U-boat Archive - U-1229 - Interrogation Report



	Op-16-Z
	Copy No. 29 of 51.

	NAVY DEPARTMENT
	OFFICE OF THE CHIEF OF NAVAL OPERATIONS
	WASHINGTON

	FINAL REPORT - G/Serial 46

	REPORT ON THE
	INTERROGATION OF SURVIVORS FROM U-1229
	SUNK 20 AUGUST 1944

	DISTRIBUTION:
	BAD
	BUORD
	BUSHIPS
	BUSHIPS (Code 515)
	BUSHIPS (Code 815)
	COMINCH (F-21)
	COMINCH (F-4253)
	COMINCH (F-45)
	COMINCH (F-40)
	COMINCH (FX-43)
	COMNAVES
	DNI (Ottawa)
	G-2 (Col. Sweet)
	Op-16-1 via Op-16-1-F
	Op-16-FA-4
	Op-16-P
	Op-16-W
	Op-20-C
	Op-23-C
	SCNRD
	Lt. Cdr. V. R. Taylor
	C.O., Naval Unit, Tracy, Calif.
	Lt. J. I. Eiband (COMNAVNAW, CSDIC, AFHQ)
	Lt. S. R. Hatton (COMNAVNAW, CSDIC, AFHQ)
	Lt. J. T. Rugh, Jr. (JICA/ME)
	COMASDEVLANT
	CINCLANT
	COM8THFLEET
	COM4THFLEET
	Op-16-1-V
	Op-30

	27 September 1944

TABLE OF CONTENTS

			Page
CHAPTER	I.	INTRODUCTION	1

	II.	DETAILS OF U-1229	2

	III.	SCHNORCHEL	9

	IV.	CREW OF U-1229	13

	V.	EARLY HISTORY OF U-1229	16

	VI.	FIRST AND LAST PATROL OF U-1229	18

	VII.	SINKING OF U-1229	21

	VIII.	INFORMATION ON TYPE XXI U-BOAT	26

	IX.	OTHER U-BOATS	31

ANNEX		CREW LIST OF U-1229 AND U.S. EQUIVALENTS OF GERMAN NAVAL RANKS AND RATINGS.



	CHAPTER I. INTRODUCTION

	U-1229, a 750-ton U-boat built at the Duetsche Werft, Finkenwerder, Hamburg and commanded by Korvettenkapitän Armin Zinke, was sunk on her first patrol on 20 August 1944, in position 42.20 N. - 51.39 W. U-1229 was sunk after being surprised on the surface by aircraft from the U.S.S. BOGUE.

	Forty men, including the engineer officer, were picked up by ships of the task group and brought into Argentia, Newfoundland, where a preliminary investigation was made. A selected group was later shipped to this country for detailed interrogation.

	U-1229’s brief and unsuccessful history had little of interest to reveal. She was, however, fitted with Schnorchel and the new Tunis G.S.R. gear, details of which are included in this report. In addition, some information was obtained on the new type XXI U-boats about which much has been rumored but little definitely known.














	- 1 -



	CHAPTER II. DETAILS OF U-1229

	TONNAGE

	750-tons.

	TYPE

	IX-C.

	BUILDING YARD

	Deutsche Werft, Finkenwerder.

	COMMISSIONED

	13 January 1944.

	FLOTILLA

	31st Flotilla.

	FIELD POST NUMBER

	M-55295.

	INSIGNIA

	“13” - painted on the forward part of the conning tower and worn on the crew’s caps.

	MAXIMUM DEPTH ATTAINED

	200 meters (off Trondheim).

	CRASH-DIVING TIME

	30/38 seconds.

	- 2 -



	GUNS

	(1) Automatic 37-mm. on Platform II. This was fitted just a few days before leaving Kiel on her last patrol.

	(2) Two twin 20-mm. cannons on Platform I.

	TORPEDO TUBES

	Four forward, two aft.

	TORPEDOES CARRIED

	Fourteen.

	DISPOSITION AND TYPE OF TORPEDOES

	Tube 1 - T-2 Tube 4 - T-5

	Tube 2 - T-2 Tube 5 - T-3

	Tube 3 - T-3 Tube 6 - T-5

	Four T-1’s on floor plates forward.

	One T-2 on floor plates forward.

	One T-5 on floor plates forward, port.

	One T-2 on floor plates aft, starboard.

	One T-5 on floor plates aft, port.

	Setting of T-5’s - SS for those in tubes; LO for those on floor plates.

	S.B.T. (Submarine Bubble Target)

	Fitted.

	ENGINES

	Two 9-cylinder M.A.N. Diesels, with Büchi superchargers.

	- 3 -

ENGINE SPEEDS

	Telegraph Speeds	R.P.M.

	K.F. (Dead Slow)	205

	L.F. (Slow)	260

	H.F. (Half Speed)	315

	2XH.F. (3/5 Speed)	395

	G.F. (3/4 Speed)	420

	2XG.F. (Full Speed)	450

	A.K. (Emergency Speed)	470 plus.

