S E C R E T

NAVY DEPARTMENT

OFFICE OF THE CHIEF OF NAVAL OPERATIONS

WASHINGTON

Final Report - G/Serial 27

REPORT ON THE

INTERROGATION OF SURVIVORS FROM U-664

SUNK 9 AUGUST 1943

S E C R E T

TABLE OF CONTENTS

				Page
CHAPTER	I.		INTRODUCTORY REMARKS	1
	II.		DETAILS OF U-664	3
	III.		TECHNICAL DETAILS AND PROCEDURE	19
	IV.		DESCRIPTION AND TECHNICAL USES OF NEW GERMAN TORPEDOES AND PISTOLS	26
	V.		GERMAN NAVAL RADIO INTELLIGENCE (B-DIENST)	59
	VI.		CREW OF U-664	64
	VII.		EARLY HISTORY OF U-664	69
	VIII.		FIRST PATROL OF U-664	72
	IX.		SECOND PATROL OF U-664	74
	X.		THIRD PATROL OF U-664	78
	XI.		FOURTH PATROL OF U-664	83
	XII.		FIFTH AND LAST PATROL OF U-664	88
	XIII.		SINKING OF U-664	96
	XIV.		TACTICS	101
	XV.		BASES	103
	XVI.		OTHER U-BOATS	106
	XVII.		SURFACE SHIPS	115
	XVIII.		GENERAL REMARKS ON U-BOATS	118
	XIX.		MORALE	122
ANNEX			CREW LIST OF U-664 AND U.S. EQUIVALENTS OF GERMAN NAVAL RANKS

CHAPTER I.  INTRODUCTION

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        The exceedingly low morale aboard U-664 no doubt facilitated the interrogation, and more than one prisoner was willing to cooperate fully with the interrogation officer.

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CHAPTER II.  DETAILS OF U-664

TONNAGE.

        500 tons.

TYPE.

        VII C.

BUILDING YARD.

        Howaldtwerke, Hamburg.

YARD NUMBER.

        813.

COMMSSIONED.

        18 June 1942.

FLOTILLA.

        Ninth Flotilla at Brest.

FIELD POST NUMBER.

        05024.

PATRON CITY.

        Gaggenau.  (Baden.)

CALL LETTERS.

        XGU.

INSIGNIA.

        Sawfish Insignia of 9th Flotilla.

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LENGTH OVER ALL.

        220 feet.

PRESSURE HULL, DIAMETER.

        15 feet.

PRESSURE HULL PLATING, THICKNESS.

        18 mm. in control room, tapering to 16 mm. in bow and stern.

SPACING BETWEEN PRESSURE HULL AND UPPER DECK.

        Normal.

DISPOSITION OF FRAMES.

Numbers	Location
0 to 16	Stern compartment
16 to 29	Diesel compartment
29 to 39	Galley and P.O.'s quarters
39 to 52-1/2	Control room
52-1/2 to 68	Officers' and C.P.O.'s quarters
68 to 82	Forward torpedo compartment

HATCHES.

        Total of 7, bow torpedo loading hatch, conning tower hatch, galley hatch, stern torpedo loading hatch, all of the foregoing hinged for opening and closing; one engine room access hatch and two battery access hatches, riveted.  The galley hatch was inaccessible after Platform II was added just prior to the last patrol.

BULKHEADS.

        One each fore and aft of control room.

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GENERAL CONSTRUCTION.

        Completely welded, including attachment of flanges to pressure hull and bulkheads.

DRAFT, FULLY LOADED.

        15 feet.

PERISCOPES.

        One observation periscope, actuated by hydraulic cylinders and wire cables.

        One attack periscope, actuated by piston, fitted with riding seat, in conning tower.

"PAPENBERG" DEPTH GAUGE.

        Fitted.  This depth gauge is located in the control room.  It was described as about 150 cm. long and 5 cm. wide; the silhouette of periscope and bridge was painted on it.  Graduated to 20 m., it is used for exact determination of periscope depth preceding and during an underwater approach and attack.

CRASH DIVING TIME.

        Before platform I was widened and platform II added, i.e. prior to last patrol, U-664 dived to periscope depth, 13 m., in 18 seconds.  After changing the superstructure the diving time was increased to 28 seconds.

