------------------------------- 6. DESCRIPTION OF PLANES SIGHTED. DATE & TIME : TYPE : LATITUDE : LONGITUDE : COURSE : ALTITUDE --------------------------------------------------------------------------- 5/7/43 1400K: SMALL : 40d - 00'N : 141d - 53'E :CIRCLING: MEDIUM --------------------------------------------------------------------------- 5/12/43 0636K: LIGHT : 39d - 22'N : 142d - 09'E : 000d : MEDIUM : BOMBER : : : : --------------------------------------------------------------------------- 5/12/43 0730K: LIGHT : 39d - 22'N : 142d - 15'E :VARIOUS : MEDIUM : BOMBER : : : : 5/14/43 1218K: SD RADAR : 38d - 43'N : 151d - 20'E : - - - : - - - :4.5 MILES : --------------------------------------------------------------------------- 7. SUMMARY OF SUBMARINE ATTACKS --------------------------------------------------------------------------- : (1) : (2)A : (2)B --------------------------------------------------------------------------- ATTACK : XAV : AX : ESCORT --------------------------------------------------------------------------- TIME : 1958 : 0115 : 0115 DATE - G.C.T. : 3 MAY 1943 : 7 MAY 1943 : 7 MAY 1943 --------------------------------------------------------------------------- LATITUDE : 45 - 20 N : 40 - 05 N : 40 - 05 N LONGITUDE : 149 - 08 E : 141 - 53 E : 141 - 53 E --------------------------------------------------------------------------- NUMBER AND TYPE OF TORPEDOES: 3 - XIV3A : 2 - X1V3A : 4 XIV3A FIRED ON EACH ATTACK : (1 TNT - 2 TPX) : (2 TPX) :3 TPX 1 TNT --------------------------------------------------------------------------- HITS : 1 TPX : 1 TPX : 0 --------------------------------------------------------------------------- NUMBER SUNK (TONNAGE) : 0 : 5,704 : 0 --------------------------------------------------------------------------- NUMBER DAMAGED OR : 1 DAMAGED : : PROBABLY SUNK (TONNAGE) : 15,650 : 0 : 0 --------------------------------------------------------------------------- TYPE OF TARGET : XAV - 1 : AK : PATROL : KAMIKAWA : YUKI MARU :(2,500 CONV) --------------------------------------------------------------------------- RANGE : 1,350 : 900 : 900 --------------------------------------------------------------------------- TYPE OF ATTACK: PERISCOPE(P): : : SURFACE(S) NIGHT(N) RADAR(R): (P) : (P) : (P) --------------------------------------------------------------------------- ESTIMATED DRAFT OF TARGET : 28' : 26' : 22' --------------------------------------------------------------------------- TORPEDO DEPTH SETTING : 12' : 15' : 15' --------------------------------------------------------------------------- BOW OR STERN SHOT : STERN : BOW : BOW --------------------------------------------------------------------------- TRACK ANGLE : 123d S : 107d S : 089d S --------------------------------------------------------------------------- GYRO ANGLE : : : 353:353 :201:203:205 : 009:016 : 355:353 --------------------------------------------------------------------------- ESTIMATED TARGET SPEED : 11 KNOTS : 9 KNOTS : 9 KNOTS --------------------------------------------------------------------------- FIRING INTERVAL : 11 SEC; 9 SEC : 10 SEC :13S:18S:22S --------------------------------------------------------------------------- SPREAD - AMOUNT AND KIND : DIVERGENT : : :(DIFF PTS OF AIM) : DIVERGENT : DIVERGENT --------------------------------------------------------------------------- WAS TORPEDO PERFORMANCE SATISFACTORY? : YES : YES : YES -------------------------------------------------------------------------- : (3) : (4)A : (4)B --------------------------------------------------------------------------- ATTACK : AK : AO : AK --------------------------------------------------------------------------- TIME : 0503 : 1840 : 1840 DATE - G.C.T. : 8 MAY 1943 : 8 MAY 1943 : 8 MAY 1943 --------------------------------------------------------------------------- LATITUDE : 39 - 02 N : 38 - 57 N : 38 - 57 N LONGITUDE : 142 - 02 E : 141 - 49 E : 141 - 49 E --------------------------------------------------------------------------- NUMBER AND TYPE OF TORPEDOES: 3 - XIV3A : 3 - X1V3A : 3 XIV3A FIRED ON EACH ATTACK : (1 TNT - 2 TPX) : (2 TPX 1 TNT) :2 TPX 1 TNT --------------------------------------------------------------------------- HITS : 0 : 1 : 2 --------------------------------------------------------------------------- NUMBER SUNK (TONNAGE) : 0 : 9,527 : 9,467 --------------------------------------------------------------------------- NUMBER DAMAGED OR : : : PROBABLY SUNK (TONNAGE) : 0 : 0 : 0 --------------------------------------------------------------------------- TYPE OF TARGET : AK : AO : AK : KINRYU MARU : HUZISAN MARU :HAWAII MARU --------------------------------------------------------------------------- RANGE : 2,900 : 1,200 : 1,200 --------------------------------------------------------------------------- TYPE OF ATTACK: PERISCOPE(P): : : SURFACE(S) NIGHT(N) RADAR(R): (P) : (R) (P) : (R) (P) --------------------------------------------------------------------------- ESTIMATED DRAFT OF TARGET : 28' : 28' : 28' --------------------------------------------------------------------------- TORPEDO DEPTH SETTING : 15' : 18' : 18' --------------------------------------------------------------------------- BOW OR STERN SHOT : BOW : BOW : BOW --------------------------------------------------------------------------- TRACK ANGLE : 090d P : 100d P : 090d P --------------------------------------------------------------------------- GYRO ANGLE :001:002:359 : 340:335:334 : 357:355:352 --------------------------------------------------------------------------- ESTIMATED TARGET SPEED : 10 KNOTS : 10 KNOTS : 10 KNOTS --------------------------------------------------------------------------- FIRING INTERVAL : 12 SEC; 23 SEC : 17 SEC 13 SEC :13SEC 14 SEC --------------------------------------------------------------------------- SPREAD - AMOUNT AND KIND : DIVERGENT : DIVERGENT : DIVERGENT --------------------------------------------------------------------------- WAS TORPEDO PERFORMANCE SATISFACTORY? : NO* : YES : YES --------------------------------------------------------------------------- REMARKS: * I DUD, 1 PREMATURE, 1 ERRATIC RUN. --------------------------------------------------------------------------- : (5)A : (5)B : (5)C --------------------------------------------------------------------------- ATTACK : : : --------------------------------------------------------------------------- TIME : 1338 : 1338 : 1507 DATE - G.C.T. : 12 MAY 1943 : 12 MAY 1943 : 12 MAY 1943 --------------------------------------------------------------------------- LATITUDE : 38 - 40 N : 38 - 40 N : 38 - 52 N LONGITUDE : 142 - 53 E : 142 - 53 E : 143 - 00 E --------------------------------------------------------------------------- NUMBER AND TYPE OF TORPEDOES: 2 - XIV3A : 2 - X1V3A : 1 XIV3A FIRED ON EACH ATTACK : (1 TNT - 1 TPX) : (1 TPX 1 TNT) : TPX --------------------------------------------------------------------------- HITS : 1 : 0 : 0 --------------------------------------------------------------------------- NUMBER SUNK (TONNAGE) : 0 : 0 : 0 --------------------------------------------------------------------------- NUMBER DAMAGED OR : : : PROBABLY SUNK (TONNAGE) : 9,257 : 0 : 0 --------------------------------------------------------------------------- TYPE OF TARGET : AK : AK : AK : ANYO MARU : MYOKEN MARU : ANYO MARU --------------------------------------------------------------------------- RANGE : 1,200 : 1,200 : 1,800 --------------------------------------------------------------------------- TYPE OF ATTACK: PERISCOPE(P): : : SURFACE(S) NIGHT(N) RADAR(R): (R) (P) (N) : (R) (P) (N) : (R) (P) (N) --------------------------------------------------------------------------- ESTIMATED DRAFT OF TARGET : 30' : 24' : 30' --------------------------------------------------------------------------- TORPEDO DEPTH SETTING : 18' : 18' : 18' --------------------------------------------------------------------------- BOW OR STERN SHOT : STERN : STERN : BOW --------------------------------------------------------------------------- TRACK ANGLE : 095d P : 126d P : 090d S --------------------------------------------------------------------------- GYRO ANGLE : 190:183 : 149:150 : 008:1/2 --------------------------------------------------------------------------- ESTIMATED TARGET SPEED : 8.5 