U. 607

INTERROGATION OF SURVIVORS

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September, 1943.

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C O N T E N T S

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I.

Details regarding	1)	Radar Decoy Balloon
	2)	Electric "Curly" Acoustically directed torpedoes.
	3)	Magnetic torpedo pistols
	4)	Ultra-violet searchlights
	5)	New U-boat types
	6)	New U-boat armament
	7)	Modified Conning Tower
	8)	U-boat A/A/ gunners course at Swinemünde

Konter Admiral	-	Rear Admiral
Kommodore	-	Commodore (2nd Class)
Kapitän zur See	-	Captain.
Fregattenkapitän	-	Commander.
Korvettenkapitän	-	Lieutenant-Commander.
Kapitänleutnant	-	Lieutenant.
Oberleutnant zur See	-	Sub-Lieutenant.
Leutnant zur See	-	Junior Sub-Lieutenant.
Oberfähnrich zur See	-	Senior Midshipman.
Fähnrich zur See	-	Junior Midshipman.
Marinestabsarzt	-	Surgeon Lieutenant.

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II.

DETAILS OF U.607.

(i)	Displacement:	500 tons
(ii)	General Construction:	Type VII C Standard
(iii)	Building Yard:	Blom and Voss, Hamburg
ARMAMENT
(iv)	Guns:  (Disposition):	No 88 mm (3.46") gun forward; one G.A.F. type machine gun, M.G.81 mounted on each side of conning tower; two single 20 mm (0.79") guns, one on each side of bandstand; a 20 mm. quadruple gun mounting on an extended gun platform aft.  An extra Ordnance Artificer was carried for maintenance of this equipment.
	(Description):
	(a)  M.Gs. 81:	This type give a phenomenal rate of fire of between 1200 and 1500 rounds per minute per barrel.
		Ammunition was in 500 rounds disintegrating (articulated) link belts.  For convenience of feed it was split up into smaller lengths of 200/250 rounds.  These rounds were kept in iron boxes about 15" long, 10" deep and 4" wide.  The boxes were passed up from the Control Room as required.
		A prisoner estimated that it did not take more than 20 seconds for a belt to be changed.  About 25 boxes each with 500 rounds were carried in all.  It was said that the guns did not stand up well to rough treatment and were soon affected by sea water
	(b)  Single 20 mm (.79") Guns:	Type C.38.  One fitted on each side of bandstand.  Each gun could be brought to bear from 00 to 1800 on its own side. If one gun were out of action its sector could not be covered by the other.
		Elevation limits were 850 and depression 40.
		To give fair conning tower clearance the guns had to be elevated to 350.
		The C.38 type has a cocking toggle above the gun which makes access to the breach easier and so simplifies clearance of stoppages.  The gun has a control lever on the right which permits either single shot or automatic firing.  The following were stated to be the most common stoppages:
	(i)	Breech block jams in breech end of barrel.
		Remedy:  two men jump forward and force the barrel to the rear.
	(ii)	Breech block does not go forward owing to bad maintenance.  Remedy:  oil.
	(iii)	Separated case.  Remedy:  None.
		There was one ready use locker containing seven magazines of 20 rounds each, fitted on the bandstand.

