U-boat Archive - U-187 - Interrogation Report

INTERROGATION OF SURVIVORS FROM "U 187," A 740-TON U-BOAT,

SUNK ON 4th FEBRUARY, 1943, BY H.M.S. "VIMY"

________________

I. INTRODUCTORY REMARKS

"U 187." a 740-ton U-Boat commanded by Oberleutnant zur See Ralph Münnich, was sunk at 1337 Zone Time on 4th February, 1943, in position 50° 12' N., 36° 34' W., by H.M.S. "Vimy," escorting Convoy S.C.118.

It was "U 187's" first patrol and the first experience as Commanding Officer for Münnich, who did not survive.

Forty-five men of the U-Boat's total complement of 54 were picked up by "Vimy" and "Beverley."

Survivors included two officers, one subordinate officer, three Chief Petty Officers, 10 Petty Officers and 29 other ratings.

Security-consciousness among prisoners was not highly developed.

This report contains comprehensive details of "U 187's" working up trials in the Baltic (see Appendix "A") and her first and last patrol, as well as additional information regarding G.S.R., R.D.F., extensible look-out masts as fitted to "U 187's" series, and other comparatively recent innovations of the U-Boat arm.

As "U 187" was sunk before she herself could claim any success, no information could be obtained regarding an actual attack on a convoy, but one or two prisoners talked freely upon modern operational practice as applied to U-Boats.

Key to equivalent Royal Navy and German Navy ranks used in this report:

Konteradmiral	Rear-Admiral
Fregattenkapitän	Commander (Senior Grade).
Korvettenkapitän	Commander (Junior Grade).
Kapitänleutnant	Lieutenant-Commander.
Oberleutnant zur See	Lieutenant.
Leutnant zur See	Sub-Lieutenant.
Oberfähnrich sur See	Midshipman (Senior Grade).
Fähnrich zur See	Midshipman (Junior Grade).

(Ing.) after a rank denotes Engineer Officer, as

Kapitänleutnant (Ing.)

Lieutenant-Commander (E).

"Der Reserve" after a rank denotes a Reserve Officer.

________________

II. DETAILS OF "U 187"

(i)	Displacement	740 tons.
(ii)	Type	IX C.
(iii)	Building Yard	Deschimag, Bremen.
(iv)	Armament	(a) Guns:
		One 105 mm. (4.1 in.) forward.
		One 37 mm. (1.45 in.) aft.
		One 20 mm. on bridge. for which two spare barrels were carried.
		Mountings for four M.G.s on conning-tower.
		Two machine pistols, Type M.P.34, with 32 round magazines, carried as close-range defence weapons against aircraft and to repel boarding parties.
		(b) Torpedoes. Twenty-one carried. Distributed as follows:
		Six electric torpedoes in tubes.
		Four electric torpedoes in bilges forward.
		Two electric torpedoes on bow compartment floorplates.
		Three electric torpedoes on after torpedo compartment floorplates.
		Six air torpedoes in upper deck containers.

(C49073) *3

(iv)

Armament contd.

(b) Torpedoes. contd.

A torpedo rating said that the voltage of the electric torpedoes had to be kept up to 110 volts. Beneath this figure the certainty of hitting a target could not be guaranteed. He added that the voltage of "U 187's" electric torpedoes was kept up to between 115 and 120.

(N.I.D. Note. Some information regarding new types of torpedoes was obtained from prisoners, but this has been considerably supplemented by information from survivors of "U 432" and "U 444," two more recently sunk U-Boats. It has therefore been decided to collate all information regarding these torpedoes obtained from survivors of the three U-Boats and publish a complete summary in a later report.)

(c) Torpedo Pistols. These were four whiskered. Type G.7.H.

(d) Torpedo Arming Fans. It was stated that arming fans had to make 326 revolutions before the torpedoes became "live."

(e) Torpedo Tubes. Four forward, two aft. One prisoner stated that the tubes were modified while "U 187" was undergoing final adjustments at Stettin, to permit the use of new types of torpedoes.

(v)

Propulsion

(a) Diesel Engines. Two 9-cylinder, 4 stroke, Type M.9 V.40/46 M.A.N. Diesels. (See C.B. 04051 (53), Section VII (vi).)

(b) Diesel Superchargers. These were driven by the main engines; ratio 1:7. (See also section V (xxii).)

(c) Diesel Oil Consumption. An average of 180 grams (.4 lb.) of oil were consumed per h.p. per hour.

(d) Diesel Engine Performance. On two Diesels (in calm weather):

170 r.p.m.		7 knots (dead slow).
240 r.p.m.		11 knots (slow).
300 r.p.m.		15 knots (half speed).
415 r.p.m.		17-1/2 knots (three-quarter speed).
460 r.p.m.		18-19 knots (full speed).

(e) Fuel Tanks. "U 187" had six external fuel tanks on either side and two internal tanks in either side forward of the control room. The total fuel capacity was given as about 240 cm (20-4 tons). Ten tons of lubricating oil were carried.

(f) Electric Motors. Two Siemens motors. (For details of performance see C.B. 04051 (55) Section VII (viib).)

(g) Batteries. Type M.44 M.A.L., 62 cell.

(vi) G.S.R.

The G.S.R. was by Metox of Paris, and was hurriedly fitted only three days before the U-Boat left Kiel on her first patrol (i.e., about 9th January, 1943).

A prisoner stated that no one aboard had attended any G.S.R. course, but that while in Kiel the four W/T personnel were summoned to the depôt ship "St. Louis," where they were given a short lecture on its use. In practice the set was found to be very simple to operate and was used every night when passing between Iceland and the Faroes. At least one aircraft was detected with it and the U-Boat at once dived. The prisoner added that the majority of U-Boats are now fitted with G.S.R. and it was considered so important, that supply U-Boats carried a number of sets to fit all U-Boats which had sailed without the equipment, or were in need of spares.