KNOTS : 8.5 KNOTS : 7.5 KNOTS --------------------------------------------------------------------------- FIRING INTERVAL : 14 SECS : 15 SECS : ------- --------------------------------------------------------------------------- SPREAD - AMOUNT AND KIND : DIVERGENT : DIVERGENT : ------- --------------------------------------------------------------------------- WAS TORPEDO PERFORMANCE SATISFACTORY? : YES : YES : NO* --------------------------------------------------------------------------- REMARKS: * APPARENTLY A DUD. ----------------------------------------------- : (5)D ----------------------------------------------- ATTACK : ----------------------------------------------- TIME : 1911 DATE - G.C.T. : 12 MAY 1943 ----------------------------------------------- LATITUDE : 38 - 52 N LONGITUDE : 143 - 00 E ----------------------------------------------- NUMBER AND TYPE OF TORPEDOES: 1 - XIV3A FIRED ON EACH ATTACK : 1 TNT ----------------------------------------------- HITS : 0 ----------------------------------------------- NUMBER SUNK (TONNAGE) : 0 ----------------------------------------------- NUMBER DAMAGED OR : PROBABLY SUNK (TONNAGE) : 9,257 ----------------------------------------------- TYPE OF TARGET : AK : ANYO MARU ----------------------------------------------- RANGE : 1,800 ----------------------------------------------- TYPE OF ATTACK: PERISCOPE(P): SURFACE(S) NIGHT(N) RADAR(R): (R) (S) (N) ----------------------------------------------- ESTIMATED DRAFT OF TARGET : 30' ----------------------------------------------- TORPEDO DEPTH SETTING : 18' ----------------------------------------------- BOW OR STERN SHOT : STERN ----------------------------------------------- TRACK ANGLE : 110d S ----------------------------------------------- GYRO ANGLE : 162 ----------------------------------------------- ESTIMATED TARGET SPEED : 7.5 KNOTS ----------------------------------------------- FIRING INTERVAL : ------- ----------------------------------------------- SPREAD - AMOUNT AND KIND : ------- ----------------------------------------------- WAS TORPEDO PERFORMANCE SATISFACTORY? : YES 8. ENEMY A/S MEASURES The A/S vessels encountered definitely belonged to the second team. They invariably dropped single charges after attempting to locate us by stopping to listen. Aircraft were used to search in conjunction with these vessels, but arrived too late to be effective on all but one occasion. Only one echo ranging vessel was encountered. Their doctrine seems to require dropping lots of charges and bombs whether they know the submarine's location or not. The A/S vessels observed were all converted freighters with gun mounts fore and aft and characterized by black and white checkered painting forward and after of the bridge structure. 9. MINE SWEEPING OPERATIONS No mine sweeping operations were observed. 10. MAJOR DEFECTS No major defects were experienced. 11. COMMUNICATIONS Radio reception was good and was complete. No difficulty, other than ineffective enemy jamming and spurious transmissions, was encountered in clearing messages to NPM on 8,470 Kcs. The loop coupling adapter was tested regularly. In the KURILS, NPM could usually be copied at 60 feet, occasionally as deep as 65 feet. In the area results were not as good, reception being difficult at 60 feet. Last Serial received - Comsubpac Serial 74 Last Serial sent - WAHOO 192230 May. 12. SOUND CONDITIONS AND DENSITY LAYERS Sound conditions in the KURILS were fair to poor. The one ship sighted was not heard until at a very short range. In the area sound conditions were good to excellent. Ships were picked up at 5,000 to 8,000 yards. In the KURILS water temperature varied from 28 to 34 degrees depending upon proximity to land, ice floes, etc.; however, no pronounced gradients were encountered. In the area water temperature was usually 36 to 40 degrees. All types of gradients were encountered. In the extreme case of May 9, ten miles east of KONE SAKI, the temperature dropped from 37 degrees to 32 degrees in going from periscope depth to 100 feet. It is felt that this alone prevented the echo ranging AS vessel from gaining sound contact. The bathythermograph was used constantly during dives and was very valuable for predicting the sound conditions existing. 