Subject: U.S.S. WAHOO - REPORT OF FOURTH WAR PATROL. (Period from February 23 to April 6, 1943) PROLOGUE: Arrived PEARL on February 7, 1943 from THIRD War Patrol. Commenced refit by tender, relief crew and ships force. Shifted 4" gun from aft to forward and mounted a third 20mm gun on the former 4" gun foundation. Completed refit on February 15, 1943. Readiness for sea February 17, 1943. Conducted training February 17 to 19 inclusive. Dry-docked at SuBase PEARL February 21, 1943 for emergency repairs to No 5 torpedo tube shutter. Cleared and painted bottom. Undocked ship February 22, 1943. 1. NARRATIVE: February 23: 1300VW; Underway from Pearl for patrol area via MIDWAY. With surface escort until dark. February 23-27:Enroute MIDWAY encountering generally rough weather with mostly head seas. Conducted daily dives and training. Sighted several friendly planes enroute. February 27: 0600Y; Picked up air escort on 30 mile circle bearing east from MIDWAY. 0830Y; Moored starboard side to the port side of U.S.S. Tarpon, at SuBase MIDWAY. 1430Y; Departed MIDWAY for patrol areas having taken on 16,000 gallons fuel oil and 2,500 gallons fresh water. Crossed International Date Line. February 27 to March 11: Enroute to patrol areas conducting daily training dives, fire control drills and battle surface drills. Had the unique experience of making passage from Pearl to inside of the CHINA SEA without sighting a plane and consequently made to entire trip on the surface. The seas were generally rough and from ahead. Had to slow to one engine speed several times, because of excess fuel consumption per mile. During the first torpedo control drill after leaving MIDWAY, the gyro-setting indicator regulators were found to fail intermittently. For ten days Lieutenant R. H. HENDERSON, spent practically every moment when off watch in tracing out these troubles, finally locating them in loose connections and in improperly adjusted overload relay micro-switch. Through his untiring efforts the equipment was placed in proper operating condition prior to entering the area. He is deserving of the highest praise. It is gratifying to have a torpedo officer of his calibre aboard. March 11: 0110I; Entered assigned area. 0610I; Commenced submerged patrol in assigned area and along the NAGASAKI - FORMOSA shipping route. Seas were flat calm. March 12: During the night sighted many lighted sampans which were always in pairs. 0555I; Dived in the SHIMONOSEKI - FORMOSA trade routes, hoping the "Beauty" the U.S.S. SUNFISH hit would limp through today. It was perfect approach weather. Our plan of operation is to spend a day in each of their known shipping routes while we work our way up north where we hope to locate the route where the heavy traffic from the Yellow Sea flows into the Inland Sea via SHIMONOSEKI. 1342I; Sighted masts. Conducted approach only to identify two steam driven sampans about 500 tons each. 1728I; Sighted small (60 foot) motor sampan. Sighted numerous lighted sampans during the night and kept clear. March 13: 0600I; Dived with MAOA TO light, just off the Southwest coast of SAISHU TO, bearing 358dT. distant 6 miles where the SHANGHAI - SHIMONOSEKI traffic could pass. Also some Yellow Sea traffic could round this corner. 0700I; Sighted another small motor sampan. 0814I; Sighted smoke. Commenced approach which lasted almost five hours. The closest we could get was about 8,000 yards. Finally abandoned the approach. A peculiar mirage prevailed. As far as we could tell it was a small Inter-Island type steamer. It was either acting as a smoking decoy and patrol boat or it was trawling. We nick-named it "SMOKY MARU". 1640I; (FIRST ATTACK). The same SMOKY MARU headed directly for us. Went to battle stations and made approach. At 1704I fired one torpedo from a stern tube at 1,000 ton ship, range 1,000 yards, 90d port track, speed 12 knots. Missed, a few feet ahead of target. After our long chase this morning and being anxious to shoot something, we let him have just one. He was the type of target worth one torpedo if you sink him, but not worth two torpedoes under any conditions. The torpedo was set to run at five feet. The sea was light (condition 2), however it is believed the torpedo ran shallow. It was seen to porpoise just ahead of the target. It is possible the target did not sight it, because afterwards he held a steady course and speed. Miss was due to error in estimating mast-head height. We guessed 75 feet. Actually it was about 55 feet. This was determined by timing the run of the torpedo when it broached just ahead of the target. Target similar to U.S.S. GUDGEONS sketch of the "Q" ship but without any guns. His turn count gave him 10 turns per knot. Other boats in this area will no doubt sight this type of ship in the future. 1815I; Just as the target was going over the horizon another SMOKY MARU came out to relieve the watch. We avoided. Sighted many lighted sampans during the night. March 14: 0600I; Dived with KAKYO TO light bearing 000dT. distant 3 miles, in position to intercept some of the Yellow Sea traffic which rounds the corner for SHIMONOSEKI especially traffic from TSINGTAO. 0645I; Sighted another SMOKY MARU. He acted as if he was patrolling. He was towing nothing, yet his speed was five knots or less on various courses. The sea was flat calm. The temperature had dropped from 68d to 48d over night. 0804I; SMOKY MARU, after making a wide circle, speeded up to 10 knots. Sighted smoke. Commenced approach. During the approach had as many as five SMOKY MARUs in sight. It certainly looked as if they were acting as decoys drying to sucker us away from a good sized target that might be smoking. 1015I; Abandoned approach after establishing all targets as too small for torpedo fire. Some of these vessels remained in sight during the entire day. Sighted many lighted sampans during the night. March 15: 0600I; Dived with HEMPUN TO bearing 355dT. distant 11 miles. This was believed to be the route taken by a large volume of the Yellow Sea traffic to JAPAN. Visibility had slightly decreased with a light haze. 1414I; Sighted small patrol or gun boat range about 8,000 yards. When we swung ship to approach course, we lost him in the haze and were unable to regain contact. Sighted many lighted sampans during the evening. March 16: 0150I; Radar contact 10,000 yards. 0200I; Radar contact 3,200 yards and immediately sighted vessel resembling a destroyer with a very sharp angle on the bow and with moon in back of us. Dived and pointed own ship towards target for a possible "down the throat" defensive shot. Lost sight of the target when the range was about 1,400 yards. The target was not a destroyer, but another SMOKY MARU. 0320I; Surfaced when SJ radar failed to pick up anything. 0600I; Dived with CHU TO light bearing 138dT. distant 11 miles. 0620I; Sighted another SMOKY MARU. He was making radical and frequent zigs at 7 knots speed. This MAIKOTSU SUIDO is definitely not a good place for submarine attacks. It is shallow, with islands and shoals everywhere. However, we considered it worth while to reconnoiter to see where this Yellow Sea traffic is located. We call this channel "Sampan Alley". Sighted several lighted sampans during the night. 1940I; Upon surfacing set course North and when we crossed the path of the ships sighted by the U.S.S. HADDOCK we changed course and followed this track heading us for the proximity of SHANTUNG PROMONTORY. Our SJ radar went out of commission during the night. We have no technician aboard, but Lieutenant C.C. Jackson II and our leading radioman have been relieved of all duties, while concentrating on this valuable instrument. MARCH 17: Did not dive this morning. Visibility was excellent and sea calm. Had some difficulty in dodging all of the junks and trawlers to prevent being sighted. 0800N; Dived on what we thought was a plane contact. After talking it over, considered contact was very likely a flight of three geese. Stayed submerged while a few junks got out of sight. 1000H; Surfaced. 