U.S.S. TREPANG (SS-412) — war patrol report SS-412_TREPANG_Part2.pdf

— page 1 —
```
CONFIDENTIAL                       U.S.S. TREPANG (SS12)
SS12/41-6-3                         Report of Fifth War Patrol
Serial (09)

1214   Having communicated with PINTADO and LUCID, and his
       cover has not shown up, concluded strike was again canoill
       reversed course to open boche.

1200   Position: Lat. 34-01'. N.
       Long: 137-03'. E.

1230   Received despatch cancelling strike.

1247   Divad.

1247   Surfaced.

2245   Received orders to proceed to rendezvous with DEVILFISH, thence to Areas 1, 2, and 3.

June 30
0350 (T)  S/C #1 - SJ radar contact at 7,000 yards.  Heavy overcast, intermittent rain.  On course 160°T, speed 6.5, lookouts report
         TOKYO BAY TO FORT SHIMA, possibly closing on down to the
         SOKTIE.  Lowered sound head - no pinging.  Pulled ahead to a
         point, 5,000 yards on his starboard bow.

0515   Divad and went to Battle Stations Surfac...

0536   Watched target go by at 150 yards - Sugar Charlie Sugar of
       about 500 tons.  Armed with 2 guns of about 37mm size.
       Manned Battle Stations Surfac...

0305   Made Battle Surfac at range of 4,000 yards, continuing
       with 5" only.  First 2 rounds fired, 1 with a
       Next 12 rounds were 16, 16, fired, of which a portion
       The target got only 2 short bursts on a gun before
       opened fire again.  Closed target to 1,200 yards, firing 5"
       40mm, and both 20mm's.

0617   Target burst into flames from Aft and
       well closed.  Observed about 15 men on deck, 1
       American Marine officer in the Water Captain's chair,
       and an incomplete uniform, most of them wearing caps,
       and at time soldiers had on full packs.  Attempted to pick
       up a prisoner, but none would scout a line.  Especially
       wanted to get the Navy officer, who had his face full turned
       up, but only covering his raft's were in the water and the gun...
       -12-
       [STAMP: ENCLOSURE (A)]
```

— page 2 —
```
CONFIDENTIAL
U.S.S. TREPANG (SS-412)
C3142/A16-3
Serial: (09)                            Report of Fifth War Patrol.

0645
Target sank--oil still burning on water. Looks like it might have been carrying some gasoline.

0930
Passed through NAINFO SHOOT between MIKURA SHIMA and RACHITO SHIMA.

1200
Position: Lat. 33-51.8 N.
         Long. 110-26.0 E.

1803
SD contact at 10 miles, closed to 7, where pip faded out. Never sighted.

July 1
0010 (x)
Made rendezvous with DEVILFISH. Transferred our 7 survivor and CROOK, Paul O., 857 OA 73, T/0(T), V-6, LINT(3).
We were suffering from equipment failure, to DEVILFISH. CDR had an attack of appendicitis 2 days previously, but was
now over it. However, he was still under treatment and there was a good chance to attack right before the end of the patrol. Received 20 rounds of 5" ammunition from DEVILFISH.

0100
Dense fog set in and held for next 36 hours.

0503
Made 30 minute trim dive, Went to 350 feet to check gradient.

1200
Position: Lat. 37-38.8 N.
         Long. 114-33.5 E.

1335
SJ contact on KIRIKAMAH SAKI at 55,000 yards.

1404
Made 20 minute trim dive.

1900
Closed coast and patrolled north just over 100 F, figuring that nothing could run close to the fog. Slowed and lowered sound head gray hair hour to listen for pinging.

July 2
0333 (x) SD contact at 7 miles, opened.
-13-
```

— page 3 —
```
CONFIDENTIAL                U.S.S. TREPANG (SS412)
SS12/A16-3                  Report of Fifth War Patrol.
Serial (09)

0500    Commenced patrolling on surface about 10 miles off KOBE
        SAKI in dense fog.

0848    Decided to patrol submerged for a while, depending on
        sound and SF for contacts.

1200    Position: Lat. 39-30.3 N.
        Long. 142-07.0 E.

        Fog commenced lifting. Headed toward beach.

1520    S/C #2 - Slighted small fishing boat coming out of cove
        north of KOBE SAKI and heading up the coast.

1610    Patrolling 5-6,000 yards off KOBE SAKI.

        Headed to southwest.

2058    Surfaced 7 miles off KOBE SAKI and commenced surface
        patrol.

JULY 3
0635 (TK)  Fog bank rolled in.

0710    Submerged for sound and ST patrol on 100 fathom curve.

1125    Fog lifted; commenced closing YOSHITAKA WAN.

1200    Position: Lat. 39-16.2 N.
        Long. 142-11.7 E.

1430    Commenced patrolling 4,000 to 6,000 yards off YOSHITAKA
        WAN.

1512    Heard pinging to northward, gradually getting stronger.
        Pinging stopped.

1505    S/C #3 - Sighted small craft resembling fishing boat
        coming down coast from direction where pinging had been
        heard. Tracked into YOSHITAKA WAN.

1600    S/C #4 - Tracked 2 sets of screws out of same cove and
        northward. Finally made out 2 small vessels through fog,
        which was again coming in. Both passed 1,000 yards away.
        One looked like same as S/C #3.

1650    Pinging commenced to northward and gradually drew away.
        Looks like S/C #3 is a fisherman converted to a small
        [UNCLEAR: best guess]
-14-
```

— page 4 —
```
CONFIDENTIAL                       U.S.S. TREPANG (SS-112)
SS-112/16-3                        Report of Fifth War Patrol.
Serial (09)

                                    patrol boat.

2052                               Surfaced 7 miles from coast and commenced open...
                                   Decided to try our luck to northwest—don’t believe
                                   there is any traffic running down the coast here. Set course
                                   for LINTU SAKI.

July 4
1200 (TK)                         Position: Lat. 41-21.3' N.
                                   Long. 142-21.3' E.

1354                               Submerged for periscope patrol about 30 miles west of
                                   LINTU SAKI.

1805                               Surfaced. Patrolling on surface between ERIMO SAKI and
                                   TSUGARU KINKTO.

July 5
0427 (TK)                         Submerged for periscope patrol on 100 fathom curve off
                                   South Coast of HOKKAIDO. Visibility poor.

1000                               Visibility improving—colored band to 6,000 yards and
                                   commenced patrolling.

                                   Selling amounts in 1st.

1200                               Position: Lat. 42-08.6' N.
                                   Long. 142-23.8' E.

2057                               Surfaced 4 miles from coast and the spot all clear.
                                   Set course for TSUGARU NANKO.

July 6
1200                               Submerged for periscope patrol.

                                   Position: Lat. 41-36.6' N.
                                   Long. 142-29.1' E.

                               Surfaced for 1 hour to air out boat.

2047                               Surfaced.

July 7
0372 (TK)                         Submerged 12 miles southeast of [UNCLEAR: text] I can
                                   closing coast.
```

— page 5 —
```
CONFIDENTIAL
U.S.S. THRESHER (SSN-612)
SS/42/A-6-3
J. L. L. (c)

Report of Fifth War Patrol

0515
S/0/45 - Crossed 100 fathom curve. Sighted ship rounding SHIRTA SAKI - source of all the smoke. Eventually identified as a tug with tow, but it’s very hard to see at moments throughout the night. Finally got close enough to see that she was towing a barge, making about 2 1/2 knots.

0630
Patrolling 50 fathom curve, 7,000 yards from b...

0748
S/0/46 - Sighted 2 small fishing type vessels coming up coast from south. Looked as if they were making a search, as some seemed to change course to avoid. Good look at one as they passed showed a 50 foot “deck-over” vessel with 2 masts, looking painted gray, with numbers on the bow. Fairly certain that they were fishing boats.

0845
S/0/47 - While guiding the 2 small patrols of S/0/46, sound reported pinging to the northwest. Saw a larger type patrol boat coming down from northwest, sighted a 100 fathom curve at the same time sound reported a slight change to the west - look in that direction revealed a slight trace of smoke, but nothing more. We now had 5 patrol vessels (counting fishing) located, and it is possible our personnel might not be as secretive as they think. In the middle of a rapidly diminishing order, Commanded heading for deeper water while we still had time.

0933
S/0/48 - Sighted masters of 2 ships on bearing of 190° southwest, as 2 minutes later saw the bridge of the an unclassified mining vessel. S/0/48 is still slowly circling for the way southward. Had lost track of 2 small ones. The torpedo approach, but has not been drawn for out of position by the observations of the past 2 hours.

1016
Whether small coastal freighters and aquired surface craft, flanked to seaward by the escort, passed 250 yards range, and proceed on around SHIRTA SAKI. Resumed patrol on 50 fathom curve.

1108
Sighted first type plane over SHIRTA SAKI.

1200
Position: Lat. 14-13.8' N.
Long: 141-30.2' E.

ENCLOSURE (A)
```

— page 6 —
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CONFIDENTIAL                U.S.S. TIRPITZ (S3l2)
SSh12/A16-5
Serial (09)

                       Report of Fifth War Patrol.

1252  "Smoke" finally identified as a tug with tow. Now
passing us about 3,000 yards to shoreward.

1318  S/C 19 - Sighted smoke, then 3 ships rounding SHIMPA
S/W and heading south. All of them were small, but the
was a little larger than the others. They were
coming about 700 yards apart, the largest one in the
lead. They must have missed their secret. Commenced
approach.

1350  Torpedo Attack [UNCLEAR: MAL and JIB] - Fired 3 torpedoes at leading
freighter, and 3 at second freighter, all bow tubes. First
two yards, broke 119 P. F. Two hits in first
target sank him immediately. In spite of excellent work
on the part of the fire control party in that they took
only 11 seconds between 2nd and 3rd torpedoes, the second
target evaded by turning towards us. I undoubtedly saw
the torpedoes as soon as it was raised for the final
bearing, but could not see the most proper action to take.
The ship could have gotten out of the way of those torpedoes.
The third ship joined the second in maneuvering, incidentally
blocking the picture. The second, when she was able, turned
toward showing up on the screen to look up ourselves, but
we were dropped in the process of the second to miss. Set course to
arrive at 0000 and to continue to watch for foreigns of pursuit.

1511  Two depth bombs close aboard. They shook us up pretty
much, brought down a shower of oil, with some consequent
and misadjustment of machinery, particularly the
engine room. Enclosed is a report of the damage. The ship
running at 56 knots for 5 minutes. Might of made the purpose
of course for more than a week or so. Now deep,
this should have done more than an hour sea.

1534  Sound contact - servants and ping below 140 Kcs; sounds
like a freighter, as it has a frequency of about 25 per
minute.

1547  First of about 60 depth charges aimed at us during the
next 5 hours.

1550  Sound contact on another set of screws. These two
harassed us the rest of the afternoon, but were never very
close.

-17-
ENCLSOURE (A)
```

— page 7 —
```
CONFIDENTIAL                U.S.S. TREPANG (SS412)
SS412/446-9                 Report of Fifth War Patrol.
Serial (09)

2113                       Surfaced after 17 1/3 hours submerged.  Patrolling between
                           SHEMYA SANKT and ERNIE SANKT.

July 8
0356 (K)                  Submerged for periscope patrol.

0713                      Heard first of many depth charges dropped during day.
                           The Japs must be on a false scent.  They dropped several
                           patterns of from 10 to 14, so they must be on the first
                           team.

1200                      Position:  Lat.  41-57.5 N.
                           Long.  142-54.7 E.

1605                      Surfaced for 1 hour.

2030                      Surfaced.

2209                      S/C flo - SJ contact at 12,800 yards on single ship.
                           Tracked on course 600°, speed 11 knots not zigzagging.
                           Opened out to 15,500 yards and could still hold track
                           easily.  It is a very dark night, completely overcast,
                           with occasional light rain.  As there was a good chance
                           he would be able to see him, I wanted to make sure he is
                           friendly submarine, though there was still chance of it.
                           PARMC was patrolling Area 1 East, well clear of this spot
                           and had no knowledge of anyone else in this vicinity.
                           Sent out a contact report on area frequency.
                           Japs jamming frequency badly, but proceeding.  Major "Tom"
                           flashed and his position, but transferred.

2325                      Occist at 6,000 yards, stopped, and lowered a sound head.
                           Plunging at about 13.5° on bearing of contact.  Started
                           in for attack.

2338                      Torpedo Attack #2 - at range of 2,100 yards, 190° starboard
                           track, commenced firing 2 torpedoes at target 0.0.  Both
                           could just make out target at 2,500 yards.  First hit
                           did not show two lines of a dust cloud.  Third
                           hits.  First hit caused 10 second delay.  About 2
                           minutes later explosions similar to depth charges were
                           heard and seen.  Flip disappeared from screen at 3,100
                           yards.