It was stated that "U 187's" G.S.R. aerial, which was attached to the centre of the base of the forward periscope, was similar to the type previously described by prisoners from other U-Boats namely diamond-shaped, the upper arms being slightly shorter than the lower ones. The horizontal


	3

	crossbar in the centre had two insulators to prevent salt water entering the cables. The horizontal dipoles started below and above the right insulator, continued to the right, then made a sharp loop to the other end of the crossbar and returned to the right insulator. The vertical dipoles started from the left insulator to the left hand of the horizontal bar. Prisoners said that the aerial, and particularly the wooden socket in which it fitted, was frequently broken by heavy seas. It was thought that a new type aerial frame made of Plexiglass was now in production.
	When the G.S.R. was being used, the operator within the U-Boat listened with headphones on and ordered a deck-hand to rotate the bar until any sound he might detect was at its loudest pitch. He then knew, from the position of the aerial, the approximate bearing of the enemy or its reciprocal. In order to ascertain whether the enemy was in front or behind the aerial, a rating held two tubular shaped pieces of iron horizontal and parallel to the aerial, and approached the ends of the pieces gradually towards it. If the sound then faded considerably, or even faded out altogether, this proved that the direction of the enemy was on the same side of the aerial as the iron rods. The prisoner admitted that this was a very primitive operation, and added that "U 187" was fitted with an early type G.S.R., the improved models not yet being in large scale supply.
	A prisoner gave the range of the G.S.R. of his U-Boat as 15 miles.
	The set was said to be extremely sensitive to electrical machinery within the boat, and a P.O. telegraphist related that they dived four times on one day before they discovered the false alarms had been caused by a pair of electric hair-clippers.

	(vii) R.D.F.
	A number of prisoners confirmed that "U 187" carried R.D.F., the Second Lieutenant stating that all U-Boats are now fitted with it.
	A P.O. telegraphist made the following remarks:
	He had had no course in R.D.F., but had seen the set from the outside. It was kept locked up and only one specialist in the crew was allowed to service it in the event of breakdown.
	He believed that it was only fitted to the larger U-Boats, and that it was used for locating targets which had been lost in darkness, fog or snow.
	There are a number of fixed dipoles on the forward face of the conning-tower, about eight in number, the exact number being unknown. The diploes are approximately 15 cm. in length, 10 cm. distant from the conning-tower, with vertical polarization; one set for sending and one for receiving. There is a double cable from each pair of dipoles, about 2-3 cm. thick, armoured, and the glands were these cables pass into the control room are fitted with screw caps. Should the cable be damaged, it is cut and the cap screwed over the cut end to prevent the entrance of water.
	The set is in two sections, each about 1-1/2 metres high by 40 cm. wide, and has no maker's name, but is thought to be by GEMA. The left-hand half has tuning and control knobs for receiver, transmitter and power supplies, and also has a button for calibration. The right hand side has a cathode ray tube, about 10 cm. in diameter, covered by a lens about 20 cm, square; control knobs for cathode ray tube; azimuth handle and scale on the right side, and instruments on a sloping panel about half way up.
	The cathode ray tube is fitted with a scale in sea miles, reading up to 10, but the trace extends beyond the end of the scale, and it might be possible to pick up an object at 12 miles. Calibration is checked by pressing button and seeing if the spot moves to the far end of the scale. Azimuth is found by altering the phasing of the dipoles, and thus moving the beam from side to side. This is controlled by a lever on the right-hand side of the set; the measurement is made by moving this until maximum echo is obtained, and reading off on a scale at the base of the lever, the maximum deflection of beam being 10° to port (red figures) and starboard (green figures). For further azimuth search, it is necessary to turn the whole U-Boat.
	Frequency was said to be under 100 cm.; high tension supply once transformed, up to 8,000 volts.
	Owing to increased distances, the set did not prove so useful in the Atlantic as it was on trials in the Baltic. The accuracy of the set is not very great, a maximum of half a mile, but this is not necessary, as it is only used until the object comes within visual range. (See also Section V (xviii).)

	(viii) W/T Equipment
	"U 187" was fitted with three transmitters, all by Telefunken:
	(a) One 200-watt short-wave; 20-80 metres, normally used for communication.
	(b) One long-wave, 500-1,000 metres, used for emergency transmission and D/F transmissions.
	(c) One 40-watt emergency transmitter, ranges 20-80 metres, and a long-wave range somewhere between 500 and 1,000 metres, but transmissions on this range were not good.
	Five receivers were carried:
	(a) A short-wave 20-200 metres, eight bands (Stufen).
	(b) One universal receiver, 10-20,000 meters, eight bands (Stufen).
	(c) One D/F receiver, 500-20,000 metres, five bands (Stufen).
	(d) and (e) Two broadcast receivers, one Radione and one N.Z.51, the latter supplied by the Kriegsmarine Werft, Kiel.

	(C49073) * 4

(ix) W/T Aerials, etc.

"U 187" carried an extensible aerial projecting, when fully extended 20 to 22 ft. above the conning-tower. This was used during very rough weather or for transmissions when in sight of a convoy.

The D/F aerial is retractable under protection of the conning-tower, and this aerial is used for long-wave receptions when completely submerged. Reception is possible down to 48 ft.

(x) Hydrophones

Multi-unit type fitted; 24 receivers on each side of the bows. K.D.B.; None.

(xi) S.B.T.

S.B.T. apparatus was fitted in the heads on the starboard side of the stern compartment. It was operated only by control-room personnel. It is believed that a number of acoustic pills were ejected during the hunt which finally led to "U 187's" destruction.

(xii) Echo-sounding Devices

A P.O. Telegraphist prisoner said that "U 187" was fitted with "Shallow" and "Deepsea" sounding devices. These had three ranges, as follows:

1st		Down to 400 ft.
2nd		Down to 3,250 ft.
3rd		Down to 9,750 ft.

He added that the last two ranges are recorded by a sound indicator. At each 3,250 ft. an illuminated mark appears on a scale.

(xiii) Diving

(a) Crash Diving. Prisoners said that the best crash-diving time obtained during trials in the Baltic was 38 seconds to periscope depth.