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	(c)  20 mm (.79") Quadruple Mounting.	This mounting had a crew of three; one gunlayer and two loading number.  The controls consisted of two pedal triggers, the left firing pedal controlling the two left guns and the right firing pedal controlling the two right guns.  All barrels could be fired simultaneously.  The gunlayer sat on a seat revolving round with the gun.  A dial on each side indicates the elevation of the gun.  Elevation limits were from slightly over 500 and depression to 90 depression but through an angle to 180 to either side of the fore and aft line, looking forward, the guns had to be elevated to 450 for fire to clear the conning tower.  Training was then possible through 3600.  Elevation was controlled by an elevating wheel on a vertical axis and training by a wheel or a horizontal axis.
		Range was given as 2,000 yards, but it was more usual to wait for range to close to 1,000 yards before opening fire.  The guns were magazine fed, each of the loading numbers loading two guns.  Rate of fire was 60 rounds per minute per. barrel: a total of 240 rounds per minute.  When a magazine was empty it was automatically released.  (N.I.D. Note:  The Automatic release is not in accordance with British practice).  120 boxes of ammunition were carried with 100 rounds in each.  Rounds were in magazines held 40 rounds.  The 40-round magazines were those first loaded on the quadruple gun when surfacing, in order to give adequate time for more magazines to be brought from the lockers while the first burst was being fired.
		Ammunition was both tracer and armour piercing, the tracer being extinguished at 1,500 metres.  There were four ready use lockers, each containing seven magazines in rear of the gun.  On submerging it was necessary to screw down the lids of those lockers, but in an emergency they were all merely closed.
		Armour plating:  The gun had two shields which folded back to lessen water resistance when the U-boat dived.
		Mounting:  The gun was mounted on ball bearings.
		Gun sights:  (See also Section V).  A ring and bead sight was fitted with a target speed bar graduated from 10 metres/second to 200 metres/second.  In the case of U.607 the bar was set at 60 m/second.  (N.I.D. Note:  This would allow for a mean aircraft speed of 135 m.p.h.)

(v)    Torpedoes and Mines:  According to an officer prisoner seven torpedoes and eight T.M.C. mines were carried on the last patrol.  One prisoner said that the mines were to be loaded two to a tube; that two spare torpedoes were stowed on the floor plates in the bow compartment, and probably spare mines in the forward bilges and on bow compartment floor plates.  Upper deck containers had been removed.

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"curly"/. . . .

        "Curly" torpedoes were carried, which traveled a maximum of 6 minutes completing 28 "legs".  Their speed was 30 knots and their rate of advance 6 knots.  Long "legs" were 900 metres and short "legs" 630 metres.  Legs were 60 metres distance apart.  Initial straight run could be set up to 4,000 metres.  (N.I.D. Note:  The accuracy of this information is doubtful.)

        Torpedo tubes:  Four bow; one stern.

        Torpedo pistols:  Pi2, improved type only, carried on last patrol.

(vi)  Bridge Structure:  Before sailing on her last patrol U.607 was fitted with a new type of bridge structure.  This was in three sections.

        The forward section comprised the bridge, the sides and front of which were protected by 2 - 3 cm. (1" - 1.18") thick welded armour plate.

        The steel doors hinged on each side of the conning tower, could be swung back to meet just by the after periscope, affording protection to bridge personnel.  The doors were left open when the U-boat dived.  When shut a space below them allowed for water clearance.

        The centre section comprised the bandstand, which stood about 20" above the level of the bridge.  The bandstand had been widened by about 20" on either side, to facilitate the mounting of the two single 20 mm. guns.

        Port and starboard ladders led down through openings in the bandstand guard rails to a lower bandstand, on which was mounted the 20 mm. quadruple gun.

        Spare barrels for the 20 mm. gun were carried in a store below the lower bandstand, which had an opening on the main deck.  The lower bandstand was protected by guard rails.

        The new bridge structure took about 20 days to fit.

        Two hydrogen bottles about 5 feet high were secured on the port side of the forward section.  Those were for use with R.D.B. (Sec. (xi))  (N.I.D. Note:  Those bottles should not be confused with the acetylene bottles frequently carried for welding purposes.)

(vii)    Propulsion:  (a)  Diesels:  M.A.N.

                            (b)  Motors and Switchboards:  Brown Boveri Company.

(viii)    Radar.  Fitted.  Wavelength was given as 80 cm.  The aerial was of mattress type and was mounted on the port side of the bridge.  It could be raised and lowered by an electric motor in the control room, and when not in use was housed in a slot in the bridge fairing.  Measurements were given as, roughly, 39" x 23" x 8".  A prisoner said that the whole rectangle was covered in wire mesh except at the top, that the diploes were fixed vertically to an unknown number of insulators in the middle and were slightly curved at the top.  When raised, the aerial "box" just cleared the top of the bridge fairing.  It could be revolved by means of a flexible shaft and a hand wheel.  Range was not more than 20 miles.  The apparatus was constantly being damaged when dives to considerable depth were made, and was practically useless.