July 9
0414 (K)                  Submerged off entrance to TSUGARU KAIYO for periscope
                           patrol.
                           -18-                       EXCLUSION (A)
```

— page 8 —
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CONFIDENTIAL
U.S.S. TRENTON (SS412)
SS412/16-3
Serial (09)

1200
Position: Lat. 44-46.1 N.
Long. 141-59.2 E.

1256
Surfaced for 15 minutes.

1268
Sighted float type plane through periscope—being plane conscious now getting bombed, want to 200 feet.

1315
Surfaced. Patrolling off TSUGURU KINTO and eastward of SHIRYA SAKI.

July 10
0535 (K)
Submerged 15 miles east of SHIRYA SAKI and commenced closing to 10 miles.

0632
Blowed up echo ranging.

0645
S/C #1 - Sighted a KIKOBEN No. 1 making a swoop northward, passing about 12,000 yards from us.

0924
Sighted S/S #1 coming back down from northward. Watched him pass 5,500 yards away and disappear to southward of SHIRYA SAKI.

1200
Position: Lat. 44-27.0 N.
Long. 141-43.2 E.

2115
Surfaced. We heard distant echo ranging from SHIRYA SAKI several times during the afternoon but no ships rounded the point. Patrolling off SHIRYA SAKI during night.

July 11
0042 (K)
Submerged off intrusion to TSUGURU KINTO. Heard distant echo ranging several times, but had no contacts.

1200
Position: Lat. 44-47.9 N.
Long. 141-41.0 E.

1516
Surfaced for 30 minutes.

2059
Surfaced. Patrolling 20 miles to eastward of SHIRYA SAKI.

July 12
0404 (K)
S/C #2 - SJ contact at 12,000 yards. As dawn is already at hand, want to battle stations immediately and launch in.
```

— page 9 —
```
CONFIDENTIAL
U.S.S. TIRPITZ (SS-412)
Serial (09)
Report of Fifth War Patrol.

0420  For attack, depending on fire control party to cut a solution on the way. Fortunately there is a low, heavy overcast with which our conning tower blends nicely.
        At range of 3,500 yards nearest pip suddenly disappeared. Reversed course at flank speed. We and found a 10° starboard track, target speed 9 knots. Would have had it in less than 3 more minutes. He couldn't possibly have seen us, was never sighted him. Apparently it was time for his alarming dive, or possibly he was an air detector. Sent contact report to CSD, CERO, and PDR. A.M. to head southward for Lifeguard station, ordered to coordinate a search with CERO tonight. This one was hard to take.

0832  Submerged.
1200  Position: Lat. 40-37.1 N.
       Long. 142-18.5 E.
1807  Surfaced.
July 12
0500  (K) On Lifeguard station for carrier strike. Weather very poor--raining and low visibility. Considered that strike would probably be postponed.
1015  Now convinced that strike is off-submerged.
1200  Position: Lat. 38-50.7 N.
       Long. 142-04.8 E.
1328  Weather clearing--surfaced.
1531  Now certain that there will be no activity today--submerged.
2053  Surfaced.
2129  Exchanged signals by SJ with KILOWATT.
July 13
0500  (K) On Lifeguard station for carrier strike.
05.5  In communication with CLF and have SD and sight contact with 2 HELLCATS at 6 miles. Sighted numerous friendly planes throughout the day.
-20-
ENCLOSURE (A)
```

— page 10 —
```
CONFIDENTIAL                       U.S.S. THRESHER (SSN-593)
                                   Report of Fifth War Patrol.
                                   Serial (09)

0745       CAP relieved by 2 more HELLCATS.
1001       CAP departed without relief—Somebody must have slipped
           somewhere along the line. We did not greatly need them,
           so decided not to further load the conversation on
           especially as I felt sure they would arrive in time.
           However, during the remainder of the day we were
           without thought there were always friendly planes within sight.

1055       SJ interference—must be from friendly surface forces—
           there are no subs in the vicinity.

1200       Position: lat. 36-57.0 N.
           Long. 142-16.1 E.

1215       Received messages from CSP that battleships, cruisers, and
           destroyers would bombard WAIKIKI, just 20 miles from us,
           at 1300.

1231       Sighted 3 battleships closing coast to north of us.

1300       Sighted 2 cruisers with DEs.

1316       From distance of 30,000 yards observed the loading EH Air
           the first salvo of the war at the island of KALAI.

1405       S/C (3) - Observed smoke to southward and thought it
           was a ship closing us with zero angle on bow. Called on
           vessel closing us with zero angle and borrowed 4 fighters to
           investigate.

1430       Watched two fighters make 2 strafing runs on target.
           They reported that it was stopped, but still color
           that they had to return to station. Decided to hold
           him off, since he was only 5 miles away and we had nothing
           else to do.

1515       Made out target to be a small lugger of about 75 tons.
           Is now underway again, making 7 knots towards us.

1530       Opened fire at 1500 yards with 40mm, 20mm, and .50 cal.
           guns. Closed to 1000 yards. Target finally caught fire
           and was still burning briskly a half hour later when
           soon. No personnel seen.

1540       Set course back to station. Bomber Aircraft Group now with...
                                   -21-
```

— page 11 —
```
CONFIDENTIAL                U.S.S. THERAPY (SS412)
S3l12/A16-3                 Serial (09)
                             Report of Fifth War Patrol

1700    - Strike completed for the day--submerged.
2038    Surfaced. Commenced a sweep northward along the 100
        fathom curve, hoping that the bombardment would stir a
        movement of traffic towards TSUGARU STRAIT. Nothing
        observed in KAMISHI.

2150    Apparently our lines was a good one--received despatch to
        keep clear of this area to southward as a division of
        cruisers and a squadron of destroyers were going to take
        anti-shipping action commencing at midnight. Was just
        able to get clear in time.

2320    SJ interference to eastward--the anti-shipping sweeps
        coming in.

July 15
0006    (K) SJ contact on friendly aircraft @ 10 miles.
0246    Submerged to work on radar.
0507    Surfaced on Lifeguard station.
0530    SD contact and in communication with CAP planes.
0611    Two HELICANS arrived on station.
0655    CAP reports someone in trouble--will try to bring the
        to us.
0703    Fighter ditched about 17 miles to south of us; three planes
        circling him. One fighter CAP went off on search, the
        other remained with us. Thanks 9934.
0748    Sighted pilot on a raft. Fighter CAP relieved.
0756    Picked up Ensign William J. KINGTON, 363494, USNR, from
        U.S.S. ESSEX. Set course back to station.
1000    Fighter CAP relieved.
1155    Fighter CAP relieved.
1200    Position: Lat. 35-54.5 N.
        Long. 112-08.7 W.
1400    Fighter CAP relieved.
                             -22-
                             ENCLOSURE (A)
```

— page 12 —
```
CONFIDENTIAL                U.S.S. TREPANG (SS-112)
                             Report of Fifth War Patrol.

1455                          Fighter CAP departed from station.
1600                          Not being assigned any further lifeguard duties, set
                             course northward, planning on getting in some more
                             ambushed patrol off SHIRTAI SAIT in hopes that the J
                             would be attempting to get their ships into the J.
                             Sm.

JULY 16 (T)
0430 (R)                     Submerged.
1200                          Position: Let. 40-52.9 N.
                             Long: 142-36.8 E.
1315                          Surfaced for 20 minutes.
2035                          Surfaced, Petrolling on surface between SHIRTAI SAIT and
                             BRITNO SAIT.
2100                          Exchanged signals on SJ with PARCHE.

JULY 17
0005 (T)                     Received despatch from CSP ordering us to Lifeguard static
                             220 miles southward of us at 0500. Set course for new
                             station at 4 knots speed.
0130                          Transmitted TRP-6's serial seven notifying CSP that we
                             would not arrive on station until 1300.
1200                          Position: Let. 38-31.7 N.
                             Long: 142-16.3 E.
1230                          On station.
1301                          SD contact and in communication with British Fighter CAP.
                             Sighted shortly afterwards.
1341                          Sank floating mine with .50 cal.
1408                          Sank another floating mine with .50 cal.
1452                          Fighter CAP departed station-weather getting bad.

JULY 18
0500 (T)                     On Lifeguard station for today's strike. Weather very poor
                             raining, low visibility, and low rolling.
                             -23-
```

— page 13 —
```
CONFIDENTIAL
U.S.S. TREPANG (SS412)
Serial (09)
Report of Fifth War Patrol.

0600  Assumed strike had been postponed--submerged.
       Position: Lat. 57-54.3 N.
                Long. 142-01.5 E.
1337  Surfaced. Still no signs of air activity.
1444  Submerged.
2054  Surfaced.

July 19
0530 (K) On Lifeguard station for strikes. Still missing.
0850  Assumed strike had been postponed--submerged.
1200  Position: Lat. 36-25.1 N.
       Long. 144-52-6 E.
2048  Surfaced. Commenced working northward again.
2300  Received despatch orders to leave area July 21.
2353  Commenced converting #3 and #5 fuel ballast tanks.

July 20
0952 (K) Submerged.
0957  Surfaced. Set course for ERITICO SACHI.
1200  Position: Lat. 40-03.5 N.
       Long. 143-00.8 E.
2200  Commenced patrolling northward along 100 fathom curve off east coast of HOKKAIDO.

July 21
0337 (K) Submerged for periscope patrol off KUSHIRO.
1100  Have been unable to fix position because of fog. Having no fathometer now, decided to open coast and surface.
1200  Position: Lat. 42-31.3 N.
       Long. 144-20.5 E.
1559  Surfaced.
```

— page 14 —
```
CONFIDENTIAL                       U.S.S. THRESHER (SSN-593)
SSN-593/A16-3                      Report of Fifth War Patrol
Serial (09)

1900    Departed Area I. Set course for MIDWAY.
1938    SD contact at 12 miles - divided.
2015    Surfaced. Conducted training dives and dives enroute to base.

July 22
1200 (K) Position: Lat.  43-03.1 N.
                Long:  150-57.1 E.

July 23
1200 (L) Position: Lat.  42-51.0 N.
                Long:  158-42.6 E.

July 24
1200 (M) Position: Lat.  37-23.0 N.
                Long:  165-45.0 E.

July 25
1200 (N) Position: Lat.  34-12.7 N.
                Long:  169-12.2 E.

July 26
1200 (O) Position: Lat.  31-17.3 N.
                Long:  174-13.0 E.
2400    Set clock back 2½ hours to conform to plus 12 zone time.

July 26
1200 (P) Position: Lat.  29-12.2 N.
                Long:  179-07.0 E.

July 27
0530    Made rendezvous with planes.
0800    Arrived MIDWAY. Conducted sound tests.
1500    Departed MIDWAY.
July 27-31 Enroute Pearl Harbor.

-25-                             ENCLOSURE (A)
```

— page 15 —
```
CONFIDENTIAL                U.S.S. TIRPANG (SS412)
C312/A16-5
Serial (09)                Report of Fifth War Patrol.

(C) WEATHER
In the area south of HONSHU and in the vicinity of NAIRO SHOTO
weather was generally poor. Minimum sea was three feet with frequent
force 5 and 6 seas. Sky was always 90% to 100% overcast at night
but of varied colors during the day. In the off the eastern coast of North
HONSHU and southern coast of HOKKAIDO haze with low visibility was the usual
condition with occasional sight of moon spilling subdued rays. This caused
on days when visibility conditions permitted tidal currents proved
valid necessitating cautious periscope exposure. Occasional short-lived
periods of good visibility were experienced between North HOKKAIDO. Visual
proceedings in this area close in for the offshore surface patrol on foggy
days and a close inshore submerged patrol on comparatively clearer days.

(D) Tidal currents were dominated by the warm KUROSHIO and the cold
OYASHIO. These were further complicated by a cold current coming out of
TSUGARU KAIKYO. In general the OYASHIO set to the south along the coast
of northern HONSHU, the KUROSHIO to the northeast and was experienced
around 30 to 40 miles off the coast. Currents along the southern coast of
HOKKAIDO ran to the southeast. The following currents were observed
repeatedly:

                     MONBUKU LIGHT (HOKKAIDO)  - - - -  1.40° C.  1.7 kt.
                     TSUGARU KAIKYO (eastern entrance) -  9.90° C.  2.0 kt.
                     SHIRAKABA SAKI (south of, along coast) -  19.00° C.  2.8 kt.
                     FOO SAKI (south of, along coast) -  20.00° C.  2.0 kt.

(E) NAVIGATIONAL AIDS
Only two coloristical fixes were obtained in area due to complete
overcast over 95% of the time. In the area navigational aids were
at a minimum with points and distances along the northern coast
of HONSHU and the southern coast of HOKKAIDO more frequently
on the charts. Larger scale routes would be convenient in fixing runs but is
not recommended to a range of routes out to the following points that
were finished to a range of routes out to the following points:

                     TODD SAKI - white, irregular.
                     SHIRAKABA SAKI - white, flashing once per minute.
                     KONOHI SAKI - white, irregular.

26                       ENCLOSURE (A)
```