(b) Deepest Dive. It was alleged that "U 187" was taken down to 440 ft.

(c) Depth Gauges. Depth gauges were graduated to 200 m. (about 650 ft.) but graduations, although not figures, continued to about 250 m. (772-1/2 ft.), where a red-line appeared. According to one prisoner, depth gauges in the bow and stern compartments are sometimes disconnected during attacks should the crew show signs of panicking.

(xiv) Extensible Look-out Mast

"U 187" was fitted with an extensible look-out mast immediately abaft the conning-tower, so that when raised there is no space between the two. Then the mast is lowered, its head lies about a foot before the after torpedo hatch. It is about 48 ft. high and carried a collapsible crow's nest.

The mast is raised by telemotor system employing oil pressure of 990-1,280 lb. per sq. inch. The telemotor control is on the bridge. By pressing down a handle the mast is raised; by pulling up the handle the mast is lowered. The mast was said to be U-shaped in section, with rungs between the two edges of the U. Then first fitted, it was possible to fold one's arms around the mast and slide down in case of alarm. The mast in this form was not found to be strong enough and, indeed, "U 187's" mast broke during her Baltic trials. It was then strengthened by two vertical rails running parallel to the edges of the U. Beside trying to strengthen the mast, there rails enabled look-outs to descend quickly merely by grasping them with their hands and sliding down. The masts are believed to be fitted to a series of U-Boats, beginning with "U 178."

It was stated that the mast cannot be used in seas over Force 3.

(xv) Binoculars

Prisoners had never heard of the use of periscope-type binoculars in U-Boats. Those used by the ratings were the same type as those of the officers, although somewhat inferior.

(xvi) Conning-tower Badge

"U 187's" conning-tower badge was a white horse, a replica of the sign of the White Horse Inn on Wolfgangsee.

(xvii) Yard Number

"U 187's" yard number was W.1027.

(xviii) Field Post Number

"U 187's" field post number was M.09255.


	5

	III. FIRST AND LAST PATROL OF "U 187"

	(i) 12th-14th January: Kiel to Kristiansand S.
	At 0800, 12th January, 1943, "U 187" left Kiel leading six 500-ton U-Boats in line ahead. Of those six 500-tonners, one was commanded by Oberleutnant Mahnke, one by Oberleutnant Thäter, and one by Oberleutnant Tinschert. "U 187" proceeded on both Diesels at "Half-speed," i.e., about 15 knots. Just before reaching the Skagerrak, the U-Boats were joined by a 600-ton Sperrbrecher which led them, still in line ahead, and spaced at roughly one cable intervals, to a point off Kristiansand S.
	"U 187," the Sperrbrecher and the six 500-ton U-Boats entered Kristiansand S. on the early afternoon of 14th January, but three 500-tonners left later the same day. The Sperrbrecher secured next the pier, and alongside her, beam to beam, lay the four U-Boats. "U 187," herself next the Sperrbrecher, had on her seaward side, a U-Boat commanded by a "small fat man" and bearing a Globe and the four points of the compass as conning-tower badge. A further U-Boat had a Red Devil holding Neptune's trident as badge.
	(N.I.D. Note. It is considered that, even with her minesweeping circuit switched off, the Sperrbrecher's residual field would effect the degaussing of the U-Boats alongside.
	That night, "U 187" charged batteries, and topped up with fuel and fresh water. The customary pre-patrol carouse took place. All but the duty watch went ashore, where they quartered in a former school building now taken over by German infantry and Alpine troops. The evening began with the showing of a film, "Daughter, Beware!" Later, all became drunk. On "U 187" the officers settled down to a comfortable session, to which they invited C.P.O. Tidjen, the Sperrbrecher's captain. The bottle passed freely. Leutnant zur See Strait became insensibly intoxicated and had to be put to bed by Buschmann, the Junior Officer. Despairing of reviving Strait, Buschmann finally emptied a bucket of water over him. This water soaked the bunk beneath Strait, belonging to Meyer, the Engineer Officer. This started an altercation between Meyer and Buschmann, whereat the latter took fright and disclaimed responsibility.

	(ii) 15th January: Kristiansand S. to Farsund
	The U-Boats, again escorted by the Sperrbrecher, got under weigh at 0830 the next morning. Trimming practice was carried out in Kristiansand Fjord, dives being made to 65 ft., while the Sperrbrecher dropped depth-charges in the distance to accustom the crews to this experience.
	Weather worsened on this day, and at midnight the U-Boats put into Farsund, where they lay at a pier. Prisoners inferred that, because of congestion within the U-Boat, some of the complement slept ashore that night.

	(iii) 16th January: Departure from Farsund
	The U-Boats, escorted by the Sperrbrecher, sailed at 0915, and proceeded up the Norwegian coast.

	(iv) 17th January: Off Bergen
	Prisoners agreed that "U 187" arrived off Bergen at about noon on 17th January. At 1300 the Sperrbrecher signalled "U 187": "God Speed!" and parted company. Soon after "U 187" lost sight of the remaining U-Boats, none of which she ever saw again.
	Course of approximately 315° was now set, "U 187" remaining on the surface for the rest of that afternoon. In the ensuing night the sound of a steamer was picked up on the hydrophones and Münnich ordered "U 187" to submerge to 130 ft. He then decided that the ship must be friendly, and "U 187" surfaced and continued her journey as before.

	(v) 18th January: On Passage to Patrol Area
	"U 187" submerged in the early morning of 18th January and remained submerged all day. She surfaced in the evening and continued thus throughout the night.

	(vi) 19th January: On passage to Patrol Area
	Early on this day "U 187" again submerged and did not surface again until nightfall. At 2100 there was a sudden alarm when an aircraft was detected by the G.S.R. "U 187" dived to about 38 ft. and remained submerged for two hours. According to one prisoner "U 187" had reached the latitude of 64° 30' N. by the end of this day.