1055H; Dived. Too many trawlers and junks were in sight to dodge all of them. This area appeared to be a shipping route too. A half dozen trawlers remained close to us the remainder of the day. 1835H; Surfaced. Many lighted sampans sighted during the night. March 18: 0455H Dived with SHANTUNG PROMONTORY light bearing 231d distant 19 miles. The weather started out hazy and finally ended up with a thick fog. Remained submerged while we worked on SJ radar. Took a few soundings. Weather cleared up at the end of the day. Radar is back in commission. Congratulations to Lieutenant C.C. JACKSON II and J.P. BUCKLEY, RM1c. Upon surfacing set course for ROUND ISLAND light off the entrance to DAIREN. We are bound and determined to find some traffic. March 19: 0422H; (SECOND ATTACK). Sighted freighter. Went to full power and gained position ahead, tracking with radar. 0455H; Dived when light enough to see through periscope. 0515H; Fired one torpex torpedo at medium sized freighter identified as KANKA MARU, 4,065 tons, range 750 yards, 120d port track, speed 9 knots. Hit. After part of ship disintegrated and the forward part sank in two minutes, and 26 seconds. These Torpex heads carry a awful wallop. 0520H; Surfaced to see if anyone survived that blow. Lots of debris and a row boat were observed but no one left to tell on us. 0530H; Sighted another ship. 0535H; Dived. Ship turned out to be a junk. So commenced submerged patrol off DAIREN. 0755H; (THIRD ATTACK). Sighted freighter with large angle on the starboard bow. Commenced high speed approach. We had to run over seven (7) miles. 0916H; Fired two Torpex torpedoes at what appeared to be a new freighter or naval auxiliary in ballast with guns forward and aft; similar to the TOTTORI MARU 5,973 tons, 125d starboard track, speed 9 knots, range 1,800 yards. First torpedo hit under his foremast with a terrific blast, but his bow remained intact, however, we could see a tremendous hole up his side. Second torpedo hit him amidships, but it was a dud, The co-approach officer saw a small plume and both sound operators heard the thud of the dud. 0921H; Checked the set up and fired another torpedo. The target maneuvered and avoided. 0926H; Fired fourth torpedo right up his rump. Again the target maneuvered and avoided. Target fired at periscope. We certainly hated to see this one go over the hill. The water is so shallow around here, we cannot afford to tangle with a concentration of patrols. That dud cost us one fine ship plus two other precious torpedoes and a chance to shoot at more targets at this spot. 0930H; Continued submerged patrol heading away from the scene of the morning engagements. Except for one day of fog, the weather has been perfect. Tonight we are patrolling along the route our two victims came in on yesterday. It leads to a light off the KOREAN COAST and just South of CHINNAMPO. We shall patrol off of this light tomorrow. No small fishing boats sighted to-night - the first time "no-see"!! March 20: 0310H; Sighted ship. Commenced approach. 0440H; Dived. 0515H; Broke off the approach when target turned out to be a small patrol or trawler. The visibility was so good that this small craft was sighted at an unusually long range. Sighted several smoking ships well inshore and over the horizon. We are going over there to-night and patrol off CHOSAN MAN Point tomorrow. The traffic to CHINNAMPO, a large port, must pass that point, so we hope to have some luck. March 21: The currents encountered around this port were really strange, but conformed with those shown on the chart. 0510H; (FOURTH ATTACK). O.O.D. picked up ship with a range about 7,000 yards and angle on the bow 30d starboard. Commenced approach immediately. At second observation ship had changed course 60d to his right putting us on his port bow so we swung ship again and closed at high speed. 0700H; Fired three torpedoes at large freighter identified as SEIWA MARU 7,210 tons, range 1,600 yards, 117 port track, speed 11 knots. Third torpedo hit him amidships and he went down by the bow attaining a vertical angle and was out of sight in four minutes. We counted 33 survivors in the water (temperature of water and air 40d F). There was debris for the survivors to cling to. Considered they could last but a couple of hours. Took several pictures. This was a torpex head and the really blow a ship to pieces and the sound is terrific to us. Twice a wash basin has been knocked off the bulkhead in the forward torpedo room. 0930H; (FIFTH ATTACK). O.O.D. sighted ship range 13,000 and angle on the bow 5d starboard. Maneuvered for a stern shot. 0958H; Fired a spread of three torpedoes at large freighter identified as NITU MARU, 6,543 tons, 87d starboard track speed 10 knots range 800 yards. Two torpex torpedoes hit, one under his bridge and the other under the mainmast. This ship went down vertically by the bow and was out of sight in three minutes 10 seconds. Had the water been deeper he would have sunk faster, because the bow was resting on the bottom as it sank. Two junks were nearby and they appeared to be heading to pick up survivors. Ordered battle surface to destroy the junks. 1037H; Surfaced and found junks fleeing away instead of heading for the survivors. We chased them, but when we were within two miles of the beach and nearing shoal waster we broke off the chase. Also we were just outside of a large port and we did not want to invite trouble, so we headed back for the survivors. Decided to hunt for anything worth salvaging and pick up a survivor. We found four survivors. Two on the bottom of one overturned boat, one on the bottom of another over-turned boat and a fourth floating by in a life jacket. We attempted to pick up at least one of them. They seemed to ignore us entirely. After a few minutes of this indifference we said to hell with them and went after something worth salvaging. Picked up a couple of House Flags which we cannot identify. One large life ring with S.S. NITU MARU - TARUNI painted on it and a large book which appears to be a Merchant Marine Manual. 1138H; Departed this area at full power and then commenced a surface patrol heading for SHANTUNG PROMONTORY at two- third speed. March 22: Patrolling off SHANTUNG PROMONTORY. Weather has freshened up with seas and wind from the northwest and horizon slightly hazy. 0700H; Made trim dive and inspected main motor that was noisy. Found loose brush and repaired it. 0815H; Surfaced and continued surface patrol now heading for a point off LAOTIEHSHAN PROMONTORY which is just around the corner from PORT ARTHUR. We believe we can contact some CHINWANGTAO traffic here. 1400H; Dived upon sighting two power sampans. 1435H; Surfaced when they appeared to be trawling, and continued on towards our new patrol area. There is, no doubt, a lot of shipping in this area, but one must find it to sink it. We believe we are heading for a good spot. There is never much water in this "wading pond" known as the Yellow Sea. We have to be careful with our angle on dives to keep from plowing into the bottom. Aircraft and patrols have been scarce, because we are in virgin territory, however, she "ain't" virgin now and we are expecting trouble soon. We hope to get at least four more ships and then expend our gun ammunition on our way home. We have sighted lots of fishing junks, sampans, trawlers, etc., but only a few cargo carrying junks. March 23: 0043H; Sighted small ship with sharp angle on the bow and dove. Commenced approach, lost our target in haze. 0305H; Surfaced and continued toward our patrol station. LAOTIGHSHAN [sic] CHANNEL can be also called "Sampan Alley". We were literally surrounded by them. Strongly believe the ship we just dived for was a junk, because after surfacing we saw a junk that looked like our target. 0410H; (SIXTH ATTACK). Sighted small freighter and commenced approach tracking by radar. Checked his course and speed and attained position ahead. 0430H; Dived continuing approach. 