— page 17 —
```
U.S.S. TATANG (SS-12)
SS 12/A16-3
Serial: (09)
Report of Patrol Trip

(5) AIRCRAFT CONTACTS

Only 9 enemy planes were contacted during a thirty day period off NAGATO, TOKYO, west coast of Northern Honshu, and south coast of HOKKAIDO. Made a sight contact with what was identified as a TRAIL, one believed to be a twin-engined figure eight while two were single-pontoon, single-engined monoplans similar in appearance to RYAN. The remaining one was sighted at night (no evidence of having radar) and could not be identified. To us, the TATANG cases with the new comments, Japanese aircraft are becoming scarce.

-28- ENCLOSURE (A)
```

— page 18 —
```
CONFIDENTIAL                       U.S.S. TIRPITZ (SS-412)
Scale: 1/2(416-3)                  Report of Fifth War Patrol.
Sern: 199
(H) ATTACK DATA

                       TORPEDO ATTACKS #1A & #1B

                       ATTACK #1A          ATTACK #1B

Tube #1                121 P              117 P
Track Angle            29 S  21 L        27 L  18 R
Gyro Angle             4°                 4°
Depth Set              4'                 4'
Power                  45.9 K             45.9 K
Hit or Miss            Hit                Miss
Erratic                No                 No
Mark Torpedo          23                 23
Serial No.            625086  53113      625353  33800
Mark Exploder         6-4                6-4
Serial No.            20148  18893      6333   1201
Mark Warhead          16-1               16-1
Serial No.            18240  17900      14324  17684
Explosive             TORPEX             TORPEX
Firing Interval       ---  9 sec.        9 sec.  11 sec.  7 sec.  10 sec.
Type Spread           0  2               1 R     2  1 R
Sea (state)           3                  3
Overall Activity      U.S.S. APOLLO (A525)
Remarks               (a) Length of run (best est.)  900 yds.
                     (b) Duration of run.  35 sec.  36 sec.
```

— page 19 —
```
CONFIDENTIAL
U.S.S. TREPANG (SS-412)
Serial # A16-3
Report of Patrol
(Part 1)

(E) ATTACK DATA (Cont'd)

U.S.S. TREPANG
SS 412 TORPEDO ATTACKS #A & #B
PATROL #5
TIME: 1350(K) DATE: 7/7/45 LAT. 41-21.5 N. LONG. 141-28.0 E.

TARGET DATA - DAMAGE INVOLVED

DESCRIPTION: Periscope sighted smoke, then convoy of three small freighters rounding SHIRYA SAKI in column, headed south, hugging the beach. The leading ship was identified as a small freighter, which allowed us to get 900 yards range estimates. A 10° port track torpedo was being torpedoed, so that a periscope set-up could also be made on the second ship.

SHIPS SUNK (SU): One (1) small freighter similar in appearance to NITIMAN MARU, p. 178, ONI 208-J (revised).

SHIPS DAMAGED: None.

DAMAGE METER: Through periscope, observed two hits and saw ship sink.

TARGET DRAFT 18' | COURSE 200° T. | SPEED 10 K. | RANGE 900 yds.
(at firing)

OWN SHIP DATA

SPEED: 2.3 K. | COURSE 290° T. | DEPTH 64' | ANGLING 10° dive.
(at firing)

FIRE CONTROL AND TORPEDO DATA

Type Attack: Good visibility, day periscope, divided fire. Fired three torpedoes at leading freighter (two hits) and three at second freighter in column two yards astern of the first ship. The second ship unobservedly saw our exposed periscope or was able to see torpedoes fired at the leading ship for he was able to turn out of the way of the three directed at him even though 11 seconds elapsed between the firing of #3 and #4 torpedoes.

-30-

[STAMP: ENCLOSURE (A)]
```

— page 20 —
```
CONFIDENTIAL                U.S.S. TRITON (SS-12)
S314.12/1463                Serial (009)          Report of Fifth War Patrol

(H) ATTACK DATA (Cont'd)                     TORPEDO ATTACK #2
| Tubes Fired      | #1  | #2  | #3  | #4  |
||-----|-----|-----|-----|
| Tubes Angle      | 125 S | 124 S | 126 S | 123 S |
| Gyro Angle       | 10 R  | 9 R   | 11 R  | 6 R   |
| Depth Set        | 4'    | 4'    | 4'    | 4'    |
| Power            | 45.9 K| 45.9 K| 45.9 K| 45.9 K|
| Hit or Miss      | Hit   | Hit   | Miss  | Hit   |
| Erratic          | No    | No    | No    | No    |
| Mark Torpedo     | 23    | 14-34 | 23    | 14-34 |
| Serial No.       | 63067 | 40130 | 49282 | 26339 |
| Mark Exploder    | 6-4   | 6-4   | 6-4   | 6-4   |
| Serial No.       | 18553 | 20164 | 8648  | 17467 |
| Mark Warhead     | 16-1  | 16-1  | 16-1  | 16-1  |
| Serial No.       | 17701 | 18190 | 14-301| 17739 |
| Explosive        | TORPEX| TORPEX| TORPEX| TORPEX|
| Firing Interval   | ---   | 9 sec. | 9 sec. | 7 sec. |
| Type Spread      | 1/2 R | 1/2 L | 1/1 R | 1/4 L |
| Sea (state)      | 1     | 1     |       |       |
| Original activity | U.S.S. APOLLO (A325) |
| Remarks          | (a) Length of run (best est.)  2250 yds  |
|                  | (b) Duration of run.  Lt. 273. 1m. 258. 1m. 21s. |
|                  | ENCL. (A) |
```

— page 21 —
```
CONFIDENTIAL                U.S.S. TIRPITZ (SS412)
SS412/A6-3                  Serial (009)
                            Report of Midit War Patrol.

(H) ATTACK DATA (Cont'd)
U.S.S. TIRPITZ             TORPEDO ATTACK #2
TIME: 2338(K)              DATE: 7/8/45  LAT: 41-35.0 N.  LON:  136-  E.

TARGET DATA - DAMAGE INFLICTED
DESCRIPTION:               Single DD or DE, possibly an anti-submarine vessel.
                           Contact made at 12,000 yards on 67 degrees true.
                           Dark night, complete overcast with occasional light rain.
                           The 84 indicated a slight spot the size of our own
                           periscope destroyer. A 150 degree arc, torpedo
                           used a target length of 225 feet, measured in hits,
                           indicating the target was probably larger than this.
                           Target silhouettes seen at 0.0, 0.0, which states that
                           it had the lining of a destroyer type.
                           Target was playing on 13.5 T.

SHIPS SUNK:                One (1) DD or DE (estimated 1000 tons).

SHIPS DAMAGED:             None.

DAMAGE DONE:              Saw ship explode. Pip disappeared from radar
                           screen at 3,400 yards.

TARGET DRAFT:             10'  COURSE  050° T.  SPEED  11 K.  RANGE  1. K.
                           (at 1,000 yds)

OWN SHIP DATA

SPEED  11 K.  COURSE  000° T.  DEPTH  Surface  (C)

FIRE CONTROL AND TORPEDO DATA
Type Attack:              Night surface radar attack after one and one-half
                          hours of tracking. Look low outline of
                          just visible at 2500 yards. Commenced firing
                          torpedoes forward at 2100 yards. Three hits.

-32-

[STAMP:  HECL. (A)]
```

— page 22 —
```
CONFIDENTIAL

U.S.S. TRITON (SS-201)
Report of Fifth War Patrol.
Serial (09)

(H) ATTACK DATA (Cont'd)
U.S.S. TRITON GUN ATTACK #1

TIME: 0605(K) DATE: 6/30/45 LAT: 33-19.8 N. LONG: 139-...

TARGET DATA - DAMAGE INCURRED

SHIPS SUNK (SC): One (1) Sugar Charlie Sugar of about 600 tons.
DAMAGE INFLICTED: Saw ship sink as a result of numerous hits from 5"/25, 40mm, and 20mm guns.

DETAILS OF ACTION

Made battle surface at ST radar range of 4,000 yards, opening fire with 5"/25 only. First 3 rounds fired were HE for spotting. The next 12 rounds were Mk. 14 (loaded). The target got off only 2 short bursts from one gun (appeared to be two 37mm) before one of the Mk. 14 exploded right over her, amidships. Fired good fire again. Closed target to 1200 yards, firing 5"/25, Mk. 14, and both fire again. Target soon burning into flames and sank 40 minutes after battle surfaced. Ammunition expended: 5"/25, 0 rounds (12 rounds Mk. 14, 0 fused and 28 rounds Mk. 29 fused); 40mm, 32 rounds; 20mm, 32 rounds HIT; 20mm, 360 rounds HIT and 180 rounds HE; 50:1, 20 rounds.

-33-
[STAMP: EXCLUSION (A)]
```

— page 23 —
```
CONFIDENTIAL                U.S.S. THRESHER (SSN-12)
SSN12/A46-3
Serial (69)                  Report of Fifth War Patrol

(7) ATTACK DATA (Cont'd)
U.S.S. THRESHER

GUN ATTACK #2
PM: 75
AIR: 1530(X)  DATE: 7/14/45  LAT: 38-42.6 N.  LONG: 141-31.2 E.

TARGET DATA - DAMAGE INCURRED
SWINGS DESTROYED (3): One (1) lugger of approximately 75 tons.

DAMAGE SUSTAINED BY:
Observed many hits by 40mm, 20mm, and .50 cal. guns. Target caught fire and was still burning briskly a half hour later when last seen.

DETAILS OF ACTION
Opened fire on 7 knot target at 1,500 yards with 40mm, 20mm, and .50 cal. guns. Closest to 400 yards. No personnel seen aboard target. Ammunition expended: 40mm, 66 rounds (AS rounds HE); 20mm, 906 rounds (600 rounds HEIT, 300 rounds HET); .50 cal., 1,040 rounds (416 AZ, 416 incendiary, and 206 tracer)

-34-
ENCLOSURE (1)
```

— page 24 —
```
CONFIDENTIAL                       U.S.S. THETIS (SS142)
SS142/126-3                        Serial (09)
                                   Report of Fifth Patrol

(I) MINES
     The THETIS sank two mines (moored type) during her 5th war patrol, disposing of them with a 50 caliber machine gun at Lat. 38-16.0'N., Long. 112-20.2'E. .50 caliber ammunition seems quite effective in disposing of this type of mine.

(C) ANTI-SUBMARINE MEASURES AND TACTICS
     about an hour and a half after torpedo attack (A and B), while running at periscope depth in a secure area, we were attacked by a plane. Two bombs were dropped close aboard, causing numerous minor casualties and permanently grounding out the fathometer. The periscope has not been raised for 48 hours.

     We did not click on the radar, in view of the conditions, it is estimated that the life of the radar was slight. After the bombing we went deep and held our depth at a half hour later 2 anti-submarine vessels stayed at the source of the bombing at this time about 3000 yards to the south. The depth charges exploded for five hours while we gradually moved the ship to the north.

     The other ship must have been a destroyer of some type with a frequency less than 14, 108. This instrument's frequency must have been close to 15, 108. It is believed that it was a destroyer before this.

     To determine our sighting, a torpedo boat was sighted at a maximum range of only 800 yards.

     The coast in the vicinity of SHITTA SAKI was closely patrolled during this time, the enemy apparently the closer for the day. This observation is based on experience.

     One destroyer escort was detected sinking a mine passage or anti-submarine sweep between SHITTA SAKI and SHITTA SAKI. No radar was detected, so we were undetected at a range of 2,000 yards on the surface.

                                   [HANDWRITTEN: END OF PAGE]
```

— page 25 —
```
CONFIDENTIAL                       U.S.S. THRESHER (SSN-412)
                                   Report of Fifth War Patrol.

(I) MAJOR DEFECTS AND DAMAGE

C. O. R.
None.

MACHINEERING
Major Defects - Excessive chattering of brasses in all main engines has been experienced by this ship ever since commissioning. This has been a constant source of trouble at all revs, requiring maximum use of brasses resulting in an excessive amount of hours in order to keep them in service. In spite of constant attention, the condition still exists. Two advanced base refits have been made to rectify this situation, and have proven futile to date.

Minor Defects - The combination of results in chipping brasses and excessive wear on the connecting rods has become very critical. The connecting rods have become badly grooved and are now in a condition that is dangerous for the operation of the engines. The wear is now over 300 inches to .005 inches. That condition, if not corrected, will result in a complete failure of the engines.

As yet, no direct cause of this chattering has been determined. Careful observations by the ship's force, however, indicate that while operating with a surface speed of 1300 r.p.m., there is excessive cavitation and the output and pitch of the propeller is greatly improved.

(L) RADIO
Radio From occasional jamming (see section (V)), radio reception was good throughout the patrol. A detailed report is being forwarded to Com.SubRadio.

The new Lifeguard Group is a vast improvement in Lifeguard communications. The JAR terminal for sub. to sub. correlation is a splendid idea which will come into its own when all submarines have received a modification which provides two
```