	(vii) 20th January: On Passage to Patrol Area
	"U 187" continued to approximately latitude 65° N., where she altered course to 225° to make the passage of the Rosengarten. She had submerged in the early morning but surfaced in the evening and increased speed to 12 knots.

	(C49073) B*


	6

	(viii) 21st/22nd January: Passage through Rosengarten
	"U 187" passed through the Rosengarten between 21st and 22nd January. No evidence was obtained that she deviated from her routine of submerging by day and surfacing at night. At this time orders were received from Admiral U-Boats to report weather and position. Weather, which had been bad, was reported during daylight. It was not until night fell and the stars came out that "U 187" was able to fix and report her position.
	A P.O. Telegraphist prisoner stated that signals giving area of operations were all decoded in their final stage by Münnich, who alone had the tables. Each morning the prisoner had to record "U 187's" position and the receiving strength of the shore wireless station, in order to note where communication between U-Boats and base was worst.
	Several drifting mines were seen in the Rosengarten area.
	It would appear, from prisoners' statements and from one survivor's diary, that "U 187" altered course southwards after traversing the Rosengarten. This was confirmed by the First Lieutenant.

	(ix) 22nd/23rd January: Instructions received from Admiral U-Boats
	The P.O. Telegraphist prisoner said that at about this time, a signal was received from Admiral U-Boats instructing "U 187" to join Group Landscnecht comprising a group of 15 U-Boats in all, the remainder being commanded respectively by Zittewitz, Schröter, Werner Schutze, Soden, Schwantke, Jessen, Gretschel, Mumm, Teichert, Thurmann, Langfeld, Rudloff, Tinschert and Mengersen. The First Lieutenant confirmed the majority of there names, but said that he did not think Schroter or Mengersen formed part of the Group. All these U-Boats were keeping watch on the former "Irland" wavelength, known at that time as the "Diana" wavelength. The object of the formation of Group Landsknecht was to intercept an outward-bound convoy from England.
	"U 187" took the most northerly position in the sweep which extended for approximately 340 miles to the south, the U-Boats on parallel courses being spaced at intervals of about 20 miles. The P.O. Telegraphist prisoner stated that this sweep was 220°, speed of four to five knots was ordered, on the surface day and night. It had been calculated that Group Landsknecht would contact the convoy on either 23rd or 24th January.

	(x) 23rd January: (?)
	One day after the formation of Group Landsknecht one of the most southerly U-Boats in the sweep, commanded by Oberleutnant zur See Langfeld, reported that she had only about 25 tons of fuel remaining. She was allegedly instructed by the Admiral to remain in position and await further orders. (N.I.D. Note. Langfeld commanded "U 444," sunk on 11th March, 1943.) Seas now began to increase in violence and speed had to be reduced accordingly.

	(xi) 24th January: (?)
	The storm reached its peak on this day, sea Force 11 or 12 being recorded. Prisoners stated that at about this time "U 187's" G.S.R. aerial was repeatedly damaged by the battering she was receiving.

	(xii) 25th January: Group Landsknecht is disbanded
	The storm continued unabated and because of this orders were given by the Admiral to disband Group Landsknecht, the U-Boats having only been able to make two to three knots against the weather instead of the calculated four to five knots. It had been found impossible to serve meals and at these times "U 187" submerged for two hours while meals were taken in two watches.
	The P.O. Telegraphist prisoner stated that shortly before the disbanding of Group Landsknecht he intercepted a signal on the "Grönland" wavelength from a U-Boat captain named Bleichrodt claiming sinkings from a small convoy off Greenland. To an inquiry from Admiral U-Boats as to whether his sinkings had been made from a coastal or an England bound convoy. Bleichrodt replied that only a few ships had been seen. According to the prisoner Bliechrodt was operating in a second group known as Gruppe Haudegen which had been sweeping an area between Greenland and Newfoundland. Other U-Boats in this group of 11 in all were commanded by Hackländer, Huth, Hesemann, Thacher and Mahnke, but prisoners could not remember all names.

	(xiii) 25th/26th January: Formation of Group Pieil
	Following the disbanding of Group Landsknecht, "U 187" received orders to proceed west with the other U-Boats and herself to take up a position on the Newfoundland Bank. It was calculated at the time that she would need between two and three weeks to do this. Shortly afterwards, however, a further signal was received ordering the former Group Landsknecht U-Boats to reform as Group Pfeil in order to intercept a large eastbound convoy, probably on its way to Russia, which was then expected. The First Lieutenant stated that the Admiral signalled that the convoy was to be stopped at all costs as it was possibly carrying supplies for the Eastern Front. Group Pfeil proceeded westward on the surface, the U-Boats spaced twenty miles apart.


	7

	(xiv) 26th/31st January: "U 187" proceeds Westwards
	Nothing out of the ordinary occurred between the 26th and 31st January, as "U 187" continued westwards. Prisoners stated that seas lessened on the 26th but again increased in violence on the 29th.
	During this period the P.O. Telegraphist prisoner stated that he intercepted a number of signals from other U-Boats. These were mainly reports of position and weather. Wolfbauer, far to the south, reported that he had carried out his refuelling orders and requested permission to return. Another U-Boat reported that a Leutnant Feutsch had been washed overboard.

	(xv) 1st February: "U 187" unsuccessfully chases a 12,000-ton Steamer
	On the afternoon of 1st February, prisoners stated, a single 12,000-ton, grey painted, steamer was sighted proceeding east along the so-called "Swedish Lane," (described as a neutral shipping lane between two German blockade areas). The steamer was observed through rain squalls at a distance of about three miles. "U 187" at first turned away to avoid being seen. It was then observed that the steamer was zig-zagging and an attempt was made to close her from astern. Torpedo tubes were ready to fire and the steamer was almost within range when she suddenly zig-zagged again and disappeared behind a rain-squall. Endeavours to pick her up with R.D/F. and later, on submerging with G.H.G. proved fruitless. A report was then made to the Admiral that contact had been lost with a suspicious steamer independently routed. "U 187" then put about and proceeded at her best speed throughout the night to regain position in Group Pfeil. She accomplished this the following morning.