0443H; Fired one TNT torpedo at medium sized collier, identified as KATYOSAN MARU, 2,427 tons, range 1,000 yards, 88d port track, speed 8 knots. Hit collier just under the bridge. The ship was immediately enveloped in a screen of coal dust. She settled fast and slowed down. 0457H; Surfaced to head for our patrol point,. It was now the crack of dawn and we had about ten miles to go. The collier we had hit thirteen minutes earlier was not in sight. 0535H; Dived when it was getting so light we believed we might be sighted from the beach. Since this collier appeared to be about the same size as the one we sank the other day we had decided to hit her with a TNT war head to see if we could obtain a comparison. Our conclusion is that all TNT war-heads should be converted to Torpex, because they cannot compare to Torpex. Torpex has the necessary force to sink ships. 0923H; Sighted a SMOKY MARU near PROMONTORY, about ten miles away. He was probably going to try and gain some face for the "NIPS". 1003H; SMOKY MARU must have dropped a depth charge. Something like a far-away depth charge was heard. 1004H; SMOKY MARU dropped second depth charge. 1031H; Third depth charge. 1032H; Fourth depth charge. 1830H; Surfaced and set course for a point a little to the Northwest of ROUND ISLAND which is off DAIREN. We feel the shipping will avoid coming into DAIREN direct and will attempt "an end run". Had to run the gauntlet again as we passed through "Sampan Alley". They have secured the light on ROUND ISLAND, so we know they are rerouting their traffic. March 24: 0505H; Sighted single float type airplane. 0645H; Sighted smoke and commenced approach. If we took the normal approach course, the target and WAHOO would end up behind the breakwater at DAIREN. Knew we could not close the target sufficiently for an attack, but we closed at high speed just to check his course and position. 1330H; Established the "NIPS" end run route and commenced heading for it. This freighter was between 4 and 5,000 tons. She passed 16,000 yards ahead of us. We hope to get a couple of ships over on this route within the next day or so and before the "Nips" learn of our presence. 1924H; (SEVENTH ATTACK). Radar made contact at 10,000 yards bearing about 090dT. This was considered fine radar and operator performance as the contact was noticed on the same bearing and just short of land contacts. This indicated to us that we had a ship and that we were right on its track and we were about to stop their endrun play. Commenced surface approach tracking by radar and maneuvered for a stern shot. It was quite dark. 1949H; Fired a spread of three torpedoes at a large tanker with engines aft, identified as SYOYO MARU 7,499 tons, range 1,700 yards, track 80d starboard, speed 12 knots. The first two torpedoes had premature explosions at end of 18 second run. Third torpedo missed. 1955H; Fired fourth torpedo and it missed. 2000H; The tanker let go several 4 or 5 inch rounds at a range of about 3,000 yards using the Nip's famous flashless powder. One of the shells landed directly ahead us and burst with a loud bang. We dived and tracked the target. Here again faulty torpedoes frustrated an attack, wasted four valuable torpedoes that we have carried over 5,000 miles, almost caused the WAHOO to be destroyed, and allowed the target the time to open up on its radio and frustrate our newly discovered , fertile, shipping route. 2014H; (EIGHT ATTACK). Surfaced after fourteen minutes of ducking target's shots. He was still shooting, but it must have been at random as he had not seen us the past fourteen minutes. Went ahead full power to get up ahead of this fellow quickly or we would both end up in DAIREN HARBOR. 2054H; When were well ahead and had the target in the middle of a rising moon we dived. 2122H: Fired a spread of three torpedoes at target 1,200 yards range, 90d starboard track, target speed 10 knots. Second torpedo with TNT head, hit him in the engine room. He sand in 4 minutes 25 seconds going down by the stern. The target was loaded to the gills with fuel oil. It is interesting to note that when we tracked this target at slow speeds we get one target speed and when we were making high speeds, we obtained another target speed. The slow speed tracking is more accurate. This is caused by pitometer log inaccuracy. 2134H; Surfaced and headed south for another likely spot off O TO Light. March 25: 0157H: (NINTH ATTACK). Sighted ship. He had a green light burning constantly which appeared in every respect to be his starboard sight light. Three hours prior to this our SJ radar training gear jammed and we were still trying to repair it when this contact was made consequently had to conduct approach without radar. The moon was bright, so maneuvered for a favorable position ahead. 0355H; Dived and commenced submerged approach. 0436H; Fired a spread of two torpedoes at a medium sized freighter, later identified as the SINSEI MARU 2,556 tons, range 1,300 yards, 87d starboard track, speed 8 1/2 knots. First torpedo exploded prematurely at the end of 26 second run. Second torpedo exploded prematurely at the end of a 49 second run and about fifty yards short of target. 0444H; (FIRST GUN ATTACK). Battle surfaced. First 4 inch shot it target in after deck house at 3,800 yards range. Closed in on target and raked him with 20mm. and holed him with almost 90 rounds of 4 inch. Target caught fire in several places. Her life boat was dangling from the forward davit. Passed about twelve survivors in the water all sort'a chattering. The crew yelled to the survivors, "So Solly, Please". 0510H; (SECOND GUN ATTACK). Lookout reported ship on the horizon. Proceeded at flank speed to investigate, leaving first freighter on fire and listing. Upon closing found target to be a neat little diesel driven freighter quite similar to HADACHI MARU, 1000 tons, but definitely a cargo ship. 0535H; Commenced firing on second freighter with 20mm. and 4 inch. He caught fire several times, but the fire was extinguished by her crew or it went out on its own accord. She speeded up to about 13 knots and appeared to be trying to ram the WAHOO. We had no trouble in keeping clear. A member of her crew was in the foretop waving his arms - maybe he was conning ship. A few 20mm. hits in his vicinity caused him to slide down a guy wire like a monkey. Repeated gun fire soon had her blazing all over and dead in the water. Quartermaster reported first freighter listing badly during this engagement and before cease firing he reported first freighter sinking rapidly, and finally she was seen to sink. 0614H; After expending 170 rounds of 4 inch and about 2,000 rounds of 20mm. on these two freighters, proceeded on our course for our patrol point off O TO Light. Anyone who has not witnessed a submarine conduct a battle surface with three 20mm. and four inch gun in the morning twilight with a calm sea and in crisp clear weather, Just "ain't lived." It was truly spectacular. Our deck took a beating. Practically every blast of the 4 inch would give a hit on the target and a partial hit on the WAHOO. The wooden decking would tear and take off with each shot. 0625H; Watched freighter sink through No. 1 periscope. 0640H; Aircraft contact. Dived. This is bad for us, because it spoils our new hunting ground. The aircraft is bound to have seen the freighter burning and then sink. So remained submerged conducting high periscope observations. 1222H; Sighted large passenger freighter with large angle ont he bow with range about 16,000 yards. Commenced high speed approach. Took observations at 8,000 yards generated range. Our set- up checked surprisingly well. Continued high speed approach. Took another observation when generated range was 5,000 yards. Target had reversed course and the range was about 12,000 yards. It was possible the target sighted us, but we doubt it. We believe he had an air escort or an aircraft hovering our area warned him. Anyway we lost the best target we have seen this trip. 1345H; Sighted aircraft. Something was evidently cooking. As our battery was low, we cleared the area on new course at best speed. 