— page 27 —
```
CONFIDENTIAL
U.S.S. TENTH (SSA12)
S3.12/A6-3
Serial (09)

Report of Fifth War Patrol.

Outside of burning up T-R tubes (the entire on board spares allowances was used up), the ST required no more than its regular weekly tune up.

SD - The SD round in another excellent performance on this patrol. The transistor frequency was assigned from 112 to 115 MG during the patrol. This seemed to eliminate the dead spaces around 10-12 miles and proved very beneficial. The only casualty was a lazy electrical circuit on a very high pilot current.

(M) SOLAR AND SOUND CONDITIONS
Sound conditions of SINTA SAKT were fair to good in spite of some very strange and erratic SSB cards. During the strike on 7 July a listening area of about 5,000 yards was observed which had a land horizon. Target was not detected when it was in the sea around. Firing was detected at about 10,000-15,000 yards.

3 July - 7.5 KGs of SINTA SAKT.
7 July - 1.5 KGs of SINTA SAKT.
8 July - 1.5 KGs of SINTA SAKT.
11 July - 1.5 KGs of SINTA SAKT.

The following results resulted from the two close bombs taken on 7 July:

JF - One connection of [UNCLEAR: on] Myrphobic length - loose, let me know and I will send it in.
NM - Zero ground population included. Telemeter out of commission for remainder of patrol.

(O) DENSITY LAYERS
Many strange density layers were encountered in the area off northeast shores, the general trend of which was enough strong negative regions extending behind the surface in 60 ft. 25 SSB cards were taken in this area and are being forwarded to the U.S. Chief of Naval Operations. Following is a summary of representative cases:

-3E-
```

— page 28 —
```
U.S.S. TREPANG (SS-412)
SS/12/41-5-3
Serial: (09)
Report of Flight War Patrol

CARD 10: COMPARATIVE POSITION: CHARACTER OF UTILITY LAYER
5-1  5/1/45  1.30 M.  30 M.  Active from surface to 120 ft.  4° change
5-2  5/1/45  1.50 E.  120 M.  190 ft. to 30 ft.
5-3  5/1/45  1.30 N.  Isothermal to 180 ft.
5-4  5/1/45  1.40 N.  Isothermal to 195 ft.
5-5  5/1/45  1.50 N.  Changing from surface to 200 ft.
5-6  5/1/45  1.30 N.  250 ft. to 60 ft.  Isothermal.
5-7  5/1/45  1.10 N.  Changing from 60 ft. to 250 ft.  Isothermal.
5-8  5/1/45  1.30 N.  250 ft. to 210 ft.  Sharp layer.
5-9  5/1/45  1.30 N.  210 ft. to 60 ft.
5-10 5/1/45  1.30 E.  60 ft. to 70 ft.
5-11 5/1/45  1.30 E.  70 ft. to 80 ft.
5-12 5/1/45  1.30 E.  80 ft. to 90 ft.
5-13 5/1/45  1.30 E.  90 ft. to 100 ft.
5-14 5/1/45  1.30 E.  100 ft. to 110 ft.
5-15 5/1/45  1.42 R.  Horizontal surface to 80 ft.
5-16 5/1/45  1.42 R.  Horizontal surface to 90 ft.  50° change.
5-17 5/1/45  1.42 R.  Horizontal surface to 100 ft.
5-18 5/1/45  1.42 R.  Horizontal surface to 110 ft.
5-19 5/1/45  1.42 B.  180 ft. to 110 ft.  Isothermal 110 ft.
5-20 5/1/45  1.42 B.  280 ft.
5-21 5/1/45  1.30 N.  Horizontal surface to 80 ft.  100° layer.
5-22 5/1/45  1.30 N.  80 ft. to 90 ft.

[STAMP: ENCLOSURE (A)]
```

— page 29 —
```
CONFIDENTIAL                       U.S.S. TREPANG (SS412)
SS412/A16-3                        Serial (09)
                                   Report of Fifth War Patrol

CPT NO:  0C0DADIES; POSITION; CHARACTER OF DENSITY LAYER
5-22-15  19° 39' N.  119° 07' W.  Isothermal surface to 80 ft.  60' layer
5-23-15  19° 34' N.  119° 07' W.  Isothermal
5-24-15  19° 30' N.  119° 07' W.  Isothermal surface to 80 ft.  70' layer
5-25-15  19° 26' N.  119° 12' W.  Isothermal surface to 80 ft.  80' layer
5-26-15  19° 23' N.  119° 39' W.  Isothermal surface to 80 ft.  80' layer
12/4/15  19° 43' N.  143° 03' E.  2.80 ft.

(F) HEALTH, FOOD, AND HABITABILITY

One case of acute appendicitis developed early in the patrol.  Rodium sulphur treatment was given and after 3 days the patient was over the attack.  He was transferred soon afterwards to a submarine returning to Guam.  Several head colds and tonsillitis cases recovered after treatment.  In general, the medical care was very good.

The food was excellent, being of good quality and variety, and exceptionally well prepared.

Habitability was very good.  Most of the patrol was spent in weather with an air temperature of 50-60 degrees.  This made inside temperature of the boat ideal.

(Q) PERSONNEL
(a) Number of men detached after previous patrol - 3
(b) Number of men on board during patrol - 77
(c) Number of men qualified to stand watch or patrol - 53
(d) Number of men qualified to end of patrol - 53
(e) Number of unqualified men making first patrol - 3

*One T130 was transferred to DEWLINE early in patrol due to appendicitis.

-40-
```

— page 30 —
```
CONFIDENTIAL
U.S.S. TREPANG (SS412)
SS412/A16-3
Serial (09)

Report of Fifth War Patrol

Up until this patrol all of us considered the furnishing of lifeguard services as the very dullest of our duties. However, the results of this patrol, however, have changed our viewpoint entirely as we now realize the importance and high morale factor in aiding those who are struggling in the water to escape drowning. To be able to rescue those victims was a decided boost to our morale also as we are grateful to be able to save lives for a change.

(R) MILES STEAMED - FUEL USED
GUAM to Area                1,251 miles        12,950 gal.
In Area                      5,894 miles        59,250 gal.
Area to MIDWAY              2,150 miles        279,700 gal.
MIDWAY to PEARL HARBOR     1,370 miles        17,200 gal.
TOTAL                       10,663 miles      119,110 gal.

ENCLOSURE: (A)
```

— page 31 —
```
CONFIDENTIAL
U.S.S. THETIS (SS412)
SS412/A16-3
Serial (09) Report of Fifth War Patrol

(S) DURATION
Days enroute to Argo

— page 32 —
```
CONFIDENTIAL                       U.S.S. THRESHER (SSN-312)
SSN12/A16-3
Serial (09)                       Report of Fifth War Patrol.

DATE        LOCATION        FREQ   PPI   STRENGTH    REMARKS
6/77/45     20-28.2        80     500   100 Moderate  Sweeping Irregularity.
            140-08.5

7/7/45      13-59.0        210    4000  7 Strong     Steady.
            13-59.1        21     300   8 Moderate   Swooping.
            13-59.7        175    70    8 Moderate   Swooping.
            13-59.8        180    2000  7 Strong     Swooping.
            13-59.9        180    250   10 Moderate   Steady.
            13-59.0        77     500   20 Weak      Swooping.
            13-59.1        25     300   5 Moderate   Swooping.
            13-59.2        160    500   9 Saturated   Swooping Slowly.
            13-59.3        164    500   12 Strong    Steady.
            13-59.4        152    500   5 Strong     Steady.
            13-59.5        5      5     5 Strong     Steady.
            13-59.6        199    500   7 Moderate   Swooping.

7/23/45     13-59.7        10     500   13 Moderate   Swooping.
            14-00.0        39     500   10 Moderate   Swooping.
            14-00.1        42     500   9 Weak       Swooping.
            14-00.2        42     500   10 Moderate   Swooping.
            14-00.3        162    500   10 Saturated  Steady.
            14-00.4        130    500   10 Saturated  Steady.
            13-59.9        105    400   7 Moderate   Swooping.
            13-59.0        180    500   10 Saturated  Swooping Slowly.
            13-72.2

[STAMP: EXCLUSION (A)]
```

— page 33 —
```
CONFIDENTIAL                U.S.S. TINOSA (SS-283)
C-412(A16-3)                Report of Fifth War Patrol.
Serial (09)

(S) DURATION
Days enroute to Area 4
Days in Area to 32
Days enroute to Base 21
Days submerged

(T) FACTORS OF ENDURANCE KILLING
Torpedoes, number 12
Fuel gallons 14,600
Provisions, days 25
Personnel, days 30

Limiting factor this patrol - Operation Order.

(U) COMMUNICATION AND RADIO COUNTERMEASURES

(A) RADIO
The Jap is getting better with his jamming, but he still does
not stick it out long enough to be really directive. Frequently
parts of messages were blocked out on the first skid, but they
were easily recoped on later sides.

9090 and 950 Kcs, the two frequencies which were usable in
the skeds, were jammed mightily by a CW signal or carrier of
intensity than the NBM signal. The jamming could be tuned out,
and never caused messages to be missed on all skeds.

TOKYO is evidently on the mailing list for Scripps, as the
error frequency, as well as both AIR CW frequencies, are jammed
almost constantly and with few more, different than skeds.
The carrier frequency was used only for WQ (301302) and the
[UNCLEAR: 113802] of SHIRYA BACH. The messages were clear to the
PARIS and CERO, not more than 200 miles away.

Some days, the jamming was a CW signal keyed apparently to
random.

(3) RADAR
(I) Interception of enemy signals.

DATE          LOCATION AREA  FFP  STRENGTH  REMARKS
6/7/45        19-47 N, 112  500  5 Structured Study.
440-48.3
```

— page 34 —
```
CONFIDENTIAL                       U.S.S. TETRANG (SS-412)
SSh12/A16-3
Serial (09) Report of Fifth War Patrol.

DATE       LOCATION          FRQ.   PRF.   PT.   STR.   COND.   REMARKS
           (LAT. & LONG.)   (KCS)  (KCS)  (FT)   (KTS)  (KTS)   (SWEPTING)

6/17/45    20-28.2 N 80-500  100    Moderate  Sweeping Irregular.
7/17/45    14-08.5 N 139-50.1 1000   7 Strong  Steady.
7/18/45    13-50.1 N 129-10.1 215    300     8 Moderate  Sweeping.
7/19/45    13-29.7 N 175-70.0  70     8 Moderate  Sweeping.
7/20/45    13-29.7 N 180-200.0 200    10 Strong  Sweeping.
7/21/45    13-29.7 N 180-250.0 10     Moderate  Steady.
7/22/45    12-29.0 N 77-500   20     Weak     Sweeping.
7/23/45    12-29.0 N 300-300  8      Moderate  Sweeping.
7/24/45    13-29.3 N 160-500  5      Saturated  Sweeping Slowly.
7/25/45    13-29.3 N 164-500  12     Strong  Steady.
7/26/45    13-27.6 N 152-500  5      Strong  Steady.
7/27/45    13-27.6 N 159-500  7      Moderate  Sweeping.
7/28/45    13-29.7 N 110-500  7      Strong  Sweeping.
7/29/45    14-10.0 N 74-500   13     Moderate  Sweeping.
7/30/45    14-10.0 N 162-400  10     Saturated  Steady.
7/31/45    13-29.3 N 165-700  7      Moderate  Sweeping.
8/1/45     13-29.1 N 180-500  10     Saturated  Sweeping Slowly.
```

— page 35 —
```
CONTINENTAL                       U.S.S. T.L.A.N. (S.S. 414)
SS414/Al-3                        Serial (09)
Report of Fifth War Patrol.

DATE        LOCATION        FREQ.   DEPTH   PW STRENGTH   REMARKS
67/6/75     34-28.0 N      500     34       Moderate      probably big boat spring antenna mentioned in patrol
             137-12.5 E
             34-27.5 N      80      500     20       Weak   Steady.
             137-12.5 E
             34-26.5 N      159     250     10       Moderate
             137-12.5 E
             34-25.0 N      160     500     7        Strong  Swooping.
             137-12.5 E
             34-24.5 N      112     500     20       Moderate  Swooping slowly.
             137-12.5 E
67/7/43     34-23.0 N      158     500     10       Moderate  Slow swoop.
             137-12.5 E
             34-22.5 N      154     500     5        Weak    Slow swoop.
             137-12.5 E
             34-21.0 N      161     300     12       Over IFF band E-2y Bit.
             137-12.5 E
             34-20.5 N      160     400     30       Weak    Swooping.
             137-12.5 E
             34-19.0 N      99      400     10       Weak    Swooping.
             137-12.5 E
             34-18.0 N      164     500     3        Strong  Steady swoop.
             137-12.5 E
             34-17.5 N      137     1/4     7        Saturated  Swooping.
             137-12.5 E
             34-16.0 N      162     500     3        Strong  Swooping.
             137-12.5 E
             34-15.0 N      74      500     15       Saturated  Swooping.
             137-12.5 E
             34-14.0 N
ENCLOSURE (A)
```

— page 36 —
```
CONFIDENTIAL                U.S.S. TREPANG (S312)
S312/12/16-3
Serial (09)

Report of Tich Wk. Patrol.