	(xvi) 2nd/3rd February: Extensible Look-out Mast Used
	On the evening of the 2nd or 3rd February, "U 187's" extensible look-out mast was raised and used for the first time during her patrol.

	(xvii) 4th February: Events leading up to the Sinking of "U 187"
	At 0700 Zone Time
	On 4th February, Leutnant zur See Strait relieved Leutnant zur See Buschmann on the bridge as Officer of the Watch. The two Officers, however, remained talking together for some time. Sea was Force 5 or 6.
	0800
	A burst of Very lights was seen to port. "U 187" immediately closed the position to investigate. Prisoners claimed that these lights first disclosed to them the position of a convoy which was, in fact, S.C.118. They presumed the lights were fired either as a signal to the ships to alter course, or to close up.
	0900
	Buschmann, Strait and the Chief Quartermaster reported the smoke plumes and mastheads of a large convoy 10 miles distant. They estimated that this convoy would pass from West to East across the centre of the area "U 187" was then covering.
	0955
	A "first sighting" signal was made to Admiral U-Boats. This signal was not acknowledged.
	1006
	A second "first sighting" signal was made and acknowledged. As "U 187" was the first U-Boat in the sweep to contact the convoy, she now assumed the role of "contact keeper."
	1046
	A third signal was now made giving the strength of the convoy and its position. Remaining on the surface "U 187" took up position about 10 miles ahead of the convoy. This move was later criticised by both officer and rating survivors as the first of two tactical errors made by Münnich The more experienced prisoners gave the opinion that Münnich would have done far better to withdraw and take station astern of the convoy.
	(N.I.D. Note. "Vimy" reports that at 1100Z on 4th February, 1943, while escorting convoy S.C.118, position 50° 12' N., 38° 34' W., course 036°, "Vimy" being in position B, "Beverly," when five miles ahead of the starboard wing column, sighted a U-Boat about 10 miles ahead of the convoy, course East. She immediately gave chase. Simultaneously S.S. "Toward" obtained an H/F D/F bearing on 037°, "Vanessa" thereupon ordering "Vimy" to "Beverley's" assistance.)
	1115
	From "U 187's" bridge the bow waves of two destroyers were suddenly approaching. Münnich at once ordered "Alter course, full speed ahead on the surface." This was considered by prisoners to be Münnich's second mistake. They felt that "U 187" had already delayed far too long before submerging. Münnich's intention in still remaining surfaced may be explained in part by the statement of one prisoner who alleged that he hoped still to make further signals, one of which would have been the convoy's speed and the strength of the escort. It has not been established whether this signal was actually sent.

	(C49073) B*2


	8

	1145
	Realising that by zig-zagging on the surface he could not hope to escape the destroyers, Münnich ordered "U 187" to submerge. The U-Boat did not respond well following the diving order and took a full 50 seconds to get down.
	(N.I.D. Note. At 1145 "Beverley" had reported that the U-Boat had dived four miles ahead, and by 1200 both she and "Vimy" were in the vicinity of the diving position which "Beverley" had marked with a flare. At 1203 "Vimy" obtained a good contact at 800 yards, bearing 000°, with moderate opening Doppler. This gave little time to find its movements, and by 1206 the ship was considered to be over it. A flare was dropped and "Vimy turned round to starboard but was unable to regain contact immediately. A westerly course was then steered for one mile then altering round to 060° doing an 80-80 sweep. At 1235 contact was regained bearing 009°, 1,200 yards, again with moderate low Doppler and slight movement to the left. This one produced a fair recorder trace and was attacked with a five-charge pattern at 100 ft.)

	_______________

	IV. SINKING OF "U 187"

	1235, 4th February, 1943
	Prisoners stated that "U 187" had submerged to a depth of about 260 ft. when the first series of depth-charges were heard. An experienced Petty Officer prisoner said that he was standing near Münnich at the time and he remarked: "I have never heard depth-charges dropped so far away." No damage was sustained within the U-Boat, which was then submerged to approximately 440 ft.
	(N.I.D. Note. "Vimy" reports that meanwhile "Beverley" had been unable to gain any contact and at 1253 she signalled that her asdics were out of action due to a high turn of speed. This fault was not remedied for the duration of the hunt and so she was not able to take part in any of it. In "Vimy" contact was soon regained astern fairly firm and it was next decided to carry out a hedgehog attack. "Vimy" then turned to starboard at four knots to gain sufficient accurate information. Echoes were marking fairly well on "Scale 25" and moderate left movement was obtained. At 1255 the ship increased to eight knots. Target movement had eased up a bit and when switching to "Scale 10" the traces became very poor. The hedgehog was fired on a poor trace with 3° left deflection at 1300. A queer "dull" echo was heard for the next few transmissions which may have come off the bombs.)
	1300
	In "U 187" a second series of explosions was heard rather nearer than the first. Prisoners said that no appreciable damage was done, but "U 187" was trimming badly and that whenever she lay on an even keel she tended to rise. Because of all this all the crew who could be spared from action stations were sent forward to the bow compartment. Here they appear to have become alarmed, for Leutnant zur See Strait stated that he was sent forward to calm the men. One of his actions was apparently to disconnect the depth gauge in this compartment.
	(N.I.D. Note. "Vimy" reports that no results were heard from her second attack and the ship turned right around to starboard regaining contact at 1310 bearing 290°, 1,500 yards with moderate opening Doppler. A fair trace was obtained with slight right movement and was attacked with a 14-charge deep pattern at 1315.)
	1315
	"U 187" survivors said that a third depth-charge pattern fell fairly near the U-Boat and caused the first major damage. Lights failed in the listening room and in the conning-tower, the G.H.G. was temporarily put out of action and depth gauges in the conning-tower and stern compartment broke. Some prisoners believed that the after hydroplanes were affected by this attack and added that "U 187" suddenly became stern heavy and rose rapidly to about 250 ft. before she could be checked. She had been proceeding at 2-3 knots. Münnich again ordered her down to 440 ft.
	The P.O. Telegraphist prisoner stated that throughout these attacks he had been on duty in the listening room. Each time he had reported; "Run in beginning. Alter course"; Münnich had said, "Yes," but had kept the U-Boat on the same course, except for a slight alteration after the second attack. The Junior Officer who was seated beside the prisoner had added that it was not necessary to alter course. The P.O. Telegraphist claimed that immediately before each attack an acoustic pill was ejected from the S.B.T. apparatus. The First Lieutenant confirmed this, but said that he thought that the U-Boat was moving so slowly that the pills may even have betrayed her position.
	(N.I.D. Note. Following her attack at 1315 "Vimy" reported that she ran out astern until range was 1,700 yards and came into the attack again. Echoes were becoming very weak and in "Scale 10" only two echoes left a mark, the remainder had to be positioned by ear and eye. Inclination was slight closing and the target appeared to be moving slowly right. Thus "Vimy" dropped her second and successful 14-charge pattern at 1333.)