FUEL OIL CAPACITY

250 tons.

SCHNORCHEL

Fitted on starboard side, just forward of the conning tower - normal position for Type IX-C U-boats. (For information on operational experience with Schnorchel, See Chapter III.)

MOTORS/GENERATORS

Siemens.

SWITCHBOARD

Siemens.

BATTERIES

Afag type, two banks of 62 cells each - 12,000 ampere hours capacity. A device was described by prisoners to

- 4 -

prevent chlorine gas in the event of damage to the batteries. A chalk substance, about 1-cm. in depth was packed around the outside of the cells. Acid spilling from cracked cells would be absorbed by this substance. It was estimated that acid from as many as 35 cells might be absorbed this way.

MOTOR SPEEDS

	Telegraph Speeds	R.P.M.

	K.F. (Dead Slow)	90

	L.F. (Slow)	120

	H.F. (Half Speed)	180

	G.F. (3/4 Speed)	220

	A.K.. (Full Speed)	250

COMPRESSORS

One electrical; one Junkers air compressor.

RADAR

Not fitted. Should have received one, but there was a shortage at the base.

R.D.B. (Radar Decoy Balloons)

Carried. Stowed in four or five boxes containing 20 each, but never used.

R.D.S. (Radar Decoy Spar Buoys)

Not carried.

- 5 -



	D/F GEAR

	Standard Lorenz D/F set fitted.

	H/F - D/F

	Not fitted.

	G.S.R.

	(1) Wanz G-2 - said to have been very dependable at all times.

	(2) Naxos-2 - two sets carried; one for “Fliege” and one for “Mücke” aerials.

	(3) Borkum - not used, carried only as a spare in case the Wanz broke down.

	G.S.R. AERIALS

	(1) Two basket-type aerials for the Wanz G-2. One atop the Schnorchel on which continuous watch kept while proceeding at Schnorchel depth; one in normal position on the bridge.

	(2) One “Fliege” and one “Mücke aerial, the combination of which is called Tunis. (See accompanying sketch.) Both aerials are mounted on opposite sides of a portable shaft which fitted into a socket at the forward end of the periscope block.

	It was stated that “Mücke covers a range of 2-4-cm. It is actually set for exactly 3-cm. The wave-length is determined by the detector tube and a number of spare tubes were carried. The “Fliege” aerial was

	- 6 -



	said to be set for exactly 9-cm., but covering a range from 8-12-cm.

	“Fliege” and “Mücke” are each connected to a Naxos 2 amplifier in the listening room. The operator, fitted with headphones, stands on the bridge and continually rotates the aerial. The switch is always in the position “both”. When a signal is received in clear weather and in daylight the operator will throw the switch to “Fliege” or “Mücke” immediately after giving the alarm. Usually, however, the operator will, as soon as he has given the alarm, lift the receiver from its socket and start down the hatch preparatory to crash-diving. It was also stated that the new Naxos amplifier was a marked improvement over the old type, and far more sensitive.

	A continuous watch was kept on Tunis and Wanz while surfaced, and as the radiomen frequently had other duties to attend to, other members of the crew, particularly torpedomen, were trained to take over Wanz-G.S.R. watch when needed.

	TRANSMITTERS

	(1) 200-watt Telefunken short-wave transmitter.

	(2) 150-watt Telefunken long-wave transmitter.

	(3) 40-watt Telefunken emergency transmitter.

	- 7 -



	RECEIVERS

	(1) Telefunken all-wave receiver.

	(2) “Grossschiff” type short-wave receiver.

	U.K. GEAR (VH/F)

	Not fitted.

	G.H.G. (Multi-Unit Hydrophones)

	Atlas type fitted.

	ECHO SOUNDER

	Atlas Echolot fitted.

	U.T. (Underwater Telegraph)

	Fitted.

	ROTARY CONVERTERS

	(1) 6 KVA.

	(2) 1 KVA.

	(3) 0.3 KVA.

	WATER DISTILLER

	Produced about 10 liters per hour.

	RUBBER BOATS

	(1) Two eight-man boats.

	(2) One-man boats, slightly less than one for each man carried.

	COLOR

	Medium gray.

	- 8 -



	CHAPTER III. SCHNORCHEL

	GENERAL

	The Schnorchel was installed on U-1229 at Oderwerke, Stettin, during the period of final overhaul (about 8 May to 20 June, 1944). As is the case with all Type IX-C U-boats, it was fitted on the starboard side, just forward of the conning tower. According to the description given by the prisoners, the Schnorchel was normal in every detail. When the mast was raised, its top was one to two feet lower than the tops of the extended periscopes.

	OPERATIONAL PROCEDURE

	The Schnorchel mast was usually raised or lowered when the boat was at a depth of 20 meters. When proceeding on Schnorchel, U-1229 maintained a depth of 13 meters. Diesel speeds were said to vary from 180 to 300 r.p.m. The normal r.p.m. when running on diesel was 270 which, in calm weather, produced a speed of about five knots.

	The normal barometric pressure in the pressure hull when operating on Schnorchel varied from about 980 to 1020 millibars. When the top of the Schnorchel undercut a wave, the floater valve was

	- 9 -



	actuated, cutting off the air supply and greatly reducing the pressure within the boat. An operator at the Diesel controls constantly watched a barometer. When the pressure dropped to 850 millibars, the Diesels were stopped.

	EXTENT OF USE

	U-1229 proceeded submerged on Schnorchel from about 28 July to about 14 August. During this period, she surfaced only occasionally for a few minutes to take navigational sights of the sun. The times for surfacing depended on the stage of the overcast. It was stated that 36 hours was about the longest period spent at Schnorchel depth without coming to the surface.

	EFFECT OF WIND AND SEA

	It was stated that the Schnorchel could not be used in a sea force greater than five or six. It functioned better in long ground swells than in a choppy sea. In the latter case, the floater valve was constantly opening and closing, making conditions within the pressure hull uncomfortable.

	TRIM

	The engineer officer always attempted to maintain trim at a depth of about 13 meters when using the Schnorchel. It was possible to proceed for several minutes with the floater valve below water level. On one occasion, one Diesel turning at 250 r.p.m., continued to run four minutes after the floater valve closed. No ill effects resulted. Effort was made never to allow the top of the Schnorchel to go deeper

	- 10 -



	than one to two meters. At greater depths, the water pressure would become too great for the Diesel exhaust and the engines would stop.

	The raised Schnorchel mast increased the difficulties of maintaining trim. The engineer officer stated that it was intended eventually to equip all U-boats with an automatic depth-keeping device. He said that the firm, Askania Werke, had been experimenting with such a device for three years but that it had not been perfected. A few boats had been fitted experimentally with this gear but it had not proved satisfactory.

	CHARGING AIR BOTTLES

	U-1229 charged her air bottles when proceeding on Schnorchel. The electric compressor was used for this purpose.

	CHARGING BATTERIES

	A number of different methods were employed by U-1229 to charge batteries when proceeding on Schnorchel. One of the most economical of these methods was to use one Diesel for both propulsion and charging. The engine ran at 250 r.p.m. and charged the batteries at 400 amperes.

	It was stated that because batteries generate gas when charged at 149 volts or higher, they were never charged at more than 145 volts. Ventilating lines were installed in each battery compartment to lead off the gas. These lines were connected with the main air exhaust line and were fitted with barometers which indicated the pressure in the compartments. A change of pressure of 14 millibars or

	- 11 -



	more indicated a dangerous concentration of gas. The gas is passed through the ventilating lines and into the main air exhaust line. It is then conducted through special leads to the Diesel air intake. Thence it is sucked by the superchargers into the Diesels and expelled through the Diesel exhaust system. Batteries were always ventilated for at least fifteen minutes after charging.


















	- 12 -



	CHAPTER IV. CREW OF U-1229

	GENERAL

	U-1229’s complement was 57, consisting of four officers, five chief petty officers, thirteen petty officers, and thirty-five men. Although a considerable number had had no previous U-boat experience, the crew was of superior caliber compared with others recently encountered. The engineer officer himself said they had developed well and had become an excellent crew.

	Prisoners were not unduly secure and several needed no urging at all to tell all they knew. This is thought to be partly due to events on the fighting fronts in the past weeks, plus a high incidence of men genuinely anti-Nazi who wanted to get the whole business over as soon as possible. It is also undoubtedly true that the unpopularity and inefficiency of their captain did much to ruin the morale of a good crew.

	OFFICERS

	Although little id known of the early career of Korvettenkapitän Armin Zinke, it is apparent that he ranks high among the more inept German U-boat commanders encountered in this war. His crew did not have a good word to say about him. During U-1229’s working up period and trials, Zinke was drunk a good deal of the time. At all times he was morose and uncommunicative both with the officers and the men, and it was seldom that he allowed anyone to address him, except in compliance with an order. His faults as a man might have

	- 13 -



	been overlooked, but survivors held him directly responsible for the loss of their boat due to his practice during the last few days of the patrol of remaining continually on the surface during daylight. Zinke belonged to the 1930 Naval Term and wore the minesweeper badge. It is believed that this was his first and last patrol on a U-boat.

	Leutnant zur See Quertin, the first watch officer, was formerly quartermaster on U-504 under Poske. He was popular with the crew, particularly as he couldn’t get along with the captain. He wore the Iron Cross 1st class.

	Nothing is known of Uhlenbrück, the second watch officer. (Not in GNL.) He joined the boat as a midshipman in Hamburg and wore the minesweeper badge.

	Büttner, the engineer and only officer survivor, was also a lower deck promotion. In peacetime he served on the GRILLE, Adolf Hitler’s yacht, which was also used as an experimental ship for steam turbines. Büttner later served on a destroyer and then commissioned U-561 under Bartels. When he left her early in 1943 he was a machinist. He attended the Marineschule at Flensburg before receiving his commission. Büttner was popular with his men and was probably a competent engineer officer. He was an ardent National Socialist, although quite ready to admit that the war, and particularly the U-boat war, was lost, and he was full of the kind of “crocodile tears” emotion so often encountered in certain types of Germans. Büttner, in addition, was extremely proud of his attainments as a U-boat engineer and frequently his vanity outran his security.

	- 14 -



	MEN

	The “greenness” of many of the crew was offset by the experience and ability of several of the petty officers. One, a coxswain who did not survive the sinking, had celebrated his 500th day at sea on U-boats in this war a few days before he lost his life.

	In conclusion, it is worthy of note that the pharmacist’s mate, who was lost in the final action, was killed at his regular action station on the 20-mm. cannon!




















	- 15 -



	CHAPTER V. EARLY HISTORY OF U-1229

	COMMISSIONING

	The crew began to arrive at the yard to stand by in the final construction about November 1943. They were quartered on the depot ship WARNOW with the crews of U-1228 and U-1230. U-1229 was commissioned 13 January 1944 and a small celebration was held on the WARNOW.

	TRIALS AND EXERCISES

	After two weeks in Kiel for her acceptance tests, U-1229 did running tests at Sonderborg. She then proceeded to the Baltic for further trials. These were accomplished without incident and included Agrufront at Hela, diving tests at Danzig, torpedo firing at Gotenhafen, and “flak” instruction and firing at Swinemünde. At the tactical trials U-1229 took part in an attack on a convoy of three or four merchant ships protected by aircraft. Two wooden torpedoes were carried, one forward and one aft, and torpedo drill without firing was carried out with them.

	FINAL OVERHAUL

	U-1229 arrived at the Oderwerke, Stettin for her final overhaul on Sunday, 7 May. Here the Schnorchel was fitted and the preliminary overhaul completed by 20 June. Three days were then spent at Swinemünde for further “flak” practice, including training ashore on the 37-mm. which had not yet been fitted. The boat then proceeded to Hela for three days for Schnorchel trials.

	On 28 June U-1229 returned to Stettin for final outfitting.

	- 16 -



	All torpedoes were embarked except T-5’s and prisoners suspected a shortage, attributed to Allied air attacks on torpedo storage locations, because of the old and battered character of the T-1’s and T-2’s which were scraped together from the training flotillas. On 7 or 8 July U-1229 left for Kiel.

	PREPARATION FOR FIRST PATROL

	U-1229 arrived in Kiel on 9 July. Before leaving on patrol the 37-mm. was fitted, the four T-5 torpedoes embarked, and the new Tunis G.S.R. fitted. U-1229 was now ready for first patrol.


















	- 17 -



	CHAPTER VI. FIRST AND LAST PATROL OF U-1229

	KIEL TO BERGEN

	U-1229 left Kiel at 0800, 13 July, escorted by a patrol boat but not accompanied by any other U-boat. Kristiansand was reached at 0200, 15 July and here U-1229 took on fuel and topped up the batteries. At 0200, 16 July they left Kristiansand and proceeded north to Bergen, hugging the coast on the surface. Bergen was reached at 1900 on the 16th and fresh provisions were taken on. At 0600, 17 July U-1229 left Bergen.

	MISHAP TO SCHNORCHEL

	After leaving Bergen U-1229 proceeded up the coast on the surface. At noon, 19 July, after the U-boat had dived and the Schnorchel was raised, the exhaust line to the Diesel broke. The break occurred outside the pressure hull where the line passed through the conning tower. Some water entered the Diesel room and U-1229 was forced to put about and make for Trondheim, which was reached about 0200, 20 July.

	In Trondheim a number of 500-ton U-boats were seen and a 750-tonner lay next to U-1229. Most of these boats were said to be in for repairs. It was during this time that the attempted assassination of Hitler occurred, and for two days, much to the annoyance of some members of the crew, the men at the base were forced to give the Hitler salute at the slightest provocation.

	DEPARTURE FROM TRONDHEIM

	U-1229 left Trondheim on 26 July and proceeded north up the

	- 18 -



	Norwegian coast on the surface. A day or so later U-1229 turned west and headed into the Atlantic.

	U-BOAT PROCEEDS ON SCHNORCHEL

	U-1229 proceeded for the next 14-18 days almost continually on Schnorchel. Usually, weather permitting, Zinke would surface every day for 10-15 minutes for a navigational sight. There was no set time for this, although an attempt was made to surface around noon when conditions were favorable. Prisoners believed that 36 hours was about the longest period spent submerged on Schnorchel without surfacing.

	Prisoners stated that the passage of the Rosengarten was made completely without incident. There were no alarms and no G.S.R. contacts. Conditions within the boat while proceeding on Schnorchel were said to have been generally pleasant. Prisoners preferred it to ordinary submerged procedure because they were permitted to smoke.

	ENGINEER’S REMARKS TO HIS MEN

	One night at 0030, just after the watch had been relieved, Büttner called the engine room ratings together in the Diesel room. He told them that the news from Germany was bad and that no one could tell what the future held in store for them. He stated that the boat was provisioned and fuelled (250 tons) to stay at sea until 1 November and warned the men to save fuel at every opportunity. He apparently didn’t tell the crew anything they had not suspected already and morale was not damaged by the warning.

	During the patrol a message was received from base that one

	- 19 -



	of the machinists had become a father of a boy.

	U-BOAT PROCEEDS ON THE SURFACE

	About a week prior to her sinking, Zinke changed his tactics and from then on U-1229 proceeded all day on the surface. Usual procedure was to dive every evening about 2000 and remain submerged for 6-8 hours while the crew rested. Prisoners were highly critical of these tactics and Quertin, the first watch officer, protested to Zinke that it was suicide, only to be reminded that Zinke was in command and to mind his own business.

	A SIGHTING AND AN AIRCRAFT ALARM

	Five or six days before the sinking the bridge watch sighted a corvette and a four motored aircraft in the distance. The Y-boat dived and no incident developed.

	At 1920, 19 August a contact was received on the Tunis G.S.R. Once again the U-boat dived out of danger. The crew by this time were becoming worried that Zinke’s tactics were going to lead to trouble. They were not wrong.














	- 20 -



	CHAPTER VII. SINKING OF U-1229

	U-1229 CAUGHT ON THE SURFACE

	Shortly after noon on 20 August U-1229 was proceeding fully surfaced, as had been her recent custom, when an aircraft was sighted coming in for an attack some distance away. Fire was immediately opened on the plane which continued to come in at a low altitude and dropped its bombs close aboard the U-boat to port. The resulting explosions hurled five members of the gun’s crew, including the pharmacist’s mate, and one of the 20-mm. cannon overboard. The five men did not get back on board and were lost. The remainder of the bridge watch scrambled down the hatch as the U-boat crash-dived.

	Within the boat there was little immediate damage noticeable although she was severely shaken up. Lighting came off the board, but was soon restored, and there was a small water entry through the conning tower hatch which was plugged without difficulty.

	BATTERIES SEVERELY DAMAGED

	The boat had plunged to 60 meters when it was realized that the batteries had been badly damaged. An estimated 35 cells had been cracked and the motors were losing power rapidly. The boat was then brought back up to 30 meters.

	In the meanwhile fear was expressed in the boat that one or more of the fuel tanks had been ruptured and that they were leaving an oil trace. (O.N.I. Note: This, in fact, was correct. Pilots were able to keep a constant watch on the U-boat’s position until she surfaced

	- 21 -



	again largely due to the presence of a bubbling oil trace.)

	ATTEMPT TO SURFACE WITH DIESELS

	The boat was now at 17 to 20 meters and it was decided to raise the Schnorchel and attempt to start the Diesels, although the top of the Schnorchel was still below the surface. The pressure on the exhaust proved too great, however, and the Diesels would not start.

	U-BOAT SURFACES AND CREW ABANDONS SHIP

	The two previous attempts having failed, tanks were now blown and the U-boat surfaced. As the periscopes and Schnorchel broached, a sharp rapping was heard in the boat which was accurately diagnosed as strafing from aircraft.

	The position of the boat was now considered hopeless and the order was given, now some two hours after the first attack, to abandon ship. AS the crew emerged from the conning tower they came under heavy strafing fire from the attacking aircraft and casualties were heavy. No attempt was made to man the guns. Zinke was last seen standing on

	- 22 -



	the bridge unwounded, but whether he was later hit by aircraft fire or went down with his boat, is not known. Querin was hit several times and was last seen dying on the U-boat’s deck.

	No attempt was made to scuttle as damage from strafing had already left the boat in sinking condition. The engineer officer stated that the tanks were shot through and he could hear the air hissing out of them as he left the boat. There was no time to send a signal to control advising them of the loss of the boat.

	Shortly after the last man had pulled away from the boat, a loud explosion was heard from the settling U-boat which prisoners took to be the batteries exploding. U-1229 then disappeared at a steep angle, bow first.

	ACTION REPORT

	(The following are paraphrased extracts from the action report.)

	At 1227½, 20 August, the radar operator of TBM-1C#19, on anti-submarine patrol, obtained a small blip which almost coincided with the pilot’s visual sighting of a fully surfaced U-boat, distance four miles. When about three miles distant, the U-boat opened fire, continuing to fire until depth-bombed. An evasive turn on the part of the U-boat caused her to present her starboard quarter to the airplane for a perfect bomb run. Two Mark 54 depth-bombs were released at 100 feet, speed 230 knots. The bombs hit on the far side (port), one very close aboard just to port of the conning tower, and the other about 40 feet from the bow. During the pull out the conning tower was strafed

	- 23 -



	by the rear gunner. Debris was seen to fly off the conning tower from the explosions and the pilot saw something fly off the stern. After two tight 3600 turns to the left and the right, the U-boat submerged.

	A sonobuoy was dropped in the swirl 15 seconds after submergence and clear rhythmic sounds like propeller beats were heard for 55 seconds. An oil slick from the point of submergence extended about half a mile, then turned sharply to the left for about another half mile before stopping.

	Meanwhile other planes were launched from the U.S.S. BOGUE and others, already in the air, were vectored to the scene. At 1419 the outline of the U-boat was spotted beneath the bubbling oil trace. At 1425 both periscopes and the Schnorchel appeared above the surface. Two TBM’s made simultaneous bombing runs, but due to overeagerness found themselves approaching each other in glides from nearly opposite sides of the U-boat and were forced to drop their depth bombs 200 feet short of the target. By 1430 the U-boat was fully surfaced and crew members began to appear with life jackets and life rafts. Strafing attacks were made simultaneously by both FM’s and TBM’s from the moment the periscopes and the Schnorchel appeared, at 1425, until they disappeared for good at 1443. Between 1435 and 1439 a TBM made four depth bomb runs, but one bomb which hit close aboard proved a dud and the other hung up in the bomb bay.

	At 1443, the stern of the U-boat lifted above the surface, the bow nosed over steeply, and the whole craft slid, at a sharp angle, into the sea. A few seconds later a heavy explosion rocked the sunken

	- 24 -



	U-boat and lifted water and debris 100 feet in the air. There was no evidence to show whether this was a scuttling charge or the result of damage previously done to the boat.





















	- 25 -



	CHAPTER VIII. INFORMATION ON TYPE XXI U-BOATS

	A considerable amount of new information on Type XXI U-boats was obtained from a well-informed prisoner. It should be emphasized that the source had never been aboard a XXI boat, but had seen them and talked to men serving on them.

	_ _ _ _ _ _ _ _ _ _ _ _ _

	TONNAGE

	Approximately 1600-tons.

	HULL

	Of new design as per attached sketch. The bow, when seen from the front, gives the impression of two superimposed hulls forming a figure of 8. This is, however, not the case. The lower bulge is a large buoyancy tank which is necessitated by the elimination of the upper-deck structure, in order to prevent the bow from being driven under. There are two vents on this tank, one at each side aft, to permit very fast flooding. In all respects, prime consideration has been given to streamlining the hull with a view to maximum submerged speed, regardless of certain disadvantages in relation to surface navigation. The conning tower, which occupies the entire width of the boat, is approximately the size of a conning tower on a IX-C boat, plus Platform I. There are no Platforms. The anchor winch and upper-deck containers have been eliminated. There is no deck armament. The keel has been encased for streamlining purposes. Sections of the hull are entirely prefabricated in a

	- 26 -



	number of yards and some inland factories. Assembly on the slips, which is very rapid, takes place in yards at Danzig and Gotenhafen.

	PERISCOPES

	Two: Extensible to permit a periscope depth of 18 meters. Source was not sure of this, but was positive that the periscopes are longer than in other U-boats.

	ENGINES

	Two new type 6-cylinder M.A.N. main Diesels fitted with a new type of Büchi supercharger. These superchargers incorporate double compression by the use of two sets of paddle wheels, thus permitting the introduction of considerably more air into the cylinders than was previously possible. Due to the elimination of the upper-deck structure, the surface speed of Type XXI boats does not exceed 20 knots, but the operation of this type of Diesel is considerably more economical than the ordinary type. The engines are of 2400 h.p. each. At 500 r.p.m. these engines produce 900 brake h.p. each on the propellers.

	OPERATING RADIUS

	At economical operation with an average speed of seven knots on Diesel electric, such a boat would run approximately 160 miles in 24 hours with a consumption of approximately 2 ½ cubic meters. Fuel capacity stated to be 450 cubic meters, which would result in a theoretical operational radius of 30,000 miles.

	- 27 -



	ELECTRIC MOTORS

	Two main electric motors at 1300 h.p. each.

	BATTERIES

	Three banks of 65 cells with a capacity of 30,000 ampere hours. By connecting these batteries in series, a tension of 400 volts is obtained. At 2500 amperes, each of the electric motors till take up about 1,000 kilowatts (1300 h.p.), thereby permitting high speeds.

	SUBMERGED SPEED

	At 400 r.p.m., a speed of 15 knots submerged can be attained and maintained for about one hour. At most economical submerged speed underwater endurance will be 75 hours. (Two to four knots.)

	CRASH DIVING TIME

	Such a boat is said to have crash-dived at high speed in 18 seconds. However, 25 seconds is considered normal.

	MAXIMUM DIVING DEPTH

	As in Type IX-C: 200 meters or better.

	SCHNORCHEL

	One fitted, starboard side, fitting flush into a recess forward of the conning tower, resting directly on the pressure hull. Maximum speed of Schnorchel seven knots. Although, theoretically, higher speeds would be possible, source stated that it would be entirely impractical because the plume set up by the Schnorchel would be such as to interfere with the operation of the G.S.R. mounted on it, and would

	- 28 -



	provide too favorable a target. In addition, he was told that higher speeds, producing higher exhaust temperatures, would provide a good target for infra-red search. Underwater release of the exhaust had not been adopted because of the stream of bubbles that would betray the U-boats course.

	TORPEDO TUBES

	Six forward, possibly two aft. (See below.)

	AUXILIARY ENGINE AND MOTOR

	Source had heard one version of the Type XXI boat according to which there were no torpedo tubes in the aft compartment. Instead, there was a third Diesel and a third electric motor driving a third propeller. This motor was said to be a 6-cylinder 1500 h.p. M.A.N. Diesel which, operating at 500 r.p.m., would produce approximately 300 brake h.p. on this propeller. This engine was also to be used for most economical operation as cruising engine for use with the Schnorchel and for charging batteries. The third electric motor would be used for most economical underwater operation at 300 r.p.m. This motor, at 550 kilowatts, would operate on a tension of 300 volts at 2500 amperes. It should be emphasized that source was not sure whether this feature had been incorporated in the Type XXI U-boats.

	ARMAMENT

	Two twin 37-mm. A/A guns mounted within the conning tower fairing. On forward and one aft, retractable. Hydraulically

	- 29 -



	raised and lowered.

	OPERATIONAL

	Source believed that a number of these boats have been built and that some of them may well be at sea as of early September 1944.




















	- 30 -

CHAPTER IX. OTHER U-BOATS

U-170

A prisoner stated that U-170 sailed from Kiel on her first patrol summer 1943. After an unsuccessful six weeks patrol she entered Lorient in July 1943. All her officers had previously served aboard U-171:

Commanding Officer:		Kapitänleutnant Gunther Pfeffer.

Executive Officer:		Hartmann.

Second Watch Officer:		Kneip (O.N.I. Note: Oberleutnant Kneip of the October 1939 Term.)

Engineer Officer		Dingeldein (O.N.I. Note: Kapitänleutnant (Ing.) Otto Dingeldein of the 1934 Term.)

U-171

A prisoner who survived the sinking of U-171 stated she made only one patrol, sinking about 30,000 tons. On her sole patrol, U-171 left Kiel and was sunk on 9 October 1942 just off Lorient. All officers and twenty-nine members of the crew of U-171 were sent to Wesermünde to stand by U-170, still under construction. Her officers were then the same as listed above under U-170.

U-428

Reported attached to the 23rd Flotilla, Danzig, as schoolboat end of 1943.

U-429

Upon completion in summer of 1943, U-429 was said to have been turned over to the Italians. She was used by them as a

- 31 -

schoolboat. Her officers were said to be:

Commanding Officer:		Oberleutnant Racky (O.N.I. Note: Oberleutnant Ernst Racky of the October 1938 Term).

Executive Officer:		Leutnant Altstädt (O.N.I. Note: Leutnant Werner Altstädt of the May 1941 Term).

Second Watch Officer:		Leutnant Kunz.

Engineer Officer		Leutnant (Ing.) Milsch.

U-540

Made tactical exercises with U-541 in spring 1943.

U-541

Under construction in January 1943. Made tactical exercises with U-540 in spring 1943. Her officers at that time were reported to have been:

Commanding Officer:		Peterson (O.N.I. Note: Kapitänleutnant Kurt Petersen of the 1936 Term).

Executive Officer:		Leutnant Hecke.

Engineer Officer		Oberleutnant (Ing.) Ulmer (O.N.I. Note: Oberleutnant (Ing.) Alfred Ulmer of the October 1938 Term).

U-1220 -U-1237

This series, which may go higher than U-1237, was said to consist of 750-ton, IX-C type U-boats, built by Deutsche Werft, Finkenwerder, Hamburg. U-boats numbering from 1220 to 1234 were reported completed, from 1235 to 1237 under

- 32 -

	construction, as of spring 1944.

U-1227	The commanding officer of U-1227 was reported to be Oberleutnant Altmeier (O.N.I. Note: Probably Oberleutnant Friedrich Altmeier of the October 1938 Term). Tactical exercises were made with U-1229 in spring 1944.

U-1228	Reported at Blohm and Voss, Hamburg for final overhaul early July 1944 and to have left Kiel on her first patrol after 13 July 1944.

U-1230	Reported at Blohm and Voss, Hamburg for final overhaul early July 1944 and to have left Kiel on her first patrol before 13 July 1944. Her commanding officer was said to be a Korvettenkapitän.

U-1234	A prisoner stated that U-1234 had been rammed and sunk in the Baltic. She was later raised and is now said to be used as a schoolboat.

_ _ _ _ _ _ _ _ _ _

BASES

23rd FLOTILLA

Commanding officer of the 23rd Flotilla, Danzig, as of late 1943 was said to be Korvettenkapitän von Bülow. About eight to twelve U-boats were then attached to this flotilla as schoolboats. Among these were U-428 and U-429. Other U-boats of the 400 series were also reported attached to the 23rd Flotilla.

- 33 -

ANNEX:	CREW LIST OF U-1229 AND U.S. EQUIVALENTS OF GERMAN NAVAL RANKS AND RATINGS

Name	Rank and Rating	U.S. Equivalent	Age

	Kapitän zur See	Captain
	Fregattenkapitän	Commander
	Korvettenkapitän	Lieutenant Commander
	Kapitänleutnant	Lieutenant

SURVIVORS
Büttner, Willy	Oberleutnant (Ing.)	Lieutenant (j.g.) Engineering duties only	30
Bessling, Heinz	Obersteuermann	Warrant Quartermaster	24
Kruse, Karl	Oberbootsmaat	Boatswain	24
Bagehorn, Heinz	Bootsmaat	Coxswain	24
Gieseler, Werner	Matrosenobergefreiter	Seaman 1cl.	19
Nitsche, Heinz	Matrosenobergefreiter	Seaman 1cl.	20
Diezel, Kurt	Matrosenobergefreiter	Seaman 1cl.	20
Böttcher, Franz	Matrosenobergefreiter	Seaman 1cl.	20
Reissmann, Otto	Matrosenobergefreiter	Seaman 1cl.	19
Hülsmann, Illi	Matrosenobergefreiter	Seaman 1cl.	21
Kehrls, Otto	Matrosengefreiter	Seaman 2cl.	19
Körpert, Raimund	Matrosengefreiter	Seaman 2cl.	19
Seibicke, Fritz	Obermaschinist	Machinist	29
Neumann, Fritz	Obermaschinist	Machinist	27
August, Gerhard	Obermaschinenmaat	Machinist’s Mate 2cl.	26
Wüstermann, Karl	Maschinenmaat	Fireman 1cl.	23
Gattner, Willi	Maschinenmaat	Fireman 1cl.	23
Hinz, Leo	Maschinenmaat	Fireman 1cl.	23
Spörer, Ernst	Maschinenmaat	Fireman 1cl.	24
Keil, Walter	Maschinenmaat	Fireman 1cl.	22
Eistel, Kurt	Maschinenobergefreiter	Fireman 2cl	21
Bieberbach, Ewald	Maschinenobergefreiter	Fireman 2cl	20
Peters, Fritz	Maschinenobergefreiter	Fireman 2cl	21
Lohrbach, Karl-Heinz	Maschinenobergefreiter	Fireman 2cl	22
Klauke, Hermann	Maschinenobergefreiter	Fireman 2cl	22
Poick, Manfred	Maschinenobergefreiter	Fireman 2cl	21
Balasus, Fritz	Maschinenobergefreiter	Fireman 2cl	24
Dunkel, Richard	Maschinengefreiter	Fireman 3cl.	19
Kaufmann, Heinz	Maschinengefreiter	Fireman 3cl.	20
Wystyrk, Max	Maschinengefreiter	Fireman 3cl.	20
Beer, Rolf	Maschinengefreiter	Fireman 3cl.	19
Middeke, Gustav	Maschinengefreiter	Fireman 3cl.	20
Sobotta, Richard	Maschinengefreiter	Fireman 3cl.	20
Gollas, Theo	Oberfunkmeister	Radio Electrician	23
Wittig, Ernst	Funkobergefreiter	Seaman 1cl.	22
Vogel, Gerhard	Funkobergefreiter	Seaman 1cl.	20
Glässner, Werner	Mechanikersmaat	Torpedoman’s Mate 3cl.	22
Götz, Adof	Mechanikersobergefreiter	Seaman 1cl.	20
Lemke, Hans	Mechanikersobergefreiter	Seaman 1cl.	20
Ernst, Friedrich	Mechanikersgefreiter	Seaman 2cl.	18

Name	Rank and Rating	U.S. Equivalent

CASUALTIES
Zinke, Armin	Korvettenkapitän	Lieutenant Commander
Querin	Leutnant zur See	Ensign
Uhlenbrück	Leutnant zur See	Ensign
Beer	Stabsobersteuermann	Chief Warrant Quartermaster
Tinnessen, Heinz	Bootsmaat	Coxswain
Heise	Matrosenobergefreiter	Seaman 1cl.
Haak	Matrosenobergefreiter	Seaman 1cl.
Hennatsch	Matrosengefreiter	Seaman 2cl.
Heinrich	Matrosengefreiter	Seaman 2cl.
Hartmann	Matrosengefreiter	Seaman 2cl.
Augstein	Matrosengefreiter	Seaman 2cl.
Ritz	Maschinenmaat	Fireman 1cl.
Sittek	Maschinengefreiter	Fireman 3cl.
Roth	Maschinengefreiter	Fireman 3cl.
Bayer	Funkmaat	Radioman 3cl.
Benker	Mechanikersobergefreiter	Seaman 1cl.
Golletz	Sanitätsobermaat	Pharmacist’s Mate 2cl.