(ix)    G.S.R.   Fitted.  A Southern Cross type aerial had been removed before the last patrol.  In its place a new drum type aerial had been fitted mounted on a fixed support before the periscope.  It could not be raised or lowered and was permanent.  The aerial itself was slightly higher than the conning tower fairing.  It was described as like a sieve, or a rotating ventilator to be found on the roof of buses or trains.  It had two dipoles, 20 cm (8") high.  Dimensions of aerial were:  Height about 4", diameter about 9".

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(x)  S.B.T./ . . . .

(x)    S.B.T.  This gear had been fitted, but was removed prior to the last patrol.

(xi)    Radar Decoy Balloons ("Aphrodite").

        (N.I.D. Note:  The following description was given by the Captain and another officer of U.607.  Certain details were also provided by a torn instruction found on a prisoner from U.461, sunk on 30th July, 1043).

        (a)  The purpose of R.D.B. is to provide a decoy target for destroyers and aircraft hunting U-boats.  The type ("Aphrodite") described below is intended for use at night, and only floats for 2 hours, so that there is no danger of its being found at daybreak.  The officers disagreed in their opinions as to its value, the abler of the two technically, thinking it silly.

        (b)  The R.D.B. consist of a rubber balloon, which is inflated immediately before use to 650 mm (26") diameter, a float and a 100 foot long connecting wire, to which are attached about four 100 foot long streamers, from which hang metal foil ribbons.  In a moderate wind the streamers are blown sideways, providing a target rectangular in shape.

        Probably 60 uninflated R.D.B. were carried stowed in cases on the deck of the U-boat.  When required for use, the balloon would be inflated with hydrogen  to a diameter of 650 mm. the diameter being gauged against marks painted on the conning tower.  The hydrogen is supplied from 30 litre hydrogen bottles carried outside the conning tower, each capable of inflating about 20 balloons.  (Note:  This refers to R.D.B. with Kapsel II, R.D.B. with Kapel I has an automatic gas generator.)

        The balloon and wire are then allowed to rise, being guided by the left hand, while the float is held in the right hand.  When the wire is all paid out, the float is heaved forcibly over the side.

(xii)    Smoke Screen Apparatus:  An Ordinary Seaman alleged that a container for creating a smoke-screen was carried.  The container was secured on the port side of the bridge next to the gas bottles.  No details were known of the method of operation.

(xiii)    Badge:  Bull of Scapa Flow (7th Flotilla Badge).

(xiv)   Camouflage:  Dark grey paint.

(xv)    Best Diving Time:  About 30 seconds to periscope depth commencing with normal watch on deck.  Rather longer commencing with the full deck complement topsides.

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III.

LAST PATROL OF U.607.

        Survivors stated that the purpose of this patrol was the laying of mines in West Indian waters in company with three other U-boats.  The Captain stated that his orders were to proceed to Kingston, Jamaica.  The other U-boats were proceeding to Haiti, where they were to watch shipping routes for two weeks before laying mines.  One of the four U-boats detailed for this task failed to make rendezvous, having had to put back owing to a structural defect.  All the U-boats had been given explicit instructions that they were not to attack convoys.

        U.607 left St. Nazaire at 0730 on 10th July, 1943, accompanied by a U-boat of the same modified type, commanded by Oberleutnant zur See Fenn.  The U-boats, Fenn leading and Jeschonnek about a cable astern, were preceded by a 4,000 ton sperrbrecher and a UJ-boat on each quarter of U.607.  Sperrbrecher and minesweepers turned back at Buoy 1, which was reached after four and a half hours' steering a general course of 270⁰.  Life jackets had been worn until this buoy was reached.

        Air escort of four Ju.88's should have picked the U-boats up at this position, but only one aircraft arrived.  This approached, fired a recognition signal and made off.

        The two UJ-boats remained in company until nightfall.

        At 2300, U.607 submerged and did not surface until 0700 on 11th July.  At 0800 Radar contacts, believed to be enemy surface vessels, were picked up and U.607 again submerged.  A signal, warning of the presence of British destroyers in the vicinity, had previously been received from C-in-C U-boats.