	9

	1330
	Prior to the fourth and last depth-charge attack the noise of two destroyers was picked up on the hydrophones, one bearing 000° and the other 180°. The P.O. Telegraphist prisoner said that he realised at once that their position was desperate. He reported: "Run is beginning"; and commented, "If we don't alter course now it's all up." This time his anxiety was shared by the Junior Officer who suddenly flung down his earphones and dashed out of the listening room white in the face. A prisoner described the explosion of this series as "like the roar of an avalanche." A Quartermaster who had been detailed off to keep a log of the attacks, said that he never had time to add the word "near" after "depth-charges." It was believed by many survivors that some depth-charges actually exploded on the outer casing. Lights failed in all compartments forward of the control room, but not aft. The gyro-compass was wrecked. A fracture 4 ft. long and 1/2 in. wide was caused in the pressure hull aft, and the U-Boat becoming stern heavy, inclined at an angle of at least 45°. In addition the port side of the control room was stove in and oil from a port fuel tank cascaded into the boat. This oil swamped the batteries generating dense fumes. At this moment Meyer, the Engineer Officer, told Münnich that the position was hopeless and they must surface at once if anyone was to escape alive. The U-Boat laboured slowly upwards, while the calmer members of the ship's company convinced that their end was near, solemnly shook hands in farewell. Prisoners estimated that "U 187" took five minutes to surface and, they added, that when she finally emerged most of their air was exhausted.
	No order to abandon ship reached the bow compartment but Strait led the men there through the galley hatch. Simultaneously, the remainder were leaving through the control room hatch. Once on the upper deck a number of ratings clustered round the 105 mm. gun for support, others misguidedly attempting to clear the gun away. This caused fire to be opened upon them from the destroyers then about 600 yards distant. Confusion reigned for some seconds until a wave swept those on deck into the water.
	(N.I.D. Note. "Vimy" reported that the U-Boat surfaced astern at 1337 bows up at an angle of 50°, later leveling out on the surface. Fire was immediately opened with "X" gun and Oerlikons, the ship was turned to starboard and full speed rung on. The U-Boat crew were then jumping overboard in the wake and just before she sank stern first at an angle of 70°, "B" gun scored a hit on her bows with H.E. DA.)
	No clear account as to the fate of Münnich or Meyer has been forthcoming. According to one prisoner he last saw Meyer hustling men up the conning-tower hatch and he believed that he stayed within the U-Boat. Münnich has been variously described as shooting himself, and as standing on the conning-tower as the U-Boat went down for the last time.
	It is not believed that any signal reporting the sinking was sent to Admiral U-Boats. The P.O. Telegraphist prisoner said that no signal was sent, firstly, because the instruments were smashed, secondly, because, in the general upheaval and scramble to leave the rapidly sinking U-Boat, no one had thought of doing so.
	Two officers, the Midshipman and 31 men were picked up by "Beverley" and nine ratings by "Vimy." Four of the ratings rescued by "Vimy" later died of wounds and were buried at sea.

	______________

	V. GENERAL REMARKS ON BOATS

	(i) Duties of a Contact-keeping U-Boat
	The U-Boat which first sighted a convoy automatically becomes "Fühlungshalter" (Contact-keeper) and is responsible for keeping Admiral U-Boats informed as to the position of the convoy.
	Her "first sighting" signal to the Admiral contains the following information:
	(a) Message in code reporting enemy in sight.
	(b) Her exact position.
	(c) Originator.
	As soon as possible after this signal has been sent a further signal is made as follows:
	(a) Size of convoy and number of escorts.
	(b) Formation.
	(c) Course.
	(d) Speed.
	If the U-Boat is then forced to submerge, by aircraft, for example, she is likely to remain at periscope depth in order that she may still receive low frequency signals from the Admiral.
	Other U-Boats in the area are given the position of the convoy by the admiral. As soon as they sight the convoy they make a short signal, which informs the Admiral which U-Boats have reached the convoy.

	(C49073) B*3


	10

	The contact-keeper reports her position approximately once an hour, but at no definite time. She has an hour and twenty minutes from the despatch of one signal in which to make the next one. Should she fail to do so within this time, the duties of contact-keeper pass to another boat. This boat then transmits an enciphered signal stating that she has taken over the duty and giving the course speed and position of the convoy, and continues to function as contact-keeper.
	In bad visibility, when other U-Boats have difficulty in picking up the convoy D/F signals are transmitted by the contact-keeper on about 440 kc/s. These signals are made at regular intervals at regular times twice an hour. The P.O. Telegraphist prisoner who made this statement at first alleged that the times were from 20-25 minutes and 40-45 minutes past the hour, but when it was pointed out that this meant an interval of 20 minutes in one case and 40 in the other, he said he was sure that the 20-25 minutes time was correct and that there was half-an-hour interval, the other must be 50-55 minutes past the hour.
	This is the only occasion, according to the prisoner, when medium frequency is employed.
	A prisoner maintained that 20 miles was the maximum range at which a contact keeper could keep in touch with a convoy, i.e., by means of its hydrophones. Ten to fifteen miles was more usual in unfavorable weather. This range was shortened at night, but was not likely to be less that five miles.