Date      Location     Freq.  Prep.  Div.  Strength  Remarks
7/28/45   1.  3  109   500   15    Saturated  Swooping.
          2.  0       500   20    Moderate   Swooping.
          3.  0       500   20    Moderate   Swooping.
          4.  95      500   15    Weak       Swooping.
          5.  110     500   20    Moderate   Swooping.
          6.  110     500   20    Strong     Swooping.
          7.  77      500   36    Strong     Swooping.
          8.  154     500   2     Strong     Swooping.
          9.  30      500   15    Weak       Swooping.
          10. 100    400   15    Moderate   Swooping.
7/30/45   1.  1      600   7     Strong     Swooping.
          2.  1      600   7     Weak       Swooping.
          3.  153    500   7     Strong     Blow slow.
7/17/45   1.  154    500   5     Moderate   Swooping.
          2.  97     1600  12    Moderate   Swooping slowly.
          3.  1      500   2     Moderate   Swooping slowly.
          4.  1      500   7     Strong     Swooping slowly.
          5.  1      324   500   7     Strong     Swooping.
          6.  1      132   500   5     Saturated  Swooping.

```

— page 37 —
```
CONFIDENTIAL                       U.S.S. TREPANG (SS412)
S3/11.2/416-3
Ser: all (09)                       Report of Fifth War Patrol.

DATE      LOCATION        FREQ.   PERT.  EV. STRENGTH   REMARKS
7/1/45    35-12N 125-45E  500     20    15  Saturated  Sweeping.
7/7/45    35-12N 125-50E  500     10    20  Weak       Sweeping.
7/9/45    35-12N 125-50E  500     12    Saturated   Sweeping.
7/9/45    35-12N 125-50E  500     10    Moderate    Slow sweep.
7/10/45   35-12N 125-50E  500     10    Moderate    Slow sweep.
7/10/45   35-12N 125-50E  500     10    Weak        Slow sweep.
7/12/45   35-12N 125-50E  500     12    Saturated   Sweeping.
7/14/45   35-12N 125-50E  500     20    Moderate    Slow sweep.
7/14/45   35-12N 125-50E  500     1.5   500  Strong   Steady.
7/15/45   35-12N 125-50E  500     1.5   500  Strong   Steady.
7/15/45   35-12N 125-50E  500     1.5   500  Strong   Steady.
7/17/45   35-12N 125-50E  500     10    15  Moderate   Sweeping.
7/17/45   35-12N 125-50E  500     10    20  Moderate   Steady.
7/17/45   35-12N 125-50E  500     10    15  Weak      Slow sweep.
7/17/45   35-12N 125-50E  500     10    20  Weak      Slow sweep.
7/21/45   35-12N 125-50E  500     1.5   500  Strong    Sweeping.

```

— page 38 —
```
CONFIDENTIAL                       U.S.S. IREDALE (SS-412)
SS/412/A16-3                       Report of Fifth War Patrol
Serial (09)

(2) Jamming, own and enemy.
No radar jamming was encountered.

(3) Deception, own and enemy.
No deception was encountered, nor was any employed by this vessel.

(V) REMARKS
None.

-47-
```

— page 39 —
```
FBS-44/A16-3
Serial: 11-0109
C-O-N-F-I-D-E-N-T-I-A-L

SUBMARINE DIVISION FORTY-FOUR
Care of Fleet Post Office,
San Francisco, California.
2 August 1945.

FIRST ENDORSEMENT to
U.S.S. TEPANG (SS-312) Conf.
Lt. Cdr. of 31 July 1945 - Report of
FIFTH War Patrol.

From: The Commander Submarine Division FORTY-FOUR.
To: (1) The Commander-in-Chief, United States Fleet.
    (2) The Commander Submarine Squadron 7.
    (3) The Commander Submarine Force, Pacific Fleet.
    (4) The Commandant, U.S. Pacific Fleet.

Subject: U.S.S. TEPANG - Report of FIFTH War Patrol.

1. The Fifth War Patrol of the TEPANG under the command of Commander RUSSELL was conducted in the Empire Areas. This patrol was of forty-seven (47) days duration, thirty-two of which were spent in the operating areas.

2. The first portion of this patrol during the period 19 - 29 June was spent on lifeguard duties off HONSHU. Nine aviators were rescued during this phase. The second phase from 30 June to 12 July was spent in offensive patrols off the east coast of HONSHU. Five contacts worthy of attack were made, successful attacks being made on three of those. An enemy submarine was evaded by submerging, just prior to attack. During the latter phase from 13 - 21 July, lifeguard duties were performed incident to carrier strikes. The TEPANG had the honor of witnessing battleship fire their first salvo at the Japanese mainland and celebrated by destroying a lugger. One Naval Aviator was rescued.

3. (a) Torpedo Attack 1A and 1B - 7 July 1945:
While patrolling submerged off SHIRATA SAKE and while dodging several small patrol boats, an uncovered convoy of direct small ships in column, about 700 yards apart, was observed rounding the point and heading south. A very favorable firing position was obtained on the column between the lead and the largest in the convoy, and the second in column. Two fish were fired from tube 23 portside, one at 1, foot depth and the other at 1, range 900 yards; the second fish was fired port side as immediately shifted to the second ship and three additional torpedoes were fired from the second launcher. Unfortunately the second ship was not hit and the second ship was hit and sunk immediately. The third ship was also hit as a result of this attack on the TEPANG, while an unidentified enemy proceeded through the area and from an unknown direction. About thirty minutes later, during which time the TEPANG was very close. The fish that stood out for the remainder of the patrol as a direct result of the bombing.
```

— page 40 —
```
PBS-44/A16-3                     SUBMARINE DIVISION FORTY-FOUR
Serial: M-0109
C-O-N-F-I-D-E-N-T-I-A-L

FIRST INDORSEMENT TO
U.S.S. TIRPITZ (SS-12) Conf.
Ltr. of 31 July 1945 - Report of
PIRHI air Patrol.

Subject:  U.S.S. TIRPITZ - Report of PIRHI air Patrol.

(b)  Torpedo Attack - 2-6 July 1945:
     A mid surface attack using radar ranges and bearings on an
     unidentified ship believed to have been a destroyer or destroyer
     escort.  Positive identification was impossible due to the darkness
     of the night.  TIRPITZ was placed on a steady course & speed 11
     knots, and rounded to be firing on a frequency of 300.  Range
     was closed to 2,100 yards without detection and a spread of four
     torpedoes, two 12s and two 11-3s, was fired with a 10° right
     spread, for a 12° starboard track.  There hit sank the target.

(c)  Gun Attack - 20 June 1945:
     Sugar Charlie's Bar.  Early morning gun attack on a large (estimated 600 ton)
     vessel.  After surfacing at 10,000 yards after observing the craft at very close range, TIRPITZ quickly eliminated
     the enemy's two guns on port bow with 5"/25 cal.  No used
     ammunition.  Enemy opposition consisted of two short bursts from
     what was considered to be a 37 mm gun.  Closing the range, the
     target was quickly destroyed by gunfire and sound direction was noted
     during the effectiveness of the fire.  I/O used communication water-tight.

(d)  Gun Attack - 12 July 1945:
     TIRPITZ, while in Orlifogd train, sighted a small vessel
     closing her from the south.  After receiving assistance from four
     friendly fighter planes who made two strafing runs on the target,
     TIRPITZ closed the small lugger of about 75 tons and set fire
     with 40mm, 20mm and 50 cal.  Fire a range between 120 and 1500
     yards.  No opposition was encountered.  Target was left burning
     briskly.

4.  TIRPITZ returned from patrol in good material condition.  The main
     motor condition is being investigated.  Radio and radar consultations were at
     a minimum which speaks well for operating personnel.

5.  A separate report covering lifeguard assignment has been submitted
     by TIRPITZ.  It appears that there is not much greater cooperation between
     aircraft and pursuing submarines.  The lack of contact on enemy planes is
     most discouraging.

     The Administrative Division Commander congratulates the Commanding
     Officer, Officers, and crew of the TIRPITZ on the damage they have inflicted
     on the enemy, and very successful performance of their lifeguard duty.

[SIGNATURE: T. H. STONE]
```

— page 41 —
```
SUBMARINE SQUADRON TEN
PDS-10/A16-3

CONFIDENTIAL

Surv. 0216
SECOND ENDORSEMENT to
U.S.S. TREPANG (SS412)
Report of War Patrol
Number Five.

3 August 1945

From:  The Commander Submarine Squadron TEN.
To:    (1) The Commander-in-Chief, United States Fleet.
       (2) The Commander Submarine Force, Pacific Fleet, Adm.

Subject:  U.S.S. TREPANG (SS412) - Report of War Patrol
Number Five.

1.  Forwarded, occurring in the remarks of the
Commander Submarine Division FORTY-FOUR.

2.  The Commander Submarine Squadron TEN congratulates
the Commanding officer, officers and crew of the U.S.S. TREPANG
upon the completion of the vessel's Fifth War Patrol.

3.  It is recommended that the U.S.S. TREPANG be credited
with the following:

    1 - AK (JU)                     2000 tons
    1 - DD or DE (EU)              1000 tons
    1 - SC (EC)                     600 tons
    1 - LCI (RC)                     75 tons
    Total Sunk                     3675 tons

[HANDWRITTEN: J. P. Peterson]
[SIGNATURE: G. E. Peterson]
```

— page 42 —
```
FP12-10(A)116-3(13)
SUBMARINE FORCE, PACIFIC FLEET
Serial 02013
[STAMP: Care of Fleet Post Office,
San Francisco, California]
10 August 1945

[STAMP: NOTE THIS ANNUAL REPORT IS
DESIGNATED PRIOR TO
FIFTH WAR PATROL.]

COMMISSIONED FLEET REPORT ID. 850
U.S.S. ESPERITO - FIFTH WAR PATROL

From: The Commander Submarine Force, Pacific Fleet.
To: The Commander in Chief, United States Fleet.
To: The Commander in Chief, U. S. Pacific Fleet.
Subject: U.S.S. ESPERITO (Sail) - Report of Fifth War Patrol
(15 June to 31 July 1945).

1. The fifth war patrol of the ESPERITO, under the command of Commander A. J. Ernst, U.S. Navy, was conducted in areas south and east of Johnston.

2. This patrol consisted of lifeguard duties and offensive patrol. Both missions were performed in an outstanding and most successful manner. Three rescues were made - the first on 23 June southeast of San Diego, two army pilots were picked up; the second on 27 June southeast of Iwo Jima, where seven army aviation personnel were picked up; and the third on 15 July off the east coast of Borneo, where a naval fighter pilot was rescued. In addition to this successful performance of lifeguard duties, the ESPERITO made two torpedo and two gun attacks which accounted for two small AK's, a destroyer or DE, and one bigger.

3. Award of Submarine Combat Insignia for this patrol is authorized.

4. The Commander Submarine Force, Pacific Fleet, congratulates the commanding officer, officers, and crew of the ESPERITO for this outstanding successful patrol. The ESPERITO is credited with having inflicted the following damage upon the enemy during this patrol:

| LINE |
| 1 - Small AK (Similar to HIGHEST MEAN) (JM) | 2,000 tons (Attack No. 1) |
| 2 - DD or DE (31) | 1,000 tons (Attack No. 2) |
| 3 - AK (505 Type) (3C) | 600 tons (On Attack No. 1) |
| 4 - MLIS (Lugger) (CD) | 575 tons (On Attack No. 2) |

TOTAL SUM | 3,675 tons

[HANDWRITTEN: authentication and distribution
on following page.]

- 1 -

[MERRILL COKSCOT,
Deputy.]
```

— page 43 —
```
FFP-10-1-(L)/A1c-3(18)
SUMMARINE FORCE, PACIFIC FLEET
Serial C0213
CONFIDENTIAL

TILLED ENDORSEMENT to
FFP-10 Report of
Fifth War Patrol.

CATSUBMARINE PATROL REPORT NO. 850
U.S.S. REPUBLIC (SS 481) - Report of Fifth War Patrol
(15 June to 31 July 1945).

Subject: U.S.S. REPUBLIC (SS 481) - Report of Fifth War Patrol
(15 June to 31 July 1945).