1458H; Sighted a new destroyer range about 8,000 yards, angle on the bow 15d port. He searched with his Q.C. Went to 150 feet, and rigged for depth charge. As water was about 30 fathoms deep, did not dare tackle this fellow with only two torpedoes aboard which from late experience would likely be prematures. It hurt our pride to have to hide in our shell and crawl away. 1655H; Heard one distant explosion. This could have been either a bomb or depth charge. The pinging had ceased after getting very faint. We figured our Dog Dog had no chance of finding us then. He may have picked up one of the two freighters sitting on the bottom and depth charged it. 1855H; Surfaced and cleared present area on three engines. 1012H; (THIRD GUN ATTACK). Sighted trawler. 1020H; Opened up with 20mm. guns and 4 inch on a diesel trawler of about 100 tons. Holed him several times. A few fires started, but was so water-soaked they soon died out. Threw aboard some home made MOLOTOV cocktails concocted and manufactured by the MIDWAY marines. They didn't burn well, due probably to the water- soaked wood. This trawler had a nice radio antenna which he probably opened up on. 1050H; Departed leaving the trawler in pretty much a wrecked condition. It was rough to board her. Otherwise we could have had fresh fish and also opened up some sea valves in her. During this engagement all three 20mm guns were jammed at the same time. These guns really do jam often. Our cooling tubes prevented several explosions like we had last trip. The guns actually boil all the water out of these tubes. Other boats should get larger tubes. March 28: Conducted surface patrol on SHIMONOSEKI - FORMOSA shipping routes. We have no had a good fix since night of the 25th. Took occasional soundings throughout the day. 1235H; Dived on radar contact; did not sight the plane. 1338H; Surfaced. Visibility was poor all day. 1800H; (FOURTH GUN ATTACK). Sighted two lighted motor sampans (FISHI MARUS). 1808H; Opened up with two 20mm. guns on the two sampans. 1820H; Secured 20mm. guns and crews after expending about 500 rounds on each sampan. They did not sink, but they have a lot of holes in them and they are quite wrecked. It was still to rough to go aboard for a mess of fresh fish. Our mouths watered at such a possibility. March 19: 0255H; (TENTH ATTACK). Sighted ship, and commenced radar tracking. 0400H; Dived when we had gained a favorable position ahead and it was light enough to see the target through the periscope. 0416H; Fired a spread of two torpedoes at fairly large freighter identified as KIMISIMA MARU 5,193 tons, range 900 yards, 90d port track, speed 8 1/2 knots. First torpedo hit under his mainmast which was our point of aim and completely disintegrated everything abaft of his stack. The forward section sand two minutes and thirty- two seconds later. The torpedo was set at 15 feet due to rough seas. This was a Torpex head and it is believed was an influence explosion. The target made a lot of noise as she sunk and broke up. We all could hear it through the hull. The second torpedo was aimed at the foremast. It missed, because the first torpedo stopped the foremast in its tracks!!!!!!! 0426H; Surfaced and headed for our base. All torpedoes expended. Made surface transit through COLNNETT STRAIT during daylight. We had a lot of small craft and a small freighter in sight, all at the same time. They did not bother us and we kept right on going. 0740I; Departed out of area. 0845I; Dived on radar contact. Did not sight the plane. 0935I; Surfaced. 1935I; Good SJ radar contact at 9,200 yards. Did no investigate nor did we sight anything. March 30: 1827I; Good contact on the SJ radar at 9,800 yards. Did not investigate nor did we sight anything. 1910I; An unusual swell washed over the bridge and flooded the main induction. Water entered the maneuvering room through the auxiliary induction causing waster to partially flood the main cubicle. Several zero grounds were created which in turn started many small fires making the control station untenable by a very caustic smoke. All main propulsion stopped and out of commission. All forced ventilation stopped. Immediately opened all battery cut-out switches which stopped the fires. Idled one engine while we took a suction through the after torpedo room hatch. This cleared the maneuvering room of smoke in a hurry, but we took quit a bit of water in the torpedo room. Commenced clearing up grounds in main control cubicle and clearing main induction of water. The following parts wee burned up or damaged and will have to be replaced during the next refit period: 3 Generator rheostat clutch switches. 1 Generator trip switch. 2 Generator rheostat filed contactors. 100 feet of wiring. 2040I; Went ahead standard speed on port shaft with No. 2 main engine on propulsion. March 31 0442I; Went ahead standard speed on both shafts. No. 1 engine available for propulsion. 0833I; Dived on plane contact. It was flying very low distance about 4 miles. Radar did not pick it up. Unfortunately we were right on the route between TOKYO and the BONINS. The sky was heavily over-cast with a low ceiling. This plane was probably piloting down the chain of the Southern Islands. 0912I; Surfaced. 1100I; All main engines available for propulsion except No. 3. 1230K; another plane contact, distance about 12 miles by radar. Did not sight it. This plane was in the same groove as the other one, this morning. We did not dive. April 2: 0910K; Sighted sail on the horizon. After closing it a bit we could see a single sail and a long hull. Believed this to be a patrol disguising himself or economizing on fuel. We were several hundred miles east of the BONINS and no sail boat had any business in these parts. Position Latitude 31d - 30' N; Longitude 150d - 25' E. April 6: 1030Y; Arrived U.S. Submarine BASE, MIDWAY ISLAND. Had second unique experience of this patrol of surfacing in middle of Yellow Sea, on March 25th and proceeding on surface from that date until arrival at MIDWAY, with only short trim dives, one submerged attack and two ducking for plane contacts. 2. WEATHER. The weather was generally crisp and clear except when southerly winds caused fog. 3. TIDAL INFORMATION. The tides and currents conformed with the information shown ont he charts and contained in sailing directions. 4. NAVIGATIONAL AIDS. On entering the areas all Navigational lights shown on chart which were encountered were burning with proper characteristics. However, ROUND ISLAND light was extinguished after the third attack in that area, and it is presumed others were put out also. On March 29 KUSAKAKI SHIMA Light was burning, but in view of the sinking twenty-six miles from it that morning it has probably been doused. 5. ENEMY SHIPS SIGHTED: Date : Time : Position :Course : Speed : Type --------------------------------------------------------------------- 3/14/43 : 1704I :Lat. 32-57 1/4 N : 404d :12 knots:1-1,000 ton AK : :Long.126-11 E : : : --------------------------------------------------------------------- 3/15/43 : 1415I :Lat. 34-04 1/2 N : 270d : High :Small patrol or : :Long.125-53 1/2 E: : :Gun boat --------------------------------------------------------------------- 3/19/43 : 0515H :Lat. 38-29 1/2 N : 305d : 9 knots:1-4,065 Ton AK : :Long.122-18 1/2 E: : :NANKA MARU --------------------------------------------------------------------- 3/19/43 : 0916H :Lat. 38-27 1/2 N : 295d : 9 knots:1-AK or NAVAL AUX : :Long.122 18 1/4 E: : :TOTTORI MARU : : : : :5,973 tons -------------------------------------------------------------------- 3/21/43 : 0700H :Lat 38-10 1/2 N : 000d :11 knots:1-AK 7,210 tons : :long.124-33 E : : :SEIWA MARU -------------------------------------------------------------------- 3/21/43 : 0958H :Lat. 38-04 1/2 N : 357d :10 knots:1-AK 6,543 tons : :Long.124-32 1/2 E: : :NITU MARU -------------------------------------------------------------------- 3/23/43 : 0443H :Lat. 38-37 1/4 N : 138d : 8 knots:1-AK 2,427 tons : :Long.121-01 1/4 E: : :KATYOSAN MARU -------------------------------------------------------------------- 3/24/43 : 1249H :Lat. 38-47 N : 265d :10 knots:Freighter passed : :Long.122-16 1/2 E: : :16,000 yards : : : : :ahead 4-5,000 ton -------------------------------------------------------------------- 3/24/43 : 1949H :Lat. 39-01 N : 263d :12 knots:1-AO 7,499 tons : :Long.122-24 1/4 E: : :SYOYO MARU -------------------------------------------------------------------- 3/25/43 : 0436H :Lat. 38-12 1/2 N : 343d :8.5knots:1-AK 2,550 tons : :Long.123-24 E: : :SINSEI MARU -------------------------------------------------------------------- 3/25/43 : 0510H :Lat. 38-10 N :Various:13 knots:1-AK 1,000 tons : :Long.123-26 E: : :similar to : : : : :HADACHI MARU -------------------------------------------------------------------- 3/25/43 : 1222H :Lat. 38-01 N : 300/ :10 knots:Passenger : :Long.123-36 E: 120d : :Freighter large -------------------------------------------------------------------- 3/25/43 : 1458H :Lat. 37-55 1/2 N : 300d :12 knots:New type DD. It : :Long.121-01 1/4 E: : :was echo-ranging -------------------------------------------------------------------- 3/29/43 : 0416H :Lat. 30-25 1/2 N : 080d :8.5knots:1-AK 5,193 tons : :Long.129-41 1/2 E: : :KIMISIMA MARU -------------------------------------------------------------------- NOTE: Sampans, Junks, Trawlers and other fishing craft were encountered daily. As many as twenty being in sight at one time from the bridge. In general those off the KOREAN COAST and in the SHANTUNG PROMONTORY and in the GULF OF POHAI were darkened and under sail. Areas listed below held particularly heavy concentrations of fishing craft. DESCRIPTIONS LOCATION TOKARA KAIKYO : 30d - 10'N : 130d E. ---------------------------------------------------------------------- SHIMONOSEK - FORMOSA (trade route) : 31d - 50'N : 127d - 25'E ---------------------------------------------------------------------- MAIKOTSU SUIDO : 34d - 20'N : 125d - 40'E ---------------------------------------------------------------------- LACTIEHSHAN CHANNEL (Loathesome Channel) : 38d - 35'N : 121d - 10'E ---------------------------------------------------------------------- Southeast of SHANTUNG PROMONTORY : 36d - 10'N : 123d - 20'E ---------------------------------------------------------------------- 6. DESCRIPTION OF PLANES SIGHTED. TIME : TYPE : LATITUDE : LONGITUDE :COURSE: ALT ---------------------------------------------------------------------- 3/24/43 0645H: FLOAT : 36d - 33'N : 122d - 12'E : SW : 2,500 ---------------------------------------------------------------------- 3/25/43 1345H:Large land : 36d - 27'N : 121d - 02'E : W : 3,500 :Bomber : : : : ---------------------------------------------------------------------- 3/31/43 0833I:Large land : 31d - 05"N : 140 - 15E : S : 1,000 :Bomber : : : : 7. SUMMARY OF SUBMARINE ATTACKS. Attack No. : 1 : 2 : 3A ---------------------------------------------------------------- Date : 3/13/43 : 3/19/43 : 3/19/43 ---------------------------------------------------------------- Location (Latitude) : 32-57N : 38-29N : 38-27N (Longitude) : 126-11E : 122-19E : 111-18E ---------------------------------------------------------------- No. of torpedoes fired : 1 : 1 : 2 ---------------------------------------------------------------- Hits : 0 : 1 Torpex : 2 Torpex : : : (1 dud) ---------------------------------------------------------------- Sunk (Tonnage) : 0 : 4,065 : 0 ---------------------------------------------------------------- Damaged or probably sunk : 0 : 0 : 5,973 ---------------------------------------------------------------- Type of target :1,000 ton AK:AK NANKA :TOTTORI MARU : : MARU : ---------------------------------------------------------------- Range of firing : 1,000 : 750 : 1,800 ---------------------------------------------------------------- Periscope Depth : 64' : 60' : 64' ---------------------------------------------------------------- Surface Night : : : ---------------------------------------------------------------- Deep Submergence : : : ---------------------------------------------------------------- Estimated draft of target: 12' : 22 1/2' : 8' ---------------------------------------------------------------- Torpedo depth setting : 5' : 10' : 10' ---------------------------------------------------------------- Bow or stern shot : Stern : Bow : Bow ---------------------------------------------------------------- Track angle : 90 P : 120 P : 126 S ---------------------------------------------------------------- Gyro angles : 174 1/2 d : 358 1/2 d :352d 8 1/2 d ---------------------------------------------------------------- Estimated Target Speed : 12 : 9 : 9 ---------------------------------------------------------------- Firing interval : : :1 min. 35 sec ---------------------------------------------------------------- Spread: amount and kind : : : Divergent : : : 2 knots ---------------------------------------------------------------- Time for target to sink : :2 min 26 sec: ---------------------------------------------------------------- Attack No. : 3B : 3C : 4 ---------------------------------------------------------------- Date : 3/19/43 : 3/19/43 : 3/21/43 ---------------------------------------------------------------- Location (Latitude) : 38-27N : 38-27N : 38-11N (Longitude) : 122-18E : 122-18E : 124-33E ---------------------------------------------------------------- No. of torpedoes fired : 1 : 1 : 3 ---------------------------------------------------------------- Hits : 0 : 0 : 1 Torpex ---------------------------------------------------------------- Sunk (Tonnage) : 0 : 0 : 7,210 ---------------------------------------------------------------- Damaged or probably sunk : 0 : 0 : 0 ---------------------------------------------------------------- Type of target :TOTTORI MARU:TOTTORI MARU: SEIWA MARU ---------------------------------------------------------------- Range of firing : 1,900 : 2,250 : 1,500 ---------------------------------------------------------------- Periscope Depth : 64' : 64' : 64' ---------------------------------------------------------------- Surface Night : : : ---------------------------------------------------------------- Deep Submergence : : : ---------------------------------------------------------------- Estimated draft of target: 8' : 8' : 27' ---------------------------------------------------------------- Torpedo depth setting : 10' : 10' : 10' ---------------------------------------------------------------- Bow or stern shot : Bow : Bow : Bow ---------------------------------------------------------------- Track angle : 140 S : 180 : 117 P ---------------------------------------------------------------- Gyro angles : 018 1/2 d : 358 3/4 d :359 3/4;356; : : : 358 ---------------------------------------------------------------- Estimated Target Speed : 7 : 7 : 11 ---------------------------------------------------------------- Firing interval : : :14 sec 9 sec ---------------------------------------------------------------- Spread: amount and kind : : : Longitudinal ---------------------------------------------------------------- Time for target to sink : : : 4 minutes ---------------------------------------------------------------- Attack No. : 5 : 6 : 7 ---------------------------------------------------------------- Date : 3/21/43 : 3/23/43 : 3/24/43 ---------------------------------------------------------------- Location (Latitude) : 38-05N : 38-27N : 38-01N (Longitude) : 124-33E : 121-01E : 122-25E ---------------------------------------------------------------- No. of torpedoes fired : 3 : 1 : 4* ---------------------------------------------------------------- Hits : 2 Torpex : 1 TNT : 0 ---------------------------------------------------------------- Sunk (Tonnage) : 6,543 : 2,427 : 0 ---------------------------------------------------------------- Damaged or probably sunk : 0 : 0 : 0 ---------------------------------------------------------------- Type of target : AK : AK : AO : NITU MARU :KATYOSAN MARU SYOYO MARU ---------------------------------------------------------------- Range of firing : 800 : 1,000 : 1,700 ---------------------------------------------------------------- Periscope Depth : 65' : 57' : ---------------------------------------------------------------- Surface Night : : : Radar ---------------------------------------------------------------- Deep Submergence : : : ---------------------------------------------------------------- Estimated draft of target: 27 1/2' : 20' : 28' ---------------------------------------------------------------- Torpedo depth setting : 10' : 10' : 10' ---------------------------------------------------------------- Bow or stern shot : Stern : Bow : Stern ---------------------------------------------------------------- Track angle : 87d S : 88d P : 80d S ---------------------------------------------------------------- Gyro angles :161;167;168d: 004d :182;182.5d : : :183.5; 196.5d : : : 358 ---------------------------------------------------------------- Estimated Target Speed : 10 : 8 : 12 ---------------------------------------------------------------- Firing interval : 10s; 16s : :12s;21s;13s ---------------------------------------------------------------- Spread: amount and kind :Longitudinal: :Divergent 1d ---------------------------------------------------------------- Time for target to sink : 3min 10sec : 13 minutes : ---------------------------------------------------------------- Remarks: * First two torpedoes exploded prematurely at end of 18 second runs. Attack No. : 8 : 9 : 10 ---------------------------------------------------------------- Date : 3/24/43 : 3/25/43 : 3/29/43 ---------------------------------------------------------------- Location (Latitude) : 39-00N : 38-13N : 30-26N (Longitude) : 122-16E : 123-24E : 129-41E ---------------------------------------------------------------- No. of torpedoes fired : 3 : 2* : 2 ---------------------------------------------------------------- Hits : 1 TNT : 0+ : 1 Torpex ---------------------------------------------------------------- Sunk (Tonnage) : 7,499 : 0 : 5,193 ---------------------------------------------------------------- Damaged or probably sunk : 0 : 0 : 0 ---------------------------------------------------------------- Type of target : AO : AK : AK : SYOYO MARU : SINSEI MARU:KIMISIMA MARU ---------------------------------------------------------------- Range of firing : 1,200 : 1,300 : 900 ---------------------------------------------------------------- Periscope Depth : 60' : 62' : 64' ---------------------------------------------------------------- Surface Night : : : ---------------------------------------------------------------- Deep Submergence : : : ---------------------------------------------------------------- Estimated draft of target: 28' : 24' : 24' ---------------------------------------------------------------- Torpedo depth setting : 10' : 6' : 15' ---------------------------------------------------------------- Bow or stern shot : Bow : Bow : Bow ---------------------------------------------------------------- Track angle : 090 S : 37 S : 90 P ---------------------------------------------------------------- Gyro angles :354 1/2d : 012d; 018d :353d; 341d :359 3/4d : : :359 1/4d : : ---------------------------------------------------------------- Estimated Target Speed : 10 : 8.5 : 8.5 ---------------------------------------------------------------- Firing interval : 44s; 30s : 15s : 18s ---------------------------------------------------------------- Spread: amount and kind :Longitudinal:Longitudinal: Longitudinal ---------------------------------------------------------------- Time for target to sink : 4min 25sec : : 2min 32 sec ---------------------------------------------------------------- Remarks: * Both torpedoes exploded prematurely. Runs 26 and 49 seconds. + This target was later sunk by 4" gunfire. : 11 : 12 : 13 Attack No. : First Gun :Second Gun : Third Gun : Attack : Attack : Attack ---------------------------------------------------------------- Date : 3/25/43 : 3/35/43 : 3/27/43 ---------------------------------------------------------------- Location (Latitude) : 38-13N : 38-10N : 33-39N (Longitude) : 123-24E : 123-26E : 125-23E ---------------------------------------------------------------- Rounds of 4" Ammunition : 90 : 80 : 11 ---------------------------------------------------------------- Hits, approximate : 60 : 50 : 8 ---------------------------------------------------------------- Sunk (Tonnage) : 2,556 : 1,000 : ------ ---------------------------------------------------------------- Damaged or probably sunk : ----- : ----- : 100 ---------------------------------------------------------------- : AK : AK :DIESEL TRAWLER Type of target : SINSEI MARU:HADACHI MARU: #825 ---------------------------------------------------------------- Range : 3,800/300 : 3,000/200 : 3,000/200 ---------------------------------------------------------------- Estimated Target Speed : Various : 13 : Various ---------------------------------------------------------------- : 14 : Attack No. : Fourth Gun : : Attack : --------------------------------------- Date : 3/28/43 : --------------------------------------- Location (Latitude) : 31-39N : (Longitude) : 127-41E : --------------------------------------- Rounds of 4" Ammunition : 20mm 700 : --------------------------------------- Hits, approximate : 400 : --------------------------------------- Sunk (Tonnage) : *** : --------------------------------------- Damaged or probably sunk : 2 sampans : --------------------------------------- : AK : Type of target : 2 sampans : --------------------------------------- Range : 1,000/50 : --------------------------------------- Estimated Target Speed : Lying to : --------------------------------------- FIRST AND SECOND SHIPS: Sprayed with 1,000 rounds 20mm. " " " " Caught fire stem to stern. " " " " Sank. Trawler: Sprayed with 900 rounds 20mm. and 7 MOLOTOV COCKTAILS. " Wrecked with 4" gun hits. Sampans: Wrecked. 8. ENEMY A/S MEASURES The enemy used gun-fire whenever possible as a nuisance factor to keep a submarine down. The night firing of the SYOYO MARU was good when our location was disclosed by our prematures. Their flashless powder gives off no more light than a dimmed green flashlight. 9. MAJOR DEFECTS Periscopes: The periscopes - particularly #2 periscope fogged badly at times. During several approaches this fogging was bad enough to necessitate ducking the periscope to complete an observation. The fogging became heavy enough during the time required to take a bearing (less than 5 seconds) to make an accurate stadimeter range impossible. This condition has existed in the past on this ship and from conversation with other officers we find that it exists in other ships. It is greatly increased by a differential in temperature particularly when the water is warmer than the air. Unless definite action is taken to correct this defect, it will continue to be a major handicap to the conduct of a successful submerged attack. #1 periscope was constantly as a high lookout while on the surface. The training of this periscope was so stiff that it greatly reduced the efficiency of the watch. The overhaul by the tender during the last refit made no appreciable improvement in this condition. Torpedoes: As noted in the narrative one torpedo failed to explode although it definitely hit the target amidships, and four other torpedoes exploded prematurely. Although at first glance this would appear to be just over a twenty percent failure, we must consider also the additional expenditure of torpedoes involved, for a target worth sinking remains worth sinking as long as she is afloat. In the case of the TOTTORI MARU, the second torpedo, a Torpex, would undoubtedly have sunk her had it exploded. As it turned out, a new 5,973 ton ship was only damaged and two additional torpedoes had to be expended under unfavorable conditions in an attempt to sink her and to preserve a new found "hunting ground". The SYOYO MARU, had been tracked by radar from 10,000 yards in. Her course and speed were most accurately known. There is every reason to believe that the initial spread of three torpedoes would have sunk her. Yet the first two torpedoes, exploded prematurely, invited counter-attack and necessitated firing an additional torpedo also requiring the expending of three more torpedoes an hour and a half later to sink this 7,499 ton tanker. Again the Japs new found traffic lane was spoiled for further attack. Against the SINSEI MARU, the two prematures necessitated a battle surface with its inherent dangers, and the expenditure of 90 rounds of 4" ammunition to sink the 2,556 ton freighter. That our position was again disclosed by this ship's radio is indicated by the arrival of a plane within two hours. Thus in fact, torpedo failures caused the additional expenditure of six torpedoes and 90 rounds of 4" ammunition. A conservative estimate is that the TOTTORI MARU and two additional ships could have been sunk if all torpedoes exploded properly, and that one SMOKY MARU could have been sunk with the 90 rounds of 4" ammunition. 10. COMMUNICATION Radio reception was good and complete. No attempt was made to use the under-water loop. Difficulty was experienced in clearing a message from in the vicinity of the BONINS. It was receipted for, probably somewhat garbled, by MIDWAY. Last serial received ComSubPac 56 Yoke . Last message sent 032130/April . 11. SOUND CONDITIONS AND DENSITY LAYERS Sound conditions were poor, undoubtedly due to the shallow water. For the same reason no density layers were noted. 12. HEALTH AND HABITABILITY The general health of the crew during the patrol was very good. Climatic conditions were rigorous, cold weather persisting practically all the time. A most adequate supply of heavy clothing was available and was distributed upon sailing. The average temperature while "on station" was approximately 40d F. There were about seven or eight complaints of colds while underway, only one requiring bed-rest. One case endured, although mildly, from the time of contraction to the end of the patrol, this by a man who was making his first run in submarines. Skin diseases were at a minimum, only one or two cases of athletes foot or "spic" itch in evidence. One man complained of boils, and was victimized constantly. There was one case of cellutitus, and the complaining patient was confined to his bunk for several days. There were no injuries other than a few minor cuts and bruises. Habitability was excellent. The fresh meats, although kept frozen at 20d, again acquired a most unpalatable taste early in the patrol. This condition persisted on each patrol in spite of every effort to locate and remedy the cause. After the second patrol of this ship shelves and spaces were installed to permit air circulation, a thorough check for possible fuel oil or freon leaks was made, and a fan installed to insure air circulation. Absorption of odors by charcoal was also attempted, but with no apparent results. During each upkeep period the chill and cold room have been completely emptied, scrubbed, and aired with blowers. The situation has been called to the attention of the tender Medical Department which could offer no solution. ============================================================================== FB5-44/A16-3 COMMANDER SUBMARINE DIVISION FORTY-FOUR Serial 04-B In Care of Fleet Post Office, San Francisco, California, April 9, 1943. CONFIDENTIAL From: The Commander Submarine Division FORTY_FOUR. To : The Commander Submarine Force, Pacific Fleet. Subject: U.S.S. WAHOO, Report of fourth War Patrol - Comments. 1. The Fourth Patrol of the WAHOO covered a period of forty-two (42) days between departure from Pearl Harbor, and return to Midway. Eighteen (18) days were spent in patrol area. Patrol was terminated by expenditure of all torpedoes. 2. During this patrol, as on the third patrol of this ship, the outstanding aggressiveness and the magnificent fighting spirit of the captain, officers, and crew were largely responsible for the splendid results obtained. 3. The Commanding Officer displayed great enterprise and excellent judgement in covering his patrol area. The area was covered in a most thorough manner. It is particularly noteworthy that in order to increase the scope of the search a surface patrol was conducted during daylight hours on seven of the eighteen days in the patrol area. This was done after experience indicated that anti-submarine measures in the area were not sufficiently effective to make surface patrol foolhardy. 4. Comments on attacks. (a) Attack No. 1. Excellent firing position, but range was in error. In this case a echo range to check the periscope range before firing would have been extremely valuable. (b) Second attack. Approach data on this attack was felt to be very accurate. Therefore, only one torpedo was fired and it did the trick. (c) Third attack. On attack 3A firing interval was excessive. However, two hits were obtained and target would probably have sunk had second torpedo exploded. On attack 3B a single torpedo fired when spread might have been used to advantage. (d) Sixth Attack. This ship was not observed to sink but the Commanding Officer feels certain she went to the bottom. He bases this on the belief that the ship was so small it could not have survived the explosion, plus the fact that ship was not sighted when WAHOO surfaced thirteen minutes after firing. (e) Seventh and Eight Attacks. While frustrated by faulty performance of torpedoes on seventh attack the /Commanding Officer would not be denied this valuable target. After an unsuccessful attack, WAHOO surfaced, gained a favorable position, and executed a second attack which resulted in the destruction of the ship. Attention is invited to the remarks in the patrol report to the effect that tracking the target with submarine making high speed gave different target speed than when tracking at low submerged speed. (f) Ninth Attack. Here again faulty performance of torpedoes ruined an attack. It will be noted that torpedoes were set on six feet depth on this attack. The sea was calm. (g) Third Gun Attack. The need for some effective means of setting fire to wooden trawlers and sampans was demonstrated during this attack. During current refit period WAHOO plans to have personnel practice throwing buckets of oil with a view to using this method of setting wooden boats on fire during future patrols. 5. Comments on Material. (a) Main Control Cubicle. As result of the flooding of the main induction small fires were started which resulted in the damaging beyond repair of certain parts of the main control cubicle. Replacement parts must be obtained from Pearl or other outside source before repairs can be completed. After the water started coming through the auxiliary induction valve it was impossible to close the valve against the flow of water. This valve is located overhead in the starboard side of the maneuvering room aft, very close to after starboard corner of the control cubicle. It is impossible to keep the water from entering the control cubicle if the leakage is at all serious. In order to prevent a recurrence of this casualty the WAHOO plans to operate with this valve closed. This will increase the temperature in the maneuvering room but appears to be the only safe procedure until such time as the design of the auxiliary induction valve is changed to correct the present undesirable features. (b) Periscopes. The difficulty with training number one periscope will be investigated during the refit period and effort will be made to improve the condition. (c) Torpedoes. Four premature explosions were experienced. It is possible that the second torpedo fired on attack number seven exploded prematurely as a result of passing into the disturbance caused by the first torpedo. It will be noted that both of these torpedoes exploded about the same distance away from the submarine. While the time of the second explosion on attack number nine corresponds quite closely with the expected torpedo run to the target, the Commanding Officer is positive that the torpedo exploded before it reached the target. The target was obscured by extensive spray from the explosion and later observations of the ship before it was sunk by gunfire proved conclusively that it was not damaged by torpedo. It was the practice on the WAHOO to keep all torpedoes set on depth of ten feet. Deep depths were not set on torpedoes. The seas were calm during firing where prematures were experienced. The Commanding Officer is convinced that Torpex heads are far superior to TNT. The outward effects of the explosions are much more pronounced and ships sink faster, indicating greater destructive power. 6. The tainting of foods kept in chill and cold rooms may eventually have an adverse effect on the health of the personnel on patrol. Investigations should be conducted to determine how this condition can be improved. It is understood that the HERRING experienced this trouble and found it necessary to renew the cork lining of the refrigerator because the cement used on the cork affected the taste of the foods. 7. WAHOO returned from patrol in very good material condition. While tired and visibly worn by the strain of the patrol, officers and crew were in good health and excellent spirits. FC5-10/A16-3(FB5-102) SUBMARINE SQUADRON TEN Serial 053 In Care Of Fleet Post Office, San Francisco, California, April 12, 1943. CONFIDENTIAL From: The Commander Submarine Squadron Ten. To : The Commander Submarine Force, Pacific Fleet. Subject: U.S.S. WAHOO (SS238), Fourth War Patrol - Comments on. 1. The fourth war patrol was again outstanding and marked by maximum aggressiveness and cool daring. The intelligent planning and sound judgement of the Commanding Officer in making his decisions enabled the WAHOO to outsmart the enemy, retain the initiative, and inflict a considerable amount of damage. 2. The patrol extended over a period of 42 days, of which nineteen days were spent in the area. The patrol was terminated on expenditure of all torpedoes. 3. One of the outstanding features of the patrol was the successful penetration into the area by surface cruising alone. The WAHOO was almost as successful on return from the area, being forced down on only a few occasions. 4. A total of 24 torpedoes were fired during ten separate attacks. Eight hits were scored, and a ninth hit was a dud. In the attack on the KIMISIMA MARU on March 29, the second torpedo would have been a hit had the first torpedo not done the job too completely. Counting this as a hit, a score of 37.5% was made. Had it not been for the dud and four prematures, this percentage would have been still higher and the tonnage sunk, although considerable, would have been still greater. 5. The gun attacks on the AK's, the trawler, and the sampans were well executed. The percentage of hits obtained and the sinking of over 3500 tons of cargo-carrying ships bye the 4- inch gun crew is most gratifying. The recommendation made by the Commanding Officer for larger tubes for the 20 MM guns is concurred in. 6. The Commander Submarine Squadron Ten takes pleasure in extending a "Well Done" to the Commanding Officer and personnel of the WAHOO for a highly successful patrol, during which the following damage was inflicted on the enemy: SUNK AK (NANKA MARU) - - - - - - - - - 4,065 tons AK (SEIWA MARU) - - - - - - - - - 7,210 tons AK (NITU MARU) - - - - - - - - - 6,543 tons AK (KATYOSAN MARU) - - - - - - - 2,427 tons AO (SYOYO MARU) - - - - - - - - - 7,499 tons AK (KIMISIMA MARU) - - - - - - - 5,193 tons AK (SINSEI MARU) - - - - - - - - 2,556 tons ** AK (HADACHI MARU) - - - - - - - - 1,000 tons ** Trawler - - - - - - - - - - - - - 100 tons ** 2 Sampans (approx. 50 tons each)- 100 tons ** __________ TOTAL SUNK: 36,693 tons ** Sunk by gunfire. DAMAGED AK TOTTORI MARU - - - - - - - - 5,973 tons FF12-10/A16-3(5)/(16) SUBMARINE FORCE, PACIFIC FLEET Serial 0484 In Care of Fleet Post Office, San Francisco, California, April 13, 1943. CONFIDENTIAL COMSUBPAC PATROL REPORT NO. 164 U.S.S. WAHOO - FOURTH WAR PATROL From: The Commander Submarine Force, Pacific Fleet. To : Submarine Force, Pacific Fleet. Subject: U.S.S. WAHOO (SS238) - Report of Fourth War Patrol. Enclosure: (A) Copy of Subject War Patrol Report. (B) Copy of Comsubdiv 44 conf. ltr. FB5-44/A16-3 Serial 04-B of April 9, 1943. (C) Copy of Comsubron 10 conf. ltr. FC5-10/A16-3 (FB5-102) Serial 053 of April 12, 1943. 1. Outstanding in aggressiveness and submarine warfare efficiency, this was the fourth war patrol of the WAHOO and the second under its present /commanding Officer. Sinking eight ships, one trawler and two sampans and damaging one other ship, the WAHOO continued the outstanding record established on its third war patrol. 2. Faulty torpedo performance in the form of prematures subjected the WAHOO to dangerous shell fire on a night attack. Another torpedo, a dud, allowed a damaged ship to get away. 3. It is gratifying to note that all of the WAHOO's gun battles were executed only after a careful estimate of the situation was made; each was carried out with military aggressiveness, professional competence and yet free of foolhardy recklessness. These attacks were carried out when they could be made with the submarine having the definite advantage. It is well to remember that our submarines are very valuable and, at the same time, vulnerable targets when gunfire is used as the attacking weapon. 4. Throughput the patrol, the Commanding Officer exhibited excellent judgement in his strategic study of the shipping lanes, thus covering the area efficiently and most productively. 5. The Commander Submarine Force, Pacific Fleet, again takes great pleasure in commending the Commanding Officer, officers and crew of the Wahoo on this, their second successive outstanding war patrol. The Wahoo is credited with inflicting the following damage to the enemy: SUNK 1 Freighter (NANKA MARU class) - - 4,065 tons 1 Freighter (SEIWA MARU class) - - 7,210 tons 1 Freighter (NITU MARU class) - - 6,543 tons 1 Freighter (KATYOSAN MARU class) - - 2,427 tons 1 Tanker (SYOYO MARU class) - - 7,499 tons 1 Freighter (KIMISIMA MARU class) - - 5,193 tons *1 Freighter (SINSEI MARU class) - - 2,556 tons *1 Freighter (HADACHI MARU class) - - 1,000 tons *1 Trawler (#825) - - 100 tons *2 Sampans - - 100 tons __________ TOTAL: 36,693 tons *Sunk by gunfire. DAMAGED 1 Freighter (TOTTORI class) - - 5,973 tons DISTRIBUTION: J. H. BROWN, Jr., (1m-43) Acting LIST III, SS Special: P1(5), EN3(5), Z1(5), Comsublant (2), X3(1), Comsobsowespac (2), Subschool, NL (2), Comtaskfor 72 (2), Comsubron 50 (2), Comsopac (2), Cinclant (2), Comtaskfor 16 (1). E. R. SWINBURNE, Flag Secretary. FF12-10/A16-3(18) SUBMARINE FORCE, PACIFIC FLEET Serial 067 Care of Fleet Post Office, San Francisco, California, 1 Feb. 1946 CONFIDENTIAL From: The Commander Submarine Force, Pacific Fleet. To : The Chief of Naval Operations Via : The Commander in Chief, U. S. Pacific Fleet. Subject: U.S.S. WAHOO (SS238) - Report of Fourth War Patrol. Reference (a) ComSubPac second cnf. FF12-10/A16-5(5)/(16) serial 0484 of 13 April 1943. 1. In reference (a) U.S.S. Wahoo was credited with sinking a total of 36,693 tons of enemy shipping and damaging one freighter of 5,973 tons. The damaged freighter was estimated to be of the TOT TORI class and was attacked in position 38-27N. and 122-18E. on 19 March 1943. Reliable intelligence, subsequently received, indicates that the KOMA MARU (very similar to TOT TORI class of 4,520 tons sank on 20 March as a result of submarine attack. The only other ship attacked in that location on either 19 or 20 March was the NANKA MARU which was sunk by WAHOO at 0513 19 March 1943 and whose loss has been verified by intelligence reports. Accordingly, WAHOO is hereby credited with the sinking of KOMI MARU - 4,520 tons. 2. Accordingly reference (a) is modified as follows: (a) Strike out all after the word "enemy" in paragraph 3 and substitute therefor: SUNK 1 Freighter (KOMI MARU) - - 4,520 tons 1 Freighter (NANKA MARU class) - - 4,065 tons 1 Freighter (SEIWA MARU class) - - 7,210 tons 1 Freighter (NITU MARU class) - - 6,543 tons 1 Freighter (KATYOSAN MARU class) - - 2,427 tons 1 Tanker (SYOYO MARU class) - - 7,499 tons 1 Freighter (KIMISIMA MARU class) - - 5,193 tons *1 Freighter (SINSEI MARU class) - - 2,556 tons *1 Freighter (HADACHI MARU class) - - 1,000 tons *1 Trawler (#825) - - 100 tons *2 Sampans - - 100 tons __________ TOTAL: 41,213 tons *Sunk by gunfire. Frank T. Watkins, Chief of Staff.