        U.607 again surfaced at 1400 and charged batteries for three hours.  That evening the third U-boat, commanded by Kapitänleutnant Köppe, joined company, having sailed from La Pallice.  It was then arranged that each boat should be guard boat for twenty-four hours.  Besides keeping W/T watch, the guard boat determined whether or not to dive on the approach of aircraft.  Should it be intended to stay surfaced and fight, the signal agreed upon was a green flag, normally kept for harbour use only, waved in the form of a figure eight.  Intention to dive was to be flashed by lamp.  The three U-boats each kept G.S.R. watch on different wavelengths.

        When surfaced the three U-boats proceeded in line abreast, U.607 being furthest to port.

        At nightfall on this day U.607 again submerged.  She reached 130 feet, her normal cruising depth, but it was decided to continue the dive to 260 feet for exercise.  This was the greatest depth reached on this patrol.

        The 12th July was uneventful.  The three U-boats remained in company, surfaced by day and submerged by night.

        At 0001 on 13th July a bottle of champagne was opened and a toast drunk by the officers in celebration of Oberleutnant zur See Jeschonnek's birthday,

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IV.

SINKING OF U.607.

        At 0755 on 13th July, U.607 had just surfaced and taken up the port position in arrowhead formation, Köppe, guard boat for the day, leading, when a Halifax was sighted astern.  Almost immediately afterwards a Sunderland was sighted ahead.  U.607 turned away from the Halifax in order to present as narrow a target as possible.  This turn increased the distance between her and the other U-boats.

Jeschonnek and his officers were all confident that the combined fire of the three U-boats would drive off the aircraft, and he and the First Lieutenant both lit cigarettes and waited for the aircraft to come within range.  Fire was opened at 1,000 yards and continued until both the single and 20 mm. guns jammed.  The quadruple 20 mm. gun remained in action.

        (N.I.D. Note:  Sunderland N of 228 Squadron reported first sighting the three U-boats in arrowhead formation at 0753, 13th July.  Halifax O of 58 Squadron sighted the U-boats five minutes later.  The two aircraft started to circle the U-boats clockwise, O/58 following N/228 in circuit about 5,800 yards from the enemy.  All three U-boats immediately opened fire at both aircraft from 20 mm guns abaft the conning tower.  The U-boats were taking evasive action, by turning in tight circles at high speed outside the U-boat nearest the aircraft, continually drawing away and turning stern on to the aircraft so that maximum fire power could be brought to bear.

        The two aircraft finally succeeded in getting into touch with each other by flying alongside, and it was agreed that O/58 should fly on reciprocal.  She turned and commenced circling the U-boats in anti-clockwise direction.  The maneuvre was successful in splitting the fire of the U-boat gunners, who slackened off and finally ceased fire after the aircraft had made two more circuits.

        After 40 minutes one U-boat became isolated, and having got some distance from the other two, was compelled to turn back to attempt to rejoin.  This gave N/228 an opportunity of carrying out an attack from an angle fine to its track.  The attack was made immediately from a very low level.

        N/228 went in through heavy fire to drop a stick of seven D/Cs Torpex, 250 lbs., 25 feet setting, 60 feet spacing, released from 50 feet, fine from the stern (port quarter to starboard bow.  It was estimated that three D/Cs fell close to the port side aft, one of the conning tower and three close to the starboard side forward.  The pilot had to jink the aircraft over the conning tower after release.  The tail gunner and at least one other of the crew saw the conning tower blown into the air.  A large portion of the bow went forward, stood on end, went over the vertical and slid into the sea.  The remainder of the U-boat rocked violently, capsized and sank.  Large pieces of wreckage and some 25 survivors were seen in the sea.  N/228 dropped a dinghy and later saw that 6 men had clambered into it.

        Prisoners said that they had had no intention of diving before this attack was made.  They ascribed their sinking to the fact that they were deserted by their two companion U-boats, who submerged under cover of U.607's fire.  This had never been intended.  The diving signal, if it was given, never reached U.607.

        One prisoner said that they felt capable of dealing with the two aircraft had they not flown on reciprocal courses.  When the final attack was made, fire from the Sunderland pierced the shields of the quadruple 20 mm gun and killed the gun's crew.  Immediately afterwards the D/Cs were dropped so accurately that the U-boat broke her back.

        The distribution of the men on deck when the vessel was sunk was as follows:  three men on the quadruple 20 mm. and one supply number; two men on each side of the single 20 mm. guns and one supply number for both; the gunnery officer (Leutnant zur See Gassauer); one hand to clear empty cartridge cases; two hands to hoist ammunition from below decks; one

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port/ . . .

port look-out; one starboard look-out; the Captain; the First and Third Lieutenants and the coxswain.  A number of these men are known to have been killed.  It was thought that only a small number of men succeeded in escaping from inside the U-boat.  None of the men thrown into the water were wearing life jackets and many speedily drowned.  A yellow raft was dropped by the Sunderland near the main group of survivors and seven men managed to clamber into it.  Of these seven men, four were officers.

        The party drifted in the raft throughout the day.  The sun was shining fiercely and the men began to suffer from sunburn aggravated by superficial burns from ignited Diesel oil.  British aircraft were continually flying over the position.  Towards noon vessels of the second Support Group were sighted and these passed close by the raft without stopping.

        (N.I.D. Note:  Captain (D) Second Support Group reported that he reached the scene of the sinking at 1143 on 13th July.  He continued: "By this time there were four aircraft flying round the position, and a considerable amount of oil was seen on the surface as well as seven disconsolate Huns squatting in a rubber dinghy.  With the prospect of a kill in front of me, I could not spare a ship to pick them up and perforce left them to a contemplation of nature while the hunt was on.")

        Towards evening the dejected party sighted five Ju.88 aircraft flying in formation at a height of some 10,000 feet.  These aircraft passed over the dinghy apparently unaware of its existence.  No other incident occurred until rescue.

        (N.I.D. Note:  H.M.S. WREN reported that, returning to the area in the early hours of 14th July, the raft was sighted in position 44.50N : 008.50W, at 0400 Zone Time.  A whaler was lowered and when it had approached the raft the survivors were asked for the number of their U-boat.  This they refused.  The whaler immediately put about and the Germans were told "No number, no rescue".  This speedily decided the Captain to divulge the number and he called the whaler back.  The party was pickled up at 0405.)

v. / . . .

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V.

GENERAL REMARKS ON U-BOATS.

(i)    Electric "Curly" Acoustically directed Torpedoes.

        The Second Lieutenant said that the latest German torpedo development was an Electric "Curly" acoustically directed torpedo, which was only fired from the stern tube.  The torpedo had to be set for a straight initial run but when this limit was reached it began to turn on a "curly" course until the target came within its acoustic field, when it at once altered course towards the noise.  The shortest initial straight run which could be set with safety was 700 meters (765 yards); otherwise the initial run could be set at any distance up to 3000 metres (3280 yards).

        The torpedo was fitted with a contact pistol and the acoustic apparatus was fitted on its top side.

        It was said to be ideal for firing at pursuing destroyers.  A great advantage was that being an electric torpedo it could be used  during the day while the normal "curly" torpedoes, being air propelled, were best used at night.

        It was said that a U-boat commanded by Oberleutnant zur See Trojer had used these torpedoes with success.

        (N.I.D. Note:  The combination of "curly" and acoustic gear in the same individual torpedo is unexpected and not at present established.)

(ii)    Ultra-violet Searchlights.

        The Second Lieutenant stated that U-boats of the 3rd Flotilla at La Pallice had been fitted with ultra-violet searchlights to protect them from air attacks.  The rays of this searchlight were invisible but any object caught within them was visible to the operator should he wear special glasses.  Should an aircraft attempt to locate a U-boat at night and be caught by the searchlight the pilot would not know he had been observed unless he himself was wearing the same glasses.  The glasses might, in addition, be telescopic.  Trials with this searchlight were in charge of Korvettenkapitän Zapp, S.O. of the 3rd Flotilla at La Pallice.

        (N.I.D. Note:  This might well be an infra-red searchlight.  Such confusion is not uncommon in prisoner's statements.)

(iii)    New U-boat types.