DISTRIBUTION:
(Complete Report)
Cornich: (7)
Ono: (6)
Cincpac: (1)
JTFPO: (1)
AitFOL: (1)
Comcarpac: (1)
Cinclement: (8)
Comblast: (8)
S/F, School, II: (2)
CO, S/F Base, PI: (2)
Comspace: (3)
Comsubpac: (2)
ComsubTrFlt (Fwd Echelon): (1)
ComsubTrFlt (Rear Echelon): (2)
Comspace: (3)
Comsubpac: (40)
ComsubSpecAdCom: (2)
SubPac, HI: (3)
Comsubsub: (2)
All Squadron and Div.
Commanders, Pacific: (2)
ComSubDrgTeBoats (Armil): (5)
Submarines: (2)
All Submarines, Pacific: (1)

[C. H. Hyslance] [SIGNATURE: C. H. Hyslance]
E. L. Lentz, 2nd,
Flag Secretary.
```

— page 44 —
```
UNITED STATES FLEET
HEADQUARTERS OF THE COMMANDER IN CHIEF
NAVY DEPARTMENT, WASHINGTON, D. C.

SECRET

F-4254

To: Secret Mail Room.

Subject: U.S.S. TERPANG (SS-942) Reports of War Patrol No. Five.

Reference: (a) ComSubConf. Memo. 77/A16-3, Ser. 0346 of
29 January 1944.

Please deliver the attached subject report to
BuOrd - BuShips - Papers - Newports News - Newports Alex. - asDevlant
(ResA) (1915) (317) P519 v. 7.

2. The Commander in Chief, United States Fleet has by
reference (a) directed that the following shall apply relative to
the handling of this copy of this report:

(a) IT IS RECLASSIFIED AS SECRET AND SHALL BE SAFEGUARDED
IN ACCORDANCE WITH THE PROVISIONS OF ARTICLE 76, U.S.
NAVAL REGULATIONS, 1990.

(b) INFORMATION RELATING TO THE FUNCTIONS
OF A VESSEL IS TO BE CLASSIFIED AS SECRET AND MADE
AVAILABLE ONLY TO PERSONS HAVING A NEED TO KNOW.

(c) REPORTS SHALL BE DESTROYED BY BURNING AS SOON AS
THEY HAVE SERVED THEIR PURPOSE. SUMMARY DESTRUCTION IS NOT REQUIRED.

(d) TRANSMISSION BY BERNSTEIN LINE WITHIN THE CONTINENTAL
LIMITS OF THE UNITED STATES IS AUTHORIZED.

[HANDWRITTEN: A. B. T. S. U. V. A. L. F.]
[HANDWRITTEN: 9/4/46]

137134
[STAMP: FILMED]
```

— page 45 —
```
DECLASSIFIED                              NAME TIRPANG
DATE 1 JULY 1944                         FROM Commanding Officer USS TIRPANG (SS-412)
                                          SERIAL 04
                                          DATE: July 1944

SUBJECT COLLISION Report
Report of circumstances of collision between ferry KLAMATH and zephyr off San Quentin Point in San Francisco Bay.
Ferry at fault. Describes maneuvers to avoid collision.
(CRYPTO: MISC)
FILED: War Diary
Separately as ORIGINAL; as CARBON COPY

MICROFILM NO.                            ACTION REPORT (NAVY FORM 1643) (11-31)
                                          C 620432

DECLASSIFIED                              NAME TIRPANG
DATE 1 July 1944                         FROM Commanding Officer USS TIRPANG (SS-412)
                                          SERIAL 05
                                          DATE: July 1944

SUBJECT COLLISION Report
Report of circumstances of collision between ferry KLAMATH and zephyr off San Quentin Point in San Francisco Bay.
Describes damage incurred.
(CRYPTO: MISC)
FILED: War Diary
Separately as CARBON COPY

MICROFILM NO.                            ACTION REPORT (NAVY FORM 1643) (11-31)
                                          C 620432

DATE 24 Feb-9 Mar 1945                   NAME TIRPANG
FROM C.O. USS TIRPANG (SS-412)           SERIAL
                                          DATE

SUBJECT SUBMARINE ACTION REPORT
Attack data of Torpedo Firing reports No. 2, 4, & 5 on MIND WAR PATROL in the Mapo Shoto and Bungo Sudo areas.
Some indication of damage.
(CRYPTO: SUBS)
FILED: War Diary
Separately
as Rec. to SUBSPAC ser 00025 of 14 Apr 45

MICROFILM NO.                            ACTION REPORT (NAVY FORM 1643) (11-31)
                                          C 620432
```

— page 46 —
```
6 May 1945
                     TREPANG
                CROSS INDEX CARD

Encounter with seaplane on Fourth War Patrol, in Yellow Sea area.

Separately under FAW 1 no ser of no date (6 May 1945)

- DATE: 7 July 1945                     NAME: TREPANG
FROM: C.O. USS TREPANG (SS-413)          SERIAL: 001
SUBJECT: SUBMARINE ACTION REPORT, Forwarding of
DATE: 31 July 1945

Forwards report of one torpedo firing on FIFTH AIR PATROL
in the areas south and east of Honshu. No hits claimed.

(CENTPAC: SUBS)
FILED: War Diary
Separately
as Enc. to SUBSPAC ser 00338 of 15 Sep 45

MICROFILM NO.
ACTION REPORT (from 1943-1)
```

— page 47 —
```
SS12/111-1
Serial (0A)
DECLASSIFIED

U.S.S. THRASHER (SS12)
c/o Fleet Post Office,
San Francisco, Calif.
2 July, 1944.

From: The Commanding Officer, U. S. Fleet.
To: The Commander-in-Chief, U. S.
The Commandant, Navy Yard, Mare Island, Calif.
Subject: Collision between Ferry Boat KALAMAZOO and U.S.S. THRASHER.

Reference:
(a) Art. 840, U. S. Navy Regulations, 1920
(b) U.S.S. THRASHER conf. desp. 093506 of

1. The statement of all the circumstances attending the collision of the Ferry Boat KALAMAZOO with U.S.S. THRASHER as required by reference (a) to accompany the report made by reference (b) is submitted herewith.

2. On Saturday, 1 July, 1944 the U.S.S. THRASHER conducted sound exercises off Sausalito, California City in San Francisco Bay in accordance with duty, Mare Island, operation order of 23 June, 1944. At 1545 Commanding Officer set course 220° true for Mare Island. Visibility clear with both ships plainly in sight, sea calm. At 1717 while making standard speed on three (3) main engines, approximately 1 knot, sighted double ended ferry boat. KALAMAZOO, the ship was heading approximately San Quentin. Her bearing was 337°, 311° T. The ferry was in the main channel. The ferry ship is 2700 tons and was middle of the channel.

3. The Captain, Officer-of-the-Deck, and Navigator were all forward on the bridge, Officer-of-the-Deck at the conning tower. The officer-of-the-Deck began taking bearings of this ferry. The bearings showed the ferry drawing near but the course safely maintain our course and served as is required of he obliged vessel. There was never any doubt in the Commanding Officer's mind until the KALAMAZOO understood the situation and expected us to pass ahead.

4. At about 1949 the Officer-of-the-Deck asked the Commanding Officer if he should stop and let the ferry pass ahead. The Commanding Officer asked if the bearing was still

( - 1 - )
* COPY *
ENCLOSURE (1)
```

— page 48 —
```
SCL/12/11-1
Serial (O)
CONFIDENTIAL
U.S.S. TREPANG (SS412)
2 July, 1944.
Subject: Collision between Ferry Boat ILLAMIT and U.S.S. TREPANG.

dropping off satisfactorily, and he replied that it was. The Commanding officer then told the Officer-of-the-Deck to maintain course and speed, and to continue to observe the bearings.

5. As the Ferry was over a mile away, and as our intention of maintaining course and speed must have been obvious and apparent, together with the constant change in their bearing and the fact that they were not in the main channel but were coming from ferry slip in shallow water, the Commanding officer did not consider the rule for the privileged vessel to sound one blast when maintaining course and speed to apply in this case.

6. At 1135-0 the ILLAMIT appeared to have increased speed and the Officer-of-the-Deck reported the rate of change in bearing to be diminishing in the pre - range approximately 1200 yards. At 1135 The Commanding officer deemed a collision was imminent due to the increased speed of the ILLAMIT, therefore times and the course to be taken were sounded and the order was given for the engines to be backed full. Right full rudder was ordered. Within a few seconds emergency astern was ordered. Desired range 2100 to 2690 R. range 800 to 1000 yards. The angle on the bow progressively 90-95 degrees. The TREPANG maintained course and speed as it was required to until ILLAMIT's increased speed did, according to the Commanding Officer's best judgment, make collision invisible to the TREPANG. The Commanding Officer therefore took the action which he believed would avert a collision.

7. No sound signals were heard from the ILLAMIT before, at the time O, or after the collision.

8. After the TREPANG's backing signal the ILLAMIT appeared to hold course and speed for the next minute.

9. At about 1955 (plus) with the ILLAMIT bearing about 330° to 335° at a range of about 600 yards, the angle on the bow of about 60° starboard, she turned toward the TREPANG presenting a sharp angle on the bow and continued to turn until she hit. At 1955 (plus) (same as above) sounded
- 2 -
COPY
[STAMP: ECLUSTER (1)]
```

— page 49 —
```
SS/12/111-1
Serial (04)
CONFIDENTIAL

U.S.S. THRESHER (SSN-12)
2 July, 1944.

Subject: Collision between Ferry Boat KLAHANT and
         U.S.S. THRESHER.

the collision alarm. It first appeared that the KLAHANT would
ram the THRESHER in the forward part of the ship, however, as
our turn to starboard increased and as the KLAHANT turned more
to the right she struck the THRESHER at 1356 between the frames 52
to 57 port side about 50 feet from the ship's engine room,
bow she was making approximately 5 knots. The THRESHER immediately took a port
list. All stop was ordered at the time.

10. There was no apparent indication that the ferry
ever did back her engines, but had only stopped them.

11. After hitting the THRESHER the KLAHANT immediately
hit us just forward of the original place of contact, this
time at frame 47-48. No apparent damage was done. Following
this the ferry drew off about 100 yards to port and then went
ahead at about five knots crossing directly across the stern
of the THRESHER and extremely close aboard, angle on the bow
105° port.

12. At 1359 ordered all ahead emergency and passed
the word collision after torpedo con. Only by the prompt and
efficient action of the control room was the Commanding Officer
able to avoid the ferry as it passed very close astern.
It cleared the stern the KLAHANT increased speed and continued
on its way to Richmond.

13. After the collision the KLAHANT withdrew and
proceeded on its way without hailing the THRESHER or stopping
to see if we were in a sinking condition or if we needed
assistance of any kind. With a list of about three degrees to
port, it must have been apparent to the personnel of the ferry
that we were damaged.

14. It is the opinion of the Commanding Officer that
the collision would have been diverted had the KLAHANT not turned
towards the THRESHER at 1355 (plus), and it is also the Commanding
Officer's opinion that the collision could have been averted
had the KLAHANT reversed her engines at full speed when the

- 3 -

* COPY *
ENCLOSURE (1)
```

— page 50 —
```
SS.12/111-1
Serial (G)
CONFIDENTIAL

U.S.S. THETIS (SC-12)
2 July, 1944.

Subject: Collision between Ferry Boat KLAMATH and
U.S.S. THETIS.

THETIS and the backing signal. Had the KLAMATH done
anything but turn into the THETIS the collision would have
been averted.

Roy M. DAVENPORT.

Copy to:
CNO
JAG
BuShips
Bureau
Com-12
Constituting
Suva, N.I., Cal.

( - 4 - )

* COPY *
[STAMP: EICLATURE (1)]
```

— page 51 —
```
End. 1 (Conf. ltr. from CO, USS THRESHER (SSN-12) to CINC,
S3A12/111- Ser (O), dated 2 July 1944.)

SCALE/111-1
(010-5662-22)
Serial 14419

July 2, 1944.

CONFIDENTIAL

From: Commandant, Navy Yard, Mare Island.
To: The Commander in Chief, U.S. Fleet.
Subj: Collision between S.S. MANTLE and U.S.S. THRESHER.

Forwarded.

1.

2. The Commandant has appointed a Board of Investigation.

3. Preliminary inspection indicates damage to the superstructure and outer hull of the U.S.S. THRESHER, amounting to $12,000, and requiring eight days' repair work.

M. S. TIDDALE.

cc:
CIO
JAG
Buildups
Power
CEN-12
Control Spc
Subdiv, M.I., Cal.

1 MI copy-by-7/6/44.

( - 5 - )
* COPY *
```

— page 52 —
```
USS TRITON (SS-212)
LT. R.S. GARNY
3 JULY 1944

CONFIDENTIAL

AT 812356 2ND JULY THE THIRTY IX KILOMETER IX OF THE RICHMOND AND
SAN PABLO FERRY AND TRANSPORTATION COMPANY REPORTED TO RICHMOND

CALL TOLLED THE USS TRITON RETURN TO PARE ISLAND GALLEY.
COLLISION OCCURRED AT QUARTER POINT 1. WITH THE TRITON AND BOGGS
FIVE SL MINUTES THIRTY SECONDS HORNET LOG OF TWO TWO HUNDRED
TWO EIGHT MINUTES OR SEVEN SECONDS WEST.