MAXIMUM DEPTH ATTAINED BY U-664.

        On several occasions U-664 dived to 250 m., without discomfort to the crew.  It was stated that the yard guarantees a boat up to 150 depth.

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BRIDGE ARMOR.

        16 mm. armor plate fitted around forward bridge fairing; armored doors, 12 mm. thickness, fitted between bridge and platform I.

GUN PLATFORMS.

        Two.  Platform I, widened prior to last patrol; platform II, added at the same time.

GUNS.

        No forward gun.  88 mm. gun removed after fourth patrol.

        Two 20 mm. cannons on platform I; quadruple mounted 20 mm. cannons on platform II.

        Two type 15 demountable machine guns on bridge.

QUADRUPLE MOUNTED 20 mm. CANNONS.

        Four barrels, two over two.  Vertical splinter shields on both sides of mount; estimated thickness 8 mm.  (See photograph.)  Seat for gunner turns with mount; it does not raise or lower with it, however.  Mount is raised and turned by hand rods.  Cable and spring arrangement acts as counter-weight.

        Aiming by ring sight.  Outer rings stated for target speed of 360 km.; second ring 180 km.; inner ring for diving planes or for target requiring no lead.

        No automatic stop; railing, both forward and aft, acts as such.

        Vertical elevation 90⁰; traverse angle 360⁰; depression angle believed 10⁰.

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        All four barrels set parallel, arranged as follows:

                                3        1

                                2        4

        Firing order 1, 2, 3, 4.

        Firing speed per minute:  (a)  theoretical - 200 rounds per barrel

                                              (b)  actual - 80 rounds per barrel

TYPE 15 MACHINE GUN.

        Estimated firing speed two-drum-shaped magazines per minute.  Each magazine contains 75 rounds; on U-664 each second round was a tracer.

20 MM.  AMMUNITION.

        20,000 round aboard U-664; packed in metal containers each containing 100 rounds.  Containers were distributed all over the boat.

        U-664 had the following types of ammunition on board:

                Incendiary - H/E, with tracer; stated to be flat nosed, yellow with red band.  Explodes on contact or may be fuzed.  (On U-664's fourth patrol this was the only type ammunition carried.)

                Incendiary - H/E, without tracer.  Yellow, no red band.

                A/P - H/E, no tracer.  Black

                May also have carried A/P with phosphorus charge, no tracer.  Blue.

        Extreme and self-destroying range stated to be 2,000 m.  Effective range 2100 - 2200 meters.

MAGAZINES.

        168 magazines carried.  Empty magazines were filled in the ammunition chamber by a loading machine.  Filled magazines could be stowed as follows:  80, four rows of 20, in the control room; four in each of the

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five pressure-proof ready-ammunition lockers below platforms I and II; 10 aft of periscope in the conning tower.

        Magazines not marked as to type or order of ammunition contained therein.

PRESSURE PROOF READY AMMUNITION LOCKERS.

        Five lockers installed before leaving on last patrol.  One located between bridge and Platform I, just aft of attack periscope; four located between platform I and II; two over two.

TORPEDO TUBES.

        Five; four forward, one aft.  All tubes fitted with F.A.T. gear since February 1943.

TORPEDOS CARRIED.

        First patrol      - 6 air, 8 electric.

 

        Second patrol - 4 air, 6 electric, 4 electric with combination magnetic-impact pistols.

        Third patrol     - 2 air, 8 electric, 4 F.A.T.

        Fourth patrol   - 8 electric, 4 F.A.T.

        Fifth patrol      - 4 electric, 5 F.A.T., 3 acoustic.

UPPER DECK CONTAINERS.

        Two carried on first three patrols; two air torpedoes carried therein on those patrols.

TORPEDO STOWAGE ON LAST PATROL.

        Four in forward tubes, 1 an acoustic torpedo; 2 on forward floor

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plates; 4 in forward bilges; 1 (acoustic) in stern tube; 1 (acoustic) in stern bilge.

EXPELLING PRESSURE.

        Stated to be 12 atm. on surface shots; 16 atm. on submerged shots.

S.B.T.

        Fitted.  (See also Chapter III.)

DEPTH CHARGE PLOTTER (D.P.C.).

        Not fitted.

ENGINES.

        Two G.W. 6 cylinder, single acting, four cycle Diesels, 1400 H.P. each with supercharging.  860 H.P. without supercharging at 350 R.P.M.

ENGINE SPEEDS.

Telegraph Speeds	R.P.M.	Speed
K.F. (Dead Slow)	185	7.2 knots
L.F. (Slow)	245	9.7    "
H.F. (Half Speed)	285	12.7  "
2x H.F. (3/4 Speed)	385	14     "
G.F. (3/4 Speed)	450	16     "
2x G.F. (Full Speed)	475	16.8  "
A.K. (Emergency Speed)	485-490	17.5  "
3x A.K. (Emergency Speed)	495	17.8  "

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        Speeds of 2x H.F., and higher were always attained with supercharging.

        At 3/4 speed (2x H.F.) with battery charging, engines turned at 350 R.P.M.  Half speed on both engines was considered cruising speed.  In operational area, one engine was run at slow speed, turning over 200 R.P.M. at a rate of travel of 4 knots.  Diesel-Electric propulsion was used only once during the trials of U-664.  An engine room petty officer stated that very few U-boats used Diesel-Electric propulsion.

SUPERCHARGERS.

        2 "Kapselgeblase".  Positive displacement (Rootes) type, fitted with mechanical friction clutch manipulated from engine control stands.  Although drive has intermediate gearing and cushioning springs, frequent replacement is necessary.

CLUTCHES.

        Disc friction type, pneumatically actuated, and with emergency hand wheel actuation.

FUEL OIL CAPACITY.

        About 140 cubic meters (120 tons).  The prisoner stated that the increased capacity was obtained by filling 3 torpedo compensating tanks is pumped into the regular tanks.

FUEL OIL CONSUMPTION.

        During tactical exercises on a 24 hour run, 22 of which were at 3/4 speed and 2 at half speed, 12 cubic meters of oil were used, or about 0.5 cubic meters average per hour, which figure normally varied

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from 0.5 to 0.55 on U-664.  On the fourth patrol U-664 ran for six weeks without being supplied.  Fuel oil consumption when running on one engine varied from 1.6 to 2.6 cubic meters per day on this patrol.

MOTORS/GENERATORS.

        Two A.E.G. double units, each normally 365 H.P., but 420 to 470 H.P. when crowded as motors.  About 50 - 100% greater generating capacity.

MOTOR SPEEDS (Submerged).

Telegraph Speeds	R.P.M.	Speed
K.F. (Dead Slow)	58	1.2 knots
L.F. (Slow) *	90	1.5    "
L.F. (Slow)	110	2.8    "
H.F. (Half Speed)	160	3.6    "
2x H.F. (3/4 Speed)	210	4.5    "
G.F. (Full Speed)	260	5.1    "
A.K. (Emergency Speed)	300	6.5    "

Note:  *  L.F. Speed with 1 motor only; all other speeds with both motors.  (O.N.I. Note:  Attention is called to the apparent discrepancy of R.P.M. and actual speed for full speed and emergency speed.)

        Survivors estimated emergency speed at about 7.1 knots before addition of platform II and widening of platform I.

BATTERIES.

        Two banks of 62 cells each, lead-acid type.  The batteries were known as model 33 MAL 800 W.  Capacity of U-664's batteries was 9,600 ampere hours; normally this should be 10,000.  At full speed the batteries were exhausted in 4 to 5 hours.  Below half speed, batteries were connected

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in parallel; at and above, in series.  At dead slow, the armatures of the motors-generators were connected in series; at 3/4 speed, in parallel.  (Connections for other speeds were not stated.)  Maximum non-spilling angle 65⁰.

ROTARY CONVERTER.

        One 0.3 K.V.A. on top of Port Motor/Generator for radio.

        One compound wound for Gyro; 110 volts, 55 or 333 cycles.

        One 1 K.V.A.

        One 1.5 K.V. for new radio apparatus, also for patent log, salinity determinator at fresh water still, multiple hydrophone, radio transmitters and receivers.

        One 6 K.V.A. for main transmitter and for all radio purposes.

        One for fire control apparatus.

        One for Echo sounder.

        One CONZ (Siemens) for radio, probably high frequency.

        No rotary converter was used for supplying constant voltage lighting current.  Battery current was fed through an automatic voltage regulator located on the auxiliary switchboard.  Hand controls also were fitted.  The automatic regulator consisted of a small motor turning a centrifugal governor which engaged a toothed rack which slid a contact back and forth on a resistance.

COMPRESSORS.

        One electric 4-stage compressor.  Capacity 6 liters per minute at 250 atmospheres.  One Junkers crankless Diesel compressor, 4-stage capacity 8 to 11 liters per minute at 250 atmospheres.  The Junkers compressor

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was mounted on a base and also had emergency suspension by wire cables from the overhead after the second patrol.  One cable had been left off due to its interference with the operation of the S.B.T. apparatus.  At the sinking, the base was knocked out; the emergency suspension proved unsatisfactory due to the one cable missing.  Both compressors were regularly exchanged after each patrol for others which had been thoroughly overhauled.

COMPRESSED AIR SUPPLY.

        Consisted of 6 groups of 2 bottles each, capacity per bottle 360 liters; total capacity 3,900 liter.  Pressure 250 atmospheres (3675 P.S.I.).  Starting air at 35 atmospheres carried in two bottles, one behind each Diesel, they were filled from Group 1.  H.P. air bottles located aft in upper deck.

OXYGEN SUPPLY.

        On last cruise six bottles of liquid oxygen replaced compressed gaseous oxygen in the oxygen system.  An ordinary pressure reduction valve was used and oxygen was added to air circulation system in customary manner.

PUMPS.

        One main ballast, double impeller centrifugal; 250 liters per minute, impellers in series; at depth of 60 to 80 meters, impellers are used in series; capacity is reduced an average of 10 liters per minute for every 10 meters greater depth.  380 liters per minute,impellers in parallel.  One auxiliary ballast, reciprocating.  Capacity, 150 liters per minute, maximum depth 30 to 40 meters.

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        The greatest depth at which ballast could be pumped outboard with both pumps in series was 240 to 250 meters.

        One auxiliary engine cooling water pump could be used to pump out forward Diesel bilge.

        Note:  bilges could also be pumped into compensating tank and blown.

SPARE PARTS.

        7 or 8 Bosch injector needle valves and springs.

        A number of intake and exhaust valves and valve springs for Diesels.

        1 Cylinder head for Diesel.

        1 main bearing for Diesel.

        No spare piston rings for Diesels or compressors were carried.

        Prisoners stated that amount of spare parts carried was small due to scarcity.

GERMAN ASDIC.

        Not fitted.

RADAR.

        Not fitted.  It was said to be installed after the completion of the fifth patrol; an extensible radar aerial was to take the place of the extensible rod aerial.

R.D.B.

        Balloons carried in three sheet metal containers stowed in the forward torpedo compartment.  The containers were marked "A.E.G."  Four

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hydrogen bottles installed prior to last patrol just abaft the 20 mm. quadruple mounted cannons on platform II.  Balloons not used, except one which was fired at for target practice.

G.S.R.

        Metox R 600 fitted; fixed round net-type dipole aerial installed prior to last patrol (see drawing).  Metox fitted with "magic eye" since fourth patrol.  A visual indicator (cathode-ray tube) was connected with the Metox prior to the last patrol; it was set atop the Metox.  Two spare cross-type aerials were carried.

D/F GEAR

        Standard D/F apparatus manufactured by Lorenz; range from approximately 12 kc. to 1500 kc.

        Special Lorenz D/F apparatus fitted prior to last patrol; range about 500 kc. to 5000 kc.  For use of radio intelligence operatives aboard after interception of convoy traffic.  (See drawing attached.)

TRANSMITTERS.

        H/F Telefunken transmitter; 200 w.; - 8 or 10 stage.

        L/F - M/F Telefunken transmitter; 150 w.; 500-100 m.; 2 stages.

        Emergency Telefunken transmitter; 40 w.; 20-60 m.

RECEIVERS.

        All wave receiver.

        H/F receiver; 20-80 m.

        Standard broadcast receiver.

        All-wave intercept receiver; used only by radio intelligence personnel (see drawing attached).

        4 - 8 m. receiver, manufactured by S.A.D.I.R. Located in listening

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room atop the emergency Telefunken transmitter.  Its aerial was a rod-type radiating aerial which was demountable and which was located on the port side of the forward conning tower fairing.