        (a)  U-boats with turbine propulsion.  The Second Lieutenant said that Blohm and Voss had completed six U-boats which had no electric motors.  They were known as type VII/42 and they were numbered from U.1060 upwards.  Trials with this type had been going on for two and a half years at Hel Peninsular in the Baltic and the present captain of the experimental boat was said to be Korvettenkapitän Otto Schuhart.

        The fuel used was liquid air and oil and the engines were turbines.  The U-boats were said to be faster underwater than on the surface and they were able to dive at phenomenal speed.  The 2nd Lt. said that he had seen one of these U-boats on trial in the Baltic.  It was about 500 tons and was faster than his own U-boat.  It had been impossible for him or any of his fellow officers to board the U-boat.  He had heard that it had a thicker pressure hull than the usual.  He understood that it carried an apparatus which extracted oxygen from the air, converted it into liquid oxygen and stored it.

        (N.I.D. Note:  There is no confirmation from other sources that liquid air has been employed for propulsion in submarines.)

        (b)  U-boats with double pressure hulls.  The Second Lieutenant also stated that a series of U-boats starting with U.851 was being built with double pressure hulls.  The space between the two pressure hulls formed fuel tanks.  This type was reputed to be able to dive to an extreme depth.  He claimed that this type of U-boat was fitted with 6 E-boat type V 20 Diesel

engines/ . . .

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engines.  They could run on two, four, or all six engines.  They were capable of a speed of 24 knots.  (N.I.D. Note:  Prisoners have previously stated that E-boat engines have been fitted in U-boats.  Owing to maintenance difficulty it is thought that this type of installation is improbable.)

        (c)  Torpedo Supply U-boats.  This type may be the same as (b).  Described as of about 1000 tons.  Has double pressure hull and the latest W/T and electrical equipment including G.S.R. capable of picking up the shortest wavelengths and possibly W I M Gerät.  She had torpedo tubes and carried between 30 and 40 torpedoes in a special Torpedo compartment.  The main use of this type was to act as a torpedo supply vessel for other U-boats (N.I.D. Note:  W I M is the German technical listening service, observing very high frequency transmission, such as Radar.  It controls certain jammers in addition.  It is not clear what is meant by W I M apparatus by this prisoner.)

(iv)    Torpedo Pistols:

        The Second Lieutenant said that he had heard of a new pistol about 3 feet long, which was shortly to be issued.  There was a small battery in the pistol.  It had already been on trial in the Mediterranean.  It was affected in some way by the ship's iron, but the de-gaussing of a ship would not prevent its explosion.

        The pistol could be set for magnetic-contact, or for contact alone, but not for magnetic alone.  It was known as M.Z. which stood for Magnetzündung (Magnetic firing).  All the torpedoes so fitted were air torpedoes.  The captain said that the ship's field did not affect the working of the pistol.  (N.I.D. Note:  The pistol referred to is probably the PI,2, which has certainly been used in electric torpedoes and probably in them only.)

(v)    "Curly" Torpedoes:  (See C.B. 04051 (64) Page 9).

        Referring to "Curly" torpedoes the Second Lieutenant said that when attacking convoys a fan of four "curlies" could be fired each with a different initial straight run setting.  In this manner a larger area of sea could be covered.  He added that U-boat officers were being sent when possible to Flensburg to attend eight day courses in "Curly" torpedoes.  Few officers took the course seriously and it was the general practice to arrive three days late, spend three days in attendance and then proceed on leave.

(vi)    New Anti-Aircraft Tactics:

        Survivors including the Captain and other officers gave their views on Germany's new U-boat A/A defences.

        At present U-boats are at a disadvantage against any aircraft attacking from dead ahead or on the bows so long as the aircraft can keep within 15 degrees up track on either bow.  Consequently a U-boat Captain always tries to bring his main armament to bear.  This means keeping his stern towards the aircraft, a maneuvre which has the advantage of presenting the smallest possible target.  In addition, U-boats are able to change direction in tighter turns than aircraft and so are felt to increase the difficulties of the bomb-aimer.

        The Captain was confident that the policy of sending U-boats through the Bay of Biscay in numbers sufficient to provide intense covering fire would be maintained.  He felt that the ultimate success of this policy would depend on whether the G.A.F. could afford to give U-boats adequate air protection.  At present he considered three passages in and out of the Bay as worth a Ritterkreuz.  Because of the policy of staying surfaced through the Bay, casualties among the guns' crews and bridge watches had become heavy, it had therefore been decided to add medical officer to the complement of as many U-boats as possible.  A Surgeon Lieutenant was carried by U.607.  The Bay of Biscay crisis area is now considered to extend to 19⁰W.

(vii)    Moral effect of the new U-boat A/A armament and future plans.

        It was suggested that the effect of the new armament has been to induce new confidence into U-boat Captains, and to a lesser extent, into

ship's/ . . .

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ship's companies.  Reports of the shooting down of aircraft receive the widest circulation.  Losses of U-boats are unlikely to become known outside of individual Flotillas.  Prisoners defended their comparative lack of success of the new armament with the plea that countermeasures to A/S aircraft have been hurried and will improve.

        Improvements anticipated by prisoners are:

        i)  Some form of automatic or computer sights

        ii)  Larger caliber guns of the pom-pom type

        iii)  Some type of F.A.C.

        iv)  A combination of all three of the above was expected.

        Prisoners also thought that the mounting of some quick firing A/A armament forward of the conning tower was planned to cope with the most feared form of attack.

(viii)    37 mm (1.46") gun.

        One prisoner who claimed detailed knowledge of this gun, although it was not fitted in U.607, gave the following information:

(a)  Loading.	Whereas the 37mm gun (land) is fed with five shot clips, the 37 mm (naval) fires only single shot.
(b)  Crew.	One layer, one trainer and one loading number.  Theoretically an extra number who acts as assistant loading number.
(c)  Recoil.	A very heavy one of about 330 lbs. checked by a spring.
(d)  Elevation and Training Limits:	Elevation 850, depression 90.  Training through 3600.
(e)  Range.	Theoretically 3,000 yards.  In practice 2,500 yards.
(f)  Weight of projectile.	2-1/2 lbs.
(g)  Ammunition.	A.P. or incendiary ammunition was fired in daytime.  A.P. tracer was used at night.  A new phosphorus incendiary shell was also mentioned; contact fuse, self destroying at about 3000 metres (3280 yards).
(h)  Gun sights.	Fitted with a pressure tight gun sight.  This consists of a box 12" high x 8" long x 4" deep with six ring sights probably on a strip of plexiglas, allowing for aim-off speeds of 50, 100, 200, 250, and 300 metres/second.  The appropriate ring sight will appear in an aperture on the left as selected by rotating a small wheel on the right.
(i)  Twin 37 mm. (1.46") gun.	The policy as to fitting of 37 mm. guns in 500 tonners is still undecided.  A number of twin 37 mm guns were said to be lying in the stores at St. Nazaire pending possible mounting.

(ix)    20 mm (.79") Quadruple gun Mounting.  (See also Section II)

        (a)  A specialist A/A gunner said that although the target speed bar was graduated from 10 to 200 metres/second and was normally set at 60 metres/second (135 m.p.h.) gunners still had to place the target in the correct place relative to the ring.  An aircraft approaching at a speed of say 180 m.p.h. would be placed a little over half way between the smaller and larger ring sight as the gunner began to fire.  (N.I.D. Note:  This seems similar to current eye shooting practice.)

(b)/ . . .

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        (b)  Discipline.  In theory range was estimated by the U-boat Captain or Officer of the Watch who then ordered open or cease fire as he thought fit.  In practice many guns crews fired independently once the initial open fire order had been given.  Range estimation was more or less guess work and no effort was made to estimate range by wingspan in relation to ring sight, or any similar method.

(x)    Closing up at the A/A/ guns.

        The O.O.W. manned the starboard M.G.81 and the Leading Hand the other.  Three other men on watch manned and cleared away the quadruple 20 mm gun.  Two ratings from the Watch below closed up at the 20 mm guns on the bandstand.  When surfaced at night one of the three after look-outs permanently manned the gunlayer's seat at the quadruple 20 mm gun.

(xi)    Specially-trained A/A gunners carried in U-boats.

      &nbs