FERRY X DANG. TO TRIM STRUCTURE AND DECK PLATING BETWEEN
ZARK FOUR INCH TO TRIM FIVE INCH ON PORT SIDE COMPLETELY ROUNDED

UP X OTHER HULL FROM TRIM IT TWO AFT OF THIRTY INCHES TOWARD
OF FRAME FIVE AND PUSHED IN A TRASHED OF THIRTY EXCEED ONE

INCLUDES X OTHER HULL AND DECK VERTICALLY FOR THIRTY INCHES ALONG
FRAME THIRTY AND WEDGED FOR ONE FROM INCLUDING ACROSS

FRAME FIVE SIX AT THE MOUTH OF CARQUINEZ AND DOG STRAITS. IS NO
DAMAGE TO PRESCOTT HULL IN MANY YARD MARY ISLAND CONDUCTING

INVESTIGATION OF DAMAGES TO BOTH VESSELS

* COPY *

ENCLOSURE (1)
```

— page 53 —
```
S3412/11-1
Serial (05)
D G CLASSIFIED

U. S. S. TREPANG (SS-412)

c/o Fleet Post Office,
San Francisco, Calif.,
5 July, 1944.

From: The Commanding Officer.
To: The Collector of Customs, San Francisco District.
Via: The Commandant, Navy Yard, Mare Island, Calif.
Subject: Collision between ferry KLAMATH and the U.S.S. TREPANG.
Reference: (a) 33 U. S. Code 361.

1. In accordance with reference (a) the following information is submitted:

   (a) U.S.S. TREPANG (SS412).

   (b) On July 7, 1944 at 1356 local war time, the ferry
   KLAMATH of the Richmond and San Rafael Ferry and
   Transportation Company enroute to Richmond, Calif.
   collided with the U.S.S. TREPANG enroute to Mare Island,
   Calif. Collision occurred off San Quentin Point at
   Lat. 37° 56' 27" N, Long. 122° 27' 07" W.

   (c) Damage incurred:
   (1) The superstructure plating and wood decking on the
   port side between frames 50 and 56 were torn up.
   Complete replacement is necessary between these
   frames and front, considered to be labor to the coming
   frames and front, which was undamaged. The salvage
   of our connection valve to main ballast tank 2D was
   deranged; the valve stem and reach rod to the main
   deck bent.

   (2) Main ballast tank 2D outside structure suffered the
   major portion of damage which was entered at approximately
   initially forward of the 1½" trestle. The outside
   plating was deformed between frames 51 and 53, and fifteen inches
   forward bulkhead of M/B 52 and fifteen inches to
   the rear of frame 52. The plating was ruptured internally
   for approximately fifteen inches between frames
   51 and 53 with additional damage to "D" strakes from the
   vertical rubbers forward approximately 20 inches and
   aft 12 inches. The weld between "C" and "D" strakes
```

— page 54 —
```
S3412/L1-1
Serial (05)
CONFIDENTIAL

U. S. S. TREPANG (SS-412)

5 July, 1944.

Subject: Collision between ferry KLAMATH and the U.S.S. TREPANG.

— page 55 —
```
U. S. S. TREPANG (SS-412)

5 July, 1944.

CONFIDENTIAL

Subject: Collision between ferry KLAHAH and the U.S.S. TREPANG.

(1) Main ballast tank 23 was deformed in the "cool" strake between frames 47 and 48 for a vertical distance of approximately four and a half feet. The web of the "C" strake longitudinal stiffener for the outer hull was collapsed between frames 47 and 48 and four horizontal T-beam stiffeners between the inner and outer hull frames were buckled, two at frame 47 and two at frame 48. There was no damage to the pressure hull plating or framing in this area. The air flask and high pressure air piping between frames 47 and 48 were not disturbed.

Roy H. DAVENPORT.

Copy to: ComSubPac.
```

— page 56 —
```
14479/1
(650-20-37473)
OFFICE OF THE
COMMANDER SUBMARINES
PACIFIC FLEET

CONFIDENTIAL

JUL 28 1944

From: The Commandant, Navy Yard, Mare Island, Calif.
To: The Commandant, Twelfth Naval District, Calif.

Subject: Collision between ferry KLAWAH and the U.S.S. TREPANG

1. Forwarded.

2. The Commandant doubts the applicability of the referenced U. S. Code to U. S. Naval vessels, but forwards this letter to the Commandant, Twelfth Naval District, for such action as he deems proper.

M. S. TISDALE

Copy to: ConSubPac
```

— page 57 —
```
F16-10(A)/4-2
SUBMARINE FORCE, PACIFIC FLEET
Serial 00025
DECLASSIFIED

Care of Fleet Post Office,
San Francisco, California,
14 April 1945

From: The Commander Submarine Force, Pacific Fleet.
To: The Commander in Chief, United States Fleet.
    The Commander in Chief, U. S. Pacific Fleet.
Subject: U.S.S. TANG (SS-306) To: Secret Report of Firing Mark 27 Torpedoes, War Patrol No. 3.
Enclosure: (a) Copy of Report of Attacks Nos. 2, 3, and U.S.S. TANG Third War Patrol--File No. S5431/Al-6 Serial (001), Pages 1 to 6 inclusive.

Enclosure (a) is forwarded herewith.

1. There is some indication of damage to the enemy in attacks Nos. 2 and 5 of these three well conducted attacks. Unfortunately, however, there is insufficient evidence to support a statement of damage. The concern that the explosion heard in attack No. 5 was believed to be an end-of-run explosion is not considered a likely explanation since the Mark 27 torpedo by basic design does not explode at the end of the run.

MERRILL CONSTOCK.

DISTRIBUTION:
Cominch (2)
CNO (2)
CinCPac (2)
Comsubpac (2)
Comsubronseven (2)
Comsubmarfor (2)
Comsubflot (2)
All Squadron Commanders (1)
All Division Commanders (1)
BUDOK (1)
US 305 TANG (I copy this endorsement only).

E. L. MYERS, 2nd.
Flag Secretary.
```

— page 58 —
```
TO:  [STAMP: SSCR]
U.S.S. TRIPANG (SS412)
SS412/A16-3
Serial (001)
Report of Third War Patrol.

(H) ATTACK DATA (Cont'd)

| ATTACK #2 |
| Tubes Fired | 19 |
| (a) Sound Conditions | Excellent |
| (b) Depth of Water | 100 fathoms |
| (c) Target T.C. | 230° T. |
| (d) Distance to Shore | 4,500 yds. |
| (e) Target bearing at firing | 050° T. |
| (f) Awareness | Target knew submarine was in immediate vicinity. |
| (g) Being Attacked | Yes |
| (h) Sound Equipment used in Firing | JP sound gear. |
| (1) Comments | Torpedo was fired just after the sound level on JP reached the point previously calibrated at 7.5. At 3½ minutes after firing, a very light explosion was heard, but screw sounds continued. It is believed that there was no connection between the explosion and our firing. The maximum noise level from the target's screws was reached 11 minutes after firing when target passed an estimated 800 yards astern, but during this entire period, the JP indicated a high enough intensity to direct the torpedo. |

[STAMP: ENCLOSURE (C)]
```

— page 59 —
```
TOP SECRET

U.S.S. TIRPANG (SS 312)
SS 312/12/A16-3
Serial (001)
Report of Third War Patrol.

(H) ATTACK DATA (Cont'd)
U.S.S. TIRPANG Torpedo Attack #2 Patrol #3
Time: 1408(I) Date: 2/24/45 Lat. 33-58 N. Long. 136-19 E.

Target Data - Damage Inflicted
Description: (3C) The target was a PC type patrol boat.
Ships Sunk: None.
Ships Damaged: None.
Damage deter- mined by:
Target Draft: 6' Course 230° T. Speed 8-10 K. Range 2500 yds (at firing)

Own Ship Data
Speed 2½ K. Course 163° T. Depth 380' Angle 5° rise (at firing)

Fire Control and Torpedo Data
Type Attack: Fired one torpedo using the JP sound gear. Generated TDC range was 1,100 yards, but later developments indicated that the range was probably 2,500 yards.

-2-
E X C L O S U R E (0)
```

— page 60 —
```
TOP
SECRET
SS12/216-3
Serial (001)

U.S.S. TREND (SS412)
Report of Third War Patrol.

(H) ATTACK DATA (Cont'd)

Tubes Fired 49.
(a) Sound Condition Fair.
(b) Depth of Water 540 fathoms
(c) Target P.C. 000° T.
(d) Distance to Shore 18 miles
(e) Target bearing at firing 165° T.
(f) Awareness Target unaware of submarine presence.
(g) Being Attacked No.
(h) Sound equipment used in Firing JP Sound Gear.
(i) Comments
State 4, sea. It is believed that this torpedo did not arm. Upon reloading it was noted that the gimbal, starter, and periscope wire had broken at the union between this wire and the reel wire. This indicated that the gimbal, starter, and periscope wire had required on the torpedo, in which case the torpedo possibly did not arm, the reason of the break was either corrosion in the reel wire or a faulty solder. In order to prevent similar occurrences it is suggested that stainless steel reels be used. Another recommended practice is to knot the reel wire on the torpedo side of the union so that this reel wire will not slip through the union if the solder should break.

[STAMP: ENCLOSURE (0)]
```

— page 61 —
```
TOP SECRET
U.S.S. TARPON (SS412)
S31412/An-3
Serial (001) Report of Third War Patrol.

(H) ATTACK DATA (Cont'd)
U.S.S. TARPON Torpedo Attack #4 Patrol #3
Time: 1046(I) Date: 3/9/45 Lat. 33-32.5 N. Long. 139-42 E.

Target Data - Damage Inflicted
Description: (X) TWO torpedo escort vessels; one escort was a
pinger and zigzagging; the other was apparently
listening and on a steady course.

Ships Sunk: None
Ships Damaged: None
Damage Determined by: None

Target Draft: 6' Course 000° T. Speed 8-11 K Range 300 yds
(at firing)

Own Ship Data
Speed 2 K Course 096° T. Depth 250 ft. Angle 10° dive
(at firing)

Fire Control and Torpedo Data
Type Attack: Fired one torpedo using JP sound gear. Estimated
range was approximately 300 yards to first target
at firing. The second target passed within 200
yards about one minute after firing. Very loud
noise level was recorded on JP. It’s believed
that this attack would have been successful except
for a material failure.

-4-
ENCLOSURE (C)
```

— page 62 —
```
TOP SECRET
U.S.S. TIRPANG (SS-142)
SS/12/A16-3
Serial (001)
Report of Third War Patrol.

(H) ATTACK DATA (Cont'd)

ATTACK #5
Tubes Fired  49
(a) Sound Conditions  Fair.
(b) Depth of Water  540 fathoms.
(c) Target T.C.  000° T.
(d) Distance to Shore  18 miles.
(e) Target bearing at firing  190° T.
(f) Awareness  Target unaware of submarine presence.
(g) Being attacked  No.
(h) Sound Equipment used in Firing  JP sound gear.
(i) Comments  State 4 sea, Eleven (11) minutes after firing a light but definite explosion was heard in the conning tower by sound. This explosion was heard by all hands in the conning tower. Since target screws continued and enemy action did not indicate any ships at it, we believe this was our torpedo exploding at the end of its run.

-5-
ENCLOSURE (C)
```

— page 63 —
```
TOP SECRET
SS142/A16-3
Serial (001)

U.S.S. TIRPANG (SS142)
Report of Third War Patrol.

(i) ATTACK DATA (Cont'd)
U.S.S. TIRPANG
Torpedo Attack #5 Patrol #3
Time: 1130(I) Date: 3/9/45 Lat. 33-32 N. Long. 139-42.5 E.

Target Data - Damage Inflicted
Description: Two unidentified escorts with one unidentified cargo carrier. These targets were picked up by sound and were not sighted until after the attack.

Ships Sunk: None.
Ships Damaged: None.
Damage Detected: None.

Target Data:
Draft 6' Course 000° T. Speed 8 K. Range 350 yds. (at firing, est.)

Own Ship Data
Speed 2 K. Course 250° T. Depth 215 ft. Angle 3° rise (at firing)

Fire Control and Torpedo Data
Type Attack: Fired one torpedo using JP sound gear. Estimated range at time of firing was 300-350 yards. Target passed overhead about one minute after firing. It is considered that this was an "A" attack and the only explanations offered for a miss are either excessive target speed, which is unlikely, or failure of torpedo.

-6- [STAMP: ENCLOSURE (C)]
```

— page 64 —
```
2 TAPI

000453
Endorsement
Cinc Pacific Fleet
To: Cominch
Via:
1. Forwarded.

MAILED 24 APR 1945

[HANDWRITTEN: H]
[HANDWRITTEN: 4163]
[HANDWRITTEN: 512]
[HANDWRITTEN: 67]
[STAMP: Ins. Gen. Pac.]
```

— page 65 —
```
DECLASSIFIED

MEMORANDUM:

From: Commander Fleet Air Wing ONE.
To: All Squadron and Task Unit Commanders.
Subject: Submarine - Aircraft Cooperation.
Enclosures: (A) Excerpts from U.S.S. TREPANG's Fourth Patrol Report
            (B) Comments on U.S.S. TREPANG's Report.
            (C) Telephrase of Message from C7F-1 to ComSubPac, 7 June 1945.

1. Enclosures (A), (B) and (C) are brought to the attention of all squadron commanders for careful study and discussion with air combat intelligence officers and pilots.

2. It is highly important that every contact made by one of our planes with a friendly submarine be the subject of thorough interrogation, analysis, and report.

3. Perfection of aircraft-submarine cooperation is of immediate urgency. Its importance must be stressed daily in every briefing.

J. D. PRICE.
```

— page 66 —
```
S E C R E T

E X C E R P T S F R O M T R E P A N G ' S F O U R T H P A T R O L R E P O R T

May 6, 1945

Position: Lat. 130-50N
Long. 124-00W

"2250
A/C J18 - SD contact at 1½ miles; shows ITF. In spite of message to the effect that friendly planes would not come closer to less than 8 miles until identification was actually established, we have been forced down in every case of encounter with this one. Turned on IFF and made a test on one of these. Fired recognition rockets.

"2256
Without any hesitation, plane continued to close and passed over storm at about 500 feet. Identified as PBM.

"2258
Plane banked and started in a rain fro 2 miles. Div'd.

"2313
Surfaced. Range 10 miles. Commenced closing again. Fired another rocket. At range of 5 miles, sent message on area frequency for plane to please leave us alone. Be immediately turned and shoved off. All we proved is that we may as well dive to the bottom as to run the risk of being bombed and still have to dive later.

REMARKS

"Our own aircraft presented the greatest mental hazard of the patrol. They never could see the slightest consideration in the problem of recognition and avoiding. On the very first case of contact with friendly recognition showing, we used on the A/C. In addition, in flying too close to planes showing ITF, we found on one occasion at night fired recognition rockets. To make sure that the planes correctly identified us, in all cases, or could have correctly identified us as stated up, we fired. In every case where we wore escorting they were 5 miles. They changed course to head for us. I did as a work of caution, but in all cases except ours. In the first two cases at night, the third occurred and the planes passed directly over us. This occasion occurred just a few days after a message was outside of 8 miles until identification was established. I decided to make a test case of this one-borne on Lieu. Outside of time, I didn't want to dive anyway. Then he passed over us at about 500 feet, opened the range, the plane passed over us in the direction that we were going. The plane banked, and started to dive when it could not. And we were inside the limit the range on the plane at a fine miles.

Then a few minutes again, we fired another rocket. A recognition. I sent to plain language to say "Hello." He immediately turned away from us to say and "to" us also. In hindcasting during our time and left us, having treated instances of this kind ours. The fourth instance was on Lifeguard Station in the daylight 150 miles.
```

— page 67 —
```
SOUTH of HONSHU.                                      S E C R E T.

A LIBERATOR was contacted at 10 miles. He closed to 6 miles, where he made one circle and then headed for us. "He dived at 4 miles and he was at 2 miles when the SD went went under. To doubt the aviators think they are making a friendly gesture by flying over us in this fashion, but we can't appreciate it, knowing that sooner or later one of them is going to mean business. The basis of the trouble is the "I have no means of telling when a plane has iden- tified us as friendly; therefore, any time one closes, it becomes an unfriendly act. Therefore it has been little trouble to dive for friendly plane contacts, but now, with numerous plane patrols in the submarine zone, it is beginning to become a nuisance. The best constructive suggestion that I can make is to indiscriminately instruct the aviators to keep at least 5 miles from the submariRM. Then when one does close, we will know that he does it recognizing us. At least the present uncertainty which confronts us will be eliminated.
```

— page 68 —
```
" south of HONSHU.
S E C R E T

A LIBERATOR was contacted at 10 miles. He closed to 6 miles, where he made one circle and then headed for us. "dived at 4 miles and he was at 2 miles when the SD next went under. To doubt the aviators think they are making a friendly gesture or thing over us in this fashion, but we can't appreciate it, knowing this sooner or later one of them is going to mean business. The basis of the trouble is that we have no means of telling when a plane has identified us as friendly; therefore, any time one closes in, it becomes an unfriendly act. Heretofore it has been little trouble to dive for friendly plane contacts, but now, with inaccurate plane patrols in with the submarine zone, it is beginning to become a nuisance. The most constructive suggestion that I can make is to indoctrinate the aviators to keep at least 5 miles from the subscribing. Then when one does close, we will know that he does it recognizing us. At least the present uncertainty which confronts us will be eliminated?"
```

— page 69 —
```
. . . ENCLOSURE B
COMMENTS ON THE P. R. 's REPORT

1. The above excerpt from the report of one of our underscored allies striking in our areas indicates many of the Submarine problems. First it was one note and got several points to make cooperation between us more effective. The main point to be stressed is to avoid closing any single blip closer than eight miles without first.

   a. Looking for IFF on an interrogator.
   b. Calling on VHF channel "Do pop'r from (plane call) identify yourself" or something equivalent.
   c. Tactics for recognition procedures.

2. It is a problem for us to effectively cover our sectors at night handicapped by requirements to avoid friendly subs which may be scattered about, but driving them down potentially can be avoided by understanding the general situation.

3. The Treng is being a little harsh in his remarks, and perhaps his nerves are about as worn as ours or with constant air threat in close proximity to enemy bases. It may be expected that in the future, use of voice identification by subs will be more quickly resorted to our mutual benefit. In this respect note that the Treng did broadcast in main lane no voice over S.F. PLAN.

4. Note also that Treng's status sub has no way of telling when lane identifies sub as friendly, takes every effort to indicate we both like to be by voice and air turning away once his identity is established.

5. If the pilot who was at 30-50N 12-00S at 2250 the night of 6 May can add anything to the Treng's report how to submit a statement covering the incident fro his view point, he will forward it to the subs.

6. In view of forth coming operations which will bring us in closer contact with submarine cooperation, all hands are enjoined to exert every effort to potentially proceeding of IFF on interrogators; (b) use of S.F. PLAN, (c) use of heed work when in sub patrol areas.

D. G. RUTT
Operations Officer,
Pilot air "Ting One.
```

— page 70 —
```
UNCLASSIFIED (C)

P. RAHRAESS OF MESSAGE FROM CFA-1 TO SCBUREAU 7 JUNE 1945

Before approaching closer than eight (8) miles, our planes will continue to make every effort to establish mutual identification with submarines at night. However, in order to effect a complete investigation of single unidentified contacts, planes may also be contacted to permit visual identification, provided that mutual identification has not been made prior to eliminate delay. We will continue to present policy of not attacking any target unless it is positively identified as a surface ship and not reported as a submarine.
```

— page 71 —
```
[STAMP: DECLASSIFIED]
[STAMP: 412-2-45A]

SUBMARINE FORCE, PACIFIC FLEET

Serial 0033
Care of Fleet Post Office,
San Francisco, California,
15 September 1945.

From: The Commander Submarine Force, Pacific Fleet.
To: The Commander in Chief, United States Fleet.
Via: The Commander in Chief, U.S. Pacific Fleet.

Subject: U.S.S. SERAPH (SS-524) - Report of Firing Mark 27 Torpedoes, Fifth War Patrol.

Enclosure: (A) U.S.S. SERAPH - Secret report of Firing Mark 27 Torpedoes, War Patrol No. 5 (C) U.S.S. SERAPH Secret Int. Msg. 15429/SS/AG-5, Serial 01, dated 31 July 1945.

1. Enclosure (A) is forwarded herewith.
2. Unfortunately no hits were obtained during this attack.

G. C. CRAWFORD,
Chief of Staff.

DISTRIBUTION:
CIO (2)
ComSubPac (2)
ComSubSpreadComd (2)
ComSubStratImp (2)
ComSubT/7th (1st Echelon) (2)
ComSubT/7th (Rear Echelon) (2)
All Division Commanders (1)
BuOrd (1)
3 Submarines
CO, USS SERAPH (less End.) (1)

[SIGNATURE: E. F. HARRIS]
B. L. INNES, 2nd,
Flag Secretary.
```

— page 72 —
```
U.S.S. TREPANG (SS412)
SS412/37/16-3
Serial 4601
S-E-C-R-E-T

Grap of Fleet Post Office;
San Francisco, California;
31 July 1945.

From: The Commanding Officer,
To: The Commander-in-Chief, United States Fleet.
Via: (1) The Commander Submarine Division 14.
      (2) The Commander Submarine Squadron 10.
      (3) The Commander Submarine Forces, Pacific Fleet,
      (4) The Commander-in-Chief, U. S. Pacific Fleet.

Subject: U.S.S. TREPANG, Secret Report of Firing Mark 27 Torpedoes, Patrol No. 5.

Enclosure: (a) Subject Report.

1. Enclosure (a) is forwarded herewith.

[C. J. Flust]
[SIGNATURE: R. FLUST]
```

— page 73 —
```
(MARK 27 TORPEDO ATTACK FORM)

U.S.S. TREGAR  Mark 27 Torpedo attack No. 1 Patrol No. 5
Time  1605  Date  7/7/45  Lat.  41-19  Long.  141-34
Sound conditions  Fair  Depth of water  200 Fathoms
Distance to nearest shore or reef  6 miles  Sea condition  3
Was it raining?  No

                       TARGET DATA - DAMAGE INFLICTED
Description  Two escort types, probably, one listening the other pinging.
Ship sunk  None
Ship damaged  None
Target draft  Unknown, course  Unknown  Speed  Unknown
Range  1500-2500 yards, estimated (at firing)
Target turn count  Slow. Target bearing at firing instant  300°
Peculiarities noted in target's sound output.  Target was using
his fathometer at 60 boats per minute.

                       OWN SHIP DATA
Speed  1.7 kts  Course  100°  Depth  250'  Angle  0° (at firing)

                       FIRE CONTROL & TORPEDO DATA
Was target aware of submarine's presence?  Yes
Was submarine being depth charged?  Yes - None also aboard

Type attack:  While worth noting, it was felt by a pink the PORTSIDE depth.
Want to 350 feet and about 30 minutes later 2 patrol boats supported on the sonar and commenced depth
charging action or use.  We started their range at
from 1500-3000 yards.  Both sets of torpedoes were
plainly all scorable, but too weak for firing e

                         N N C L O S U R E S  (A)
```

— page 74 —
```
S-E-C-R-E-T
MARK 27 TORPEDO ATTACK FORM (Continued)

Mark 27: Only one vessel was pinging and we are quite sure how was using a rethouter. The frequency on board was very loud, both heard as a dull thud at the lowest turn of the JK and as metallic clicks on the JP, which was put out of commission by the bombing and was not repaired until after firing the Mark 27. The rethouter was operated at 60 beats per minute, and it is certain that its noise level was high enough to operate the Mark 27.

Time of firing  1605K  | Tube number  7
Time of hit     |  Projectile  Unknown
JP deobold motor indication at firing  JP out of commission due to depth bombs
JP deobold motor indication 1 minute after firing  JP out of commission.
JP Gun  JP out of commission.  Filter Brand  JP out of commission
Mark torpedo  27 Mod. O "H".  Serial No. 642.  Total No. 764
Mark warhead  Serial No. 831
Mark exploder  Serial No. 1426
Aiming distance set  |

Issuing activity  BURTON 20 - U.S.S. TROUT. (519)

COMMENTS: Used a rough estimate of firing range by the JK as the JP was out of commission as a result of two depth bombs being dropped on us prior to her previously. Upon firing, the arming wire broke before pulling out of the exploder linchpin shaft, thereby causing the torpedo to remain in an unarmed condition; of the four Mark 27's the instructions for this form, we have not had this same casualty. If the arming wire is pulled out normal to the intended axis of the exploder it is possible to trouble. However when the torpedo is loaded in the tube and a strain (it being) is taken on the wire, it does so sharply (and probably binds) when it crosses the linchpin shaft housing. It is believed that in this pulley wheel installed at this point, in which the arming wire could ride and/or enter the arming wire
```

— page 75 —
```
S E C R E T

MARK 27 TORPEDO ATTACK FORM (Continued)

hole straight, would alleviate the trouble.

Target did not approach closely enough to use
sound noises for firing. However, considered
that the stateroom noise was an ideal source
and was sure its noise level was high enough,
even though the ping was in excess of 5500
yards. Only had one Mark 27 loaded and did
not desire to risk the noise involved in re-
loading in order to fire again.

ENCLOSURE (A)
```

— page 76 —
```
END OF REEL
JOB NO. H-108

THIS MICROFILM IS
THE PROPERTY OF
THE UNITED STATES
GOVERNMENT

DEPARTMENT OF DEFENSE

MICROFILMED BY
NPPSO—NAVAL DISTRICT WASHINGTON
MICROFILM SECTION
```