13. HEALTH AND HABITABILITY Health and habitability were excellent, except for one threatening case of appendicitis during return voyage. 14. MILES STEAMED Enroute to Area............................. 2,964 In Area..................................... 803 From Area................................... 3,061 15. FUEL OIL EXPENDED Enroute to Area............................. 8.68 gal. per mile. In Area..................................... 8.53 gal. per mile. From Area...................................15.80 gal. per mile. 16. ENDURANCE FACTORS Torpedoes.................................. NONE Others..................................... Indefinite. 17. PATROL ENDED Patrol ended by orders of ComSubPac after expenditure of all torpedoes. FC5-10/A16-3(FB5-102) SUBMARINE SQUADRON TEN Serial 086 In Care Of Fleet Post Office, San Francisco, California, May 22, 1943. CONFIDENTIAL From: The Commander Submarine Squadron Ten. To : The Commander Submarine Force, Pacific Fleet. Subject: U.S.S. WAHOO, Fifth War Patrol - Comments on. 1. The fifth war patrol of the U.S.S. WAHOO was again outstanding in aggressiveness and efficiency. In ten action packed days the WAHOO delivered ten torpedo attacks on eight different targets. 2. Although the results were gratifying, faulty torpedo performance cut positive results probably as much as 50%. Such must have been a source of keen disappointment to the Commanding Officer and personnel of the WAHOO. Seven hits were observed of twenty-four torpedoes fired, for a score of 29.2%. One of these seven was believed to have been of low order detonation. 3. During this patrol, aggressiveness, determination and fighting spirit of the Commanding Officer, officers and crew again manifested in the excellent results obtained. The Commander Submarine Squadron Ten takes pleasure in congratulating the Commanding Officer and personnel on inflicting the following damage on the enemy: SUNK AK (YUKI MARU Class).................................5704 tons AO (HUZISAN MARU Class)..............................9527 tons AK (HAWAII MARU Class)...............................9467 tons TOTAL 24698 tons DAMAGED XAV-1 (KAMIKAWA MARU Class)..........................15650 tons AK (ANYO MARU Class).............................. 9257 tons TOTAL 24907 tons FF12-10/A16-3(5)/(16) SUBMARINE FORCE, PACIFIC FLEET Serial 0484 In Care of Fleet Post Office, San Francisco, California, May 29, 1943. CONFIDENTIAL COMSUBPAC PATROL REPORT NO. 164 U.S.S. WAHOO - FIFTH WAR PATROL From: The Commander Submarine Force, Pacific Fleet. To : Submarine Force, Pacific Fleet. Subject: U.S.S. WAHOO (SS238) - Report of Fifth War Patrol. Enclosure: (A) Copy of Subject War Patrol Report. (B) None. (C) Copy of Comsubron 10 conf. ltr. FC5-10/A16-3 (FB5-102) Serial 086 of May 22, 1943. 1. The U.S.S. WAHOO's fifth war patrol was the third for the present commanding officer. Typical of the previous two patrols, this on was carried out in the same aggressive and successful manner. These three patrols establish a record not only in damage inflicted on the enemy for three successive patrols, but also for accomplishing this feat in the shortest time on patrol. The WAHOO has sunk a total of 93,281 tons and damaged 30,880 more in only twenty-five patrol days. 2. Once again the WAHOO utilized all the weapons available in conjunction with wound strategic and tactical judgement. This combined with team work of personnel made this fifth war patrol another outstanding example of how to conduct submarine warfare. 3. The Commander Submarine Force, Pacific Fleet, congratulates the Commanding Officer, Officers, and Crew of the U.S.S. WAHOO for this their third successive aggressive and successful war patrol during which the following damage was inflicted on the enemy: SUNK 1 Freighter (YUKI MARU Class) 5,704 tons 1 Tanker (HUZISAN MARU Class) 9,527 tons 1 Freighter (HAWAII MARU Class) 9,467 tons TOTAL 24,698 tons DAMAGED 1 Ex-Seaplane Tender (KAMIKAWA Class) 15,650 tons 1 Freighter (ANYO MARU Class) 9,257 tons TOTAL 24,907 tons C. A. LOCKWOOD, Jr.