	(ii) Attack Tactics
	As each U-Boat arrives in position she reports this to Admiral U-Boats. When a sufficient number of U-Boats has reached the convoy the signal to attack is given by the Admiral. U-Boats are ordered to attack simultaneously, if possible, so as to create the maximum confusion. The contact-keeper remains astern of the convoy.
	A prisoner stated that he had heard of U-Boats surfacing momentarily in the vicinity of a convoy in order to divert the escort's attention from other U-Boats, but he thought this practice had been abandoned as too foolhardy.
	The same prisoner added that U-Boats preferred to attack down moon should it be high and to fire torpedoes on the beam of the convoy, but should the moon be low the favorite tactic was to approach up moon, again firing on the beam. There was no rigid rule, however, as an attack was largely a matter of opportunism.

	(iii) Intercommunication between U-Boats
	This only occurs on two occasions: (a) When communication with Admiral U-Boats on normal frequency breaks down; (b) during W/T coded conversation.
	(a) Should communication between Admiral U-Boats and a group of U-Boats break down, another U-Boat still in contact with the base is detailed to relay signals. The group of U-Boats switch on to a "group frequency." The U-Boat, still in contact with both the Admiral and the group, relays signals in either direction. Every four hours, however, U-Boats in the group must try to regain contact with the base on normal frequency.
	(b) The second occasion when U-Boats communicate directly with each other is in "W/T coded conversation." This can be ordered either by the Admiral or by Senior U-Boat in any particular group and is employed for the following types of communication:
	(1) A senior U-Boat allotting other U-Boats in the neighbourhood of a convoy to attacking positions.
	(2) Enquiries as regards fighting strength (Kampfraft), i.e., the amount of torpedoes, fuel, provisions etc., remaining, upon which the fighting efficiency of the U-Boat depends.
	When either the Admiral or the Senior U-Boat in a group whishes to communicate by W/T/ coded conversation," they state the time at which this type of communication is to commence some time in advance.

	(iv) R/T Communication between U-Boats
	A P.O. Telegraphist prisoner said that short-wave W/T-R/T sets, manufactured by Lorenz, are carried by U-Boats when working up in the Baltic, and that U-Boat captains can then communicate by this means. The sets are taken out of the U-Boats prior to their first patrol, because it is suspected that in the past American stations have succeeded in picking up conversations between U-Boats operating in the Atlantic.
	The sets now have the addition of a small auxiliary transformer which does away with the need for batteries.

(v) Signals Areas

A P.O. Telegraphist prisoner stated that the signals areas for U-Boats operating in the Atlantic, organised by Admiral U-Boats, are the following:

Hubertus Area		Bounded on the east by a line from the easternmost point of Greenland southward to a position approximately in the latitude of Newfoundland. The southern boundary runs from this position westwards to the American continent.
Diana Area		Adjoins Hubertus to the south and east, extending as far south as the Straits of Gibraltar.
America I \|		To the South and west of Hubertus and Diana
America II \|		To the South and west of Hubertus and Diana
Africa I \|		To the south and east of Hubertus and Diana
Africa II \|		To the south and east of Hubertus and Diana

(N.I.D. Note. These appear to be Series 8 (Hubertus), Series 7 (Diana), Series 3 (America I and II) and Series 4 (Africa I and II). See C.B. 4002.)

(vi) Transmissions from Admiral U-Boats

The prisoner who gave the above information stated that the wavelength of the transmissions from the Admiral are changed in the Diana area, the only area in which he had operated, at the following hours: 0000, 0700, 0900, 1100, 1200, 1800, 1900, 2300. From 00' to 05' after any change, no signals are made, except tuning signals, and the signature of the transmitting station, e.g. Lorient R.X.U. This enables U-Boats to tune exactly to their Base. From 05' to 10' after a change, now signals are made from the Base; during these five minutes the Base is listening very carefully, for it is then that U-Boats make their most vital signals, such as the position of enemy convoys and warships. From 10' to 60' after any change, the Admiral can signal at any time, and does.

The prisoner believed that the wavelength of transmissions to U-Boats operating very far afield is changed hourly owing to the varying quality of reception in distant areas.

(N.I.D. Note. The times of change and the frequencies used vary with the time of year.)

(vii) Signals Procedure

Watch is always kept on high frequency, but in addition there are regular low frequency transmissions which a U-Boat can receive without extending her aerials, when submerged at periscope depth. These low frequency transmissions are from 0700 to 0900, from 1200-to 1400, and from 2000 to 2200 and consist of repetitions of all high frequency transmissions from the Admiral which U-Boats may have missed.

High frequency signals from U-Boats are immediately repeated by the Admiral to signify that the message has been received and understood. In addition these messages are repeated, two hours later, four hours later, seven hours later, 14 hours later, 20 hours later and 28 hours later, to ensure that all signals are acknowledged and that all U-Boats are able to receive all messages. The messages are dated and numbered. In spite of this procedure cases have been known to occur of U-Boats missing signals.

(N.I.D. Note. VL/F routines vary for different H/F Series.)

(viii) Additional duties of W/T Operators

Besides keeping watch on short wavelengths when surfaced and long wavelengths when submerged, W/T operators have to keep G.S.R. watch, when surfaced, on the orders of their Commanding Officer. It is also the duty of the P.O. Telegraphist to keep hydrophones manned day and night when submerged. Watches are four hours in the day and two six-hour watches at night.

(ix) Watch on W/T Traffic round Convoys

While not an order, it is a tactical recommendation that U-Boats should try and overhear merchant ships transmitting their position, name and the fact that they have been attacked, on 500 kc/s.

(x) W/T Guard in Home Ports

A boat or ship from each Flotilla, whether U-Boat, minesweeper or other craft, is detailed in each German or German occupied port to keep W/T guard. She is recognisable as she always flies the pendant "T" for "TONI." She is used as W/T headquarters, and it is part of her work to look after W/T codes for some weeks ahead.

(xi) Diving Policy

(a) Biscay Area. U-Boats proceeding submerged through the Bay of Biscay are now instructed to remain at a depth of 130 ft. during daylight.

(b) Rough Weather on Patrol. Prisoners maintained that rough weather did not normally cause a U-Boat to submerge unless it was combined with bad visibility. One prisoner said that on one occasion in the Atlantic they submerged for six hours because of bad weather and bad visibility combined.

(C49073) B4


	12

	In Sea Force of 7 or more it was the custom to submerge for the mid-day meal from about 1200 to 1400. They did not submerge for other meals, i.e., breakfast from 0600 to 0700, or tea from 1600 to 1800.
	U-Boats sometimes submerge for a few hours at night in rough weather in order to give the crew a rest.
	(c) After G.S.R. Contact. One prisoner alleged that, following G.S.R. contact with an aircraft, U-Boats submerge for between 15 and 30 minutes, and then surface and carry out another G.S.R. search.
	(d) After Aircraft Sighting. U-Boats submerge for at least one hour after an aircraft sighting, even in the vicinity of a convoy, because it is assumed that an aircraft has a patrol endurance, as opposed to total endurance, of about four hours.

	(xii) Bridge Watch Procedure and Training
	The relieving watch has always to report to the Officer of the Watch half an hour before they are due to take over, in order to get used to natural light after their period under artificial light. They are given special supplies of black coffee and pills to maintain ocular efficiency, but no anti-soporific pills.
	The Officer of the Watch has to remain permanently on the bridge, but the three look-outs are allowed to get some relaxation by changing places with the Quartermaster.
	The bridge watch, during tactical exercises in the Baltic, is expected to correctly identify different types of German aircraft.
	During these tactical exercises, tests are made to see whether the U-Boat or the aircraft spots the other first. An interval of half an hour was almost invariably observed in favor of the U-Boat. The best surprise was achieved by aircraft flying at 600 ad 900 ft., this being especially so at dawn or dusk, if they approached down sun.

	(xiii) Protection against Aircraft Attack while on Trials
	All U-Boats working up in the Baltic carry one yellow stripe about one metre wide painted diagonally across the deck four to five metres from the bows. Also a half metre wide yellow strips round the conning tower and a further diagonal stripe aft. This is so that they may be recognised easily by German aircraft.

	(xiv) Oiling at Sea
	A prisoner gave the following procedure for refuelling from a supply U-Boat at sea:
	In the supply U-Boat the fuel hose connection s are uncovered from beneath deck gratings right aft. These connections can be closed from inside the U-Boat as well as from outside in case of alarm, to prevent water entering or exuding, which might leave oil slick. A manila hawser with float attached is veered astern. To this manila is secured the fuel hose and a wire hawser. The U-Boat taking over fuel secures the manila and hauls it in with the fuel hose and the wire hawser. The wire hawser is then secured to the towing bits. The hose is connected to the supply valves in the U-Boat being refuelled. The towing hawser can be slipped in case of alarm while the hose would be severed.
	Generally two or three lengths of hose are carried. Before transferring oil, water is pumped through the hose in order to test it.

	(xv) Rendezvous with Supply U-Boats
	A prisoner said that the possibility of failing to rendezvous with a supply U-Boat seldom caused U-Boat captains anxiety. In the first place, fuel was never allowed to run so low that, should the supply U-Boat fail to arrive, the U-Boat expecting it would be helpless. If the supply U-Boat were late, it would only be a question of waiting a few days in the vicinity.
	A second prisoner said that he had never heard of supply U-Boats towing smaller U-Boats to their area of operations, but he believed it possible that, if a U-Boat ran short of fuel and a supply U-Boat had none to give her, the latter would attempt to tow the smaller U-Boat into port.

	(xvi) Markings on Practice Torpedoes
	Torpedo Testing Command (T.E.K.) torpedoes have red and white longitudinal stripes on the head.
	Torpedoes of the 8th Torpedo Firing Flotilla have red and white bands round the head.

	(xvii) Torpedoes, General
	When Air Torpedoes are embarked they are supplied sometimes in their containers and sometimes without according to whether the U-Boat has empty containers on board.
	During torpedo firing practice, torpedoes are generally fired at a range of between 625 and 1,000 yards.

	(xviii) R.D.F. with Torpedo Aiming
	A P.O. Telegraphist prisoner said that R.D.F. is often used at night in bad visibility for firing electric or air torpedoes. If the range of the target is not over two miles and a salvo of torpedoes


	13

	be fired, fairly accurate results may be obtained. The accuracy of R.D.F. is insufficiently great to direct a single torpedo "blind." The First Lieutenant said that he thought R.D.F. could be used for directing torpedo firing, but that "U 187" had never practised this method as, during her torpedo firing exercises, her R.D.F. was out of commission.

	(xix) Training of U-Boat C.O.s
	Should prospective U-Boat commanding Officers never have served as First Lieutenant in another U-Boat, they undergo the following training:
	(1) Navigational, Torpedo and W/T Courses at Flensburg.
	(2) U-Boat School at Pillau or Gdynia.
	(3) Course with the 24th (Torpedo Firing) Flotilla at Memel - firing 30 torpedoes in all, as well as additional instruction in Torpedo-Fire Control Gear (Feuerleitanlage). Among torpedoes fired are three salvoes of two, two salvoes of three and one salvo of four. Single torpedoes are fired first at slow ships and then at fast ships.
	The Commanding Officer is then appointed to stand by a boat building.

	(xx) Patrolling in Operational Squares
	It was said that in the reconnaissance sweeps joined by "U 187" the U-Boats were strung out along a line running roughly North-West to South East, and that they patrolled each in their own squares.

	(xxi) M.A.N. 9 40/46 Diesel Engines
	(1) Two well-informed Stoker P.O.s gave the following information regarding this engine: